GR Research No Res alternative?

[RickS]

To be fair, Danny shows different measurements in the waterfall charts before and after his crossover changes and adding no rez. So, he has done measurements there and I think it's fair to say that the waterfall chart can be an indication of reduced resonances in the cabinet. I will also say that I don't think any of these products will work very well (or at all) on sub frequencies. I would go so far as to say that they wouldn't do much below 300 or 400Hz, so they aren't really meant for internal standing waves or compensation for improperly braced cabinets. But they do well to deaden stuff in the 800Hz and above range, which could be very helpful on dampening internal resonances that come out of a port or a mid range enclosure as well as through cabinet walls (especially in poorly braced cabinets). I can hear a clear difference with the sonic barrier on the inside of a cabinet and I use it on anything that is producing frequencies above 300Hz. I have not done any clear testing on this but just clapping or snapping inside of a cabinet shows a massive difference.

Ok, but not sure how you tell which materials are helpful and what may be overkill, but it is your time and money.

 

[ThatSoundsGood]

Ok, not sure how you tell which materials are helpful and what may be overkill, but it is your time and money.

I take it you don't believe his waterfall measurements and the difference with the No-Rez? I'm honestly interested.

 

[RickS]

I take it you don't believe his waterfall measurements and the difference with the No-Rez? I'm honestly interested.

As posted earlier, the approach used in No-Rez is likely effective to reduce panel vibration but just comes at a steep price. As it has open cell foam too, it would likely help with some box modes too. However, Danny contends it is far better than Sonic Barrier and offers no evidence to support his claim. So, from my perspective in the GR’s range of offerings, No-Rez sits in the middle. It is not pure snake oil but is more like an expensive protein drink. Danny alleges his drink is better but he does nothing to prove it is.

 

[ThatSoundsGood]

As posted earlier, the approach used in No-Rez is likely effective to reduce panel vibration but just comes at a steep price. As it is open cell foam, it would likely help with some box modes too. However, Danny contends it is far better than Sonic Barrier and offers no evidence to support his claim. So, from my perspective in the GR’s range of offerings, No-Rez sits in the middle. It is not pure snake oil but is more like an expensive protein drink. Danny’s drink is allegedly better but he does nothing to provenit is.

I appreciate the clarity and I agree.

 

[kewlbug]

Resonix CLD w Resonix Black fiber mat. This will be 10x better than a piece of foam w a plastic backer.

Cheaper option: NVX or even amazon CLD, with your choice of foam/cotton/poly absorber. Parts express has some stuff. I've been using leftover ATS cotton panels in my projects.

 

[stultifera navis]

". A sound absorber structure comprising of the PET nonwoven, TPU honeycomb grid and PU foam was reported by Lin et al. This structure's sound absorption coefficient was from 0.88 to 0.94 for frequencies between 2000 and 4000 Hz. At frequencies of 0–4000 Hz, the average sonic absorption coefficient was 0.77, with 0.95 at 3000 Hz, which shows an idea to create extremely sonic absorbent materials [175]."

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carbon fiber and kevlar. amazing material. it 's the only tthing i use when i make stuff.

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https://www.sciencedirect.com/science/article/pii/S0142941821003330

 

[stultifera navis]

"Although flax fibre offers lower overall strength and stiffness compared to reinforcements such as glass fibre, it does offer particular advantages in vibration damping and sound absorption, along with adequate mechanical properties and a natural aesthetic to complement its environmental credentials."

Looks like flax fiber is a better solution when i comes to sound absorption.

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[RickS]

Am about to post some more measurements that will demonstrate when NoRez is effective. After testing, my newer approach is to treat panel resonances as part of the build using MLV or other appropriate materials, then add other damping materials (foam or poly/nylon) to deal with other box or port resonances as part of the final speaker design. This optimizes towards using the right type and quantities of damping materials for each problem rather than applying a multi-purpose material (like NoRez or Sonic Barrier) and hoping it does both jobs well.

