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I have a pair of Velodyne DF-661 speakers. These were sold in the mid 1990s for a very short time, and then discontinued due to bad reviews from press. The main design goal was to achieve the lowest distortion possible in a driver. You can read all about this speaker on the stereophile review. They list the amazing distortion numbers on the first page:
http://www.stereophile.com/content/velodyne-df-661-loudspeaker#TPoBAHRTIuOryBUP.97
Yes, these speakers have their problems with a slightly nasaly midrange and a subdued midbass. But the lack of distortion makes them sound absolutely crystal clear.
Since Im so used to listening to the DF-661, I demand my next pair of speakers has similar performance distortion wise. It is a requirement...
Has anybody out there been able to top these distortion measurements? Are there any speakers out there with similar design goals, being able to have incredibly low distortion throughout the 2nd, 3rd, 4th, 5th orders?
Edits: 09/04/16Follow Ups:
Look at the accuton drivers, they are very low distortion. For all their drivers, they show a harmonic distortion graph of distortion % vs frequency. The ceramic and diamond drivers are the best (and most expensive). I have heard speakers with their diamond tweeter and they were incredibly good.
Speakers that use these drivers for woofer, midrange, and tweeter are VERY expensive from what I've seen. Some use just the accuton tweeter and less expensive midrange/bass drivers. The pair I heard were in this category.
I couldn't choose a speaker based on one measurement. Listen and choose. I respect the idea that you want that measurement low. My experience
is only a few manufacturers state that spec anyway.
ET
"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936
What are the waterfall graphs use for?
And what percentage of speakers have those provided? Less than 10% for sure. Those are for measuring room acoustics.
ET
"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936
I think Seas used to make that available with their raw drivers. I remember "reading", because I honestly have no idea what I'm really looking at, about the Seas ER18RNX. People were impressed with it's performance.I have them in my speaker and I do like them A LOT!
I'm sure there are a lot of graphs speaker companies would prefer you never saw. That's why I like building Zaphs kits. He tries.
Thanks for clearing that up
Edits: 09/07/16
When I started in this interesting hobby of ours I was heavily interested in the measured results and bought almost entirely based on those results. It wasn't until I auditioned stuff pseudo blind that I found much better sound from much worse measurements. When I auditioned a big huge massive silver amplifier that I thought was a 500 watt SS beastie which turned out to be an 8 watt SET.
Then when you see the measuring done by the industry that seem to take great pains to make certain designs look good on paper like measuring SS amps at near full level where they perform best but not measuring at ten thousandth of a a watt where they perform crappy. And since most listening most of the time is well under 1/2 of a watt it might be useful to see the measurement where most of the music is mostly played most of the time - not a peak transient at full level where the ear is shoddy at determining quality anyway. Or my Cambridge Audio CD player that lists Wow and Flutter on the spec page? Why? Just to show that it's better than a turntable. Most modern turntables have wow and flutter below human auditory perception anyway. So here we have a bragging rights spec that means zilch in the real world of listening.
Even this distortion debate - one speaker has 0.2% THD at 400hz and another has 0.7% - yeah so what? I doubt either will be differentiated in real world transients (music playback).
Well I know the 0.5% difference.
But I'm also completely crazy as well!
Yep, I hear ya. The real world can really screw up those numbers chasers.
Just a guess but dynamic drivers with underhung voice coils are more linear than the more conventional overhung voice coil. And that makes me think they would have lower THD. Off the top of my head that would include companies like ATC, Magico, Rockford and a few others.
Yes, these speakers have their problems with a slightly nasaly midrange and a subdued midbass. But the lack of distortion makes them sound absolutely crystal clear.
Are you looking for crystal clarity? Or are you looking for lowest harmonic distortion? They may be related, but they're not the same thing.
The crystal clarity you hear is far more likely to be a result of the elevated frequency response from 500Hz to 3KHz than the low distortion numbers. With most reasonably designed loudspeakers, distortion is insignificant relative to other aspects of performance except in the bass. You would be very hard pressed to hear the difference between a 2nd harmonic of -45 dB at 1KHz and -60 dB at 1KHz. Whereas a few dB difference in frequency response would be obvious.
