Official Rythmik Audio Subwoofer thread - Page 667 - AVS Forum | Home Theater Discussions And Reviews
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Old 08-02-2015, 07:58 PM
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Originally Posted by tvuong View Post
^^ that is crazy great deal. Where are you?
NW Ohio
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Old 08-02-2015, 08:38 PM
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Originally Posted by jd10ac View Post
Is there anyway to find some output numbers on the L22? I also want to verify that at 20hz it is 2db above the highly regarded lv12. I am thinking of replacing my sealed 15" sub with the l22 and was hoping it would have similar output.
You mean besides the ones on the Rythmik site? http://www.rythmikaudio.com/products1.html Brian is pretty exacting, and exact, so I would trust his numbers. He's another anal design engineer...

Since this keeps coming up lately, here is the table from the Rythmik site:

Output comparison

At 20 Hz, our subs vary in their maximum output capability. The output at 20 Hz is shown relative to F12.

F12: 0db (baseline)
F8: -1.5db
L12: -1db
LV12R: +2.5db
E15HP: + 3.5db
L22: + 4db
F15HP: +4db
FVX15: +6.5db
FV15HP: +9.5db
F25: +8db

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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Old 08-02-2015, 08:45 PM
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Originally Posted by DonH50 View Post
You mean besides the ones on the Rythmik site? http://www.rythmikaudio.com/products1.html Brian is pretty exacting, and exact, so I would trust his numbers. He's another anal design engineer...

Since this keeps coming up lately, here is the table from the Rythmik site:

Output comparison

At 20 Hz, our subs vary in their maximum output capability. The output at 20 Hz is shown relative to F12.

F12: 0db (baseline)
F8: -1.5db
L12: -1db
LV12R: +2.5db
E15HP: + 3.5db
L22: + 4db
F15HP: +4db
FVX15: +6.5db
FV15HP: +9.5db
F25: +8db
I have seen those numbers but I am looking for something more like cea numbers that are easier for a novice like me to kind of make sense of.
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Old 08-02-2015, 09:01 PM
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Isn't CEA for car amplifiers? Subs are typically measured for output SPL... I am not very familiar with CEA specs so I must not understand.

* Look here: http://www.audioholics.com/subwoofer...p-measurements

That is for the FV15HP; you can subtract 5.5 dB'ish for the L22. Or, for the L22, at 1 m:

111.0 dB at 20 Hz
116.5 dB at 25 Hz
121.3 dB at 32 Hz
123.5 dB at 40 Hz and above (more or less)

HTH - Don

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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Old 08-03-2015, 02:14 AM
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If anyone is interested I just listed my (2) F25's for a very very discounted price. Have to sell off my HT room completely due to moving. Loved these subs immensely while I had them.

Wow that is a great deal, I'm tempted.
Shipping abroad would go?
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Old 08-03-2015, 05:04 AM
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Originally Posted by DonH50 View Post
Isn't CEA for car amplifiers? Subs are typically measured for output SPL... I am not very familiar with CEA specs so I must not understand.

* Look here: http://www.audioholics.com/subwoofer...p-measurements

That is for the FV15HP; you can subtract 5.5 dB'ish for the L22. Or, for the L22, at 1 m:

111.0 dB at 20 Hz
116.5 dB at 25 Hz
121.3 dB at 32 Hz
123.5 dB at 40 Hz and above (more or less)

HTH - Don
He is talking about CEA 2010 test numbers I think. Most modern DIY sub makers have at least one model with these results publish, and Databass has a ton.
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Old 08-03-2015, 05:19 AM
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Thanks, figured that out, and the link and numbers I provided are from CEA-2010 test results. I have not kept up with all the standards since letting my IHF CAC lapse...

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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Old 08-03-2015, 06:27 AM
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Originally Posted by jd10ac View Post
Is there anyway to find some output numbers on the L22? I also want to verify that at 20hz it is 2db above the highly regarded lv12. I am thinking of replacing my sealed 15" sub with the l22 and was hoping it would have similar output.
I believe you have XS30 which has two 15" drivers. Output from L22 is similar to that F15HP/E15HP, the 15" high power model.

Regarding CEA numbers, I think the most important max output data is 20hz which is the number we provide as reference. This is because 20hz is the number in practice determines the max "volume" you can set on your AVR. Once the SPL at 20hz exceed the max output, the limiter is going to kick in and that bring downs the entire frequency band subwoofer plays. 20hz is not really audible. So it needs to a lot of signal strength and that combined. At the same time, subwoofer is normally least efficient at the bottom end of FR. These two factors make the 20hz output more important.

