TerryG
Active member
Ok I know I am going to get criticized for this, but it is a thing I have been doing for years. This is not bait, but I am seriously wondering if anyone else has done this and how they may do it.
I don't like how much sensitivity(or SPL) a choke on my woofers takes up, and I don't like running them full range especially in the range of the frequency spike they make near their upper limit. So I have been using this air conditioner foam filtering as an acoustical filter. I have a speaker grill that is a couple of inches from my speakers drivers, so I make use of this room to try different materials in acoustical filters for my woofers. The lower frequencies seem to come through with little drop in SPL, and the more layers of foam the more filtering I get in the upper frequencies, and the lower the point gets where the woofer starts dropping off. I wouldn't say it is 6dbs per octave like an electronic 1st order filter but it gets closer the more layers I put in front of the woofer.
Right now with years of fiddling with this 1/4" foam and other cloth types, I have a +/-3db response from 28hz to 10K Hz at my listening chair. Which to me sounds like a bit of bass enhancement, but that probably is because we think the flat sound is measured at 3' when I listen 12' from my speakers. So I like to know what I am hearing at my couch.
I also have been using this same foam around my tweeters in a baffle which seems to help them sound sweeter, compared to just the plain hard surface around them, sort of like how JBL and EV use to do around their tweeters. Measuring the result shows some smaller spikes in response the foam removes from the tweeters frequency range
Does anyone else do stuff like this with foam to act as an acoustical xo or reflection control?
Other than unexpected or unintended results, what might be the downsides?
I don't like how much sensitivity(or SPL) a choke on my woofers takes up, and I don't like running them full range especially in the range of the frequency spike they make near their upper limit. So I have been using this air conditioner foam filtering as an acoustical filter. I have a speaker grill that is a couple of inches from my speakers drivers, so I make use of this room to try different materials in acoustical filters for my woofers. The lower frequencies seem to come through with little drop in SPL, and the more layers of foam the more filtering I get in the upper frequencies, and the lower the point gets where the woofer starts dropping off. I wouldn't say it is 6dbs per octave like an electronic 1st order filter but it gets closer the more layers I put in front of the woofer.
Right now with years of fiddling with this 1/4" foam and other cloth types, I have a +/-3db response from 28hz to 10K Hz at my listening chair. Which to me sounds like a bit of bass enhancement, but that probably is because we think the flat sound is measured at 3' when I listen 12' from my speakers. So I like to know what I am hearing at my couch.
I also have been using this same foam around my tweeters in a baffle which seems to help them sound sweeter, compared to just the plain hard surface around them, sort of like how JBL and EV use to do around their tweeters. Measuring the result shows some smaller spikes in response the foam removes from the tweeters frequency range
Does anyone else do stuff like this with foam to act as an acoustical xo or reflection control?
Other than unexpected or unintended results, what might be the downsides?
