Keith_W
Major Contributor
Would you mind posting the ETC so we can see how quickly the sound dies down?
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A comparison of the effectivity of various speaker damping materials
- Thread starter Rick Sykora
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OP
- Thread Starter
- #22
Maybe for some limited set once am done with the different materials. Did you have some particular test cases in mind?
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I follow your comments as a lurker in the background; actually, I suppose a more appropriate moniker would be “Fan Boy”’ despite my advanced age.
Thank you for all you do herein… I always learn a lot from your efforts on our behalf!
Did I mention “Thank you!!”…
Tillman
Thank you for all you do herein… I always learn a lot from your efforts on our behalf!
Did I mention “Thank you!!”…
Tillman
OP
- Thread Starter
- #24
As had posted in the C-Note review thread, here is a look at how changing the port length (to 4 inches) affects the major resonance from Amir's review...
So, this variation keeps the Acousta-Stuf but shortens the port to 4 inches. The red is the original undamped baseline and the yellow is the shorter port. The shorter port does lessen the low bass by about 10 Hz but also has higher bass output above 50 Hz. So, is a tradeoff but sounded fine to me. More notably, the ugly port leakage is reduced by about 30 dB! You may also note a high Q resonance at 1300 Hz. With a rear-facing port, doubt it is audible. If needed, could be reduced using other damping material rather than Acousta-stuf. Note the reduction in SPL for the primary vent output is likely due to mic distance inconsistency, so please ignore single digit SPL variations for this measurement. I will redo this measurement later but thought it worthwhile to share the overall result as it may be a while.
So, this variation keeps the Acousta-Stuf but shortens the port to 4 inches. The red is the original undamped baseline and the yellow is the shorter port. The shorter port does lessen the low bass by about 10 Hz but also has higher bass output above 50 Hz. So, is a tradeoff but sounded fine to me. More notably, the ugly port leakage is reduced by about 30 dB! You may also note a high Q resonance at 1300 Hz. With a rear-facing port, doubt it is audible. If needed, could be reduced using other damping material rather than Acousta-stuf. Note the reduction in SPL for the primary vent output is likely due to mic distance inconsistency, so please ignore single digit SPL variations for this measurement. I will redo this measurement later but thought it worthwhile to share the overall result as it may be a while.
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Keith_W
Major Contributor
I want to see how quickly the resonances are damped. They say that high density materials are better, but I have never seen measurements that prove it.
OP
- Thread Starter
- #26
Interesting thread. I've found this type of material to be very effective (in several layers where necessary), do you have something like that and plan to include it in your testing?
View attachment 391811
Jantzen Audio Felt for speaker damping, 8 mm - Fidelity Components Shop
Jantzen Audio Sound absorbent Felt for speaker damping, 8 mm, by 1m2,www.audiohobby.eu
Just in case you have any guidance on application, I have F13 felt in 1/8 inch and 1/4 inch thickness. The thicker one is a 2 inch wide roll and the thinner is in a couple of 16x20 inch sheets.
OK, then I would use at least a double layer of the 1/4 inch so you get 1/2 inch, and if possible attach it to all sides inside the cabinet. Either by glue or tack-it, or simply by over dimensioning the pieces a bit so that they stay in place.
EDIT: 2 inch wide roll, that wasn't much. 4 layers of the 1/8 inch then perhaps, if it's enough.
Closeup inside the coax chamber in our Saranna prototype, basically everything is covered, extra thick layer behind the driver (back wall)
OP
- Thread Starter
- #29
Not sure I have that much of the thicker one to be able to double up. More likely I can do layer of each. For the thicker open cell foams, am not doing the top as the port gets in the way.
OP
- Thread Starter
- #31
If the result isn't good I will blame the lack of material.
Ofc!, but not even sure we have same density felt or how 2 inch strips compare to full width sheets.
Will try what I have and if is shows potential, can buy more. It is not prohibitively expensive.
