For what, seals behind the basket flanges? I use the solid toolbox drawer liner from Hazard Fraught. Seriously. Works great.
borus
Luthier tube guy
Cork No it's the space in between the glass fibers that you are looking for. It is not softness of the material. The sound waves get confused with the glass and cannot find their way to the box walls. This slows them down which makes them think the box is bigger the cork will just take up space making the box smaller.
scoloheros
Super Member
I think it was mentioned on the first page, they are designed to be placed on the floor. I didn't mention this either, I did change receivers but at the same time I put them on the floor instead of on stands. There was a remarkable difference in bass so I don't know if it was the receiver that made the big difference or if placing them on the floor did.
leftfielder
Active Member
I don't know if this is relevant or not. Over on the Polk site what's big in modding Polk speakers is adding Dynamatt to the basket spars/magnets. This is supposed to reduce any basket ring back you might have. Now if you use this in addition w/ less fiberglass maybe this could be an answer. I did not even buy my Dynamatt, I asked an an auto detailer if they had any scraps and he gave me a whole bag full after doing a car's trunk.
Blue Shadow
Waiting for Vintage Gear from this century
The EPI 100 (and others) owner's manual on the engine talks about the speaker placement in relation to the walls and floor, correctly stating that the more boundaries the speaker is next to the more bass, least being sitting on a table out in the middle of the room. The most would be wall-wall-corner placement, most accurate is wall-wall or floor-wall using two not all three boundaries.
@ra.ra the use of an 8 vs a 10µF cap simply changes the crossover from 2500Hz for 8µF to 2000Hz for 10µF for an 8Ω driver. For the EPI with an 1800Hz crossover, or thereabouts, not knowing the impedance of the tweeter, the difference between the 8 and 10 caps is meh really, meh. Especially when you know that the woofer is full range and just rolls off naturally.
Looking at the fiberglass from one of these speakers, it seems they tried to cover the interior walls of the speaker, not just layer the material on the back, leaving the sides somewhat uncovered. I would make two pair or finished speakers if it is easy to remove the woofer. One pair with more fill, one with less fill but covering the entire inner wall area of the speaker and compare the two. If you use enough in one and a low enough quantity in the other you should be able to hear the difference in the two sets of speakers, allowing you to dial in the amount you like. But since you say you are bass response lacking and adding more imitates a larger speaker, baco's idea of fill 'er up, is probably correct. He kinda knows some stuff about speakers.
The theory is not something that's been guessed at, rather experiments were done
and the theory verified by hundreds of good scientists - good luck to you. Try reading
Villchur's early paper on AS, or Beranek, or Marshall Leach, or ....
Culpeper
Active Member
I'm always skeptical when engineers come up with a $3 solution to an age old problem. Like it doesn't take a rocket scientist to ask what about the added mass. I guess it just disappeared. I'm not a scientist so my only question is can the increased internal size be measured? If the science is solid it should stand up to novice or fundamental questions. Just sayin'. Not trying to undermine you.
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You didn't ask novice or fundamental questions rather you doubted it.
Read: http://techtalk.parts-express.com/attachment.php?attachmentid=63055&d=1452624890
I would have uploaded it here but it is too large, even when zipped.
Read: http://techtalk.parts-express.com/attachment.php?attachmentid=63055&d=1452624890
I would have uploaded it here but it is too large, even when zipped.
Culpeper
Active Member
That LRS link I have posted on another thread states we should place these boxes facing each other and use the tone controls.
This paper is from 1989 when the basic theory had been established decades earlier,
it provides more accurate models for simulation:
https://leachlegacy.ece.gatech.edu/papers/Filling.pdf
it provides more accurate models for simulation:
https://leachlegacy.ece.gatech.edu/papers/Filling.pdf
Culpeper
Active Member
Okay, I get it but not buying it if the EPI box is already at the optimal size.. Does the EPI box need to be virtually increased? If not, are we going to need a bigger woofer? Also, the OP needs to make sure he has about 1.5 pounds of wall insulation stuffed in those boxes to increase effective space up to 40% and to what end? Without the right equipment he has no way to measure. There is no formula So, we need the original specs of the woofer to determine the effective increase we really need to get the most out of them. Just stuffing the box with wall insulation is not enough.
I would assume that the easiest way to do the job properly is to reuse the old damping material, or to use the same amount of material but new. I believe that there is a correctish amount of damping for a given driver, box, and alignment, and absent some way of determining all effects any alteration has, its just a crap shoot. I'm sure you can boost the bass by removing damping, but it probably won't be linear bass, but will be a big hump at some frequency range.
The first thing to consider for the general case is, what is the Qtc without damping,
if it is over 1 adding damping will have a stronger effect but even so you'll probably
lower it by a few tenths for filling half of the box, then more as you get closer to the
woofer. The EPI will not change much unless you grossly over stuff.
Of course the system was designed for stuffing, it was shipped that way!
Someone provided a picture, just follow that.
Actually, the boxes look fine, if there is too much bass experiment with one half or
an entire layer more.
I have 3 EPI 100s that I need to refoam - who knows when.
if it is over 1 adding damping will have a stronger effect but even so you'll probably
lower it by a few tenths for filling half of the box, then more as you get closer to the
woofer. The EPI will not change much unless you grossly over stuff.
Of course the system was designed for stuffing, it was shipped that way!
Someone provided a picture, just follow that.
Actually, the boxes look fine, if there is too much bass experiment with one half or
an entire layer more.
I have 3 EPI 100s that I need to refoam - who knows when.
woodj
Super Member
Exactly so.