In terms of Data-bass subwoofer testing, we feel the limitation of the test method penalize the subs that extends low and that makes the measurement looks bad. For instance, if a sealed sub is down 10db at 20hz (vs another sealed sub down only 3db at 20hz), the former is going to have better distortion number at 20hz becasue it is down at least 7db more than the other model. That is why I keep joking the best bass is no bass even from measurement point of view. The same is true for impulse response and waterfall plot.

Last edited by Rythmik; 08-03-2015 at 06:33 AM.
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Old 08-03-2015, 09:18 AM
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Originally Posted by Rythmik View Post
I believe you have XS30 which has two 15" drivers. Output from L22 is similar to that F15HP/E15HP, the 15" high power model.

Regarding CEA numbers, I think the most important max output data is 20hz which is the number we provide as reference. This is because 20hz is the number in practice determines the max "volume" you can set on your AVR. Once the SPL at 20hz exceed the max output, the limiter is going to kick in and that bring downs the entire frequency band subwoofer plays. 20hz is not really audible. So it needs to a lot of signal strength and that combined. At the same time, subwoofer is normally least efficient at the bottom end of FR. These two factors make the 20hz output more important.

In terms of Data-bass subwoofer testing, we feel the limitation of the test method penalize the subs that extends low and that makes the measurement looks bad. For instance, if a sealed sub is down 10db at 20hz (vs another sealed sub down only 3db at 20hz), the former is going to have better distortion number at 20hz becasue it is down at least 7db more than the other model. That is why I keep joking the best bass is no bass even from measurement point of view. The same is true for impulse response and waterfall plot.
Thanks for the reply, I do currently have an xs30se but was wanting to compare the L22 to the much smaller s1500 I previously had. Given the size and shape of my room I should probably be looking at the fvx15 but the much smaller footprint of the L22 has me intrigued for waf.
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Old 08-03-2015, 11:20 PM
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So I finally got around to reading this and thought it was brilliant. All along I've been thinking that the damping control increases the effort of the servo to tame ringing, when actually the opposite is true: mid and low damping tells the system to add ringing electronically because the intrinsic Q of Rythmik sealed subs is only 0.3. It's all the more impressive to think that Brian is building 0.3 Q subs and is adding ringing to simulate what many other subs on the market do by their nature: ring.

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Last edited by Soulburner; 08-03-2015 at 11:24 PM.
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Old 08-04-2015, 05:19 AM
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@Soulburner

That's interesting. I've been running mid dampening as of late and feel it's a good compromise between high and low. At least according to the measurements I took a while back.

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Old 08-04-2015, 05:47 AM
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Originally Posted by Soulburner View Post
So I finally got around to reading this and thought it was brilliant. All along I've been thinking that the damping control increases the effort of the servo to tame ringing, when actually the opposite is true: mid and low damping tells the system to add ringing electronically because the intrinsic Q of Rythmik sealed subs is only 0.3. It's all the more impressive to think that Brian is building 0.3 Q subs and is adding ringing to simulate what many other subs on the market do by their nature: ring.
Any kind of frequency dependent high-pass filter is accomplished with ringing (analog or digital).
For clarity, high damping = low Q = less ringing.
The Rythmik filter switches refer to damping (1/Q).

Last edited by rcohen; 08-04-2015 at 06:22 AM.
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Old 08-04-2015, 06:01 AM
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Im still on 14hz, Hi damp, rumble filter Off/1.
wyld0 and Iain- like this.
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Old 08-04-2015, 07:18 AM
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Originally Posted by Soulburner View Post
So I finally got around to reading this and thought it was brilliant. All along I've been thinking that the damping control increases the effort of the servo to tame ringing, when actually the opposite is true: mid and low damping tells the system to add ringing electronically because the intrinsic Q of Rythmik sealed subs is only 0.3. It's all the more impressive to think that Brian is building 0.3 Q subs and is adding ringing to simulate what many other subs on the market do by their nature: ring.
What document are you referring to?

It clearly states on the PEQ page that "High Damping" switch position controls excessive "ringing", whilst "Low Damping" position has less effect on this anomaly:
http://rythmikaudio.com/amplifier_controls.html
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Old 08-04-2015, 07:25 AM
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Originally Posted by Iain- View Post
What document are you referring to?

It clearly states on the PEQ page that "High Damping" switch position controls excessive "ringing", whilst "Low Damping" position has less effect on this anomaly:
http://rythmikaudio.com/amplifier_controls.html
I think he just got mixed up when posting.

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Old 08-04-2015, 11:42 AM
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Im still on 14hz, Hi damp, rumble filter Off/1.
Same, only with no ports on my F12
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Old 08-04-2015, 11:43 AM
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Originally Posted by Iain- View Post
What document are you referring to?

