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In Reply to: RE: Best Mid-Bass of All Times! posted by Belgarchi on July 11, 2012 at 05:32:40
Hi,You may wish to peruse the attachment.
There are a number of non-linearities in speaker drivers that are fundamental.
All else being equal having a lower excursion for a given SPL (meaning a large cone/diaphragm surface) lowers one group of these non-linearities and lower signal (current) for a given SPL lowers the other group.
So, given identical LF extension the driver with the larger diaphragm and higher efficiency will generally have lower distortion, given competent design and correct assembly of both.
As for the Scan Speak Revelator, they are quite commonly covered in the German DIY Speaker press. If you looked you would find that the 5" Revelator produces over 10% Distortion (Harmonic) for 95dB/1m/100Hz.
Hardly state of the art or low distortion.
No-one seems to have thermal compression data, but looking at voice coil and magnet assembly I would be very surprised if it was less than 4dB at rated power and 2.5dB at halve power (which equates to 95dB/1m). Combined with the very low efficiency you almost certain to run into thermal compression.
If we take (for lack of data for the JBL D130) the JBL 2226 as Benchmark (this in copies and original) as it is a readily available modern 15" "Midbass", we find that it offers less than 1dB compression and less than 1% Distortion (100Hz) for 112dB/1m and much less for 95dB/1m!
So I cannot for the life of me see what recommends the Scan Speak as acceptable "HiFi" Driver, given it's gross distortion and compression.
Of course, I find some people actually prefer severely distorted and compressed music to the real thing... So if that is your goal theScan Speak "Revelator" may indeed be just what is wanted.
So if you like it, enjoy it...
But before you decide to declare it the "Best Mid-Bass of All Times!" you should at least make sure you have a foggy notion what else is out there that may aspire to the title...
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Edits: 07/11/12Follow Ups:
It is not fair to compare only the reproduction of low frequencies of a ~11 liters enclosure with the huge enclosure required by a 15" drivers, and ignore the extension, directivity and distortion in the medium range.
What I was trying to say is that the Scan Speak 8530K-00 is among the best - if not THE best - driver to reproduce low frequencies using an enclosure of 11 liters or less AND is among the best drivers in the mid-high frequencies, and exceptional combination.
Anyway, thanks for the interesting information you wrote.
Yves
Hi,> It is not fair to compare only the reproduction of low frequencies
> of a ~11 liters enclosure with the huge enclosure required by a
> 15" drivers,You set the field of comparison. You wrote: "Best Mid-Bass of All Times!"
So I countered with one produced first in 1948 that is WAY BETTER.
Now if you had claimed "Best 5" Mid-Bass of All Times!" you may still have had a fight on your hands, but your contention would have stood a chance, as the 5" Revelator is not a very bad 5" driver.
> and ignore the extension, directivity and distortion in the medium
> range.Neither extension, nor directivity (5"Drivers have awefullly crap directivity forcing extensive room treatment to deal with their lack of directivity) or indeed distortion have been ignored. In fact, you may find even a waterfall/CSD will not make the SS Rev look that good.
Most decent 15" Midwoofers can run rings around the SS Rev several times in all parameters.
> What I was trying to say is that the Scan Speak 8530K-00 is among
> the best - if not THE best - driver to reproduce low frequencies
> using an enclosure of 11 liters or lessBut what you instead said was: "Best Mid-Bass of All Times!"
You should have written: "Best 5" Mid-Bass to be used in 11 Liter boxes of All Times!".
BTW, you would still be off track, but that is another story.
> AND is among the best drivers in the mid-high frequencies, and
> exceptional combination.Based on what I hear it delivers generic low end HiFi sound, I may even be happier with an original LS 3/5 pair using KEF B110, which means not very happy at all.
But THAT is my personal opinion. From someone who considers a hornloaded 12" Driver "a jolly decent lower midrange system"...
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Edits: 07/11/12
Large woofers require 3+ ways.
The exceptional bandwidth of the Scan Speak 8530K-00 (6 to 7 octaves) allows to make an excellent 2-ways speaker.
Hi,
> Large woofers require 3+ ways.
They do not.
Over the years I have used a wide range of 12" to 15" 2-Ways as both studio monitors (JBL 4430, Urei 811/812/813, Tannoy 15" Monitor, Schulze/RFT TH315 to name some) for recording music and producing and at home.
Emphatically, you do not need to be 3-Way at least up to 15" Woofers and in principle I cannot see why it would even be needed with an 18"Woofer.
The D130 I mentioned is good to well past 6KHz!
Back in the 80's we used the later E130 with a short 100Hz rear Horn and either Piezo Tweeters or Bullets. These systems needed a touch or EQ (not a lot) and managed > 105dB/W/1m with 1 Watt, 100Hz to ultrasonic.
I occasionally also had these cab's at home with a ridiculous amount of LF EQ to get the sub 100Hz bass up. They did very well as a home HiFi system that way.
That is a 15" Woofer with around 5KHz crossover in a 2-Way...
> The exceptional bandwidth of the Scan Speak 8530K-00 (6 to 7 octaves)
Is very unexceptional. Unless you limit yourself to this kind of toys.
Even then, there is better in this very genre. Look at the "Midrange" in my current 3-Way Speakers. It has lower distortion than the Scan, better LF power handling and better efficiency, plus it covers 8.5 (appx.) octaves.
Of course, I only use it as midrange above 300Hz, as I like something a bit bigger for bass.
I'll probably soon switch over to a speaker with that horn loaded ribbon (see below) and a 15" Woofer (2-way of course), I have an eye on the Beyma 15B100 as woofer BTW, or an old Eminence Omega Pro 15...
> allows to make an excellent 2-ways speaker.
So do most 15" Midwoofers, so what?
Have a look at the Meyer X-10 Studio Monitor to get an idea what this principle actually is capable of.
BTW, I recently found a Magnetic Planar with horn which allows 600Hz crossover.
I suspect this would make a nice "extremist" 2-Way with some of the recent 21" to 24" Woofers. It would likely be fun to compare such a 2-way system with your scan speak 2-way.
Well, maybe not fun for you.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
That is a 15" Woofer with around 5KHz crossover in a 2-Way...
an interestingly shaped directivity vs. frequency pattern.
Hi,
> an interestingly shaped directivity vs. frequency pattern.
Did you measure it?
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
your 15" driver exhibits the same directivity at say 500 hz (27 inch wavelength) as it does at 5 kHz (2.7 inch wavelength)?
Hi,> your 15" driver exhibits the same directivity at say 500 hz
> (27 inch wavelength) as it does at 5 kHz (2.7 inch wavelength)?No.
The SPECIFIC 15" Driver (JBL D130) referred to has a smoothly increasing directivity with frequency and it will have a good match in directivity at the top of it's range with the recommended (very narrow directivity) tweeter.
This has some interesting results.
First, the systems "on axis" response will be flat (depending on EQ and crossover of course).
Second, the off axis response will be significantly attenuated above a few 100Hz, ultimately forming in the midrange and up to ultrasonic frequencies a CONSTANT DIRECTIVITY system.
Arguably, the dispersion angle in the midrange and up will be very limited (around 40 degrees).
This has many distinct advantages for single seat "serious listening" (by significantly reducing the amount of room effects compared to wide dispersion systems, so room treatment needs to be MUCH LESS) and can provide significantly more of the original recordings acoustics than wide dispersion systems (I tend to refer to these as "reverb effects"), but is not very conductive to background music production that produces a diffuse sound-field all across a room (buy Bose 901 or Omni's if that is what you want).
So depending on specific personal requirements the D130 & 075 2-Way crossed over at several KHz may be the best speaker possible or a shut in and boring sounding antique.
The point I was making actually was that one needs to understand all aspects of a given acoustic system and consider them, plus the given target situation and then apply accordingly.
