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"Tweaking" the Super Pensil 12.2p - Advice?

I've got them built, and up and running (see thread here http://www.diyaudio.com/forums/full-range/266717-my-super-pensil-12-2p-build-pics.html#post4159740). They sound terrific so far, but I'm wondering what improvements I can expect with stuffing and/or positioning tweaks. Right now, they are stuffed with 1# of poly fill (well teased) per cabinet. I also have the upper walls lined with 1/8" F11 acoustical felt. They are currently positioned about 36" from the back wall and about 13" off the side walls (to the center of the baffle), with a little toe in (see picture). They are 110" apart (center to center) and my listening position is about 100" back (I can adjust that easily enough).

Not knowing what these can ultimately achieve, I'm wondering what I can expect with more/less stuffing or a different positioning set-up. Sick with they are front ported, I'm thinking that the distance from the rear wall isn't critical (I may be wring) but I'm not so sure about the side wall distance.

Any suggestions? It's easy enough to change the position (although I'd like to leave my Forte II's in relatively the same place). But I need to pull the drivers to adjust the stuffing, and I dont want to do that any more often than absolutely necessary.

Thanks for your sage advice and suggestions...

Tom
 
Here's the front wall as it is currently...
 

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1) Hundred of hours of operating before they fully settle in
2) What are you powering them with?

Due to their size, all of my listening to this combo have been at Jeff's place with either of his two tube amps ( Pete Millett's Engineer's amp, or Jolida 302) .

These puppies do not camouflage any idiosyncrasies of upstream components - you might find that once they've settled in, that might be the best place to look at upgrades

of course, you need to invest in "special" speaker wire :D
 
To reiterate, I'm in no way dissatisfied with them at this point, I'm just curious what effect stuffing and placement tweaking will have.

Rather than start a new thread I searched all things "stuffing" and found this and it mirrors my question perfectly (although not so much the placement).

I am very happy with my recently finished pensil 7.3's they sound great but as with the OP I wonder is there more? I would like to know how stuffing affects the speaker output? I have stuffed with 355grams of polyfill as per the plans but was wondering when or why would I change this amount? I know I can just try it but if go to the trouble of removing the backs would I go more or less? What can I expect to hear? Are there any rules like smaller room = less stuffing etc?

Thanks
p.s. I have over 100 hours low level "radio" run in during cabinet build and then a bit more moderate level music listening since finishing.
 
frugal-phile™
Joined 2001
Paid Member
The felt at the top is to reduce early reflections thru the cone. The smaller the cabinet the greater the benefit.

As a TL the Pensil uses quarter-wave resonance to make extra bass. The damping is to kill the unwanted higher frequency resonances that we don't want. Less damping means more bass but more ripple from the unwanted harmonics. More damping gives a smoother response with less bass.

Room, room placement, and taste play a role too so there is no fixed correct amount. The back is removable so that you can play.

In our build Chris ended up pulling out about a 1/3 of the recommended damping.

dave
 
I seem to have missed the development of the 12.2p since 2012.
Does anyone have completed frequency curves of the pensil and super pensil with the 12.2p?
What sort of room size does anyone have them in? I am blessed with less cleaning and a small living rom - about 5.5m by 3.3m, so my listening triangle would be a little less than that. About 3.5m between me and the drive units.

Just interested in a reasonably priced full-range project to go with a class-T with digital sources.

Thanks all!
 
Some thoughts for m3tr0g33k

I've heard the Alpair12.2P in only two enclosures - Jeff's SuperPensil, and a moderate sized standmounted design by Dave - Mar-KenT or some such name. I think this driver really wants a larger vented enclosure to deliver its full potential in the bottom several octaves.

The SuperPensil is not a tiny box - they can certainly have placement issues, and it sounds like your room would be rather on the smallish size to fully appreciate them.

Unless you've already reason to decide otherwise, either of the 10s might be a more practical choice - they work well in a wider range of enclosure sizes than the 12Ps, and certainly can deliver decent bass response in a much smaller box than the Supers.

The most recent "digital" (Class D) amp that I've quite liked is the TPA3116, but there are numerous other candidates to consider
 
What sort of room size does anyone have them in? I am blessed with less cleaning and a small living room - about 5.5m by 3.3m, so my listening triangle would be a little less than that. About 3.5m between me and the drive units.

I have my Pensils in a slightly larger room, with an added "L" bit. The speakers aren't terribly wide, but are quite deep. You might want to consider the A10p in a Pensil box as well.

Just interested in a reasonably priced full-range project to go with a class-T with digital sources.

No T amps here, just tubes. The 12p's will play with dynamics and authority with 18 watts/ch.

jeff
 
I am keen to build to build an Alpair 12.2p loudspeaker myself. Like many others have I am considering the Pensil or SuperPensil. I note that the geometry of the speaker in the vertical/horizontal planes is the same. Only the speaker depth varies. Also, recommended stuffing density is the same and dependent on preferences.

I would like to ask the following to Scottmoose or anyone in the know please: can one consider all possible speaker depths between Pensil and SuperPensil reasonable? Would I be correct to assume that listening tests would reveal a continuum of experience such that the character of the speaker would change smoothly from the Pensil toward the SuperPensil as depth is increased? Perhaps mysterious factors (to me at least) may prevent this from being the case.

Thanks!