The DF-661 is a bad design because it sacrifices a first-order performance metric to chase a third-order performance metric. Stereophile's listening window and in-room measurements indicate that the drivers aren't even level matched. The woofer is ~6dB down from the midrange and the tweeter is ~3dB down from the midrange. Matching the levels of the drive units is one of the most basic elements of loudspeaker design. If you can't achieve that, then your design is a non-starter and the rest of the numbers don't matter.
It's like designing a fighter jet with a Mach 3 dash capability but with such a small fuel fraction that it can't fly far enough to intercept anything.
Based on your previous posts, it's hard to know what kind of sound you're after but I did see that you're on a tight budget. If you're looking for a relatively low distortion loudspeaker that sounds crystal clear and has objectively good frequency response, try the Revel M106. You can find a review with distortion measurements on Soundstage.
"a slightly nasaly midrange and a subdued midbass. "
Whatever floats your boat.
:)
For lowest THD Quad in stats, Revel Ultima Salon 2 in cones. I own neither, but have owned both, no home cookin' here.
Both also sound low distortion.
I would not put all you eggs in the measurements basket nor would I narrow it down to just one measurement. As JA noted there were a bunch of other things he didn't like in the speakers even though distortion was great.
Far too often lesser measuring equipment sounds so very VERY much superior to something with supposedly excellent measuring credentials. It's also true to note however that some stuff sounds quite good and it also measures very well. The issue is that you rarely get a complete set of relevant measurements.
Horn speakers with sensitive, short excursion drivers have some of the lowest THD measurements. Low driver distortion is the upside to horns. Horn colorations are their downside.
Overall distortion/coloration levels - or what is actually heard at the listening seat - is the most important parameter to consider, I think.
nt
I'm not a technical expert, but I believe that THD is measured under conditions that bear little or no resemblance to actually reproducing music. I've found no correspondence between THD and how much I enjoyed a component.
I on the other hand have found a quite close correspondence between a speakers THD and how much I enjoy them.
IME > 1% THD in the mid and treble is quite audible and annoying.
Luckily it is very easy to keep THD of the other components one or two orders of magnitude below 1%.
"Correlation", not "correspondence".
THD is just that: Total Harmonic Distortion. It says nothing about the spectral make up. A lot of 2nd and a little 5th sounds way different than a little 2nd and a lot of 5th.
Also, the difference in sound character from, say, one trumpet to another, or one saxophone to another, is highly dependent upon the relative strength of the various overtones of the fundamental, i.e., the make-up of the distortion produced by the instrument! This is why it's humorous when a person says that this-or-that speaker or system sounds "just like the real thing".
:)
The only people who could have any substance with a statement like that are recording engineers since they are usually the only ones who get to compare the real thing to what comes out of their speakers.
Unfortunately digital has democratised the recording process to such an extent that there are now a large number of 'engineers' and 'producers' who know very little and are seemingly deaf.
Are the real people that effect what we hear is stereo reproduction: They compile the recorded tracks from artists, musicians and performers in a listening room that doesn't muck resemble any room audio enthusiast listen in, played through loudspeakers and equipment that similarly doesn't reflex audiophile gear, onto a two or more channel "soundscape" they they create while adjusting "imaging", phase, tone, dynamics, and several other parameters to create the "Art" that becomes a pair of digital or Analog signals that reside on the "software" we send into our playback systems.
It is the miracle of desire and fallibility of human perception that allows us to emotionally respond to the playback as if it sounds "Real".
The fact that most of us do not recognized this, or if so, minimize this fact as "out of our control", is also a miracle - in a fashion - as it created the industry of hi-fi that we know and love.
Could you imagine perfect recordings? Standardized studios and environments with optimized mics and diffusion in the spaces to capture the essence of the wave forms that are then processed in a way to provide a consistent soundscape appropriate for the music performance - a listening position preferred by the engineer? The tracks also include metadata that will allow your home playback system to recreate that environment - based on a pre-assessed impulse response of your loudspeakers and room and stored in your equipment.