Any material that incorporates adhesive backing can be difficult to add after a speaker is built. Moreso with NoRez than Sonic Barrier as the panel damping layer in NoRez is much stiffer and closer to the adhesive. I have tested both NoRez and the thinner Sonic Barrier. Just go the thicker Sonic Barrier and will test it as soon as I see whether I can fit it into a built cabinet or need to build a new one.

 

[RickS]

Here is a visual look at previous NoRez vs comparable Sonic Barrier…

Sonic Barrier (SB) is on left and NoRez is on right. Aside from the finish pattern on the foam layer, the other obvious difference is NoRez is a 2 layer design vs SB is 3 layers. Aside from the likely difference acoustically, SB is much more flexible and so is much easier to add to an existing cabinet.

Here is pic of latest NoRez "2" (from GR's website)...

Here are the changes from my observations:

1. The foam appears much more open. Expect this will affect the frequencies and the damping attenuation.
2. The exposed top layer is no longer finished but the same open foam as comprises the upper layer. This may have some acoustic benefit, but also makes it more prone to trapping dust and other dirt.
3. The panel damping layer is thicker (2.75 mm vs 2 mm) is the older NoRez. The original was already extremely difficult to bend, this makes it even more key to install during the cabinet build rather than later. As usual, Danny claims thicker is better but no proof as to how much better.

Overall, NoRez 2 looks more cheaply made and the more open foam is likely to have different acoustic properties than the original NoRez. It seems more focused on the panel damping aspect which can be done with much less expensive materials like mass loaded vinyl. The Sonic Barrier (and other) vinyl sheeting is cheaper and easier to work.

I do not have any NoRez 2 on hand, so only plan to measure the older version for now.

 

[RickS]

Here is my initial comparison pass. This was done at the C-Note speaker port, nearfield without smoothing and matching speakers as closely as possible. One added note is that my goal was to look at the internal box resonance as predicted by VituixCAD (see C-Note review thread post) and not how well the materials may improve panel resonances. I plan to try to test panel resonance but will need a different test fixture.

So the red trace is the C-Note (as shipped) without any damping material. The blue trace is 1 inch Sonic Barrier as shown in earlier post and the black trace is NoRez. My takeaway is that the tested damping materials behave very comparably in this application. There is some slight difference in attenuation above 1 kHz but could be due to slight difference in the driver or other factors. In this case, would tend towards the solution that was less expensive. That would give a slight edge to SB as it is currently just under 7 cents/sq. inch whereas Norez is close to 9 cents.

Finally, I did some initial testing on lesser materials including the 3/4 inch SB I used for Directiva. None of the other materials were as individually effective at dealing with the ~800 Hz resonance as the 2 shown here. I do plan to test some additional combinations to see if they might yield as good or a better solution.

P.S. while initially applying the SB damping, I had left about an inch gap from the front baffle. In this case, it did not perform as well as NoRez. In both cases, the materials were applied along the sides, bottom and back. The port and tweeter did not allow for any to be applied along the cabinet top.

 

[ThatSoundsGood]

Here is my initial comparison pass. This was done at the C-Note speaker port, nearfield without smoothing and matching speakers as closely as possible. One added note is that my goal was to look at the internal box resonance as predicted by VituixCAD (see C-Note review thread post) and not how well the materials may improve panel resonances. I plan to try to test panel resonance but will need a different test fixture.


View attachment 391078

So the red trace is the C-Note (as shipped) without any damping material. The blue trace is 1 inch Sonic Barrier as shown in earlier post and the black trace is NoRez. My takeaway is that the tested damping materials behave very comparably in this application. There is some slight difference in attenuation above 1 kHz but could be due to slight difference in the driver or other factors. In this case, would tend towards the solution that was less expensive. That would give a slight edge to SB as it is currently just under 7 cents/sq. inch whereas Norez is close to 9 cents.

