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-   -   Alpair Pensil 12.2p Build (http://www.diyaudio.com/forums/full-range/222335-alpair-pensil-12-2p-build.html)

craigtone 27th October 2012 02:53 PM

Alpair Pensil 12.2p Build
 
4 Attachment(s)
The Markaudio 12P drivers have about 150 hours on them, so it is time to build some boxes! I was originally going for the Super Pensil 12p box, but opted for the standard Pensil due to size and also I read that there is a slight mid-bass dip in the larger box. I prefer a flat response, so I am willing to sacrifice some low end for a better balanced cabinet.

Pics attached were from last night about 11PM. I am headed to the hardware store for the rest of the parts to finish and should have final pics up this afternoon and then you won't see me for a while because I am pretty sure based off of what I heard with them running in free air that I will not be able to be pried away from them! :D

craigtone 28th October 2012 02:04 PM

6 Attachment(s)
I got them finished about 2PM yesterday and as promised, I was too busy listening to update the post. Mind you my previous speakers were RF-7's with DeanG crossovers, so the 12P does not replace them per se. I do find it to be a very smooth, balanced speaker without any emphasis or forwardness at any frequency. I did notice a little harshness at certain frequencies, but it "sounds" like it is something that will smooth out as they break-in since I did not notice it again. I was surprised at their ability to reveal information that even my 102dB sensitivity RF7 horns were not able to. I also now have a noise problem that I never had before that I will need to start tracking down. It does not change with volume, so I am thinking it may just be electron flow through the tubes.

Overall I am VERY happy with the speakers. The bass extends quite low and a subwoofer is definitely not necessary for just listening to music. I am now glad I did not build the Super Pensil as I do not feel more bass is needed (at least in my small 11x14 room).

I also played around with my Dynaco Triode/Pentode switch a bit. On slower, acoustic music, triode adds that warmth that melts your soul. Whereas with faster music (Tool's Intolerance), Pentode mode hands down! Albeit, it does add a little too much "brightness" to slower music in Pentode mode. The most stunning example to me was Tori Amos's Icicles intro. Normally it is female vocals that stand the hair on my arm at attention but her emotion played right through the Alpair's and almost brought me to tears! Piano is one of the hardest instruments to reproduce and these speakers make the piano sound like it is in the room! You can even hear the hollow echo as she pushes the pedals! Note that this is with CD! I will be on pins and needles until my HiFace 2 arrives mid next week so I can listen to some 24/96 material.

The last comment I'll make is that to date with every speaker I have owned (Klipsch, Snell, Fostex), CD sounds like it is coming out of a "plane" at the cone distance. I get good imaging, but not front to back. Vinyl and 24/96 gave me that depth. With the Alpairs, I am getting that depth on CD. The intro to Tool's Intolerance sounds like the sound is revolving around the room. Bands have a presence akin to a live show with regard to instrument placement on the stage left to right as well as front to back. These are probably the best speaker I have ever heard as far as sounding "as close to live music". I am still on the fence as the "best speaker I have ever heard" as the Audio Note AN-E Signatures top my all time list.

Someone had requested a video in another post of some 12P's playing, so here 'tis: http://www.youtube.com/watch?v=SUyo9itNeGU

OK, enough babbling ... enjoy some speaker "porn":

craigtone 28th October 2012 02:10 PM

I am curious if anyone has veneered this box design? My concern is the radiused port opening. My initial idea is to veneer the sides and top entirely. Paint the port interior and mouth including the sides and then veneer from the top of the port opening up to essentially leave just a satin black rectangle at the bottom. I am thinking Apple.

If anyone has done anything similar, I'd LOVE to see pics! ;)

nattonrice 28th October 2012 02:56 PM

There's quite a few pics in the MA forum "post pics of your pensils" (or something like that) thread.

zman01 28th October 2012 04:49 PM

Craigtone,

Thanks for the detailed review and good to know that the speakers sound good - I have a pair of A12P breaking in and probably will go for the standard Pensil also. I have my A12 Metal (previous gen) in Pensils for the past week and they sound better vs the other 3 designs I had tried earlier.

fastbike1 29th October 2012 03:09 PM

I would recommend a slight change to your veneer plan. Painting the onside of the port will work fine, although it's not that hard to put veneer inside if you want an alternative. If painting, however you still have to deal with the side and bottom edges. For this situation, I have used a full length piece of veneer for the front, then used a flush trim bit to trim out the port. Carefully make a hole in center of the port and insert the bit, then trim as usual. This will give the front a one-piece look and avoid bare edges/edge veneer seams etc.

Tonight I'll try to load a pic of an unfinished Derwent. While the Derwent is a front loaded horn you can see the technique I'm suggesting.

Quote:

Originally Posted by craigtone (Post 3218413)
I am curious if anyone has veneered this box design? My concern is the radiused port opening. My initial idea is to veneer the sides and top entirely. Paint the port interior and mouth including the sides and then veneer from the top of the port opening up to essentially leave just a satin black rectangle at the bottom. I am thinking Apple.

If anyone has done anything similar, I'd LOVE to see pics! ;)


Scottmoose 29th October 2012 03:53 PM

Quote:

Originally Posted by fastbike1 (Post 3219632)
Tonight I'll try to load a pic of an unfinished Derwent. While the Derwent is a front loaded horn you can see the technique I'm suggesting.

Back-loaded, unless you've used a very creative technique of mounting the driver... ;)

chrisb 29th October 2012 04:49 PM

1 Attachment(s)
On my Pensil 7s, I painted the visible internal surfaces of port and back panel with spray bomb, and post veneered the box with the iron on method. But I cheated and did not radius the front sides of ports, so trimming the veneer with utility knife was a breeze.
I always use only flexible paper backed veneers, and some species are easier to curve in the cross grain direction.

I'd still be inclined to try the iron - one of the advantages of not worrying about a little scorching on edges and cutouts etc, is that it defines your trim lines. You should be get the nose of the around the radiused edge of the long front panel, and combination of clamp / cold press and masking tape on the bottom plate - or just paint it and add a recessed reveal and base plate as below

Open question to Scott: considering the "length" of the ports on Pensil family, can you forsee any sonic disadvantages to not radiusing them? Too late for Craig obviously, but for other builders it would certainly simplify this aspect of the finishing.

Scottmoose 29th October 2012 05:11 PM

That's an easy one to answer Chris: I didn't specifiy a radii in the first place. It's optional for those who are so inclined, but will be primarily cosmetic; I'd anticipate audible differences to be nil. I wouldn't bother with it myself, but then, I can only use a hammer on a good day.

craigtone 29th October 2012 05:22 PM

1 Attachment(s)
I built to the Pensil 12.2p plans (attached) which call out the radius.

But yeah, if no radius I'd just veneer the entire front and trim out the port hole!

I talked to a fellow woodworker at work and he thinks it will look good just painting the port and sidewalls black and starting the veneer at the top of the port. Worst case I veneer the fronts twice! :p


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