My Super Pensil 12.2p Build -With Pics!

[tlarwa]

I wanted to share my latest speaker build. Super Pensil 12.2p cabinets with the Mark Audio 12p driver. Finished them up last night, hooked them up this morning, and just got done with my first (short) listening session. Listened to Norah Jones, Esperanza Spalding and Phil Woods, all recordings I'm very familiar with. Speakers are driven by my Fisher 400, and the source is my Empire 208/Jelco 750D/Denon 103r going through a Parks Audio Budgie tube phono preamp. Speakers are set-up in my 12x17 listening room, which is well treated.

So how to they sound? In a word, fantastic! My first impressions are that they are all I could have hoped for. Terrific imaging with wonderful resolution and separation between instruments. Bass is very taut and more than adequate, at least with these types of recordings. I haven't pushed them with any Zeppelin or Floyd yet, so how they hold up to those demands is yet to be seen. But I really built them for jazz and vocals. I have my modded Klipsch Forte II's for the heavier stuff, if needed!

Some details about the build...

You may notice they look a little different than the typical Pensil cabinet. I don't care for the exposed ply edge look, so I built them so that the only place this is visible is on the back edges. The cabinets are 3/4" oak ply, and the tops and baffles are 3/4" solid red oak. I bought 12" wide red oak, which is really 11 1/4" wide. So I didn't have to rip these boards down, I adjusted the cabinet dimensions slightly to use their full width. After conferring with the designer, Scotmoose, I learned that small cabinet dimensions adjustments were okay, as long as the height, volume and port area stayed the same as originally designed. So the speakers are 11 1/4" wide, 37" tall and 17" deep. I used two levels of internal window bracing, using 3/4" ply. The cabinets seem well braced when tested by the very scientific knuckle test. They are fully glued ... no fasteners used. I used 1/8" F11 acoustical felt to line the side walls, back walls and top at driver level (to minimize reflections, theoretically). They are currently stuffed with 1# of well-teased poly fiberfill per cabinet. The area behind the vent is not stuffed. I used cat5 wire, soldered to the terminal cups and drivers. The cabinets are resting on 2" solid brass spikes. The cabinets are stained with Zar rosewood stain and the tops and baffles were left natural. There are 2 coats of clear shellac on all surfaces. I may apply more at some point, but they look pretty nice as they are. The vent holes were interesting. I made a template the size of the vent out of 3/4" ply, and routed them out with a 1/2" dia. top bearing flush trim bit. For some reason I got some uneven edges, though. No doubt due to my less than stellar woodworking skills. I'll do better next time! But they still came out okay. And I stianed the inside of the vent rosewood, so you have that contrast between the baffle and the inside of the cabinet when you see them head-on.

All in all, I'm very happy with the results, both visually and acoustically. I'm anxious to get back into the room for more listening, but I had to stop to watch the Packers game first! I'm also anxious to try them with a SET amp, which will happen next weekend. What I'm surprised by is how efficient they seem. The MA 12p drivers are 93dB efficient, but I seem to be able to drive them just as easily as my 99dB Forte II's. They get plenty loud with my Fisher 400 at "3" on the volume scale (and yes, the drivers have been properly broken in).


I can't attach more than one image at a time from my iPad, so here's a photobucket link:

http://photobucket.com/albums/ab65/tlarwa/Super Pensil

Comments are welcome, and I'm happy to answer questions for anyone that may be thinking about a similar build. I highly recommend it!

Tom

[vinylkid58]

Very nice looking build Tom. I really like the solid red oak front baffles. Not surprised you're liking the 12p's.

jeff

[kp93300]

Excellent build. You have visual and aural beauty combined !

[Scottmoose]

Nice work indeed.

[JoeyGS]

Nice

[planet10]

Nice build

Originally Posted by tlarwa

... two levels of internal window bracing...

Vertical or horizontal?

dave

[tlarwa]

Horizontal. The cross braces are staggered between layers. Pic attached, with Miles the cat in helper mode...

[planet10]

Those won't be to bad. It is a good idea to avoid horizontal braces as they will costrict the TL cross-section.

dave

[onform]

Slightly off topic but, have you modded your Klipsch? I've got a pair of their bigger brothers with blown tweeters.

I'm thinking of a similar build for intimate listening with the klipsch for the grunt stuff.. Lol

[pjmeli]

I made a template the size of the vent out of 3/4" ply, and routed them out with a 1/2" dia. top bearing flush trim bit. For some reason I got some uneven edges, though.

Plywood edges are too irregular for smooth template routing…use mdf or solid lumber (planed edges) for much better results. I make quick templates built up from from(2) short pieces (the width of the slot) sandwiched between (2) longer pieces, fastened together with super glue (Titebond Instant Bond). Hold the template to the part being routed with double-sided carpet tape. Be careful with the amount of tape…the stuff can be hard to release.