Finally, I did some initial testing on lesser materials including the 3/4 inch SB I used for Directiva. None of the other materials were as individually effective at dealing with the ~800 Hz resonance as the 2 shown here. I do plan to test some additional combinations to see if they might yield as good or a better solution.

P.S. while initially applying the SB damping, I had left about an inch gap from the front baffle. In this case, it did not perform as well as NoRez. In both cases, the materials were applied along the sides, bottom and back. The port and tweeter did not allow for any to be applied along the cabinet top.

Excellent test here. Thanks for doing this work. It seems that both No Rez and SB are quite effective and worth it in this application and probably many others. I'm surprised to see that they both have effectiveness down to around 270Hz. Amazing!

 

[MAB]

I take it you don't believe his waterfall measurements and the difference with the No-Rez? I'm honestly interested.

Hi, can you share the link to GR-Research's waterfall measurements that show a difference? I can't seem to find them. Are the changes specifically attributed to reduction in cabinet resonances?

I am extremely skeptical that these adhesive panels provide meaningful change to the damped oscillator system of a typical speaker cabinet. They do work OK on large underdamped systems like car doors. But a speaker cabinet is in a totally different mass, spring, and damping regime than a sheet metal panel. I note that measurements showing a difference with these add-on panels use material applied to the inside of the cabinet, where it is without-a-doubt impacting internal standing waves, as well as allegedly charging the panel resonances. I have never been able to meaningfully change cabinet resonances with an approach like No-Rez. Any investigation of panel resonance needs to control for internal cabinet standing waves and volume changes. A simple test eliminating all of these confounding variables would be to apply the No-Rez or equivalent treatment to the outside of the cabinet, avoid convoluting the internal acoustic properties of the box with the structural properties.

I got fed up some years ago on DIY audio and other forums on this cabinet-resonance aspect of speakers. Every port resonance, every tweeter/midrange DI mismatch, every odd FR anomaly were allegedly solvable if I just used the most complex constructions out of the most exotic materials. Constrained layer damping, crazy materials, onerous internal bracing schemes ruin the hobby of building fundamentally good sounding speakers. I've constructed so many overbuilt cabinets, with all sorts of byzantine bracing and layering, wasting my time and energy and money chasing the unicorn, typically resulting in a bad-looking speaker that has zero sonic advantages over a well-designed and constructed cabinet made from quality speaker materials like Baltic Birch-ply.

I can't wait until someone tries to improve these imaginarily audible cabinet resonances of a speaker like this, that has no discernable parasitic resonances, but begs the addition of some form of treatment.

 

[ThatSoundsGood]

Hi, can you share the link to GR-Research's waterfall measurements that show a difference? I can't seem to find them. Are the changes specifically attributed to reduction in cabinet resonances?

He shows them in some of his videos when he adds the No Rez. It's not an A/B thing and could be due to the change in the crossover but he often does it to poorly constructed cabinets. So you can take it for what it's worth on that but I think it's reasonable that it would help reduce vibration in poorly constructed cabinets, but not properly braced ones. I do think that it reduces internal resonances and standing waves, especially in higher frequency ranges.

I am extremely skeptical that these adhesive panels provide meaningful change to the damped oscillator system of a typical speaker cabinet. They do work OK on large underdamped systems like car doors. But a speaker cabinet is in a totally different mass, spring, and damping regime than a sheet metal panel. I note that measurements showing a difference with these add-on panels use material applied to the inside of the cabinet, where it is without-a-doubt impacting internal standing waves, as well as allegedly charging the panel resonances. I have never been able to meaningfully change cabinet resonances with an approach like No-Rez. Any investigation of panel resonance needs to control for internal cabinet standing waves and volume changes. A simple test eliminating all of these confounding variables would be to apply the No-Rez or equivalent treatment to the outside of the cabinet, avoid convoluting the internal acoustic properties of the box with the structural properties.