There are good reasons for both very narrow directivity systems, omnidirectional systems and even for speakers that produce eight times more reverb effects than they reproduce the actual recording.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Edits: 07/12/12
(eyeroll)
For those not familiar with the 075 JBL "bullet" tweeter - it is an antique that dates back to 1957!No doubt, you're probably thinking - "what putz is bringing up a 55 year old loudspeaker transducer in the context of THE BEST MIDBASS EVER thread?"
Well that would be self proclaimed JBL /constant directivity expert - Thorsten...
If you've never heard a JBL D130 or 075, I can tell you from personal experience, they're not for high performance home sound. They aren't even considered high fidelity in today's pro market when compared to the 2200 series of woofers and 2400 series of compression drivers. The D130 worked fine in venues like the Grateful Dead's "wall of sound". In that application, directivity and controlled off axis response were not major concerns. Similarly, the 075 tweeter functioned reasonably well for the intended purpose.
But everything Thorsten has said in this thread about these drivers has been way off the mark. The 075 bullet was intended to be crossed down around 2.5khz - no where near the 6khz upper limit of the D130.
http://www.lansingheritage.org/images/jbl/specs/home-comp/075/page1.jpg
For those interested in taking a trip down memory lane, Audioheritage.org has a few threads dedicated to these drivers. For the most part, the knowledgeable experienced users of these drivers have commented that they were good for their day in a "Victrola" kinda way. If a Victrola is high fidelity to you - God Bless You. I suspect it isn't for most of the people that visit this website - except Thorsten, of course...
Edit:In looking above at some of the rambling stupidity posted by Thorsten, I noticed a glaring error that could probably confuse some of the less experienced people who might come upon this wacky thread. In the interest of avoiding widespread misinformation, I'll add another correction here.
Constant directivity in the context of high performance loudspeakers implies that the flat frequency response expected on axis is largely duplicated as one steps further and further off axis horizontally from the speaker. Textbook constant directivity loudspeakers will show a gradual attenuation of response with increasing off axis angle. So for example, at 30 degrees off axis, the response will be essentially flat from the lowest frequency to around 10 or 12khz - but it will be consistently down 2 or 3 db from the on axis response. As one goes further off axis to 60 degrees, it might approach 5 or 6 db of attenuation up to around 10 or 12 khz. The Revel Ultima Salon 2 and Klipsch Palladium P-17B are a couple of decent examples of speakers exhibiting constant directivity.
Look at figure 5 here:
http://www.stereophile.com/content/klipsch-palladium-p-17b-loudspeaker-measurements
and figure 6 here:
http://www.stereophile.com/content/revel-ultima-salon2-loudspeaker-measurements
Notice the slight downward tilt in response as you traverse the frequency spectrum. Also notice the roughly parallel nature of each line as you compare the successive off axis incremental plots.
Now compare those responses to figure 5 of the Tannoy TD12 which crosses its 12 inch driver over at only 1.3khz:
http://www.stereophile.com/content/tannoy-dimension-td12-loudspeaker-measurements
Notice the degree of parallelism that exists between 300hz and 1300hz between the on axis response and the 60 degree response. Compare that - over such a limited range - to the same degree of parallelism exhibited by the Revel Salon. The major departure from parallelism for the Tannoy is only happening in a narrow frequency span. If this driver were operated up to 5khz, the difference in slopes would be dramatic.
Thorsten's statement here:" the off axis response will be significantly attenuated above a few 100Hz, ultimately forming in the midrange and up to ultrasonic frequencies a CONSTANT DIRECTIVITY system."
is where the train runs completely off the tracks. If you look at the last two figures that describe the behavior of the later version of the 075 bullet tweeter here:
http://www.jblpro.com/pub/obsolete/2402.pdf
you'll see a nearly 15 db drop off from 2.5khz to 5khz in response at 60 degrees off axis but at 30 degrees off axis, the 2.5khz response value is virtually indistinguishable from the 5 khz value. This is a text book example of a driver that is NOT exhibiting constant directivity.
Constant directivity means the speaker's response level will be consistent at a given off axis angle as the frequency spectrum is traversed. Directiviy or the directivity index itself is defined as the portion of a total acoustic radiation that is being radiated in a particular direction. If a speaker possesses constant directivity, the portion of total acoustic power radiated in a particular direction needs to remain essentially constant with frequency. It doesn't mean that off axis response stays constant regardless of off axis angle. To have constant directivity, you have to see response lines from 10 degrees to 60 degrees that are essentially parallel to one another. All the response lines can can tilt downward together somewhat - a sign that output overall may be dropping with frequency - but if they aren't parallel, it signifies that the response is not exhibiting constant directivity. Clearly, from the polar plot of the 2402 (later 075 tweeter), the response lines cannot be remotely parallel and thus it cannot exhibit constant directivity. The slope of the response line from 2.5khz to 5khz at 20 degrees will be essentially flat while the line from 2.5khz to 5khz at 60 degrees will have a severe slope starting at the same point at 2.5khz but ending up 15 db down at 5khz. Hence Thorsten's characterization of the system as constant directivity is way off the mark.
Edits: 07/12/12 07/12/12
Hi,
> For those not familiar with the 075 JBL "bullet" tweeter - it is
> an antique that dates back to 1957!
Yes. And the D130 is an antique that dates back to 1948, as I repeatedly pointed out.
> No doubt, you're probably thinking - "what putz is bringing up a
> 55 year old loudspeaker transducer in the context of THE BEST
> MIDBASS EVER thread?"
As the requirement for time was "EVER" and as the D130 CORRECTLY APPLIED is quite exceptional in terms of low distortion and low compression, surely it qualifies.
BTW, I have been trying to ignore your repeated insults, but they get tiring and moreover reflect more on you than on me.
> If you've never heard a JBL D130 or 075, I can tell you from
> personal experience, they're not for high performance home sound.
I am unsure what you have heard, it would be useful if you where more specific.
> They aren't even considered high fidelity in today's pro market when
> compared to the 2200 series of woofers and 2400 series of compression
> drivers.
In the Pro Market the D130 would be hopelessly underpowered, however that does not make it low fidelity per se.
> The D130 worked fine in venues like the Grateful Dead's "wall of sound".
> In that application, directivity and controlled off axis response were
> not major concerns. Similarly, the 075 tweeter functioned reasonably
> well for the intended purpose.
You may be mistaken. If you look at the WOS you would notice that unless the drivers had very narrow "controlled directivity" the whole system would not work well as there would massive cancellation issues. And the guys who designed the WAS did know what they where doing.
> But everything Thorsten has said in this thread about these drivers
> has been way off the mark. The 075 bullet was intended to be crossed
> down around 2.5khz - no where near the 6khz upper limit of the D130.
Has it been? I did remark that the COMMON crossover for the D130 and later versions was around 2.5KHz however a higher crossover could be used and in fact I have done so, in sound reinforcement applications and quite successfully (hence I also noted the requirement to EQ out the upper midrange boost present in the frequency response of the D130).
> In looking above at some of the rambling stupidity posted by Thorsten, I > noticed a glaring error that could probably confuse some of the less
> experienced people who might come upon this wacky thread. In the
> interest of avoiding widespread misinformation, I'll add another
> correction here.
Before you correct you should perhaps read what others write
> Constant directivity in the context of high performance loudspeakers
> implies that the flat frequency response expected on axis is largely
> duplicated as one steps further and further off axis horizontally
> from the speaker. Textbook constant directivity loudspeakers will
> show a gradual attenuation of response with increasing off axis angle.
Correct.
> So for example, at 30 degrees off axis, the response will be
> essentially flat from the lowest frequency to around 10 or 12khz
> - but it will be consistently down 2 or 3 db from the on axis response.