Actually the technology exists now for the implementation of such a process. We will likely see it in home theater reproduction first probably from Sony - in partnership with Dolby or DTS.
Personally, I like to spin my own - as a little rear reverb or presence boost on a track - Set the playback of my system so it is optimized for my preferences and pleasure. A little EQ to move Diana Krall and her piano a little further away in my living room - same for Frank S. but I can't get the band up front enough to be live with Frank. I'll add a little delay or reverb as needed - or I can spread the image a little, though that can be a little dicey if there is anything panned hard left or Right in the recording - or worse, when the engineer had already speread the image beyond left and right (think "dark side of the moon" synthesizer "helicopter".
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
You missed the point.
The point being that when it comes to people judging speakers recording engineers are usually the only ones who ever get to compare their speaker's output to the actual live voice/instrument.
Unlike recording engineers mix/mastering engineers and producers care little what the original performance sounded like, it is not even necessarily in their job description.
Their job is to make the recording sound like they THINK it should sound like.
When it comes to THD of any speaker no manufacturer will ever give you the number for the lowest octave, just check any speaker specs.
The reason is obvious, at the lowest octave the THD is HUGE.
Vahe
many folks like added woofer distortion.
Why? Because it is primarily doubling distortion - simply more bass at twice the fundamental frequency. :)
I think in your rush to type you missed an 'n'. ;-)
Many moons ago I came across a test of high-$ subwoofers including THD measurement.
Only two of the eight or ten subs tested stayed below 10%THD at normal volume.
Both were studio-grade subwoofers, one from PMC and the other Genelec.
Here is one compendium:
http://www.data-bass.com/systems
And another:
http://www.hometheatershack.com/forums/subwoofer-tests-archived/
Unfortunately, a lot of the more recent tests start at 105 dB and go up to 115 or even 120 dB. So the distortion they're measuring is almost entirely dynamic compression. I don't think that's very useful since most people will never play them that loud.
I look more at the 90 dB and 95 dB results (where I can find them) since that's about the loudest I play them. At 95 dB, there are a lot of subs that can hit 20 Hz at 10% THD or less, even some sealed 12 inchers. Some of the biggest subs are at 2-3% THD at 20 Hz and 95 dB.
Take a look at the sidebar on "page 90" of the Polk SDA-SRS review linked-to. Julian Hirsh reports "we have never measured a low-bass distortion level as low as that of the [Polk] SDA-SRS."
Specs are 0.7% THD from 70 to below 20 hz except for a rise to about 2% that was traced to a measurement anomoly ("hum picked up by the system") The THD was primarily second-harmonic.
This seems...spectacular...compared to the ~10% THD of the subwoofers mentioned.
Now, being a vented (passive-radiator) box, of course the bass became increasingly out-of-phase below 53 hz; and I wouldn't place any bets on how, exactly, the THD measurements were taken. At 2.5 volts--supposedly 90 dB in the midrange--the bass output seems shy on volume. I have the sense that the article was written to appear all scientific and thorough, while in fact presenting "best-case" info. But I've been wrong before.
0.7% THD at 20 Hz is extremely low, even at 90 dB. Almost seems too good to be true.
The big Funk Audio subs might be able to equal that. Unfortunately, the distortion measurements made on the FW18 and FW21 started at 110 dB. The FW21 stays under 1% THD through the middle and upper bass at 110 dB, and it has a relatively slow rise in distortion at lower frequencies. So it's conceivable that it could remain flat at 1% or less down to 20 Hz if tested at 90 dB. Nothing else I've seen comes close. You're doing well if your sub can stay under 2-3% THD at 90-95 dB over most of it's range above 30 Hz. And all but the biggest subs show a sharp rise in distortion below 30 Hz.
Cheers!
Thanks for those, quite interesting.
Seems ported subs are on average quite a bit better than sealed when it comes to distortion.
If I remember correctly drivers start to produce more 3rd order once they run out of linear excursion so that would be something to look for.
I was hoping to find some incarnation of my woofers but no luck so far.