I got fed up some years ago on DIY audio and other forums on this cabinet-resonance aspect of speakers. Every port resonance, every tweeter/midrange DI mismatch, every odd FR anomaly were allegedly solvable if I just used the most complex constructions out of the most exotic materials. Constrained layer damping, crazy materials, onerous internal bracing schemes ruin the hobby of building fundamentally good sounding speakers. I've constructed so many overbuilt cabinets, with all sorts of byzantine bracing and layering, wasting my time and energy and money chasing the unicorn, typically resulting in a bad-looking speaker that has zero sonic advantages over a well-designed and constructed cabinet made from quality speaker materials like Baltic Birch-ply.

I can't wait until someone tries to improve these imaginarily audible cabinet resonances of a speaker like this, that has no discernable parasitic resonances, but begs the addition of some form of treatment.
View attachment 391190

 

[Ktacos]

I got fed up some years ago on DIY audio and other forums on this cabinet-resonance aspect of speakers. Every port resonance, every tweeter/midrange DI mismatch, every odd FR anomaly were allegedly solvable if I just used the most complex constructions out of the most exotic materials. Constrained layer damping, crazy materials, onerous internal bracing schemes ruin the hobby of building fundamentally good sounding speakers. I've constructed so many overbuilt cabinets, with all sorts of byzantine bracing and layering, wasting my time and energy and money chasing the unicorn, typically resulting in a bad-looking speaker that has zero sonic advantages over a well-designed and constructed cabinet made from quality speaker materials like Baltic Birch-ply.

The worst part of DIY speakers is just how much noise there is out there. I've perused the same topics and ultimately decided it was pretty silly to pursue most of the ideas I saw. A simple box with some basic bracing is more than enough IME to deliver a pretty inert cabinet that won't contribute anything to the sound.

 

[RickS]

Hi, can you share the link to GR-Research's waterfall measurements that show a difference? I can't seem to find them. Are the changes specifically attributed to reduction in cabinet resonances?

I am extremely skeptical that these adhesive panels provide meaningful change to the damped oscillator system of a typical speaker cabinet. They do work OK on large underdamped systems like car doors. But a speaker cabinet is in a totally different mass, spring, and damping regime than a sheet metal panel. I note that measurements showing a difference with these add-on panels use material applied to the inside of the cabinet, where it is without-a-doubt impacting internal standing waves, as well as allegedly charging the panel resonances. I have never been able to meaningfully change cabinet resonances with an approach like No-Rez. Any investigation of panel resonance needs to control for internal cabinet standing waves and volume changes. A simple test eliminating all of these confounding variables would be to apply the No-Rez or equivalent treatment to the outside of the cabinet, avoid convoluting the internal acoustic properties of the box with the structural properties.

I got fed up some years ago on DIY audio and other forums on this cabinet-resonance aspect of speakers. Every port resonance, every tweeter/midrange DI mismatch, every odd FR anomaly were allegedly solvable if I just used the most complex constructions out of the most exotic materials. Constrained layer damping, crazy materials, onerous internal bracing schemes ruin the hobby of building fundamentally good sounding speakers. I've constructed so many overbuilt cabinets, with all sorts of byzantine bracing and layering, wasting my time and energy and money chasing the unicorn, typically resulting in a bad-looking speaker that has zero sonic advantages over a well-designed and constructed cabinet made from quality speaker materials like Baltic Birch-ply.

I can't wait until someone tries to improve these imaginarily audible cabinet resonances of a speaker like this, that has no discernable parasitic resonances, but begs the addition of some form of treatment.

Your experience is comparable to my own. Even bracing can simply move a resonance from a lower frequency to a higher one. This is my primary motivation here is to demonstrate what is effective and what is not. Amir has tested more than a few speakers that exhibit some prominent resonance. Often it is not clear what the root cause is but I agree that panel resonances are less likely to be a major audible issue (unless the manufacturer really compromised the cabinet materials and/or construction).