This you can only find if you employ dipole or cardioid bass systems, with monopole bass or full size (not foreshortened and reduced mouth size) Bass horns you invariably have a directivity index of 0dB at low frequencies as the sound radiated will "bend around" the edges of the enclosure.
This gives to the so-called "baffle step" in the anechoic on axis response, which is actually an indication of changing directivity (not of frequency response changes per se). Above that "baffle step" the the directivity indexwill be around 6dB up to where drivers/horns etc. display a greater DI which then dominate the speakers behaviour independent of any Baffle etc.
So with real "constant directivity" speakers such usually is only possible at higher frequencies. A good example are the Speaker Systems designed by Earl Geddes which are generally accepted as "constant directivity" yet still have 0dB DI at lkow frequencies.
The second issue we need to look is exactly how much the SPL will be attenuated at a given off axis position in the frequency region of the speaker that conforms to constant directivity.
Is that 3dB down at 30 Degrees as you seem to suggest it should be?
Well, realistically it depends on the intended beamwith of the design.
If I for example design a speaker with a 40 Degree horizontal beamwidth than at 30 Degrees off axis I would expect a much greater attenuation, meanwhile if I where designing a speaker with a 120 Degree beamwidth I would be greatly disturmed if I measured a 3dB attenuation.
> As one goes further off axis to 60 degrees, it might approach
> 5 or 6 db of attenuation up to around 10 or 12 khz. The Revel
> Ultima Salon 2 and Klipsch Palladium P-17B are a couple of
> decent examples of speakers exhibiting constant directivity.
They expect a certsain particular directivity behaviour, however they are not as such indicative of the specific performance a constant directivity speaker will have, this (as remarked above) will depend heavily on the designed beamwidth.
> The major departure from parallelism for the Tannoy is only happening
> in a narrow frequency span. If this driver were operated up to 5khz,
> the difference in slopes would be dramatic.
BUT I was not recommending to operate this driver from Tannoy up to 5KHz was I now.
> " the off axis response will be significantly attenuated above a few
> 100Hz, ultimately forming in the midrange and up to ultrasonic
> frequencies a CONSTANT DIRECTIVITY system."
> you'll see a nearly 15 db drop off from 2.5khz to 5khz in response
> at 60 degrees off axis but at 30 degrees off axis, the 2.5khz response
> value is virtually indistinguishable from the 5 khz value. This is a
> text book example of a driver that is NOT exhibiting constant
> directivity.
Actually, as I suggested a 5KHz crossover (for a good reason BTW), let us look what is happening at 5KHz, shall we?
At 30 Degrees we have the -6dB point at 5KHz. For 10KHz the -6dB point is at around 22 degrees.
Now what is -6dB angle at 5KHz for a JBL D130? Well, it is basically that of a 4" Shallow Dome. As anyone who ever took some acoustics will know, this gives at 5KHz around 60 Degrees beamwidth, or in other words a -6dB angle of 30 degrees.
Holy Grass Mud Horse! The "Bass Midrange" driver and the "Tweeter have exactly the SAME beamwidth at 5KHz. Maybe this important? Nah, WTFDIK... Of course, we still have to deal with non-flat on axis (and off axis) response of the D1`30, it cannot be operated just "open", but needs a suitable LCR Equaliser to flatten up the boosted upper midrange.
As to directivity further down in the frequency response, at lower frequencies progressively more of the cone surface of the D130 comes into play (as is usual for wideband drivers that operate in effect in bending wave mode) for a 15" piston the frequency where the beamwidth is 60 degrees is at around 1.5KHz.
Se we have a system that will have a pretty constant beamwidth from around 1.5KHz to beyond 5KHz and has declined only to 45 degrees or so at 10KHz. The 30 degree off axis response will be reasonably flat from 1.5KHz to around 7KHz with a little rolloff at 10KHz and mean level that is 6dB down on the on-axis response.
I tend to consider such a behaviour a good indication of the presence "constant directivity". I measures this stuff BTW back in the 1980's in the anechoic chamber of the RFZ in Berlin, using B&K gear.
So I see you completely validated my 5KHz recommendation with your analysis of what WOULD HAPPEN IF we used the original 2.4KHz crossover... I'd thank you, but I think you are a rude and insulting little so and so, so I will leave it here.
Ciao T
PS, if you do not know the formula to calculate beamwidth vs. piston size look it up in a good beginners text on acoustics and if you doubt my point of the 4" near piston for the D130 at 5KHz look at the datasheet.
If you feel the need to further expose your ignorance, please feel free, I have a big can of "whoop-ass" with your name on it here...
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
There is way too much incoherent babbling by Thorsten above to correct point by point. So I will reiterate and re emphasize the main underlying problem as it seems Thorsten is intent on spreading his confusion to others. Thorsten doesn't know constant directivity from the tip of his nose. A given loudspeaker's beamwidth or radiation pattern cannot vary all over the place as it does with the D130 and 075 JBL and produce a constant directivity result. As the name implies, "constant" directivity means that as frequency increases across a loudspeaker's operating spectrum, the portion of radiated sound in a given direction remains essentially CONSTANT. A cursory look at the graphs I posted demonstrate clearly that the drivers in question are not capable of constant directivity - particularly over the frequency bands Thorsten was suggesting for them. Thorsen saying the 075 bullet tweeter maintains constant directivity is a clear indication that he doesn't have a clue what he's talking about. Over a +/- 20 degree window, practically every driver in existence will appear to have constant directivity. True constant directivity implies uniform radiation pattern with frequency over a wider angle - a design objective for high fidelity in a near field listening environment. Toole, who essentially wrote the book on directivity of loudspeakers, makes it pretty clear in his papers that response off axis to about 60 degrees needs to be a carbon copy of the on axis response (excepting a minor uniform level of attenuation with each increase in off axis angle). If the reader of this thread has any doubts, the Revel Ultima Salon 2 (a product design inspired in part by Toole) I linked to earlier possesses a directivity plot that is TEXTBOOK constant directivity. The response plots of the JBL D130 operated wide band and the 075 bullet tweeter responses look nothing like this. Neither do the plots of the Tannoy 12 inch two way referenced by Thorsten. Compare the plots of these speakers and you will get a better understanding of what constant directivity means and why constant beamwidth only suggests constant directivity when it occurs over a relatively wide listening angle. Forty degrees listening angle is clearly not in the same ballpark as 120 degrees. It might be in Thorsten's warped, myopic world view but not where real loudspeaker designers are concerned. Thorsten, given that every successive post of yours on this subject has provided further evidence of your ignorance on the subject, it might be wise for you to stick with electrical fuse design.
(ROFLMAO)
Hi,
> There is way too much incoherent babbling by Thorsten above to
> correct point by point.
It is all entierly coherent and consistent.
> So I will reiterate and re emphasize the main underlying problem
> as it seems Thorsten is intent on spreading his confusion to others.
It is not I who is confused.
> Thorsten doesn't know constant directivity from the tip of his nose.
Really?
> A given loudspeaker's beamwidth or radiation pattern cannot vary all
> over the place as it does with the D130 and 075 JBL and produce a
> constant directivity result.
As I pointed out, if operated correctly the beamwidth/radiation is quite constant in the range above 1KHz. Getting constant directivity below 1KHz requires either large waveguides/horns or dipoles/cardioids.
Neverthess such systems which are strictly speaking only "controlled directivity at higher frequencies are commonly sold as such.
> As the name implies, "constant" directivity means that as frequency
> increases across a loudspeaker's operating spectrum, the portion of
> radiated sound in a given direction remains essentially CONSTANT.
Yip, as I pointed out, if you use the D130 & 075 correctly this dictum is held from around 1Khz to 7KHz with a mild rolloff at higher frequencies.
You suggested earlier that "The Revel Ultima Salon 2 and Klipsch Palladium P-17B are a couple of decent examples of speakers exhibiting constant directivity."