OP
- Thread Starter
- #32
back to another measurement....
This time, it is 3/4 inch Sonic Barrier and I found this one quite interesting having used it for Directiva....
Here the damping is the green trace and the baseline in red. Was able to place some on top of the cabinet as the thinner sheet allows it to fit. So see some good attenuation from 300 to 1200 Hz and then is a bit less predictable much higher. It does clean up the main port resonance but not quite as well as the thicker Sonic Barrier. Thought it might be useful to look at how it compares to its more expensive sibling...
SB1.2 is the black trace and they both compare well between 300 and 1200 hz. The notch in the green trace at 660 Hz is partly due to the top piece as it actually touches the port tube. Above 1200 Hz, the performance is unexpectedly more mixed as the thinner SB struggles at around 1600 Hz but recovers and matches the thicker version above 2000 Hz.
This time, it is 3/4 inch Sonic Barrier and I found this one quite interesting having used it for Directiva....
Here the damping is the green trace and the baseline in red. Was able to place some on top of the cabinet as the thinner sheet allows it to fit. So see some good attenuation from 300 to 1200 Hz and then is a bit less predictable much higher. It does clean up the main port resonance but not quite as well as the thicker Sonic Barrier. Thought it might be useful to look at how it compares to its more expensive sibling...
SB1.2 is the black trace and they both compare well between 300 and 1200 hz. The notch in the green trace at 660 Hz is partly due to the top piece as it actually touches the port tube. Above 1200 Hz, the performance is unexpectedly more mixed as the thinner SB struggles at around 1600 Hz but recovers and matches the thicker version above 2000 Hz.
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OP
- Thread Starter
- #33
Next up is Dacron sheet (purchased from Madisound)...
Once again, we see some decent attenuation between 300-600 Hz, but now the main resonance only gets a trim but is more prominent than most of the other damping materials. Above 1500 Hz, the Dacron has minimal impact. Overall, is just slightly better than the Acousta-stuf damping performance.
Once again, we see some decent attenuation between 300-600 Hz, but now the main resonance only gets a trim but is more prominent than most of the other damping materials. Above 1500 Hz, the Dacron has minimal impact. Overall, is just slightly better than the Acousta-stuf damping performance.
A couple of comments:
I have seen recommendations for the felt that Sigberaudio is suggesting with the comments that you need at least 1/2". I did see your comments about your limited supply, but just wanted to add this. I tend to use this (I think I have 3/8" from McMaster Carr) against the walls AND then 1 inch denim insulation on top of that.
Supposedly melamine foam is really good. This is basically Magic Erasers - however, while magic erasers are kind of pricey you can get 50 or 100 packs of generic melamine foam squares on Amazon for cheap. I got a 100 pack but don't know if I'll get to use them for speakers because I let my wife and kids know about them and they keep taking them to clean the kitchen and bathroom.
I have seen recommendations for the felt that Sigberaudio is suggesting with the comments that you need at least 1/2". I did see your comments about your limited supply, but just wanted to add this. I tend to use this (I think I have 3/8" from McMaster Carr) against the walls AND then 1 inch denim insulation on top of that.
Supposedly melamine foam is really good. This is basically Magic Erasers - however, while magic erasers are kind of pricey you can get 50 or 100 packs of generic melamine foam squares on Amazon for cheap. I got a 100 pack but don't know if I'll get to use them for speakers because I let my wife and kids know about them and they keep taking them to clean the kitchen and bathroom.
OP
- Thread Starter
- #35
A couple of comments:
I have seen recommendations for the felt that Sigberaudio is suggesting with the comments that you need at least 1/2". I did see your comments about your limited supply, but just wanted to add this. I tend to use this (I think I have 3/8" from McMaster Carr) against the walls AND then 1 inch denim insulation on top of that.