It is hard to get those numbers these days for complete systems, however, most of the driver units these days from reputable companies today have fairly low distortion levels, except at the bottom range.
For low distortion bass you need large drivers. Good new is that our hearing is much more tolerant to distortion at lower frequencies than upper ranges.
Also, many electrostatics, ribbons and some planars, like my favorite Eminent Technology LFT-VIIIs, offer low distortion levels through most of the range as long as not pushed too hard.
Of course, it will be hard to find a speaker with such abomination of the frequency response as DF-661.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"One must be sane to think clearly, but one can think deeply and be quite insane."
Try ME Geithain if you can get them where you are.The larger ones show very little THD ( <0.45% from 100-10 000Hz at 96dBspl) and the K models also have a cardioid bass response down to at least 30Hz.
The 901K cost £8.5k per pair in black or £10k with a nice veneer.
Since they are active you would need a preamp with balanced output.
If you click on 'Acoustic Diagrams' you will find the distortion graph.
Edits: 09/05/16
As with most such questions it would help us to recommend something if you would kindly give us some idea of your budget.
Assuming that budget is not of prime importance for the moment, the more expensive ranges of ATC speakers using their super linear magnetic material (look for SL in the model number) are renowned for particularly low distortion though I can't give figures offhand. I am thinking of e.g. the Classic range. Worth stretching to the slighly more costly active models IMO. The smaller models (say the SCM 50ASL) I think are around $20K in the US for those with a nice veneer finish (the speakers not the purchasers :-)
The Stereophile review of the Velodyne DF-661 was less than flattering. The THD was indeed low but so was the sound quality...
"As promising as I feel the DF-661's drive-unit technology to be, I was very disappointed in its overall sound quality. Imaging seemed laterally precise, but there was insufficient soundstage depth. There was no low or midbass at all, which endowed the speaker with a very lightweight character. The lower midrange—the power region of orchestral sound—sounded lean and lacking in clarity. And the upper midrange sounded both too forward in level and too aggressive at anything other than moderate listening levels. Playing a recording already too bright in its intrinsic tonal balance—Queen's Live at Wembley '86 (Hollywood HR-61104-2), for example—was an unpleasant experience on the Velodynes.
As to the benefits of Velodyne's Distortion-Free design philosophy, I couldn't get past the DF-661's departure from a flat response—its linear distortion, if you will—to hear them."
Maybe these...
JBL has some papers on their compression midrange cone driver CMCD.
Quad, King Sound, Martin Logan, Apogee, Acoustat, and Magnepan all have extraordinarily low distortion.
They are all electrostatic or planar magnetic.
Meat; It's the right thing to do. Romans 14:2
Ken Kessler compared the Quad 989 to the the B&W N801 - the N801 had FAR less THD than the Quad. It was also pair matched better (albeit a still lousy +/-2.9dB).
with the 989s or the measurements.Just the laws of physics doesn't permit what Mr Kessler was saying..There are three types of speakers that are considered the worlds fastest loudspeakers...It has always been common knowledge that ESLS are the fastest speakers with the lowest distortion just by the fact that the diaphragm is so light and is driven at the perimeter to where there is no drag coefficient to speak of that will come into play.ESLs also have very few crossover components unless it's a multi panel speaker like my CLXs and even those are using two toroid audio transformers .There isn't too much in the signal path and even my old ML Monolith 2s,I used to drive direct with the Citation 2 amps but had an input R/C network rolling it off at 100cps and I let the powered subs do the rest.
The next ones are the planar magnetics like Apogee and Magnepans.Those also have the speed by nature of design of the quasi-ribbon and the way that magnets move the ultra light diaphragm from the outer edges like the ESL does.
Last but not least would be compression field coil drivers.Those babies are wicked fast with low distortion and also have the dynamics along with the price..YIKES.
I would be curious as to know the method Ken Kessler used to measure the distortion in the B&W and Quad speakers and how he arrived at the measurements..I find it hard to believe that a conventional speaker with several crossover points and conventional cone drivers would measure lower distortion than either an ESL or Planar Magnetic for that matter.