It clearly states on the PEQ page that "High Damping" switch position controls excessive "ringing", whilst "Low Damping" position has less effect on this anomaly:
http://rythmikaudio.com/amplifier_controls.html
That's what I thought as well - but read that post I linked to:

http://forum.ascendacoustics.com/sho...3395#post33395

Last edited by Soulburner; 08-05-2015 at 12:18 AM.
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Old 08-04-2015, 07:59 PM
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^^^^
I hope we are all clear on damping vs Q value.
Additional information about extension filter is at the bottom of this page.

http://rythmikaudio.com/eq.html

In PEQ that we control the boost or cut, higher Q value means narrow bandwidth.






-

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Old 08-05-2015, 12:16 AM
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I was just reading about bass traps to reduce ringing and it led me to a thought regarding Rythmik servo subs.

If your subs are putting out sound energy with much less ringing to begin with, does that reduce your need for bass traps to "clean up"?

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Old 08-05-2015, 06:15 AM
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No. Bass traps do not clear up "ringing" from the sub itself, only from room modes and room boundary reflections. They can't fix the source; GIGO (garbage in garbage out).

I suspect this hypothesis, if what you read does imply that bass traps clean up the source, is because bass traps work better at higher frequencies so may absorb some of the distortion rather than letting it reflect back into the room.

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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Old 08-05-2015, 06:16 AM
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Quote:
Originally Posted by Soulburner View Post
I was just reading about bass traps to reduce ringing and it led me to a thought regarding Rythmik servo subs.

If your subs are putting out sound energy with much less ringing to begin with, does that reduce your need for bass traps to "clean up"?
I'm not Rythmik, but here is the answer...

Ringing can be introduced by the sub system (combination of physical and electronic aspects) and/or room resonances (modes).
It certainly helps to start with a sub that doesn't create ringing, but a room will usually introduce its own ringing (not necessarily at the same frequencies).
You can combat room ringing by properly positioning multiple subs and/or using bass traps.
Also, it is often possible to electronically combat ringing by cancelling it out via room EQ.
For best results, use a combination of all the above.

With room EQ, in some cases EQing for a flat response will coincidentally cancel out some of the ringing. In some cases, room EQ makes ringing worse.
Fancier room EQ systems (Dirac, Trinnov, Audiolense, Acourate) will optimize both frequency response and impulse response and more reliably reduce ringing.
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Old 08-05-2015, 06:32 AM
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BTW, you can measure this stuff by checking out the waterfall and impulse response graphs in REW.
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Old 08-05-2015, 09:10 AM
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Originally Posted by DonH50 View Post
No. Bass traps do not clear up "ringing" from the sub itself, only from room modes and room boundary reflections. They can't fix the source; GIGO (garbage in garbage out).

I suspect this hypothesis, if what you read does imply that bass traps clean up the source, is because bass traps work better at higher frequencies so may absorb some of the distortion rather than letting it reflect back into the room.
I realize that subs are one of several factors, and I should have stated "if you have bass traps large enough to affect subwoofer frequencies". Probably a silly late night question because they would be huge, but you can see what I was thinking.
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Old 08-05-2015, 09:19 AM
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Well, my answer's the same if you are talking about the sub itself. No amount of treatment can alter distortion from the source, or the direct sound you hear. If you are talking about room modes and boundary reflections, then again to me the sub itself does not matter except a sub that has distortion (THD, IMD, ringing, whatever) may excite frequency peaks a "clean" sub would not. However, you can have a clean sub playing a signal at one of the peaks, and that frequency will still be louder (and a null is still a null, etc.)

Bass traps and other acoustic treatments are to clean up the room, not the sub.

A new slogan? Start clean, stay clean. Rythmik.

IMO! - Don

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Old 08-05-2015, 09:45 AM
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Originally Posted by Soulburner View Post
I realize that subs are one of several factors, and I should have stated "if you have bass traps large enough to affect subwoofer frequencies". Probably a silly late night question because they would be huge, but you can see what I was thinking.
you can potentially over-do with bass traps. The reason we can create 3-D sound image is becasue wall reflections (floor and ceiling too). If you want to imagine a world without room reflection at all, it is like walking into an open outdoor space. So we know we need wall reflections to create image space. The trick is how to get just the right amount.

Room EQ can also do damage to sound stage. I had heard some of the bad room EQ where the sound is very good, but the imaging is terrible. The singer voice appears to sound like 5 times bigger than their life size and the reason for that is extra ringing introduced by the EQ.

It takes time to learn the art of sound. A lot of us think if we hear the same thing as other do, then we all hear the same thing. But that is not true. I look up in the sky every night and all I see is lots of stars. My friend can point me which star is Orion and which is Sirus. We both see the same sky and yet we have different interpretation of what we see at different level of detail (or what our brain thinks).

