Mechanical Sectioning .vs. Silicon dots for resonance control

[bolserst]

Originally Posted by arend-jan

The picture you show has the back grill removed. This metal grill originally has a sheet of natural fibre cloth on the inside (attached with a sticky tar like substance to the grill) which damps the main resonance peak of the bass panels.

Arend-jan,

When the grill+damping cloth are in place, do you know what the distance would be between the diaphragm and the damping cloth?
Would you happen to have any pictures of the inside of the back grill showing this cloth?

Thanks for the info.

[arend-jan]

Hi Bolserst,

The distance between the bass panel and the back grill would be a couple of cm.

[bolserst]

Originally Posted by bolserst

Previously, I had thought that mounting tightly woven cloth on the inside of the stator closer to the diaphragm would provide better damping than when it was mounted outside the stator. However, I tried this 2 weeks ago, and the LF damping was identical between the two mounting techniques. I did not compare high frequency effects.

Just wanted to add a note about comparison of damping affects with cloth mounted inside the stator .vs. outside the stator. I was looking back over my measurements, and again noted that the damping of the fundamental resonance was the same. However, damping of the higher frequency diaphragm modes was slightly improved with the cloth mounted inside the stator, closer to the diaphragm. Not a huge improvement, but measureable.

[Dave]

Hi Bolsert,

Do you have any photos of your test set-up of the damping materials?

[bolserst]

Originally Posted by Dave

Hi Bolsert,

Do you have any photos of your test set-up of the damping materials?

I thought I described the setup pretty well in post #25 and #26 where I showed the results.
The testing was done on a panel similar in size and construction to those used by Capaciti and Audiostatic for full range ESLs.
" The ESL panel used for the test was 60" tall x 8" wide "

For the Near Field tests:
" Microphone was placed 1" in front of the midpoint of the diaphragm "

For the Far Field tests:
" Microphone was placed 1 meter in front of the midpoint of the diaphragm "

I'm not sure what additional information pictures would provide, but here are a few of the NF setup:
1) panel with no damping
2) panel with felt on rear stator
3) panel with felt on front stator
4) panel with mesh on rear stator

Hope this helps...