Speaker enclosure vibrations - part II - ABX wanted!

[Thomas_A]

Hi all,

based on a thread at SHF and my previous thread here I posted two recordings of speakers with the same form (see my Avatar). One is built with the usual 19 mm MDF and the other pair with 9+9 mm MDF and damping glue. The recording was made using a 540 Hz signal, where the cabinet vibrations are worst, and ≈80 dB at LP. I also posted an ABX with the files with positive result. Now, it is always difficult to make such tests when files are recorded in-room, due to small variations in the file. There is no response though on the files at SHF and since I know there is larger interests in ABX at ASR, I would like to see if some people here could make an ABX and post. There is always a possibility to trim ad adjust the files to better SPL match as well.

My old thread at ASR is here:

'Speaker enclosure vibrations - a few measurements with accelerometer'

Aug 4, 2022

There are been quite a number of threads dealing with vibrations in speaker cabinets, both in relation to "speaker feet" and vibrations in enclosures themselves. I recently took out my ACH01 accelerometer to do some measurements, both speaker feet and enclosures. There was some initial measurements posted in another thread, and here I have repeated these with some modifications. For test one I wanted to test speaker feet, i.e. the so-called "spikes" against soft feet. However, I do not want to destroy my wooden floor or my speakers so I choose to put the speakers on the floor and use three...

• Thomas_A
• Replies: 163
• Forum: Speaker Reviews, Measurements and Discussion

• 

The recorded files:
19 mm MDF:

Dropbox

www.dropbox.com

Constrained layer MDF:

Dropbox

www.dropbox.com

A tip when listening is not to use too high or too low volume. It would be most appreciated if some of you could post ABX results. It is not a difficult test.

 

[Thomas_A]

Bumping this one. It would as mentioned be appreciated with some ABX test results. Mine is here.

 

[RobL]

I can’t seem to get the ABX plug in to work, or I’d post a result for you. FWIW, I can easily hear the difference between the files…even on my ipad speakers.

 

[Thomas_A]

I can’t seem to get the ABX plug in to work, or I’d post a result for you. FWIW, I can easily hear the difference between the files…even on my ipad speakers.

Many thanks. It’s very obvious on small built-in computer/iPad speakers. But a bit leas on ordinary speakers or headphones. But anyway very audible.

 

[Thomas_A]

Here is also the accelerometer measurements with 3rd and 5th harmonics, measured on the front baffle. Blue=19 mm MDF; red=constrained layer.

 

[smcc]

that's basically night and day...even listening at 60dB with 50dB background noise here

 

[rynberg]

Here is also the accelerometer measurements with 3rd and 5th harmonics, measured on the front baffle. Blue=19 mm MDF; red=constrained layer.

You are using dB, what reference are you using?

 

[Thomas_A]

You are using dB, what reference are you using?

This is just relative difference between the enclodures. I can’t translate to acceleration units.

 

[somebodyelse]

Files are different lengths, so some ABX apps refuse to use them.

 

[Thomas_A]

Files are different lengths, so some ABX apps refuse to use them.

Yes. I am not an expert of trimming files to the exact same length and level though. It is probably a simple thing to do.

 

[kemmler3D]

Can't do the listening test right at the moment, but the accelerometer results seem pretty dramatic. What kind of bracing was used in these cabinets? I know CLD construction is popular with DIYers that want to go the extra mile, but there's always some debate as to whether it's worth it... this would seem to be an unambiguous yes...

 

[Thomas_A]

Can't do the listening test right at the moment, but the accelerometer results seem pretty dramatic. What kind of bracing was used in these cabinets? I know CLD construction is popular with DIYers that want to go the extra mile, but there's always some debate as to whether it's worth it... this would seem to be an unambiguous yes...

They surely look dramatic and these are non-linear effects. These small 9 liter speakers have a cubic form but front baffle is cut and slanted. There was never bracing in these due to their small size and irregular shape. Just 19 mm MDF or 9+9 mm MDF with 1-2 mm DG-A2 damping glue.

 

[kemmler3D]

Ah interesting. I think I've seen debates on whether CLD is worth it in the context of adequate bracing... But even 19mm plywood is often considered pretty good / stiff/ inertv on its own... Maybe not!

 

[Thomas_A]

Ah interesting. I think I've seen debates on whether CLD is worth it in the context of adequate bracing... But even 19mm plywood is often considered pretty good / stiff/ inertv on its own... Maybe not!

Since it is structures that have resonances, all dimensions including thickness affect the results. Perhaps it is just a case of bad enclosure dimensions. My initial thought was that the walls have quite different dimensions, thereby distributing the resonances over a broader frequency range. But as it seems there is a rather high peak between 500-600 Hz. At the time I built these 20 years ago I just had the hand and fingers to detect enclosure vibration that was felt mainly between 500-600 Hz. The CLD solved that.

Looking at reviews here, there are quite a few smaller speakers showing increase in distortion in the same fr region (400-800 Hz). I just wonder if these are enclosure effects and not the actual driver. The AIYIMA S600 is one example.

 

[JSmith]

I would like to see if some people here could make an ABX and post.

