Some of you may remember my idea of using a sand-filled sock and coiling it at the bottom of a column loudspeaker in order to mitigate the effects of the top to bottom standing wave.
Having lived with this concept for a while and after taking some measurements I have abandoned this idea. The effect of the sock was to spread the frequencies of the standing wave and to make them less pronounced in their effects. However, I ended up putting more long-haired wool as stuffing around the centre of the enclosure to mop up the standing wave. After adding the stuffing it didn't seem to matter whether the sock was there or not so I removed it.
I'd like to apologize to all sock users out there. However, it was an idea worth trying. Perhaps it would be more useful in other enclosures.
Anyway, I thought I should report my latest findings on this one.
Having lived with this concept for a while and after taking some measurements I have abandoned this idea. The effect of the sock was to spread the frequencies of the standing wave and to make them less pronounced in their effects. However, I ended up putting more long-haired wool as stuffing around the centre of the enclosure to mop up the standing wave. After adding the stuffing it didn't seem to matter whether the sock was there or not so I removed it.
I'd like to apologize to all sock users out there. However, it was an idea worth trying. Perhaps it would be more useful in other enclosures.
Anyway, I thought I should report my latest findings on this one.
Of course, the other advantage is from the mass- it helps stabilize the column. So it was STILL a good idea.
As a sock user of the not so distant past, I'm wondering if you would share how you suspend the stuffing in the middle of the enclosure? Also, a question of methodology; do you have a test enclosure and the end result was from trial and error or more scientific than that?
Oh well. Nothing ventured, nothing gained. Progress marches on.😀
There is still the matter of Helmholtz resonators to suppress standing waves. I haven't given up on that.
There is still the matter of Helmholtz resonators to suppress standing waves. I haven't given up on that.
Sock Stories
Lexicon used to include sand filled sock with its Opus DAW. It was used in a steel leg brace to keep it from resonating.
I had a friend who used a rolled up pair of socks to tune the ports of his speakers. He claims that a certain passage of a Queen album caused them to get sucked inside.
How bout a big plaster cone to help the standing wave issue? I know it reduces the volume of the box, but it seems like it will break the waves nicely.
I have also pondered the use of rings in the box spaced to fit where the peaks of the standing wave would occur. My idea is to diffuse the energy rather than damp it. Kind of like the RPG diffusers based on Maxwell’s residual decay equations.
Lexicon used to include sand filled sock with its Opus DAW. It was used in a steel leg brace to keep it from resonating.
I had a friend who used a rolled up pair of socks to tune the ports of his speakers. He claims that a certain passage of a Queen album caused them to get sucked inside.
How bout a big plaster cone to help the standing wave issue? I know it reduces the volume of the box, but it seems like it will break the waves nicely.
I have also pondered the use of rings in the box spaced to fit where the peaks of the standing wave would occur. My idea is to diffuse the energy rather than damp it. Kind of like the RPG diffusers based on Maxwell’s residual decay equations.
My enclosures are quite narrow and they also have ridges going all the way down. They seem to hold the wool in place without any other fixing, although I have used silicone sealer (bathroom sealer) to hold a little wool on the walls behind the drive units.
As for 'trial and error' or test enclosures: I did originally build a rectangular enclosure of the same cross-section to test the anti-resonant properties of the egg-shaped interior. Just speaking into the hole for the drive-units showed up such a vast difference that further testing wasn't necessary. Listening to the Nonsuch 4s revealed a slight weakness in the upper bass and I used the ETF5 software to take measurements. These confirmed a dip in the response which I assumed was the result of the standing wave/sock combo. This disappeared after I added the stuffing. Then I took measurements with and without the sock and couldn't detect any change except for the slight differences caused by the small loss of volume with the sock in place.
I agree, Keltic, that there could be mileage in the Helmholtz resonator concept but haven't yet had time to explore this further. I'm not sure that the plaster dome would give any improvement over the sock. I can't quite visualize what the rings do - but if it's good enough for Maxwell... 😀 Da5id4Vz, could you expand a bit on this idea?
As for 'trial and error' or test enclosures: I did originally build a rectangular enclosure of the same cross-section to test the anti-resonant properties of the egg-shaped interior. Just speaking into the hole for the drive-units showed up such a vast difference that further testing wasn't necessary. Listening to the Nonsuch 4s revealed a slight weakness in the upper bass and I used the ETF5 software to take measurements. These confirmed a dip in the response which I assumed was the result of the standing wave/sock combo. This disappeared after I added the stuffing. Then I took measurements with and without the sock and couldn't detect any change except for the slight differences caused by the small loss of volume with the sock in place.
I agree, Keltic, that there could be mileage in the Helmholtz resonator concept but haven't yet had time to explore this further. I'm not sure that the plaster dome would give any improvement over the sock. I can't quite visualize what the rings do - but if it's good enough for Maxwell... 😀 Da5id4Vz, could you expand a bit on this idea?
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