Choosing Acoustic Foam For BB Speakers

[MyOhMy]

Hi All,

I'm looking trying to improve the sound quality of the speakers in some of my three-piece boxes, mainly those at the lower end of the cost spectrum(!), to reduce the 'hollow plastic' sound that is often an unwanted feature of these speakers.

In most cases, the speaker boxes are of a thin-ish plastic construction and quite small. I've searched the 'net and found various types of acoustic foam available from different types of 'flat' foams to patterned, with an egg crate design being very prolific.

Bearing in mind that many of these low end speaker cases are quite small therefore internal space needs serious consideration, has anyone tried a particular type or size of foam with a good degree of success? 2"/50mm egg crate is available from most reputable suppliers but seems a little on the large side for such small speakers and I'm having a problem finding a smaller egg crate design. I feel that using 2"/50mm egg crate foam will only result in the foam bunching in the corners/turns to the point of filling the entire enclosure - but would this be OK anyway?

Thanks guys, look forward to tapping the wealth of experience of the members here.

 

[Reli]

I believe in the loose, white pillow/down type of material (I forgot what it's called, but you can order it from audio shops).

I don't believe in those pink/purple sheets of compressed matting that some 3-piece boomboxes have. That stuff isn't as effective IMO.

 

[MyOhMy]

I believe in the loose, white pillow/down type of material (I forgot what it's called, but you can order it from audio shops).

I don't believe in those pink/purple sheets of compressed matting that some 3-piece boomboxes have. That stuff isn't as effective IMO.

thanks, Reli. I have a small amount of this and tried it in one speaker with very little difference but I'm thinking I need to double-up on the amount I use plus, I will have to use a fine net (or similar) to prevent the filling wandering into the spider. Does this make sense?

 

[jimmyjimmy19702010]

The white acoustic fill (pillow stuffing) is mainly used to help eliminate standing waves that cause the reverberations that cause the speaker boxes to emit their own sound track.

I completely fill the speaker boxes with this material. But don't put in so much that you have to force it in. This will cause the drivers to 'see' a greater volume of air behind them. Many of these low rent models tend to leak air around the drivers and tweeters which kills the bass with a sealed type box (non reflex). Sealing up these leaks will improve the bass.

There is only so much you can do though with the basic models sound wise.

James....

 

[MyOhMy]

The white acoustic fill (pillow stuffing) is mainly used to help eliminate standing waves that cause the reverberations that cause the speaker boxes to emit their own sound track.

I completely fill the speaker boxes with this material. But don't put in so much that you have to force it in. This will cause the drivers to 'see' a greater volume of air behind them. Many of these low rent models tend to leak air around the drivers and tweeters which kills the bass with a sealed type box (non reflex). Sealing up these leaks will improve the bass.

There is only so much you can do though with the basic models sound wise.

James....

Many thanks, jimmyjimmy19792010, you've explained this very well. I wasn't expecting anything like perfection with the low end speakers I'll be working on, merely an improvement in the reduction of the 'hollow plastic' effect to enhance my listening pleasure.
Thanks, again.

 

[MyOhMy]

Update:

I used my available but limited amount of the white downy-type filling in a Hitachi TRK-9100 and a Sharp GF-A2 to very good effect. Gone is the 'hollow plastic' sound from the speakers which now also produce much more bass, these speakers will never perform anything like high end speakers but the improvement is significant indeed and well worth the effort.

Thanks, Guys!