Sure;

foo_abx 2.2.1 report
foobar2000 v2.24.6
2025-08-05 20:24:46

File A: Constrayed layer 540 Hz.wav
SHA1: 6ae6491849c9b3a60c787f847b9eacac4ef6d432
File B: MDF 19 mm 540 Hz.wav
SHA1: ed6f562d6f516c7620437a0ae112c63436eefa58

Output:
Default : Primary Sound Driver
Crossfading: NO

20:24:46 : Test started.
20:27:31 : Test restarted.
20:27:31 : 01/01
20:31:28 : Test restarted.
20:31:28 : 02/02
20:31:42 : Test restarted.
20:31:42 : 03/03
20:31:55 : Test restarted.
20:31:55 : 04/04
20:32:09 : Test restarted.
20:32:09 : 05/05
20:32:28 : Test restarted.
20:32:28 : 06/06
20:32:42 : Test restarted.
20:32:42 : 07/07
20:32:55 : Test restarted.
20:32:55 : 08/08
20:33:10 : Test restarted.
20:33:10 : 09/09
20:33:22 : Test restarted.
20:33:22 : 10/10
20:33:34 : Test restarted.
20:33:34 : 11/11
20:33:49 : Test restarted.
20:33:49 : 12/12
20:34:02 : Test restarted.
20:34:02 : 13/13
20:34:16 : Test restarted.
20:34:16 : 14/14
20:34:30 : Test restarted.
20:34:30 : 15/15
20:34:39 : Test restarted.
20:34:39 : 16/16
20:34:39 : Test finished.

----------
Total: 16/16
p-value: 0 (0%)

-- signature --
1a9fdfe920d632154a07e9b251c014eb42c3627d

foobar2000 ABX Log Signature Tool

www.foobar2000.org

JSmith

 

[Thomas_A]

Sure;

foobar2000 ABX Log Signature Tool

www.foobar2000.org

JSmith

Many thanks!

 

[NotInYourHead]

Since it is structures that have resonances, all dimensions including thickness affect the results. Perhaps it is just a case of bad enclosure dimensions. My initial thought was that the walls have quite different dimensions, thereby distributing the resonances over a broader frequency range. But as it seems there is a rather high peak between 500-600 Hz. At the time I built these 20 years ago I just had the hand and fingers to detect enclosure vibration that was felt mainly between 500-600 Hz. The CLD solved that.

Looking at reviews here, there are quite a few smaller speakers showing increase in distortion in the same fr region (400-800 Hz). I just wonder if these are enclosure effects and not the actual driver. The AIYIMA S600 is one example.

I have Edifier MR4s, which have distortions in that FR. The box is bare, no bracing and has only a small wad of polyester for "damping".
A DIYer replaced the midbass driver with a SB Acoustics equivalent and add sufficient damping, which lowers the distortions quite well. Hard to tell which plays the biggest role, but I believe it's the latter.

 

[test1223]

Hi all,

based on a thread at SHF and my previous thread here I posted two recordings of speakers with the same form (see my Avatar). One is built with the usual 19 mm MDF and the other pair with 9+9 mm MDF and damping glue. The recording was made using a 540 Hz signal, where the cabinet vibrations are worst, and ≈80 dB at LP. I also posted an ABX with the files with positive result. Now, it is always difficult to make such tests when files are recorded in-room, due to small variations in the file. There is no response though on the files at SHF and since I know there is larger interests in ABX at ASR, I would like to see if some people here could make an ABX and post. There is always a possibility to trim ad adjust the files to better SPL match as well.

My old thread at ASR is here:

'Speaker enclosure vibrations - a few measurements with accelerometer'

Aug 4, 2022

There are been quite a number of threads dealing with vibrations in speaker cabinets, both in relation to "speaker feet" and vibrations in enclosures themselves. I recently took out my ACH01 accelerometer to do some measurements, both speaker feet and enclosures. There was some initial measurements posted in another thread, and here I have repeated these with some modifications. For test one I wanted to test speaker feet, i.e. the so-called "spikes" against soft feet. However, I do not want to destroy my wooden floor or my speakers so I choose to put the speakers on the floor and use three...

• Thomas_A
• Replies: 163
• Forum: Speaker Reviews, Measurements and Discussion

• 

The recorded files:
19 mm MDF:

Dropbox

www.dropbox.com

Constrained layer MDF:

Dropbox

www.dropbox.com

A tip when listening is not to use too high or too low volume. It would be most appreciated if some of you could post ABX results. It is not a difficult test.

There is no need to conduct a blind test the differences are very big.

This is a showcase how much differences some enclosure details can make.

It would be really great to show/ post the equivalent acoustic measurements and harmonic distortion of both enclosures. I am interested to see how big of a difference it makes.

Best
Thomas

 

[Thomas_A]

I have Edifier MR4s, which have distortions in that FR. The box is bare, no bracing and has only a small wad of polyester for "damping".
A DIYer replaced the midbass driver with a SB Acoustics equivalent and add sufficient damping, which lowers the distortions quite well. Hard to tell which plays the biggest role, but I believe it's the latter.

Dampiing material matters as well yes. I fill with glass fiber to about 50 %. But in my case it was not sufficient to drive the resonances to inaudible levels.

 

[Thomas_A]

There is no need to conduct a blind test the differences are very big.

This is a showcase how much differences some enclosure details can make.

It would be really great to show/ post the equivalent acoustic measurements and harmonic distortion of both enclosures. I am interested to see how big of a difference it makes.

Best
Thomas

Some are made in the thread I linked to in first post.

Post in thread 'Speaker enclosure vibrations - a few measurements with accelerometer'

Oct 30, 2022

Today I made some acoustic measurements of the two speakers, about 2.9V signal, frequencies 510 Hz, 620 Hz, and 790 Hz, and RTA using REW. Speaker A is the old one with 19 mm MDF and speaker B with constrained layer damping. Note that the two 5 inch drivers are different Peerless drivers, but as mentioned, I do not have the previous conventional cabinets that I made for the newer CSX drivers. Matching levels were difficult, but THD was consistently lower in speaker B, and especially around 600 Hz.

At 510 Hz, speaker A

Speaker B:

620 Hz, speaker A

...

• Thomas_A

•