Now I realize that distortion doesn't tell the whole story and many tines doesn't mean much.. Just saying.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
The low frequency distortion of an ESL comes from a couple things. First, for it to get LF at all, being a dipole, it has to either use resonance or some kind of EQ to compensate for the inherent back-cancellation rolloff..... most ESLs use both, the diaphragm resonance is set to a value that gives bass while still keeping stiff enough suspension for allowing for good behaviour at higher freqeuqncies. The original QUAD used a higher step-up ratio to allow for bass EQ, which means the diaphragm has to move further, which pushes it further into nonlinearity. The solution is to make it bigger or change to a cone driver at LF, which some designs do.The second factor in an ESL is the step-up transformer core, which likes to saturate when fed from high level low frequency, like all transformers do. Just the nature of the beast. Voice coils and magnets have difficulties, too, but they aren't usually being pushed as hard to get output as ESLs.
While the ESL principle can have very low distortion at midband and HF, it doesn't do so well at VLF. Not really many (maybe any?) dipoles do, they are at a disadvantage down very low because front and back cancel. Doesn't meant they can't sound good though.
_
Make super easy diffusors:--> http://www.diyaudio.com/forums/everything-else/269366-making-easy-diy-depot-sound-diffuser-panels-step-step.html#post4215464
Horn Design Spreadsheet:--> http://libinst.com/SynergyCalc/
Edits: 09/09/16
First - I got the model wrong it was the 2905.In the lab report section under lab report the last line they say the speaker was bettered by the B&W 802 for THD. (got the B&W wrong from memory too) but hey close enough - the 2905 is supposed to be the better speaker over the older Quads.
And to be fair the reviewer loved the speakers regardless and liked them better than the Scintilla (although that IMO isn't a shock as I have auditioned both as well and came to that conclusion in about three notes. ESL is simply a helluva lot more natural sounding than ribbons. And you can run a SET on them.
PS I also like Quad - I just find them too expensive and as Ken notes they will never do the things is favorite boxed speakers can do - I can't live without those things - perhaps Ken and others can. Although Apparently Ken now has Sonus Faber which he claims is better than ESL on vocals - so whatever. To be fair he reviewed these Quads in 2006 and it's 2016 so a lot can happen - like he found that midbass is tough to live without - and dynamics, and bass and treble.
It's the pair matching that is rather horrendous
Edits: 09/07/16 09/07/16
I knew you liked the Quads from past posts and I realize that your response to the OP was simply reiterate the fact that we can't go by distortion as a tell all to speaker quality and I agree.. I was just curious about that reviewer because I always equate lower distortion to faster speeds and I have never seen any conventional cone drivers to have the ability to match the speeds of the low mass planar types..That's all I was saying.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
I was just curious about that reviewer because I always equate lower distortion to faster speeds and I have never seen any conventional cone drivers to have the ability to match the speeds of the low mass planar types.
Why would you equate lower distortion to faster speed? The only case I can think of when they've had anything to do with each other was back in the days when amplifier slew rate was low enough to cause TIM.
Also, the mass of a conventional tweeter dome is less than a big sheet of coated mylar. The frequency response of a Quad ESL doesn't even make it to 20 KHz. That's not very fast.
The speed of sound in air at typical room temperature, air pressure and humidity is about 1,129 feet per second, or just a little less than one foot per millisecond. I am puzzled about what the poster meant when he wrote that he equates lower distortion with faster speed.Edit: Seriously, did I actually write "less", rather than "more"?
;)
Edits: 09/10/16
The original Infinity Modulus system might be just the ticket.
Edits: 09/14/16 09/14/16
The issue may relate to volume level which is not always stated. And what frequencies.
I maintain that all speaker types have their pros and cons and as the OP referenced JA - well the speaker had very low distortion but the reviewer rather disliked it because of tone etc.
I think it's rather easy to push a panel and single driver to compression - whether that shows up as distortion I don't know but the 2905 and other panels I've tried generally don't do any midbass or bass dynamic drive. So sure it may not distort but then it's also not reproducing the oomph that is on the recording. So the choice is 80% of the bass material wit 0.01% THD - or do you want 95% of the bass material but with 0.8%THD? (subjective listening).
