Extraordinary claims made about Rythmik Subwoofer !!

[snoopy]

Originally posted by badman
Did you start the thread for pure bashing sake? By all accounts, both subjective and objective, the rythmiks are in the elite few for subs of this type. Once you bring horns into the picture, sure, you can get more clean output. But to dig nearly as deep, the cost and size of the horn itself is a lot more than a goodly number of the rythmiks scattered around the room, which would perform much nicer under the test conditions.

Comparing apples to apples, the rythmik is an excellent performer. I've only heard them a couple times, and unfortunately, never in a system where I could give them a fair shake. But I've recommended them based upon reputation and technology many times, and everyone always returns glowing reviews. One friend's complaint was that it had so much super deep output that he had to stack a lot of books on the sub to keep it from dancing around, even though it wasn't audibly distorting.

I never brought horns into the picture. My beef was the claims being made on the website were exaggerated somewhat without being substantiated !!!

There has been plenty of opportunity for the proprietor of the said company to come onto this forum and to put forth his case but instead there have been a whole lot of apologists trying to defend the indefensible !!

[snoopy]

Originally posted by AKSA
No, Snoopy, you are dead wrong and you dismiss pjpoes with appalling arrogance......

Most SET amps measure somewhere up to 5% THD, yet they have qualities which make them amongst the most expensive, sought after amps in high end. You are saying all these audiophiles are idiots, and have no right to enjoy what they clearly enjoy. An absurd, elitist, purist argument.

You should recognise that it is distortion profile which is important; read Geddes. Your argument is entirely academic. Some like it savory, some like it sweet..... that is the market.

Hugh

They're entitled to have their opinion on what sounds good to them. But if you make the claim about the objective performance of something you need to step up to the plate and substantiate it with evidence, otherwise retract the claim !!

[AKSA]

I think this is precisely the point. The lumped THD parameter is not a good or reliable indicator of sound quality and with a global fb amp it is relatively easy to drive the measured THD down low - as the spec wars of the eighties showed. These amps were sold on spec - mid fi Japanese mostly - and they were objective measurements with poor correlation to their sonic qualities.

Now there are many boutique manufacturers, particularly of tube amps, who don't even bother to publish detailed THD specs (though increasingly some are now identifying the order of their amp distortions), and who sell their amps based almost exclusively on review and testimonial - all of it rhapsodising about the sonic qualities, a so-called subjective measure.

These products either succeed or fail in the marketplace, and very often you would find that the buyers audition them in their system before purchase. This is a pretty acid test, I go through it all the time with my products, but it is still subjective because it relies on whether the customer likes the particular 'sound', whatever the hell that is, and interestingly, the math and measure engineers, of whose august body you are doubtless an eminent member, are unable to plausibly explain these preferences. I applaud Geddes for attempting to do just this, and he is a qualified engineer, of whom you should clearly approve, at least in the sense of club membership.

Why is this so? Where is your expertise here, apropos of your earlier comment about the appallingly dishonest non-engineers who from sheer guesswork create these sub-standard products deliberately to fleece naive audiophiles? How can you add to the body of knowledge, improve the correlation referred to by pjpoes between objective measurement and subjective sound assessment. It would be a welcome change to simply bashing the corrupt jockeys who ruthlessly ply their trade at the expense of the uneducated audiophiles out there. Can you improve upon Geddes work?

I'm well aware you do all this for sport, Snoopy. But your approach needs to be tempered with something constructive to say rather than the negative, pro-scientific creed you peddle which frankly does not account for taste in audiophiles at all.

Hugh

[snoopy]

Originally posted by AKSA
I'm well aware you do all this for sport, Snoopy. But your approach needs to be tempered with something constructive to say rather than the negative, pro-scientific creed you peddle which frankly does not account for taste in audiophiles at all.

Hugh

You're not aware of anything. You don't even know me so how can you make this judgment about me !! I've got better things to do than make a sport out of challenging other peoples erroneous claims on their audio equipment. Just as you are critical of the early Japanese equipment then anything today is fair game as well.

The whole audio fraternity doesn't just consist of yourself and your opinions. There are other people who are reading this thread who most likely have a more objective criteria in evaluating audio equipment than you have and I'm sure they would be happy that someone like me has brought this to their attention

If you make a claim about your audio equipment then you need to step up to the plate and substantiate it with evidence. It's not acceptable to obfuscate the issue using paranormal science or audiophile speak !!

[AKSA]

Interesting. Actually, Snoopy, I believe I made an offer to you once before on another forum to meet and discuss these weighty issues and you knocked it back. What makes you think I wish to know you now?

If you make a claim about your audio equipment then you need to step up to the plate and substantiate it with evidence. It's not acceptable to obfuscate the issue using paranormal science or audiophile speak !!

Aha!! So this is apparently about my claims!! I had suspected, but never realised. But I must say it's nice to be thought of as an exponent of paranormal science.

It's a shame you did not wish to meet to discuss these weighty matters, I guess I'll never know now what those beefs really were!! Unless, of course, you choose to pick up the telephone and make a local call! Rather than make these negative comments in a public forum, you might have the opportunity to confront the perpetrator, and state your moral high ground. But I don't believe you have the stomach for that....

Have a nice day,

Hugh

[pjpoes]

Snoopy you really shouldn't dismiss what I say, but instead use this as an opportunity to learn what the current thinking in science is. It is actually you who is using a non-objective assessment, not me. It's not just about liking certain types of distortion, its about the audibility of distortion. You are assuming that someone has proven that there is a correlation between THD and IMD and its audibility, i.e. our ability to hear it (objectionable or not). That isn't the case, and this is nothing new, its just very easy to measure, and so, common practice.

