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24.21.76.104
playing politics with customs or what-ever. The DCX crossover is slated for arival the end of July. I'll be too old to enjoy by then. Can you guys suggest an alternative? The DBX at $1000 is over budget. Need two full stereo bandpasses and stereo woofer low pass (even though I will use Bash sub amps, I want better control) and something better than fixed 24 LR slopes.
To make clear, I have stereo woofers, mid-bass, extended mids and super tweeters. This is for high end home use. Two of the right units should work. Thanks, Zene
Follow Ups:
Managed to score a used Ashly 4001 for $270. It will do for some time. Good info gang. Thanks, Zene
NM
Quick follow up. Thanks, Guys. Multiple 2-way units (Rane or others) will not give me band passes unless there is someting I don't understand.
My system is a ongoing experiment making plug-in cards impossible.
Am I wrong by thinking I need slope choices?
Options are greater if I can settle for 24LR. I will be using RTA for evaluation. Zene
If there is anything to be gained by other slopes depends on your drivers.
As long as they cross to each other well within their flat response limits I can't see how you could gain anything by using different slopes. After all 24dB LR's are so widespread because they are pretty much the only ones producing a flat output and no phase shift whilst maintaining a decent impulse response (you may not be able to measure this with a hardware RTA but possibly with more advanced software ones). The reason they are not widely used in passive designs is that steeply sloped passive xovers tend to 'ring' (self-oscillate) due to being made up from inductor/capacitor (LC) circuits and as such resonate at the crossover frequency producing a surprisingly clean sinewave which is, unfortunately, entirely unrelated to any music you might be trying to listen to.
But anyway, unless your drivers demand a certain overlap you may well end up creating problems where there wheren't any by choosing other slopes.Any phasing issues should be addressed by having the voice coils in the same plane!
A crossover is not the place to try to fix basic design deficiencies...
If it is impossible to get them in the same vertical plane tweeter coils should be further back from the listener then woofer coils!!! The reason being that fundamental tones should reach the ear before their harmonics because if the brain detects harmonics first it actually synthesizes a suitable fundamental. So a late arriving fundamental does play a major part in listening fatigue, something many people try to solve by rolling off the treble. A case of treating the symptom not the cause.Can't say anything about Rane but the BSS can be used as either 2way stereo or 3/4way mono, the KT as two 2way stereo or 3/4stereo. Both with all the necessary band passes perfectly executed but you will have to flick a switch to tell in which mode to operate...
Dear Sir,thank you very much for your valuable post.
With reference to your words " tweeter coils should be further back from the listener then woofer coils!!!" I would like to ask your opinion about this.
I found a pair of Tannoy Eaton where the tweeter coil plane is behind that of the woofer.
I was somewhat worry about the time alingment of the driver.
Do you say that a time delay with the woofer before the tweeter is tolerable ?
Besides, do you have any experience of the Behringer units ?
I would like to start cheap (with 24dB/octave filters anyway) in my firts experiment with an active crossover.Thank you very much again.
Kind regards,beppe
italy
Physically positioning the tweeter slightly backwards to line up with the woofer really has nothing to do with the harmonics' arrival in relation to the fundamental, as you would hear the effects most readily with pink noise, a notably non-harmonic program source. It's actually about making the crossover region smooth and free of cancellations, lobing, and other problems where the same sound comes from more thann one source.-Bob
Thank you Sir for the very interesting advice.
You say:" It's actually about making the crossover region smooth and free of cancellations, lobing ...".
How can it be assessed the lack of cancellations, lobing, etc.?
I mean, which in your opinion is the test that can be carried out on speakers and that can expose these problems ?
I think this is a very interesting point indeed.
To be clear I am trying to find out a pair of small bookshelf stereo monitors able to reproduce a really great soundstage, expecially in the depth direction.Thank you very much indeed.
Kind regards,beppe
italy
What I am saying is that a speaker which has the tweeter coil further away from the listener is a) less fatiguing to listen to and
b) closer to reality
then if it is the other way around.The reasoning behind both is based on the fact that because we split the audio signal into bass and treble we are inevitably splitting fundamental tones from their harmonics.
With regular flat-fronted speakers the treble coil is nearer the listener and so harmonics can reach the ear before their fundamental. The brain is very good at distinguishing harmonics from fundamental tones and if faced with harmonics but no fundamental it simply creates one. That is how we get the impression of deep bass from small speakers.
A late arriving fundamental just serves to confuse the brain and leads to listening fatigue.
Also in reality a fundamental always precedes its harmonics; never the other way around.So with your Tannoys you are already better in that respect then the vast majority of other speakers. If you really need to align them you will need to delay the bass by about 0.2ms.
My experience with Behringer products is such that if I never have to touch another of their products again it will still be too soon...
Dear Sir,thank you so much again for your extremely kind and valuable reply.
Your words that I am quoting: " a speaker which has the tweeter coil further away from the listener is a) less fatiguing to listen to and
b) closer to reality" are more than enough for me.
I feel that the time alignment of the drivers is not the easiest thing to carry out.
It is very important to me to know that in the case the tweeter arrives after the woofer the disaligment is tolerable.
This saves me a lot of trouble.
Now if only I could find a nice 24dB/octave two way crossover and of course not very expensive I could try it with the Tannoy.Thank you very much again.
Kind regards,beppe
italy
Hi Beppe,
unfortunately Tannoys need a bit more then just a plain crossover!