It may be that it's something you have to "get used to" and over time you will gravitate to the sound. I grew up with horns and dynamics to me is the lifeblood of music.
My old AN J/Spe did quite well in THD measurements of Hi-Fi Choice. Interestingly the THD was much lower in the bass.
Living in HK I think I could actually own a Quad - the high humidity though would concern me. And they would have to be placed close to side walls. If I do bring in a panel - the tall skinny variety would likely work better. I've always wanted a panel - and a good horn. I like the different flavours
Living in HK I think I could actually own a Quad - the high humidity though would concern me
That can be a concern but I run a dehumidifier 24/7..My ML CLX system is setup in the basement because it's very roomy but when I had the Beveridge model 3s,I had a hell of a time keeping the panels working because they didn't like the Michigan Climate where I live because I'm a in valley.I sold the speakers for what I had into them so I lost nothing and the guy moved to Arizona and had no problems with them..The Acoustats I had,I never had a lick of problems with either.I agree with everything you just posted and you are right in that all speakers have their pros and cons..This is why I use dynamic speakers for the bass and ESLs for mids and highs..I like all speaker types tho.. You will notice that many people that like ESLs,also love horns as well and vice versa.Same with Maggies or Apogees. We like that openness.
Are you in Hong Kong or Canada?
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
I live in Hong Kong now because well they actually pay teachers a real wage unlike North America. You know I worked as an accounting clerk back in 1999 making $40,000 a year with no education. Today - 2016 a starting teacher with 5.5 years minimum (requiring at least a BA and Bed start at $45,000). I would have left the field if I stayed in Canada.
The upside is I have more money to spend on audio as my apartment by the government is paid and I don't need a car here. So while that is nice - the downside is that my apartment isn't much bigger than fifth wheel.
So big speakers are out of the question. The near wall and corner AN E is understandably a great choice in a small apartment but most front ported or sealed cabinets will work fine. And the ceilings are very high so tall narrow speakers would work. Given the entire thing is concrete there is no bouncy walls or floors to sing along with the music which is also a big plus. Especially for my suspended turntable.
One attractive thing about Quad is the high impedance and general ease of drive. The problem is that I leave for a month every year so I would need to keep the dehumidifier on all the time when I am not there. I'm not big on leaving electronics on 24/7 for 30-35 days. A dehumidifier I believe require the water to be removed from the tanks frequently.
The alternative is a ribbon and I just haven't liked the ribbons. Something is lost. I could see myself with a ESL though. I may look again at King Sound. I met the owner here when we were both CD player shopping a few years back. He bough a Cayin (apparently for a friend who wanted the model) and I bought the Line Magnetic 215.
"I live in Hong Kong now because well they actually pay teachers a real wage unlike North America."
Yet, you live in a small apartment, while pretending to be a reviewer.
I gotta get me a gig like that.
I am a reviewer nothing to pretend about. Granted I may not be your cup of tea. It's not like there is a reviewer university that doles out degrees.Stereo equipment should work in a small room too. It merely limits the kinds of speakers I can review. But more people live in apartments than in houses. Especially true outside of North America. So my abode is more in line with more people. And there are plenty of readers in Asia and Europe.
My apartment is made of all concrete a big trump card over most north American homes that are made of wood flooring and wood walls and plaster wall dividers.
Edits: 09/08/16
Have you got any measurements to back that up?
The planar I have found measurements for do not look in any way promising.
Magnepan 1.7 (see link). Useless below 600Hz but would make a good if quite large mid/tweeter.
The graphs show that a Magnepan 1.7 is not a good subwoofer at relatively high SPL, which is what everybody knows.
But the same THD of distortion at 50Hz is much less audible than that same at 1kHz, where the distortion products lie in the ear's most sensitive frequency range. (1.5-4 kHz?)
Have you actually looked at the THD over frequency curve?
They don't really excel anywhere in the audible spectrum and are seriously flawed below 600Hz.
I never had great expectations for them in the low bass but 10% at 400Hz at a relatively low 90dB is unacceptable.
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