Geddes on Distortion

Dr. Earl Geddes has done honest scientific research which he and his colleagues put through a peer reviewed process. That is an important part of the scientific process, to ensure that incorrect bunk doesn't end up being accepted as scientific fact. It also means that until you earn your PhD, perform an acoustic study on the audibility of distortion which concludes as you have, and put it through the peer reviewed process, you shouldn't argue with it.

Geddes on distortion measurements
This is unfortunately a long read with a lot of crap, but if you read Dr. Geddes posts, as well as those of a few others, you will find great information suggesting what I am telling you, and also suggesting that we have known this for at least 20 years now.

Studies looking at the audibility of distortion at low frequencies has shown that even 10% is often not very audible or audible at all. You have the issue that all speaker produce distortion, and certain distortions are not only more audible, but more bothersome than others. One of the problems with IMD is that the 2nd and 3rd might be low in level, but the 4th is fairly high, but the percentage would still be low. This means that the percentage would imply good distortion performance, but wouldn't be revealing whats really going on. The situation only gets more complicated from there, but that at least scratches the surface as to what is wrong with your argument.

[snoopy]

Originally posted by AKSA
Interesting. Actually, Snoopy, I believe I made an offer to you once before on another forum to meet and discuss these weighty issues and you knocked it back. What makes you think I wish to know you now?



Aha!! So this is apparently about my claims!! I had suspected, but never realised. But I must say it's nice to be thought of as an exponent of paranormal science.

It's a shame you did not wish to meet to discuss these weighty matters, I guess I'll never know now what those beefs really were!! Unless, of course, you choose to pick up the telephone and make a local call! Rather than make these negative comments in a public forum, you might have the opportunity to confront the perpetrator, and state your moral high ground. But I don't believe you have the stomach for that....

Have a nice day,

Hugh

This thread has got nothing to do with your equipment. And there is nothing that can be said to you in private that can't be said on this forum regarding this issue. Besides I suspect that you have actively campaigned to have me removed from this forum and other forums so why would I want to meet you ??

The other thing is I'm not making negative comments. The claim was made on a vendors website about the objective performance of their equipment and so far there has been no explanation as to why the actual measured results are so vastly different.

There is nothing complicated about this issue. You are the one who is complicating it using fallacious arguments. Either step up to the plate or back off !!

[AKSA]

You are retracting now....... and then adding a malicious statement that I have deliberately canvassed to have you removed from other forums. Emphatically wrong. I have never interferred with your membership on SNA, or anyway else for that matter.

Since this is now personal, you are making comments you could later regret, and you do not wish to personally meet to resolve this, I will not comment further as the forum should not be subjected to yet another train wreck. I strongly refute your ludicrous 'objective' claims as pseudo-science and exhort you to read Geddes carefully, searching for flaws, so that you might fully comprehend the psycho-acoustic nature of sound reproduction and what it means for THD.

I might also suggest you build a few amplifiers which are very similar in topology and componentry, making tiny changes, comparing 'subjectively', and try to correlate what you find with the THD measurements. A very good place to start is lag compensation and current mirror topologies.

Adios,

Hugh

[Cloth Ears]

Originally posted by snoopy
The whole audio fraternity doesn't just consist of yourself and your opinions. There are other people who are reading this thread who most likely have a more objective criteria in evaluating audio equipment than you have and I'm sure they would be happy that someone like me has brought this to their attention

Yet it does appear that the whole of this thread does consist of yourself and your opinions. It does not appear that any of the other posters have agreed with your position, so it appears that there is no-one who is "happy that someone like me has brought this to their attention".

I've had posts removed from this thread because I was defending another member of this forum, and by doing this was conducting a personal attack on you - that may be so (it wasn't intended that way and I apologise if you took personal offence). But you have refused to admit that your one man diatribe against this company, (on the basis of one published test whose veracity you cannot even confirm), is also a personal attack.

You may very well have a point, ("You may be wrong but you may be right " to quote Billy Joel), but there's been no new evidence, no contact with the manufacturer, no contact with the conductor of the test and no indication that this may change. It's just repetition of a stated position no matter who posts an opinion to the contrary. It just doesn't read well.

Life is too short - it's all music!

[snoopy]

Originally posted by AKSA
You are retracting now....... and then adding a malicious statement that I have deliberately canvassed to have you removed from other forums. Emphatically wrong. I have never interferred with your membership on SNA, or anyway else for that matter.

Since this is now personal, you are making comments you could later regret, and you do not wish to personally meet to resolve this, I will not comment further as the forum should not be subjected to yet another train wreck. I strongly refute your ludicrous 'objective' claims as pseudo-science and exhort you to read Geddes carefully, searching for flaws, so that you might fully comprehend the psycho-acoustic nature of sound reproduction and what it means for THD.

What has Geddes got to do with an erroneous claim made about the objective performance on someone else's website ?? You haven't even read this thread properly have you ??

Whether Geddes thinks that THD is important is irrelevant. The following is the claim being made on the website. Even the guy selling this subwoofer thinks that low distortion is important so your argument is totally fallacious !! Read the thread properly instead of interjecting

Direct Servo technology: why do we need it?
Conventional subwoofers have extremely high distortion. Well regarded conventional subwoofers typically have measured distortion levels exceeding 15% at 20 Hz at 100 dB. This includes many subwoofers costing more than US $3000. We think this is far too high. A well designed servo subwoofer will achieve distortion levels under 3% under the same conditions.

http://www.rythmikaudio.com/technology.html