Supposedly melamine foam is really good. This is basically Magic Erasers - however, while magic erasers are kind of pricey you can get 50 or 100 packs of generic melamine foam squares on Amazon for cheap. I got a 100 pack but don't know if I'll get to use them for speakers because I let my wife and kids know about them and they keep taking them to clean the kitchen and bathroom.
The purpose of this project is to get beyond the subjective and better quantify the damping materials. As I mentioned I have been guilty of guesstimating too. Using the felt on hand, I would get to 3/8 inch thickness. If I have enough of the 1/4 inch perhaps can get to 1/2 inch but will need to check. As some combining of material may yield better results, is likely worthwhile to do some layering as you have done. Notably mixing more dense material and less dense like the 3 layer Sonic Barrier shows potential benefit.
How did you determine how much of each damping material you used? As this is a science-based comparison, my results are meant to be repeatable. So someone else should be able to purchase the exact same damping material. McMaster Carr has at least 5 different types of felt. So while I like the idea of felt, need to be specific about which one I test. Did you use F13 or something else?
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Yes, I realize you are trying to take a scientific approach. But I wasn't, I have typically just lined the speaker with what I have - either just denim damping material (I now use the Sonic Barrier Acousta-Blue at Parts Express) or Sonic Barrier + Felt, depending on whether I am aiming for a budget build or not. (For a budget build I used to use Frost King denim insulation but I now have a pretty good stock of Sonic Barrier and it is much, much better.)
My felt is F13 from McMaster Carr. I got 3/8" rather than 1/2" because I was being cheap.
My suggestions for your scientific approach was just (1) try combining materials (like felt + denim) and (2) try melamine foam.
OP
- Thread Starter
- #37
Fair enough. As you know, some of this stuff is expensive and some of it is reasonable. Buying multiple variants of the same material adds up quickly. So if I can layer thinner products and get the same result, it is cheaper and just may find that less is good enough. Had already planned some combo testing but likely using what I already have. It is a pretty representative mix.
So before I buy any other damping material, plan to see if anyone has some to spare first. Using denim is popular but not clear how to get consistency. Saw the Sonic Barrier and seems to ruin one of the original reasons to use denim - its economical. What is less clear is shredded denim seems to have started as a box stuffing but the newer stuff seems more targeted to panel damping. Otoh, shredded denim seems more like cotton to me and already have plenty of cotton to try. Melamine seems like an open cell foam and have plenty of foam variants already. If am going to test another material, it better be cheap/free or shown to be exceptional in some way.
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If you want some F13 Felt, 1"
If you want some 1" Sonic Barrier and some melamine foam squares PM me the measurements you need and your address. (I know the measurements of the C-Notes, but not sure exactly what sides, top, back etc. you are lining.) If I happen to find the felt, I can send it too.
I looked around for my F13 felt and don't seem to find any. I can check again tomorrow but I just built a speaker in August so I may really be out. I do have some 1" Sonic Barrier.
Open cell foam like egg-crate foam or mattress topper will likely measure the worst. In other people's tests that I have seen, melamine foam is one of the best (no idea why). The other thing that people really love is Merino wool (for stuffing, not lining). But you are right, the F13 felt and merino wool are NOT cheap.
If you want some 1" Sonic Barrier and some melamine foam squares PM me the measurements you need and your address. (I know the measurements of the C-Notes, but not sure exactly what sides, top, back etc. you are lining.) If I happen to find the felt, I can send it too.
I am not sure that McMaster Carr F13 felt is very comparable to the mixed type felt I mentioned. It seems very uniform, is it stiff?
The Jantzen Audio felt is 1600 g/m², if I understand the american measurements correct, this is most similar in density to the 1/4" F13. But the Jantzen thingy is made up of a mix of various materials. Not sure how it compares to uniform felt like the F13.
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- Thread Starter
- #40
Yes, F13 wool is soft and fairly uniform…
The 1/4 inch F13 feels like a heavy wool coat. The 3/8” version is comparable density to the Jantzen and just a bit thicker.
The above pic is 1/8” F13.
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