 

[MAB]

He shows them in some of his videos when he adds the No Rez. It's not an A/B thing and could be due to the change in the crossover but he often does it to poorly constructed cabinets. So you can take it for what it's worth on that but I think it's reasonable that it would help reduce vibration in poorly constructed cabinets, but not properly braced ones.

Yes, completely agree.

I do think that it reduces internal resonances and standing waves, especially in higher frequency ranges.

Also agree, but lots of inexpensive and simple to apply cabinet stuffing does that. For instance, I posted some data on this a couple months back, the context was how much stuffing do you need to control standing waves in a midrange (answer: not much)...

I have a midrange, a cabinet, and some Jute and Polyfill stuffing.

The midrange volume is much smaller than the overall cabinet dimensions suggest - about 3 liters.

The midrange is easy to remove with threaded inserts. The MDF is sanded smooth for a good seal. I used an electric driver and set the torque to 11 which gives a repeatable seal.

I did 5 treatments, the first control is with no stuffing. I did subsequent runs with single layer of Jute, and the same with single layer Polyfill. The quantities are typical cabinet treatment. I also doubled the amount of Jute. Last is with double Jute and all the Polyfill I could fit. The pictures below are of the actual cabinet stuffing for a few runs.

I measured both the impedance and frequency response. I marked the position of the speaker carefully to get some level repeatability in the FR measurements.

Here is the FR in the cabinet with no stuffing:

The impedance trace shows resonances at 770Hz, 1kHz, 1.9kHz, and 6.9kHz. The 6.9 kHz is the classic cone breakup mode. The others are less clear.

Looking at the distortion of the driver in empty cabinet, the 6.9kHz breakup mode shows ramifications in the distortion, with a peak in 3rd order HD at 6.9kHz / 3 = 2.3kHz, 5th order peak at 6.9kHz / 5 = 1.38kHz, 7th order peak at 6.9kHz / 7 = 986Hz. etc...

Let's see how this changes with the addition of the various damping:

Once you line the cabinet, the resonance frequency response irregularities at 1kHz and 1.9kHz go away. Jute or Polyfill, even stuffed to the gills doesn't dramatically change the residual resonances.

Looking at the distortion with single layer of Jute, you can see the resonances at 1kHz and 1.9kHz clean up in the 2nd HD trace, the odd order HD components are mostly the same though.

This makes sense, the internal cabinet dimensions are 7 inches deep by 4 inches wide, and even a 1cm layer of Jute is enough to break up the standing wave.

None of the treatments make any difference in distortion performance above single layer of Jute or Polyfill:

None of the treatments make a difference in midrange impedance resonances compared to single layer of Jute or Polyfill:

Stuffing amount and type does affect the woofer/box resonance at 118Hz, lowering the impedance peak and slightly lowering the system resonance as predicted. You can see that the game of lowering the system resonance by overstuffing is counteracted by lowering of system efficiency after more than single layers are applied, so the often-repeated statements about 'improved bass performance' with large amounts of stuffing is also a fantasy. Somehow that myth needs to be put to rest as well, I should redo this with a woofer instead of a midrange to drive this point home.

Lastly, here is a different cabinet I made, with a diffuser on one wall. It tames the mode between front and back of the cabinet, does nothing for the other dimensions' cancelations, and was a pain to build.

Tweaks like this are of little to no value, and distract from the already difficult task of making good speakers.

 

[MAB]

Your experience is comparable to my own. Even bracing can simply move a resonance from a lower frequency to a higher one. This is my primary motivation here is to demonstrate what is effective and what is not. Amir has tested more than a few speakers that exhibit some prominent resonance. Often it is not clear what the root cause is but I agree that panel resonances are less likely to be a major audible issue (unless the manufacturer really compromised the cabinet materials and/or construction).

Agreed Rick. Simple solutions are often most effective. Looking forward to more of your tests. I am thinking of doing a test of a cabinet with successive amounts of external panel resonance damping (to keep from changing the internal standing wave resonances).