I know that that the top portion of the Pensil cabinet needs to be lined, in addition to the fiberfill at 75-1.0#/cu.ft. of volume. I have 3 options readily available to me, and was wondering which one is optimal, or if I need to buy something else.
Option one is 1/8" thick F11 acoustical felt. I've used this in the past to cover surfaces that were going to "see" the speaker cone.
Option 2 is a product we use at work to make acoustical panels. It's a 100% polyester sheet, in varying thicknesses (I have 1/2" and 1" at home). It's made to absorb sound, and the 1/2" has a .45 NRC (noise reduction coefficient) while the 1" has a .65 NRC. Would this be suitable? Tne product is called ReCore. You can Google it to see what it's all about.
Option 3 is the denim insulation product (can't think of what it's called). I think I used this in my FH3 build. The problem is that it's not in a nice even sheet form, so it's tougher to glue to a surface.
I've also been told to use 2" acoustical foam. I'm thinking this may be similar, or at least function similar, to the ReCore that I have?
And how far down the cabinet should I go with the lining? Should it be on the inside of the top, baffle, side walls and back walls?
Thanks,
Tom
Option one is 1/8" thick F11 acoustical felt. I've used this in the past to cover surfaces that were going to "see" the speaker cone.
Option 2 is a product we use at work to make acoustical panels. It's a 100% polyester sheet, in varying thicknesses (I have 1/2" and 1" at home). It's made to absorb sound, and the 1/2" has a .45 NRC (noise reduction coefficient) while the 1" has a .65 NRC. Would this be suitable? Tne product is called ReCore. You can Google it to see what it's all about.
Option 3 is the denim insulation product (can't think of what it's called). I think I used this in my FH3 build. The problem is that it's not in a nice even sheet form, so it's tougher to glue to a surface.
I've also been told to use 2" acoustical foam. I'm thinking this may be similar, or at least function similar, to the ReCore that I have?
And how far down the cabinet should I go with the lining? Should it be on the inside of the top, baffle, side walls and back walls?
Thanks,
Tom
It does? News to me. 😉
I specifically designed the pensils to use stuffing only, but if you wish, you can line the top. The impact will be minimal since the alignment is adjusted to taste / best suit your system requirements via the density of the stuffing. If you decide to line the top, avoid foam.
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Hmmm ... I must've read it somewhere. I've read pretty much every thread, so there's no doubt I came across some "mis-information" along the way! But hey, far be it for me to second guess you on this one. I'm more than happy to just use fiberfill!
Thanks for the clarification!
Thanks for the clarification!
Tom /Scott, perhaps I'm guilty for that mis-information - I know that I routinely line all cabinets with 1/2" Ultra-touch without necessarily consulting that part of any written instructions. That was certainly the case in pair of A12P SuperPensils that Jeff & I built a while back, and for that matter a current build of 12PW/A7P MTMs ( not a tiny box, BTW)
It does tend to aid in gripping of loose fibre fill to avoid it shifting or falling out of place if optimum fill quantity for the system is in the light side, and without a duplicate pair of builds for comparison, it's hard to prove that the extra lining is detrimental.
What I would opine is that the trouble to fabricate bracing between opposing panels is not a waste - although not necessarily as elaborate as the full length interlocking holey braces that I've suckered myself into incorporating on taller designs such as the Pensils, aforementioned MTMs, etc.
It does tend to aid in gripping of loose fibre fill to avoid it shifting or falling out of place if optimum fill quantity for the system is in the light side, and without a duplicate pair of builds for comparison, it's hard to prove that the extra lining is detrimental.
What I would opine is that the trouble to fabricate bracing between opposing panels is not a waste - although not necessarily as elaborate as the full length interlocking holey braces that I've suckered myself into incorporating on taller designs such as the Pensils, aforementioned MTMs, etc.
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i have found that lining the inside of the rear panel with insulation used for air conditioning improves bass definition quite a lot. Bass becomes more tuneful , the start and stop of double bass is easier to appreciate
In my superpensil 12 P build, the rear panel insulation lining is about 4 to 5 cm thick.
In my superpensil 12 P build, the rear panel insulation lining is about 4 to 5 cm thick.
The effects, as ever, vary with the material used & what stuffing density is employed. Along with personal taste.
Can someone confirm the recommended stuffing density? I think I read .75/SF to 1#/SF, if I'm not mistaken. Is that correct? And run it to just above the top of the vent? Also, is polyester fiberfill from Joann's acceptable?
Joann's fiberfill will work. You still may need more or less than the recommended. It's always to taste anyway.
I started with a 560 gram bag, and split it between the two boxes. Stuffed the top two thirds, and used tulle to suspend the fluff. As I haven't changed it, this is probably a good place to start.
jeff
jeff
Doh! My bad, I meant cu. ft. So 1.5# to 2# of fiberfill ought to do it for me (I think the cabs are a little more than 3 cu.ft.). Thanks for then clarification ... I would have been over-stuffing them.
The back panel only show one layer of the insuflex. By trial and error, i have increased to 3 layers.
Regarding the stuffing material, my suggestion is to place the speaker in the listerning position and to try different amount of stuffing and tune it by your own ears. This has quite a lot of effect on the sound.
You can test the effect of stuffing vs sound changes over a period of few days. The optimum amount varies with set up.
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Insulflex? That's a closed cell rubberised foam insulation as I recall; it may have a minor effect on panel damping, but its acoustic damping properties like all closed cell foams (as the name suggests) are close to nil. So while it'll have a small effect on box behaviour it won't be through it's acoustic damping properties, or the lack thereof.
I line the back panel becuase i notice that vibration of the box is most obvious in this position.
Adding the insuflex increase the mass and I notice less back panel vibration.
Adding the insuflex increase the mass and I notice less back panel vibration.
No doubt. That is panel rather than acoustic damping however; these are very different functions we need to be careful to describe / discuss separately to avoid confusion.
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