The Salon 2 shows an interesting pattern where up to around 1KHz there is no directivity control whatsoever while above 1KHz it shows a smoothly increasing directivity with frequency.
So you seem to be making things up as you go along, as clearly one of your two statements is untrue....
In fact, I would suggest that the system made up from D130 & 075 hews closer to the textbook definition than the examples you cited, though any of them are not "constant directivity" below around 1KHz.
> A cursory look at the graphs I posted
You seem confused. You posted no graphs. You posted a link to a datasheet for the 2402 (which I agree has the same general radiation pattern as the 075).
You posted nothing for the D130 as nothing exists.
Using conventional acoustics we can however estimate the off axis behaviour of the D130. When you combine this with the data on the 2402 you get a system where above 1.5KHz and up to 7KHz with a constant beamwidth (or constant directivity which is another way of saying the same thing) and a gently narrowing beam angle above and a widening beam angle below.
> demonstrate clearly that the drivers in question are not capable of
> constant directivity - particularly over the frequency bands Thorsten
> was suggesting for them.
First, you have no data on the D130 and you have shown yourself ignorant of basic laws/computations common in acoustics.
I am pointing out that the -6dB Beamwidth of the D130 is appx. 60 degrees from around 1.5KHz to 5KHz and that the 075 has a beamwidth of 60 degrees at 5KHz.
As a result both drivers have matching beamwidth at the crossover point I suggested (we used a 3rd order HPF on the tweeter BTW) and as a system you have pretty constant directivity at frequencies above 1KHz, which in the reality of making speakers is pretty good.
> Thorsen saying the 075 bullet tweeter maintains constant directivity
You need to read again what I wrote, before you claim things I never wrote.
> is a clear indication that he doesn't have a clue what he's talking
Really. Interesting.
> about. Over a +/- 20 degree window, practically every driver in
> existence will appear to have constant directivity. True constant
> directivity implies uniform radiation pattern with frequency over
> a wider angle
If the designed beam-width happens to be 40 Degrees than a +/- 20 Degree window is what you would expect. If you designed for a 60 Degree beam width you would expect a +/- 30 Degrees window.
If you actually understood the meaning of constant directivity you would realise that ANY given beam-width or window can be constant directivity, IF (and this is the key) the off axis response follows the on axis one, but with attenuation.
So a +/- 20 Degree or +/- 30 Degree Beamwidth is perfectly acceptable as "constant directivity", if the other requirements are observed.
In fact, you can buy waveguides/horns with a range of coverage angles, COMMON (but not exclusive) ones are 40/20, 60/40, 90/40, 60/60 and 90/90 (first number horizontal beam width, second number vertical beam width). All of these are offered in "constant directivity".
> a design objective for high fidelity in a near field
> listening environment.
Who is talking near field listening? Stick to the topic.
> Toole, who essentially wrote the book on directivity of loudspeakers,
Correction, directivity in speakers was well documented long before Toole however Floyd E. Toole did some rather interesting work on speaker directivity for domestic listening.
The directivity of the Revel Saloon Speaker you referenced before is based on his work.
> makes it pretty clear in his papers that response off axis to about
> 60 degrees needs to be a carbon copy of the on axis response (excepting
> a minor uniform level of attenuation with each increase in off axis
> angle).
Really, would you care to substantiate this with with a citation from the actual paper (including page/chapter) where he says that this is the ONLY option?
> If the reader of this thread has any doubts, the Revel Ultima Salon 2
> (a product design inspired in part by Toole) I linked to earlier
> possesses a directivity plot that is TEXTBOOK constant directivity.
Actually, this a plain wrong. Plain to everyone to see, the plot from Stereophile was posted above.
It is very easy to see that even above 1KHz (never mind below) the 60 Degrees curve is NOT a carbon copy of the on axis curve but significantly non-flat. And it is actually a good thing that it is so...
Floyd E. Toole main point is that any change in directivity must be smooth and gradual and a situation where first the directivity increases (that is a narrower beam-width) and then decreases (that is beam-width widens) must be avoided.
Now if you cross the D130 & 075 with the original JBL 2.4KHz crossover you will have exactly this problem and you have a rather non-flat frequency response.
Which is why a few of us in the 80's in East Germany re-engineered a fair few Enclosures that uses these items and which had become available quite cheaply into something with a much more linear frequency response AND with a much more even off axis response (if strongly attenuated).
So let's consider. You attribute to Floyd E. Toole statements he never made (to me to), you cannot read basic graphs.
You real problem here is two fold.
First, you have very specific fixed Dogma's according to which the world is supposed to work and a low tolerance to anything that seems to challenge them.
Second, you have enough knowledge to get yourself into trouble, but enough indepth knowledge to understand the subject enough to make sense.
> The response plots of the JBL D130 operated wide band and the 075
> bullet tweeter responses look nothing like this.
How do you know? Again. I have measured such systems, have you?
> Compare the plots of these speakers and you will get a better
> understanding of what constant directivity means and why constant
> beamwidth only suggests constant directivity when it occurs over
> a relatively wide listening angle.
Clearly, you lack understanding what constant directivity is.
A system having a 40 * 20 Degree coverage angle is constant directivity, if it conforms with the basic requirement of an off axis response that equals on axis, but attenuated.
Tou give you an idea of a horn for such a system, look up (for example) the Electro Voice HP4020 Horn .
> Forty degrees listening angle is clearly not in the same ballpark
> as 120 degrees.
Of course not. But 120 Degrees constant beam-width is as much constant directivity as 40 Degrees constant beam-width.
Constant directivity is not defined by a specific angle, but by CONSTANT DIRECTIVITY at a given specified angle...
> It might be in Thorsten's warped, myopic world view
Sorry, but it is that in any decent text on the subject, the tie in to a specific beam-width angle you wish to establish as fact does not exist. In fact, if anything results from a warped, myopic world view it is the incredible bunk you have been spouting...
> Thorsten, given that every successive post of yours on this subject
> has provided further evidence of your ignorance on the subject, it
> might be wise for you to stick with electrical fuse design.
Well, I repeat, someone is clearly ignorant about such things as what constant directivity is in the textbooks and in colloquial use, or how real loudspeakers behave and other such minutiae. So far you have not shown any indication of even the most basic understanding of the Topics you have been so eagerly discussing...
So on the next round you expose less ignorance, perhaps you allow me to suggest a little remedial reading, so we at least understand the terminology...
An excellent overview of different approaches and results for controlling directivity as well as extensive references is given by Siegfried Linkwitz .
Earl Geddes takes a more narrow but well reasoned and supported view of the subject in his paper "Directivity in Loudspeakers" .
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Thorsten said regarding Floyd Toole's objective regarding constant directivity of loudspeakers :
"Really, would you care to substantiate this with with a citation from the actual paper (including page/chapter) where he says that this is the ONLY option?
I've read various papers from Toole and distinctly remember him using the words "carbon copy " to describe frequency response measured far off axis in comparison to that measured on axis or close to on axis. I said nothing about "ONLY OPTION" so cut the projection crap. But since you challenged me on this very basic concept - I'll direct your attention to figure 25 on page 14 here:
http://www.harmanaudio.com/all_about_audio/loudspeakers_rooms.pdf
Once again, I'll reiterate for other potential readers here - constant direcitivity in the context of a loudspeaker indicates response lines off axis that are essentially the same as the on axis response only shifted down a few db in sensitivity. One should see what looks like a number of parallel lines that extend out to about 60 degrees. This is a speaker that possesses constant directivity - NOT TO BE CONFUSED WITH CONTROLLED DIRECTIVITY WHICH THORSTEN CLEARLY HAS DONE. The 075 bullet tweeter is a narrow directivity(+/- 20 degree) high output tweeter capable of 110 db at 1 meter and 1 watt. It was never intended to be used in people's living rooms and anyone who suggests it for such an application is totally clueless. The poor, uneven off axis response at frequencies it was intended by JBL to be crossed up to the D130 at are precisely the problems Toole has focused on in his papers - such as the one linked to above.