The tweeter, as is normal for compression drivers which cover a wide range, needs some eq to produce a flat response. It needs a wide but shallow notchfilter at around 3kHz to get rid of a slight response peak (I understand Altec have the same problem, they just never addressed it.) and a 6dB/oct boost from 5kHz, pretty much the same as modern constant directivity horns. Tannoy addresses all this within their passive crossover but you will most likely need a parametric equalizer.
The good news is that all this processing is far more precisely done at line level and the results are more then worth it. Stick with it and you will end up with one of the most accurate speakers possible.If you haven't already done so I suggest you join the Tannoy yahoo group
Dear Sir,thank you so much again.
Your advice is very important to me.
Honestly I thought that Tannoys were more flat in their response.Kind regards,
bg
I'm with you beppe, thx again Evil Prince of Darkness.
I found a Ashley 4001 used that should destroy that digital piece of junk (Be-something). And, you saved me lots of work trying to align my coax speakers, let alone super tweeters.
Do you have guidelines for setting back vc's? Seems as if you suggest doing time align in reverse. Is only the tweeter crossover point affected by harmonics? Would that be an offset in ms or by ear?
Zene
To reiterate:
Ideally you want all vc's in the same vertical plane!!!
If this is not possible it is better to have the higher range vc's further away from the listener then the lower range coils as opposed to the other (more usual) way around.Its usually coaxial drivers where you can't physically align the vc's but all coaxials I know that are worth owning (Tannoy and... err, Tannoy and well Altec, may be) have the tweeter coil further back and here the very real advantage of having a point source (lack of comb filtering for instance) far outweighs the mostly theoretical disadvantage of slightly imperfect vertical alignment. And the dis advantage is mostly theoretical since the only time-related connection between a fundamental and its harmonics is that harmonics are never produced before the fundamental and usually after. Think of a plucked string: It swings at its resonant frequency (fundamental) until the vibration reaches the end of the string and gets reflected back by its termination (saddle and bridge if its a guitar) when these reflections start to interfere with the original vibration harmonics are produced.
So the time when the earliest harmonics appear depends on the string length.For Tannoys the physical delay between woofer and tweeter is about 2ms which is too short to be noticed. (Don't know about other coaxials; measure the distance and work out how long sound takes to travel it, if you can be bothered)
It is also too short to be fixed with anything other then a digital delay which would require an unecessary step of conversion and all its problems if, like me, you still use analog sources. There is the passive all-pass Tannoy used on some speakers but it creates more problems then it solves.
Ever noticed that it is only owners of regular speakers who point out the alignement thing?
My guess is that they are just trying to defend their choice of an inherently inferior and substantially cheaper design. Never heard a Tannoy owner complain...Not quite sure about your last two questions, Zene.
But I am adding supertweeters and two subwoofers to my Tannoys. I will make sure that the subwoofer coils are aligned with the Tannoy LF coil ( I am building the subs myself) and
I will recess the supertweeters in a waveguide so the ribbon ( I like ribbon tweets) is aligned with the HF coil. If neither were possible I'd make sure the subwoofer coil is slightly in front of the Tannoy coil and the supertweet slightly behind.
The waveguide also helps controlling HF dispersion to something closer to the Tannoy tweeters 90deg. but delving deeper into this would be a completely different thread...Of course for passive xovers all bets are off due to the unavoidable phase shift introduced by them. Although there is at least one very clever design which uses this fault to its own advantage and that is Tannoy. Tannoy drivers with AlNiCo magnets (up to HPDs) have their tweeter coil a quarter wavelength (at xover frq.) behind the woofer and with cunning choice of slopes this results in an in-phase output! But this too is not in time as the tweeter is delayed by exactly one cycle.
BL ... Good informative clear answers. (Others take note: Your three "nots" in one sentence is not very helpful. And, while I'm on a tiny rant, neither is "There is no comparison beteween the XT12 and Pyle 3456". Takes forever to decifer which he thinks is better)
I will certainly pay more attention to phase. Was geting lazy, thinking electronics solves anything. Zene
Thanks, Zene!
As the Lord of Darkness I just like to shed a bit of light on some subjects while I am waiting around to harvest the souls of people who sell (or buy; gullibility is no defense in my business) $500/meter cables...As for electronics solving probs: Yes sometimes they can but mostly they just 'paint over' them. There is no substitute to getting the basics right.
I suggest you get a couple of s/h BSS FDS360's or one Klark Teknik DN800 if you are after audio quality and control.
You won't be able to change frequency or slope on the fly though as these are analog units,
you'll need either a soldering iron or a few $'s (KT frequency cards are about £15-25 over here). But they are fully adjustable for level, steepness and type of slope and phase.
Eq cards, both shelving and parametric are also available, at a cost, should you need them.
KT are still making the DN800 (a bit pricey, though still cheaper then their digital xover)
for applications where audio quality is more important then the convenience of digital.
If you want to buy new try the LabGruppen xovers and stay clear of analog ones where the xover frequency is adjustable by a pot! Those are rubbish and can have tolerances of 20%.Behringer and 'high end' I always understood to be mutually exclusive terms...
To find out what B******** is really like try surfing over to a pro sound forum like gearslutz.com. You'll find their stuff most likely under the heading "Low End Theory"!Basically you will be better off with another brand... any other brand.
http://www.rane.com/ac22b.html
Ranes active xover slopes are 24db per octaveAt least the two Rane xovers I have do
My old Rane AC23B had more flexibility than I ever needed (including delays for time-alignment), except that the slope couldn't be changed. Many other active stereo X-overs on the market are similar. If what you're seeking is a higher-order active slope (like 48dB/O), then you might check out Marchand Electronics in NY.www.marchandelec.com
Symmetrix used to have an active 18dB/O unit many moons ago, but you're on your own for finding that one!
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