Hello Wayne, Eager to know whether the addition of dacron/polyfill sheets decreases the box volume. I understand fibre glass in effect increases the Vb.
Wayne Parham Messages: 18790 Registered: January 2001
Illuminati (33rd Degree)
I've tried various products over the years but always come back to R11/R13. Some provide damping but some do nothing as all. Best way to tell is to measure the sound inside the box by putting a microphone in the port. Ideally all that would be inside the box is sound below 100Hz. The damping material that comes closest to that is what you want. You also want as little effect below 100Hz as possible so that the box doesn't become de-tuned. Easy way to measure tuning is to check impedance and look for changes in the impedance peaks.
Hi Wayne, Roland, This link was posted today on the DIYAudioForum for the thread "Port calculations" and is also very technical, helping with the research that others are doing with this intricate subject. Regards.
feket663 Messages: 28 Registered: August 2009 Location: Hungary
Chancellor
Dear Wayne! My 4PI speakers nearly complete. Here's a picture of them.
A single question is even: The damping material (about 3 inch thick fiberglass insulation material) is enough, too much or too small quantity?
I listened a lot, but I think a bass response a bit wawy. A deep bass is ok, but the 60-70 hz range is a slightly less. This can occur when an inadequate amount of damping material?
Can you send me a pic of 4PI's inside with damping material?
Thanks for help!
Istvan from Hungary
Wayne Parham Messages: 18790 Registered: January 2001
Illuminati (33rd Degree)
Looks good. You put in the right amount of damping material, from what I can see.
How long have you had those woofers? I ask because 2226 woofers tend to be pretty stiff out of the box. They're underdamped at first. The alignment shifts to where it is supposed to be after several hours at moderate power. You can move some woofers back and forth by hand to do this "break in" process, but I prefer to let the motor do it for me.
Wayne Parham Messages: 18790 Registered: January 2001
Illuminati (33rd Degree)
Next step then (in my opinion) is to getcha some subs. I love the sound of my four π speakers even without subs, but adding them puts them really over the top. It's really about smoothing the response as much as it is about increasing extension.
One thing that happens indoors is the reflections from the walls causes self-interference that is additive at some frequency/positions and destructive at other frequency/positions. These room modes are sometimes pretty noticeable all the way up into the lower midrange, to 150Hz or maybe even 200Hz or so. The end result is dead spots in the room - frequencies that are sucked out and can't be corrected with passive or active equalization.
The best way to fix this is to add bass sound sources in different positions in the room. I find having subs placed several feet from the mains usually helps a great deal. Again, it's about smoothing the response, filling in holes made by room modes. That's the goal. You can't even really tell the subs are on, but response is smoother. They do reach lower too, but when setup right (which is pretty easy to do), it sounds like all the sound is coming from the mains. You can't tell the subs are even on. The sound is just smoother.
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