The internet is a great place to gather and share information. Unfortunately, any idiot can link to someone's website or paper and claim that they know what is being said. In the process, it is not unusual for the idiot to twist or misinterpret what is being said and then disseminate that misinterpretation widely on forums such as this.
Thorsten also said:
"Who is talking near field listening? Stick to the topic."
Most living rooms, based on the wavelengths generated in audio systems, constitute the near field zone. Scan Speak, a prominent loudspeaker manufacturer, has dedicated itself to designing and building some of the best loudspeaker drivers for this environment - the low sensitivity 8530K being a prime example. The two drivers you brought into this discussion were never intended for home use. They were designed to be used in large spaces and in public address applications where far field conditions dominate. None of the virtues you have tried to describe for them have any use in a home listening environment. Their performance is exactly the opposite of what Toole lists in his papers as design objectives for home use. I've been staying on topic. You on the other hand have not. Perhaps you should heed your own advice or better yet, see a psychiatrist for your various neuroses and projection issues.
Hi,Okay, lets clear up some more confusion.
There is much woffle that is completely meaningless and empty verbiage which I cut...
> I've read various papers from Toole and distinctly remember
> him using the words "carbon copy " to describe frequency response
> measured far off axis in comparison to that measured on axis or
> close to on axis.Then it should be trivial to supply the reference. BTW, I have ALSO read the papers AND retained copies on my hard drive for reference...
> http://www.harmanaudio.com/all_about_audio/loudspeakers_rooms.pdf
Does not contain "carbon copy"...
> But since you challenged me on this very basic concept -
> I'll direct your attention to figure 25 on page 14 here:This is labelled "design objective for a room friendly loudspeaker"...
It does not show either a constant directivity or a controlled directivity system. It does show what Dr. Toole recommends and many others (if you had cared to peruse some of the references I provided you with) would disagree, though all would generally agree that figure 25 is a better choice than figure 24.
However, many would submit that this here is an even better choice than figure 25:
And even though this speaker (the Geddes "Summa") has a large variation in directivity below 1KHz, it is generally nevertheless considered "constant directivity", both by it's designer and audio professionals in general.
AND if you had paid any attention, you would have noticed that the Speaker system using D130 and 075 crossed over at around 5KHz will actually exhibit a SIMILAR off axis response, though not with as smooth curves.
> Once again, I'll reiterate for other potential readers here - constant
> direcitivity in the context of a loudspeaker indicates response lines
> off axis that are essentially the same as the on axis response only
> shifted down a few db in sensitivity. One should see what looks like
> a number of parallel lines that extend out to about 60 degrees. This
> is a speaker that possesses constant directivity - NOT TO BE CONFUSED
> WITH CONTROLLED DIRECTIVITY WHICH THORSTEN CLEARLY HAS DONE.Nope, what you claim to be a "constant directivity" speaker, namely the typical design following Dr. Toole's recommendation are precisely NOT Constant directivity, becuase they show a rising directivity index with frequency. What is important with designs that follow this principle that rise in directivity is smooth and continous.
Again, had you perused the references I gave you you would know that...
To take something from Siegfried Linkwitz's site about a good example of what Dr. Toole advocates:
This loudspeaker exemplifies Floyd Toole's loudspeaker directivity requirements. They are the result of extensive listening tests where different box loudspeakers were ranked according to preference. The directivity index increases smoothly from 0 dB to 10 dB, without signs of the two crossovers in its frequency response. Moderately wide dispersion horizontally. (SL)
So, if anyone is confused about constant directivity, controlled directivity and what Dr. Toole advocates it appears that this person is you. Further, you ascribe to Dr. Toole claims you cannot back up (and which I doubt he would have made like that) and misrepresent your misunderstanding as his intentions and recommendations, when nothing could be further from the truth.
> The 075 bullet tweeter is a narrow directivity(+/- 20 degree)
> high output tweeter capable of 110 db at 1 meter and 1 watt. It
> was never intended to be used in people's living rooms and anyone
> who suggests it for such an application is totally clueless.Are you SO SURE about that?
So if JBL had domestic styling 2-Way systems using the 075 marketed as HiFi Speakers these where "never intended to be used in people's living rooms" that would make you a boldfaced liar and actually the one who is "totally clueless"...
Now, let's look at the 1957 Catalog JBL issued for home customers (they had different ones for pro audio)...
Wow... I spy with my little eye the 075, so clearly JBL intended it for home use...
Even further, JBL's Systems/Pricing Page from this catalog shows many 2-Way systems using the 075...
Even worse, the 1976 Home Components catalog still has the 2-Way D130 and 075 in the list of recommendations .
Quel Domage, either everyone at JBL from AT LEAST 1957 to 1976 (or later - I still remember seeing this Combo in the 80's) according to you was totally clueless .
> The poor, uneven off axis response at frequencies it was intended
> by JBL to be crossed up to the D130 at are precisely the problems
> Toole has focused on in his papers - such as the one linked to above.Now we come to the crux of the matter. And I agree, the original JBL system with a 2.4KHz 2nd order Crossover network created quite a few problems, not just in directivity but also in the frequency response, as I found out in the mid-80's when such systems came my way (long story how).
As we had a fair few of these available and as they had some interesting characteristics to their sound quality we did a fairly comprehensive job of characterising them and the re-engineering them.
Now this was over two decades ago, so I am not 100% on specific values (and the papers are long lost), however we used two LCR Equaliser on the D130, but no lowpass, to get the frequency response pretty flat, a short "Hornreflex" for the Bass which gave a boost in the 100-500Hz range that was a bit low and a 3rd order highpass somewhere around 5KHz for the Tweeters.
As I commented also before, this system measured pretty flat on axis and had a very CONSTANT DIRECTIVITY Response off axis. As Constant Directivity was one of the big buzzwords of the time and one needed to buy very expensive new horns to get this "Constant Directivity" we where pretty pleased that we achieved the same using very different means.
It may surprise you, but I have been dealing with such things like speaker directivity for the better part of three decades, in practice.
> The internet is a great place to gather and share information.
Yes, it be a good ting if you did that a bit more. You would perhaps come across a little less clueless if you did.
> Unfortunately, any idiot can link to someone's website or paper
> and claim that they know what is being said. In the process, it
> is not unusual for the idiot to twist or misinterpret what is
> being said and then disseminate that misinterpretation widely
> on forums such as this.That sounds like an excellent description of what you have been doing, if I may say so.
> Most living rooms, based on the wavelengths generated in audio systems,
> constitute the near field zone.Really? Now, exactly what is the definition of "near field" in the context of acoustics?
Do you even know? Here a good (but not exclusive) definition...
The near/far field transition is typically defined at a distance of d^2/l, where d is the effective diameter of the driver, and l is the wavelength of sound. Note that means that as you either increase the diameter OR play a higher frequency, the near/far field transition occurs at a further distance.
Taking for example a 4" radiating diameter and 1KHz we get what distance as near/farfield transtition?
Are you really suggesting that anyone lives in a shoecarton?
Honestly, your total lack of understanding acoustics makes it again time for a double-facepalm for you, honestly, I would think your face should smart something fierce by now...
Now, I would really suggest you actually apply yourself to the subject and gain some basic understanding, if you wish to debate the merits or not of my original recommendation, which send you on this thread of perfect and utter tomfoolery. As the old sages used to say, a little knowledge is a dangerous thing.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Edits: 07/14/12
There was no "pro division" and "consumer" or "home" division of JBL in the 50's. Lansing's focus and experience was with large spaces such as theaters and broadcast production facilities. The mix/match brochure which in some instances utilized the bullet tweeter contains speakers that were "functionally designed for professional and 'built - in' use" as well as speakers that appeared to be designed as home furniture. Because Lansing decided to use some of the same drivers in cabinets that could be put in a home does not mean the drivers were originally designed for that purpose. The acoustical interactions between loudspeakers and different spaces were not known at that time anywhere near like they are today. And opportunistic business decisions drove marketing - not always correct science or engineering.
