Re vent placement, no it shouldn't have a significant impact on GD as far as the box is concerned. When I designed it, I assumed the vent to be on the back -Dave has drawn with it on the front since either can be employed. Doesn't affect the box behaviour significantly, but it will interact with the room differently. If you're planning on putting them close to a boundary, then front is likely to be preferable.
Like any speaker, the room (and placement) dominates the LF performance. They should do decently mounted on-wall. They might have a bit of a lift low down, and they might not image as well, but you really have to try it in your own room.
dave
bass reflex, four speakers
Dear Scott,
Dave was kind enough to inform me how to increase the cross sectional area of the pensils in order to accommodate four 10p's. However the size would be too big and impractical for me. I was wondering if I could also increase the cross sectional area of the bass reflex to accommodate four 10p's? Also, would four 10p's in a bass reflex be able to reach around 30hz?
Dear Scott,
Dave was kind enough to inform me how to increase the cross sectional area of the pensils in order to accommodate four 10p's. However the size would be too big and impractical for me. I was wondering if I could also increase the cross sectional area of the bass reflex to accommodate four 10p's? Also, would four 10p's in a bass reflex be able to reach around 30hz?
Unfortunately, I already have the four pairs of 10p and will also be using the Minidsp Dirac live for eq.
I'm a bit puzzled as to what to use as dampening.
If I use that white poly fluff type stuff that you get on a roll from an upholsterers, how thick does it need to be? I was looking at some today but it was only about 15mm thick and could be squished down to nothing. Couldn't image that would be a lot of good.
If I use that white poly fluff type stuff that you get on a roll from an upholsterers, how thick does it need to be? I was looking at some today but it was only about 15mm thick and could be squished down to nothing. Couldn't image that would be a lot of good.
Two layers aught to handle it. I prefer fiberglass, but that's just me. Polyfill does work OK, and the real Dupont Hollowfill works better. Even though you are doing a BR, there is nothing wrong with putting a wad of polyfill in the middle of the box behind the driver. Just be careful that you don't use enough to change the alignment.
Bob
Bob
This talk of cabinet damping/lining is making me question my choice of using some fairly dense foam-based carpet underlay ( I believe it is 11mm 'Cloud Nine Cumulus' - quite popular in the UK).
I'm aware this isn't optimal, but could it actually be adversely affecting the sound (I have Alpair 10.3 MA in CGR bass reflex box). Can anyone suggest what identifiable sound impact it might have? I've never been 100% satisfied with them and am trying to get WA(F) to build some Pensils in an attempt to make them more dynamic at low vols and warmer sounding (plus the added LF will help).
I'm aware this isn't optimal, but could it actually be adversely affecting the sound (I have Alpair 10.3 MA in CGR bass reflex box). Can anyone suggest what identifiable sound impact it might have? I've never been 100% satisfied with them and am trying to get WA(F) to build some Pensils in an attempt to make them more dynamic at low vols and warmer sounding (plus the added LF will help).
Pithy? If you insist. 
Yes. In general, for these duties it's against reason and god (whichever you believe in). Closed cell foam is utterly worthless for acoustic damping, i.e. attenuating reflections, unwanted Eigenmodes &c. since its absorptive properties are minimal at best. It can have some uses for panel damping, but that's a different matter, and a well designed box in a suitably stiff material should need very little in the way of damping to attenuate panel modes < -35dB nominal audibility threshold.
If advice is desired: rip it out. Replace it with some decent BAF wadding, Ultratouch recycled denim, a decent wool / natural fibre carpet underlay or similar felt. You will be surprised. Most notably through the midband, which should subjectively open up quite nicely.
Yes. In general, for these duties it's against reason and god (whichever you believe in). Closed cell foam is utterly worthless for acoustic damping, i.e. attenuating reflections, unwanted Eigenmodes &c. since its absorptive properties are minimal at best. It can have some uses for panel damping, but that's a different matter, and a well designed box in a suitably stiff material should need very little in the way of damping to attenuate panel modes < -35dB nominal audibility threshold. If advice is desired: rip it out. Replace it with some decent BAF wadding, Ultratouch recycled denim, a decent wool / natural fibre carpet underlay or similar felt. You will be surprised. Most notably through the midband, which should subjectively open up quite nicely.
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