Extraordinary claims made about Rythmik Subwoofer !!

[snoopy]

Originally posted by seanzozo
Snoopy,

OK I am done...If it isn't obvious that the Rythmik is at least a good deal and well engineered -- then well I give up.

Sean

Forget about the Velodyne DD-18 then. That is not the issue here. Look at the THD level of the Rythmik subwoofer at 105 dB @ 30 Hz !! Surely you're not saying that this is good engineering ??

Now look at the claims made by the manufacturer !!

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.

Where is the under 3% distortion as claimed ?? Am I missing something here or does anyone else see what I am seeing ??

[snoopy]

Originally posted by seanzozo


None of this considers the possible difference in testing regimes. Because I am anal I read the regimes AND I went to find an overlapping test and found that the testing is not comparable.

The ULTIMATE AV tests place the mic .2-.5m but it appears that the normalize to 1 m becasue there is about a 6db difference between tests there and the home theatershack tests which use 2m placement-

Correct me if I'm wrong but the theatershack tests are done using ground plane measurements which incur a 6dB gain which is why the microphone is set at a distance of 2 meters and not 1. So the results have not been diminished as you claim they have

[mbutzkies]

A couple of things.

Rythmik audio has an adjustable F3, it was tested at 14Hz, if htshack tested at 28hz it would have significantly better distortion numbers. it is trading excursion for extension.

Second, The Rythmik is billed as a SQ sub not an SPL sub. Don't expect a 12" sealed sub to compete with 18" sealed subs, or 12" vented subs in a high spl test.

Third, The distortion by order test is much more indicative of SQ than distortion by db.

Fourth, I agree with what seanzozo said.

[Cloth Ears]

Originally posted by snoopy
Correct me if I'm wrong but the theatershack tests are done using ground plane measurements which incur a 6dB gain which is why the microphone is set at a distance of 2 meters and not 1. So the results have not been diminished as you claim they have

snoopy,

You've decided to bash Brian and his subwoofers on this forum. You don't appear to have ever listening to, or measuring them yourself. You've decided to take this upon yourself without even asking your authority (Ilkka from hometheatershack) for his opinion on the results of his testing. And you ignore his posted comments, such as:

• The 12" sealed Rythmik Audio DS is generally a really good subwoofer. It has versatile settings for extension and shape of the frequency response, which both help to match the subwoofer and the room.
• The upper end stays really clean even when pushed really hard, but when listening to material with lots of high amplitude low frequencies (HT use), you will start to hear some amp clipping noises (ticking, crackling) at certain point.
• Brian decided not to use any amp limiters, which helps to preserve the maximum dynamic capability of the amp. But as you can see from the THD graph, distortion grows pretty large below 30 - 40 Hz when pushed hard. If one is using one of the lesser extension settings, naturally the low end compression and distortion are lowered too.
• You should notice that I used the lowest extension and low-Q settings in my tests, which make the compression and THD graphs look somewhat worse when compared to subwoofers with lesser extension.
• So always remember to check the real output and extension from the frequency response and maximum output graphs when making any comparisons.

The Rhythmik subwoofers are some of the best available for the price, and would show better than any pre-built items at 4 times the price. What's your beef with them?

Consider yourself corrected !

[Cloth Ears]

snoopy,

I finally read your posted quote from the Rythmik site:

Originally posted by snoopy from the Rythmik website
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.

Where in that quote does it say that Rythmik subwoofers achieve 3% distortion at 100dB? And, would you seriously expect that every subwoofer in the range would achieve the same specification? I would find it much more realistic that this might be achieved in the largest subwoofer, using the reflex enclosure, and the 20Hz high-pass filter - not the smallest sealed enclosure that is sold by this company.

(This was supposed to be in the previous post, but I forgot it and tried to edit too late.)

[snoopy]

Originally posted by Cloth Ears


snoopy,

You've decided to bash Brian and his subwoofers on this forum. You don't appear to have ever listening to, or measuring them yourself. You've decided to take this upon yourself without even asking your authority (Ilkka from hometheatershack) for his opinion on the results of his testing. And you ignore his posted comments, such as:[i][list]
[

The Rhythmik subwoofers are some of the best available for the price, and would show better than any pre-built items at 4 times the price. What's your beef with them?

Consider yourself corrected !

Excuse me !!! I did not set out to criticize any particular person in fact I never made reference to the guy who owns the company because I don't even know him or his name. I just saw what was written on his website and the test results from an independent tester which did not correlated very well with the claims being made. Even blind Freddy can see this !!

All things being equal, those tests run by hometheatershack were applied to a dozen other sub woofers so it is fair to make relative comparisons as another poster did even if you think those original tests are flawed.

My beef is that I don't condone misleading or false advertising of any sort. People like yourself should be thanking me for bringing this to everyones attention rather than trying to sweep it under the carpet.

[Cloth Ears]

Originally posted by snoopy
Excuse me !!! I did not set out to criticize any particular person in fact I never made reference to the guy who owns the company because I don't even know him or his name.

The company's been set up by one person, ipso facto, if you criticize the company, you criticize the person. But I understand that you didn't mean to...

Originally posted by snoopy
My beef is that I don't condone misleading or false advertising of any sort. People like yourself should be thanking me for bringing this to everyones attention rather than trying to sweep it under the carpet.

Unfortunately it isn't false or misleading. You just didn't read it properly. Your quote doesn't say that Rythmik subwoofers achieve any particular level of distortion. Only that "A well designed servo subwoofer will achieve distortion levels under 3% under the same conditions." Nowhere on the site does it claim 3% distortion at 100dB at 20Hz.

I also notice that you seemed to miss out the sections where Ilkka (of hometheatershack) praises the unit. And you still insist on using his test as the basis for your derogatory comments.

Continuing on in this vein indicates that you have some sort of serious problem in admitting your own mistake in misreading the stuff on the Rythmik website.

[snoopy]

Originally posted by Cloth Ears
snoopy,

I finally read your posted quote from the Rythmik site:


Where in that quote does it say that Rythmik subwoofers achieve 3% distortion at 100dB? And, would you seriously expect that every subwoofer in the range would achieve the same specification? I would find it much more realistic that this might be achieved in the largest subwoofer, using the reflex enclosure, and the 20Hz high-pass filter - not the smallest sealed enclosure that is sold by this company.

(This was supposed to be in the previous post, but I forgot it and tried to edit too late.)

If it doesn't say this then the vendor of this product is essentially shooting himself in the foot by implying that his own product is NOT "well designed", using his own words.

The problem is that the claims made on the website are not backed up by any objective measurements and now that I have found some measurements done by an independent body, some people on this website are still in total denial !! I don't get it

[snoopy]

Originally posted by Cloth Ears



Unfortunately it isn't false or misleading. You just didn't read it properly. Your quote doesn't say that Rythmik subwoofers achieve any particular level of distortion. Only that "A well designed servo subwoofer will achieve distortion levels under 3% under the same conditions." Nowhere on the site does it claim 3% distortion at 100dB at 20Hz.

Yes I did read it properly and are you then saying that this criteria doesn't apply to his own product in which case it is a direct admission that his product is not "well designed", using his own words !! I quote again directly from the website:-

A well designed servo subwoofer will achieve distortion levels under 3% under the same conditions.

Originally posted by Cloth Ears

I also notice that you seemed to miss out the sections where Ilkka (of hometheatershack) praises the unit. And you still insist on using his test as the basis for your derogatory comments.

Which is why I invited comments from others regarding the objective measurements.

[lumanauw]

Gentlemen, please remember that we don't tolerate personal attacks around here.