Also, a speaker that exhibits constant directivity doesn't preclude a slight narrowing of response with frequency. The key to constant directivity design is the uniform response lines (or essentially parallel response lines)over successively wider listening anlges at the frequencies where directivity can be controlled - from approximately 1 khz to 10 khz. As noted earlier, the Revel Ultima Salon 2 excels in this capacity as evidenced by the Stereophile test plots I linked to earlier and as suggested by figure 25 on page 14 of Toole's white paper that I linked to. Bringing up the flatness or lack thereof for a directivity index plot is a side distraction that confuses people like you.
Everything I've stated in this thread has been derived from personal experience and from the experience of other's like Toole and Olive. My experience with JBL goes back to the first set of speakers I ever owned - JBL L 19's back in grammar school in the 1970's when I first started building loudspeakers and amplifiers. There's nothing you're going to be able to tell me that I don't already know about Jim Lansing and the company he formed. My understanding and knowledge goes far beyond advertising brochures. And despite all my concerns over your ignorance and misguided assertions, I can at least give you credit for recognizing the inherent value of JBL product quality in general. Where specifics are concerned, however, you still remain completely out to lunch.
And yes, I know the difference between near field and far field and the murkiness of the subject based on the relationship to wavelength - that's why I stuck with an absolute. If the dimension of the lowest produced frequency can exist well within the distance from the source to the listening reference point - it HAS to be considered far field. I expected you'd nitpick this issue too since as evidenced by all of your posts, it's in your nature to use the sharing of information as a competitive exercise rather than a means to benefit oneself by learning from others while occasionally helping others learn from one's own experience.
"I have you here at a disadvantage of course, as I am quite familiar with such systems." - Thorsten earlier in this thread.
ugh
Hi,
> If the dimension of the lowest produced frequency can exist well
> within the distance from the source to the listening reference point
> - it HAS to be considered far field.
Nope, the definition used in common acoustic texts is quite precise. It includes wavelength and radiation area for reasons that should be self explanatory.
Of course you make up definitions that suit you and your agenda on the spot (like so much else in this thread), however that does not make them true.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Thorsten babbles:
"Nope, the definition used in common acoustic texts is quite precise. It includes wavelength and radiation area for reasons that should be self explanatory."
Since there are many wavelengths involved, a definition based upon a specific wavelength is not useful or accurate. This definition is more useful and accurate in the context of a typical loudspeaker listening environment than anything you're likely to come up with that's based on the Fraunhofer definition of far field:
"The near field is the area very close to the machine where the sound pressure level may vary significantly with a small change in position. The area extends to a distance less than the wavelength of the lowest frequency emitted from the machine, or at less than twice the greatest dimension of the machine, whichever distance is the greater. Sound pressure measurements in this region should be avoided."
And it is commonly accepted in the industry and can be found here:
http://www.acousticvibration.com/sound-basis.htm
And it is exactly the same definition I used.
Now who is inventing what?
That approach is exactly the opposite of what JBL does with many of their systems. They run midrange drivers up to frequencies where the image gets very narrow and then - transition to a wide dispersion tweeter!
That results in a very strange pinched in the middle "fun house mirror" image. :)
"That results in a very strange pinched in the middle "fun house mirror" image."
Or the inverse of having accentuated highs and lowes in proportion to the mids. The music of the far east is well served by speakers of this sort, hence why these horn speakers sell so well there.
I had the old L300s in my ear bleeding younger daze and can attest that the off axis sound out of them is like a ragged edge. Thosrten can bring us as many graphs as he cares to. The reality is that those speakers absolutely stink in comparison to what we have available today. The Paragon, while a beautiful piece of wood, would probably greatly disappoint us all. I believe the myth is probably far greater than the actual performance that it could muster, and may be the reason it is merely on display in the lobby of 8500 Balboa Blvd.
Hi,
The L-300 is not an example of what I was writing about.
Why does everyone always want to generalise? I wrote specifically about one specific pair of drivers, their properties and specifics in their use. If you have anything else (e.g. the L-300) then you are talking about something completely unrelated.
It is like I am talking about a classic Jag and you insist on bringing in a Yugo "because it also has wheels", pointless...
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
OTOH, you never know. Thorsten may be on to something. Perhaps the old Cabaret portable sound guitar speakers with their K or E series drivers will become the new "high end"... And for the truly "enlightened" audiophiles like Thorsten, they'll have to take out the 800 and 1500 hz crossovers and bump those big 15 inch "full range" drivers up to 5000 hz or so...
Perhaps this will be the image/look of the new audiophile illuminati...
http://www.audioheritage.org/html/profiles/jbl/cabaret.htm
(eyeroll)
Last time I heard an old Cabaret speaker, I had to walk away with my ears covered - it was that bad.
Hi,> OTOH, you never know. Thorsten may be on to something. Perhaps the
> old Cabaret portable sound guitar speakers with their K or E series
> drivers will become the new "high end".Who knows. If you address the particulars well enough they can give the basis for something quite interesting.
> .. And for the truly "enlightened" audiophiles like Thorsten,
> they'll have to take out the 800 and 1500 hz crossovers and bump
> those big 15 inch "full range" drivers up to 5000 hz or so...I see you are cherrypicking again what wish to quote and what not.
What I did actually write that first it was neccesary to equalise the severely non-flat response of the Drivers, in our case we combined acoustic means (short rear horn at LF) and electrical means (LCR Traps). Once this is done the resultant frequency response is flat and the off axis response by far better than you think.
Many modern "Mid-Bass" drivers also have a severely non-flat response that must be equalised. If you listened to them without EQ you would amazed just how bad they sound...
You can of course just use a normal line level equaliser and do the same.
> http://www.audioheritage.org/html/profiles/jbl/cabaret.htm
>
> (eyeroll)
>
> Last time I heard an old Cabaret speaker, I had to walk away with my
> ears covered - it was that bad.Did you take care to equalise the system for flat response before listening? Otherwise I would be unsurprised.
Again you ignore most of what I wrote and cherrypick something that you can use to be negative. What I have described is not only possible, the results are quite good, good enough for me for example to call the D130 "The Best Mid Bass Driver ever", though the 15" Tannoy Monitor Red, the 15"EV SP-15 with Alnico Magnet and the old Alnico Magnet Altec 604 run it a more than close joint second.
Just get over it. You do not know all there is to know in the world (neither do I, though it seems more than you on the topic).
Stop insisting that white must be black because you say so (and because you lack the understanding to see that what I called white was white) and you may find we have more views in common than apart, though I tend towards a far more narrow directivity as desirable than your key source and that for very good reasons.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Edits: 07/16/12
Hi,> Ah, narrow directivity tweeter
Well I did say it was an 075.
Google Image Search for JBL 075
> That approach is exactly the opposite of what JBL does with many
> of their systems.Actually, the serious studio systems (and the derivative Home Versions which since the 1980's have generally not been sold in the US but strictly in Europe and Asia - e.g. Everest 4400, K2 and so on) have exceptionally well controlled directivity, though usually much wider than the original 1950's D130 & 075.
So you must be talking about the consumer grade stuff they generally sell in the US...
> They run midrange drivers up to frequencies where the image gets
> very narrow and then - transition to a wide dispersion tweeter!
>
> That results in a very strange pinched in the middle "fun house
> mirror" image. :)Yes, that is generally a very bad idea.
Given the JBL is part of Harman and Floyd O'Toole worked/works for Harman I am a little surprised such designs would actually be sold, but there is a large gap between actual engineering and marketing and customer expectations in Audio.
