Pass Aleph Amplifier Chassis Group Buy Proposal

[opc]

Hello Everyone,

The purpose of this post is to see if there is any interest in an organized group buy for an amplifier chassis "kit" intended for the Pass Labs Aleph series. I'm currently working on a monoblock pair of Nelson's Aleph 2 amplifiers, and I'm stuck at a standstill with the chassis'.

I have already purchased four large heatsinks from a company here in Canada called R-theta, so the kits would not include heatsinks. The plan was to have the front panels, back plates, tops, and bottoms machined by a company called "emachineshop". (check them out at www.emachineshop.com) I have already done all the technical drawings and design, but during the process I realized that even a quantity of 10 units dropped my unit price to less than 1/3 of a single unit.

Here are some details on what I have already:

- All panels are machined 1/2" thick 6061-T6 Aluminum except the back.

- 32 microinch surface finish bare aluminum (perfect for anodizing).

- All bolt holes are drilled and countersunk.

- Enough heat dissipation for up to 300 watts total (per chassis) with a 20 degree C rise.

- Back panel is powder coated black 0.118" thick carbon steel with vent holes and all jacks.


Well, if a 2D picture is worth a thousand words, a full 3D rendered model must be worth more like a million. If you want to see all the details of the intended design, please download the CAD program from http://www.emachineshop.com/download/index.htm (it’s only 5.3MB, and it’s free) and open the .ems file at the end of this post. Then all you have to do is render it (click the pyramid in the toolbar) and you’ll be able to see the full design and rotate it and whatnot.

The estimated cost right now for the front, back, top and bottom would be about $350 US per chassis. A single chassis would house a small Aleph, but it’ll take two for the bigger versions All that would be left to buy is the bar stock to hold it all together (about $35), the bolts (about $15) and the heatsinks from R-theta (I paid $45 CDN each for the four mine). Assembly would also be up the buyer, as it simplifies shipping. Just for reference the R-theta heatsink used is model #65340 cut to 9” length.

The goal of all this is to get a very professional looking chassis that will fit most of the larger class A amplifiers people are building. The prices are high, but that’s the name of the game with small run high quality parts. This group buy would be run as a not for profit setup, but I would like to get about ½ off on my purchase for the time and effort involved in such a big buy. The $350 dollar price is based on 10 units (5 pairs), so if there are more people interested that price should drop somewhat. An ideal number for me would be a total of 10 pairs which should land the price at just under $300 per chassis.

Anyone who is interested, or who would like to know more, please feel free to post a reply here or send me an e-mail. If you have any comments or suggestions please let me know on the forum so others can read it. Please keep in mind that I’m trying to make these as generic as possible, so don’t ask to have your name machined in the front panel. The back panel has a generic punch out for an IEC plug, a standard 30A switch, and a regular sized hole for a single RCA jack and a specific hole for a Neutrik XLR connector. The holes for the binding posts are on 19mm centers, so most posts should fit. Please don’t ask for changes to this layout, unless you truly believe it will be beneficial to everyone. I’ll leave it up to the individual to make their own parts fit.

Thanks for reading, and I’ll be checking back daily for any changes!

Cheers,

Owen Columbus

[kilowattski]

Your price seems a bit high. DiyAudio member Jrsun has run group buys for Aleph chassis on this forum in the past for $200/chassis with the metal nicely annodized and including the heatsinks . Your price is almost double without the heatsink. I am always interested in a nice chassis group buy, but not at that price. BTW, I suggest that the bottom be made of 1/4" aluminum and the top be made from .100 aluminum. I think 1/2" for the top and bottom is way overkill.

Here is the thread for Russells Aleph chassis group buy: urgent ! 2nd class A amp enclosure GP

[Mattyo5]

Thats a sweet looking case, but for $350 + heatsinks... uh.. thats a bit much. I'm not convinced that those sinks can do 300 watts of heat w/ 20deg C rise either. Sweet looking case though, $300 inc. heatsinks wouldn't be a bad price... heatsinks should almost for sure be bigger though. Just my 2cents.

-Matthew K. Olson

[opc]

Hey Guys,

Sorry for the late reply today, I spent the evening breadboarding my BOSOZ linestage. It sure doesn't look pretty, but it gave me a good evening of listening!

Kilowattski,

Maybe you're right about the overkill size, but that was sorta what I was going for. I guess the general public doesn't budget as much for their chassis as I was ready to. Nonetheless, I went ahead and priced it out again with good old black powder coated 0.118" steel plates for the top, bottom, front and back. The basic layout would remain the same, but just not as substantial. The price break turned out to be huge, since I can get all four panels on the same turret punch sheet. If I went that way we'd be looking at about $180 US for all the plates, both heatsinks included (anodized black to match), and all the bars and hardware. Maybe this would be a better way to go… the top plates alone on the other design were over $100 each! Could anyone else posting comments please let me know what they’d prefer?

Matthew,

The heatsinks with the design are some of the largest I've ever seen anywhere. That includes this site. Maybe the cad drawing didn't really do them justice, but we're talking about an 8mm thick base, 60mm tall fins, and an overall size of 9" by 11". The data sheet gives them a CW rating of 0.5 deg /watt / 3" length, which is a total of 1.67 deg / watt for each 9" sink. An Aleph 2 dissipates 150W per sink, so that's about 25 degrees assuming they're hanging in free air. Once mounted to a chassis made of an additional 40lbs of aluminum, I think the 20 deg. above ambient estimate is pretty safe. The other upside to the sinks is the fact that R-theta was a real pleasure to deal with when I ordered mine. If you have a specific type you'd prefer let me know and I'll look into it, but I'd really rather stick with the spec'd units. If any of my numbers are off please let me know too, and I'll look it back over.

Thanks for the comments so far; keep em’ coming and hopefully we can get the ball rolling on this!

Cheers,

Owen

[kilowattski]

Owen,

I like the 1/2" front panel and 1/4" bottom (for those heavy toroidals). 0.118 is good for the top and back. Here is a picture of a chassis I built with the configuration I stated. The front, top and back panels are not pictured.

[opc]

Kilowattski,

That's a beautiful chassis! Did you do the machining yourself or do you know someone who does it? I'm gonna head back to the drawing board and try to get a price on something with a steel top and back, a 1/4" bottom, and the same 1/2" front in the original design. The fronts are going to add quite a bit to the price, but they really do make for a much nicer amplifier.

I'll let you guys know a price when I get everything done.

Cheers,

Owen

[kilowattski]

One of my neighbors owns a machine shop so I asked him if he could build it for me. He of course said no. But he said he would teach me how to use a Bridgeport and let me come in on Saturdays to work on it. So I built it myself. With the learning curve and all it took 8 months. Near the end he let me use a Bridgeport with a DRO (digital read out) which make it go a little faster.

[Peter Daniel]

Here's Aleph 4 in monoblock version using 11" lengths of those heatsinks. They are about right.
Yet another Aleph 4

[Mattyo5]

opc, look at peter's link. that aleph 4 is running 260 watts dissipation at 60 deg C w/ 11"x11" sinks.

currently i'm going to be using 15.5"x19" x 1" sinks for my aleph 2s... 2 of those per channel for 300 watts dissipation, so i have to argue w/ the 9x11" size being adequate...unless those fins are 3" long. Now, I do agree that heatsinks are DANG hard to find and very difficult to get better than RTHETA's. I'd increase the length on those sinks though ... anyone else jump in here please.

-Matthew K. Olson

[fcel]

Opc,
On your 1st post, you have attached a .ems zip file of your chassis design. Can you post a acad zip file here? And including any updated chassis design that you have done.