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Old 08-05-2015, 10:52 AM
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Originally Posted by Rythmik View Post
you can potentially over-do with bass traps. The reason we can create 3-D sound image is becasue wall reflections (floor and ceiling too). If you want to imagine a world without room reflection at all, it is like walking into an open outdoor space. So we know we need wall reflections to create image space. The trick is how to get just the right amount.

Room EQ can also do damage to sound stage. I had heard some of the bad room EQ where the sound is very good, but the imaging is terrible. The singer voice appears to sound like 5 times bigger than their life size and the reason for that is extra ringing introduced by the EQ.

It takes time to learn the art of sound. A lot of us think if we hear the same thing as other do, then we all hear the same thing. But that is not true. I look up in the sky every night and all I see is lots of stars. My friend can point me which star is Orion and which is Sirus. We both see the same sky and yet we have different interpretation of what we see at different level of detail (or what our brain thinks).
The "sound" of a room greatly effects how music played in it, both live and reproduced, sounds. The two extremes are a gymnasium and outdoors---I've played in and dislike both, gyms having too much echo and outdoors being too dead, with no resonance. Acoustical engineers have determined the optimum amount and length of reverberation that makes for good sound in a room, and build spaces for live music performance based on those numbers. Old churches were designed and built as they were for the same reason.


For music and home theater listening, a mix of absorption (bass traps in room corners, and absorptive panels at loudspeaker first-reflection points) and diffusion (diffusers "scatter" sound reflected off them in different directions, rather than as does a mirror) makes for a good-sounding room.
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Old 08-05-2015, 11:05 AM
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This is off topic but I see everyone talk about adding bass traps but I saw a video with Floyd Toole he said he disapproves of using them. Why?
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Old 08-05-2015, 11:33 AM
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Read the two posts right above.

I personally usually prefer to take the room out of the picture and treat heavily. With absorption, this means any ambiance is in the recording and your speakers must reproduce that accurately. My current room is not large and with big planer speakers I am pretty close to near-field so it sounds great with a bunch of absorbers. In a large room I prefer a mix of absorption and diffusion as stated above. Unfortunately I have rarely had a nice big room for my stereo. One caveat is the mix may be done with a typical room in mind and not the (typically dry) mastering studio.

For subwoofers, it takes a lot of material to accomplish anything. Fundamental room nulls are almost impossible to fix; boundary reflections that are a little higher in frequency can often be improved.

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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Old 08-05-2015, 11:59 AM
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This is off topic but I see everyone talk about adding bass traps but I saw a video with Floyd Toole he said he disapproves of using them. Why?
Toole has mentioned more than once that spending money on subwoofers only to absorb much of that low frequency energy away is not his preferred approach to good bass reproduction in a room. Instead, his choice for subwoofer optimization is a combination of placement and equalization.

In the low frequencies, where problems tend to be minimum phase, fixing a problem in the frequency domain (e.g., pulling down a peak) can yield a likewise improvement in the time domain (reduce long decay time). Doing this with passive absorption is much harder.

One of Toole's examples of improving the bass using placement alone:


Sanjay
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Old 08-05-2015, 01:39 PM
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^^^ +1.

Another way to think of it is that peaks can no more than double the signal level (for a single mode). That's 3 dB in power. A little bit of EQ is enough to tame a peak. A null, however, happens when the signals cancel and can be infinitely deep if they cancel perfectly. In practice I have seen 20 to 40 dB nulls in rooms, meaning you would need 100x to 10,000x the power to pull them up. Not terribly practical so EQ is not terribly useful. Treating the room to kill a null requires a LOT of absorption and you end up killing everything (all the other frequencies) in an attempt to get rid of the main (fundamental) nulls, again not terribly practical. Absorption attempts to make the room appear larger by killing reflections that create the nulls, but in the deep bass region common absorption materials don't do a lot (yes they can help, but...) Practical solutions are to move the listening position out of the null and/or stick an active source at the null to counteract it (thus without needing 10,000x the power if you used just one sub at the same place as in Toole's picture). Other solutions are to use resonators or active absorbers to selectively tune out (suppress) specific null frequencies.

I have a ton of absorption in my room but mainly to smooth out higher modes and boundary reflections. The 30 Hz fundamental null I have struggled with has been reduced but is still large (10+ dB deep) even though I have thick (12") corner traps in front and virtually all other walls and ceiling covered by 4" or 6" absorbers with 2" or so air gaps. I have already moved as far away as I can, not very far... My plan for finally addressing the null is another pair of subs, which will unfortunately be on the back wall instead of in the null (unless I block off the door and live in the media room, which has certain appeal, but... )

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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f12g subwoofer , lv12r , Rythmik , Rythmik Audio , Rythmik Audio F12 Direct Servo Subwoofer , Rythmik Audio F15 Subwoofer , servo sub
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