The Kind of "JBL" I am talking about is probably best embodied by the original Everest (D4400) though the more recent one is also pretty awesome and the S9500 and related Speakers.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Edits: 07/12/12
So you must be talking about the consumer grade stuff they generally sell in the US...
And the once popular 4310/4311 pro monitor series.
Hi,
> And the once popular 4310/4311 pro monitor series.
Funny, those.
They where basically 2-Way with Supertweeter. They used a 12" up to around 1.5KHz handing over to the 5". Not an ideal choice.
They where probably designed when the real Engineers where out for a beer or two...
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Legitimately, the 8530 has an Fs that is closer to 45hz than 30hz. It's response drops off significantly below 60hz in most alignments. So realistically, it's good for about 5 octaves. Six octaves would mean a crossover around 3800 hz which is too high for a 5 inch midwoofer as off axis response drops off sharply due to combing effects. Similarly, use of large drivers (12- 15 inch) has serious drawbacks when implemented in two ways and crossed over from 1500 hz up. Wide variations in off axis response when transitioning from an oversized driver to a tweeter (whether a five inch crossed at 3.8khz or a 15 inch crossed at 1.5khz) kills imaging performance. A smooth transition is required from one driver to the next to achieve a well balanced, high fidelity end result. The Scan Speak 15W8530 is still an excellent driver with a good, usable, 5 octave bandwidth. But it is not the best thing since sliced bread as the OP seems to suggest. Like anything else, it has its strengths and limitations. It's primary limitation is pretty well acknowledged by the company that makes it. It's advertised as a MIDWOOFER - not a woofer, not a tweeter, and not a full range.
Edits: 07/11/12
Hi,> Similarly, use of large drivers (12- 15 inch) has serious drawbacks
> when implemented in two ways and crossed over from 1500 hz up.Not really. It has some fundamental design requirements that need to be understood, considered and implemented, as has every engineering project under the sun.
> Wide variations in off axis response when transitioning from an
> oversized driver to a tweeterAre an indication of very poor design.
Let us take an example of a good design, that originally derived in the mid 40's from german designs but moved beyond the original.
In this case we have a driver that is coaxial and uses the cone as waveguide.
(an interesting aside, in the 1980's then new Cepstral analysis and extensive listening confirmed the cone shape originally derived from german designs as one of the absolute best waveguides, over all the the then and even now fashionable "CD" geometries)
This driver has a near constant directivity index between 500Hz and 5KHz, above 5KHz DI increases and below 500Hz (depending on box size and mounting) it decreases.
When mounted and placed correctly the system has a flat on and off axis response from the LF Cutoff to around 5KHz with a falling off axis response above 5KHz.
The driver in question BTW is a 15" 2-way Tannoy coaxial from the same era as the JBLD130.
> (whether a five inch crossed at 3.8khz or a 15 inch crossed at 1.5khz)
> kills imaging performance.Actually, using a driver/system with insufficient DI is what kills imaging, or large changes of DI over a narrow bandwidth.
The problem you suggest can only happen in hamfisted designs turned out by those who fail to understand the first things about speaker performance and design.
BTW, once you understand the action of the D130 Cone system you will understand why it actually offers a 40Hz-6KHz usable bandwidth with a pretty flat power response (that is integrating on and off axis response) and in fact a rather flat response at the listening position, without needing massive room treatment to control the reverb caused by poor speaker directivity.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Edits: 07/11/12
Operating a driver at frequencies where the wavelength is smaller than the driver's diameter results in frequency combing or destructive interference off axis. This is acoustics 101. If you wanna argue that fundamental point, go read some basic texts on acoustics or talk to the hand.
Thorsten said:
"The D130 I mentioned is good to well past 6KHz!"
The D130 was a 15 inch driver. The wavelength at 6khz is about 2.25 inches. If one were to cross that driver over to a tweeter anywhere near 6khz, there would be a very narrow dispersion pattern between 1500 hz and the crossover frequency. At the crossover frequency, the dispersion would flare out or as is commonly said in the industry- "bloom". This may be high fidelity to you. To me and the industry professionals I know, it's rubbish. All of the JBL drivers I've ever used were extremely well made, low distortion units. But that doesn't fix a novice's poor design or misuse of a driver.
Hi,> Operating a driver at frequencies where the wavelength is smaller
> than the driver's diameter results in frequency combing or destructive
> interference off axis. This is acoustics 101.Indeed, had you ever progressed to acoustics 102 you could have noticed that your 101 version only applies to rigid pistons, which do not even exist in in Thiel & Patner / Accuton drivers.
So, acoustics 102 is to stop engaging with unrealistic oversimplified theoretical models and to engage with the real devices, something that based on literature I read in my misspend youth was quite common in German acoustics decades before I was born....
> If you wanna argue that fundamental point, go read some basic texts on
> acoustics or talk to the hand.Look who is talking. I read those decades ago and actually spend time observing said rules in practice.
> "The D130 I mentioned is good to well past 6KHz!"
>
> The D130 was a 15 inch driver.Correct. It also used a "NAWI" profile cone and a fairly soft paper for the cone. This has, invariably if we observe acoustics based on evidence, certain results.
> The wavelength at 6khz is about 2.25 inches.
And?
> If one were to cross that driver over to a tweeter anywhere near 6khz,
> there would be a very narrow dispersion pattern between 1500 hz and
> the crossover frequency. At the crossover frequency, the dispersion
> would flare out or as is commonly said in the industry- "bloom".Surely, this would depend on a number of factors.
For example, given the driver does not use a rigid piston, we experience reducing radiation diameters with rising frequency. Of course the cones profile will still provide a waveguide.
So as long as we match the directivity of the 15" Woofer where it hands off to the tweeter we are likely in pretty safe territory. Now the tweeter commonly used by JBL "back in the day" was the 075, basically a 38mm ring radiator with a fitted waveguide that provided 40 Degrees -3dB beam-width from a few KHz to supersonic frequencies.
Unsurprisingly this fits the bass/mid driver very well.
Now you may be considering some Spam Skweek Darkenator or other HF driver designed and employed contra lex naturam as mate, ignoring the hopeless of any SPL match or any attempts of matching directivity, these are quite poor specimens to do HF.
Well, an uninitiated, ignorant novice may try such.
> This may be high fidelity to you. To me and the industry professionals
> I know, it's rubbish.You expose nothing here than your total lack of understanding basic acoustics, or a refusal to put them to work. Come on, we are talking > 60 years ago stuff here.
> All of the JBL drivers I've ever used were extremely well made, low
> distortion units.So they are.
> But that doesn't fix a novice's poor design or misuse of a driver.
This I agree with completely.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Edits: 07/11/12 07/11/12
"So, acoustics 102 is to stop engaging with unrealistic oversimplified theoretical models and to engage with the real devices, something that based on literature I read in my misspend youth was quite common in German acoustics decades before I was born...."
- Thorsten on the value and benefit of running a 15 inch woofer at tweeter frequencies.
I got your real devices right here, Thorsten:Here's a the current list of top rated loudspeakers from one of the most popular review magazines in the world today:
Aerial 20T - 2 9" woofers crossed over at 300hz
B&W 800 Diamond - 2 10 inch woofers crossed at 350hz
KEF 207/2 - 2 10 inch woofers crossed at 120hz
Revel Ultima Salon II - 3 8 inch woofers crossed at 150hz
Sonus Faber Amati Futura - two 8.75 inch woofers crossed at 80 hz
Sony SS-AR1 - two 8 inch woofers crossed at 400hz
Vandersteen 7 - 12 inch sub woofer crossed at around 90hz
Vivid Giya1 - 2 11 inch woofers crossed at 220hz
Verity Audio Sarastro II- 11 inch woofer crossed at 150 hz
Wilson Maxx 3 - 13 inch and 11 inch woofers crossed at around 150hz
Revel Ultima Studio 2 - 2 8 inch woofers crossed at 230hz
MBL 101E Mk.II - 12 inch woofer crossed at 105hz
See any 12 or 15 inch drivers on this current highest rated speaker list crossed over higher than 500hz, let alone up near 5 or 6khz?
Btw, Einstein - the 15 inch woofer in the Meyers Sound X-10 is crossed over at 950hz - which is about as high as anyone would want to go in order to maintain a reasonably high level of fidelity. JBL has been crossing over its 14 inch woofers in house systems at 750hz and lower for years (my old 250Ti Limiteds cross at 400hz). So nice try on the Meyers - but as usual - WRONG.
Given your apparently high opinion of your understanding and experience, I'm guessing that you think all the folks who built the above speakers didn't pass "acoustics 102" yet. Or perhaps they're all part of a conspiracy to ban 15 inch woofers from the home loudspeaker market, right?
Tell you what Thorsten. RMAF is coming up this fall. The show could always use some added comic relief to draw attention away from borish, snobbish, audiophools constantly badgering one another about who makes the best loudspeaker... Perhaps you could help lighten the mood a little by giving a seminar on why you think the industry has it all wrong - that it should be using 15 inch woofers in controlled break up crossing over to tweeters at several thousand hertz... That should get some laughs if nothing else.http://www.youtube.com/watch?v=BNsrK6P9QvI
Edits: 07/11/12
Hi,
> Double face palm time, yet again...
Yup.
Stereophile review of JBL Synthesis 1400 Array BG loudspeaker which uses a 14" Midbass crossed over at 750Hz.
Stereophile review of Tannoy Dimension TD12 loudspeaker which uses a 12" Midbass crossed over at 1.3KHzHz.
Stereophile review of Tannoy Churchill loudspeaker which uses a 15" Midbass crossed over at 1.1KHz.
Not reviewed but very much worth a good listen is the Meyer Sound X-10 Studio Monitor which uses a 15" Midbass crossed over at 950Hz.
In the history of Studio Monitors many examples of 15"2_ways may be found, be they from Kinoshita, TAD/Pioneer, JBL, Urei, Altec and many others.
The example of the D130 with 075 Tweeter crossed over at around 5KHz is extreme, HOWEVER, as the tweeter has constant directivity at 40 Degrees Dispersion you may find yourself surprised just how well this actually works acoustically.
I have you here at a disadvantage of course, as I am quite familiar with such systems.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Or are you just one complete non stop joke?
Everything you just posted was a repeat of what I've been saying. Crossing a 15 inch woofer above 1.5khz (up to 6khz as you suggested earlier) is something a total novice or fool would do. And then after contradicting yourself by requoting the information I originally posted, you claim:
"I have you here at a disadvantage of course, as I am quite familiar with such systems."
Technically, given everything you've been babbling about in this thread, you wouldn't know your rear end from a hole in the wall. I suspect that given the response of others to your non sense in this thread, I'm not alone with this sentiment.
But you apparently have no shortage of audacity or arrogance. For that, you get high marks.
Hi,> Are you as deranged as your posts suggest?
>
> Or are you just one complete non stop joke?Well someone here clearly is.
I have no particular agenda (e.g. I do not own a warehouse full of NOS D130 and 075 which I am trying to talk up in value - I wish I did though).
I merely use them as an illustration that most "truisms" and generalisations (such as "A 15 Driver must be crossed over below XXXHz" or "A 5" Mid bass is the best in all time") are in fact completely false.
Now I should note that I am not suggesting to generalise from concrete examples (e.g. the D130 & 075 crossed at 5KHz), so for example a Car Audio 15" "Competition" Subwoofer Driver most certainly would not be suitable to a two system crossed over at 5KHz, yet it is possible to make such system GIVEN THE RIGHT DRIVERS AND ENGINEERING.
I notice that you omitted to answer my question if you actually measured such a system (especially DI) as I described (that is very precisely the JBL D130 and the JBL 075 crossoed over at around 5KHz)?
Have you? (I have, BTW).
And if you have not measured it, how can you claim to know what it measures like?
And it would seem you have also omitted to peruse the specifications issued by JBL for these drivers either (which may prove illuminating, FWIW).
> Everything you just posted was a repeat of what I've been saying.
Actually posted a list of speaker references where the highest crossover was 400Hz for 8" Woofers, which did not include a single 15" (FWIW) and with which you suggested that was some general technical consensus or some such that large drivers must be crossed over low (below 400Hz, which you suggest should be the maximum for an 8"Driver in your post).
I pointed out that very successful designs exists that do not follow these rules and in fact cross over very large drivers quite high, compared to your examples.
Now the JBL D130 I have been consistently referencing is a wideband 15" that does operate up to 6KHz quite successfully (the old EV SP-15 and the Goodmans Axiom 401 also did quite well, all said, but their Cone/Whizzer design kind of played havoc with the directivity and frequency response) and I did not suggest that any other drivers where suitable to such a design.
The D130 of course has narrow dispersion at higher frequencies, which is why the competent Engineers at JBL elected to mate it with an equally narrow dispersion tweeter, so the directivity index for the complete system is both very high (in other words it creates very little room reverb) and quite even from the midrange and up.
You may very well debate with me if a high and slow change/constant directivity index is a good thing for music reproduction or not, that I would suggest is a matter of taste. Some people like Bose 901's, some like MBL Omni's, some like very narrow dispersion systems instead.
Let them all eat cake. We baked a very nice Almond cake with German Buttercreme frosting recently (thanX to massive willpower by all of us some is still left, but not by tomorrow Tea time), I suggest something at least as nice, or nicer (Schwarzwälder Kirschtorte?).
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Edits: 07/12/12 07/12/12
I don't remember seeing measurements of a 12" or 15" woofer at 45° looking 'flat' above 1,500 Hz. Flexible cone or not, and whatever its shape is.
Yves
Hi,
> I don't remember seeing measurements of a 12" or 15" woofer at 45°
> looking 'flat' above 1,500 Hz. Flexible cone or not, and whatever
> its shape is.
Why would remotely desire flat response at 45 Degrees? I would desire significant SPL Rolloff, ideally all the way to the bass, but practically to as low as possible, which incidentally mandates a large acoustic structure (Baffle, Horn, Cone).
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
...he's moreso referencing the beamwidth transition from driver to driver in the crossover region. A radical shift in dispersion in the crossover region is not generally filed under "well blended".
You would think coincident driver arrangements would avoid lobing tilt issues though...
Cheers,
Presto
Hi,
> I think he's moreso referencing the beamwidth transition from driver
> to driver in the crossover region.
Alas, so am I.
Of course we need to match woofer's and tweeter's off axis response. However HF drivers exist with any dispersion pattern under the sun (and absent something suitable simply design a suitable waveguide), so it is up to the designer to match the HF directivity to that of the LF.
Now just because this directivity (Index) is high for the LF it does not follow that there will not be a smooth transtition.
> A radical shift in dispersion in the crossover region is not
> generally filed under "well blended".
Well, what can say? You are preaching to the first apostle perhaps?
> You would think coincident driver arrangements would avoid lobing
> tilt issues though...
They do. I am quite fond of Coaxials, back to the old Schulze/RFT TH315 (developed from the first ever coaxial be Dipl Img Exckmiller) I owned i n the 80's.
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Folks,This german site has some interesting actual measurements of drivers. Some you must subscribe, however that which I wish to illustrate is available openly...
Here a Thai Copy of the JBL 2226 , which measures worse, but not "way bad" compared to the original.
And here a Parts Express ownbrand (Dayton) 6.5" Driver , incidentally one that is designed for relatively low distortion.
Look at the distortion and compression at comparable SPL's...
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
Edits: 07/11/12
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