Millett "Starving Student" hybrid amp - Page 216

As promised, here are some detailed pics of both the prototype PCB (silver case) and the production PCB (black case). Click for bigger pics -

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Note that everything is tied to the top plate - the center standoff locks everything in place, but you must choose the correct bend on the MOSFET leads to coordinate this (see below). You should leave enough lead length to the back plate to swing it up and over the body of the case as shown. Then the entire assembly - top plate, PCB, and endplates slide out of the case body.


For the standard configuration and the pre-punched Hammond case, we'll use the 3rd slot from the top, as shown here.


Another view showing the entire assembly - front plate, top plate, back plate and PCB. Caps are Panasonic FM 680uf 63V for the power/decoupling caps and the new Nichicon Muse KW's at 480uf 63V for the output coupling caps. 0.22uf 250V Wima MKP10's all around. V-D resistors everywhere with Muse ES at 220uf 16V rounding out Dsavitsk's mods.


A bit out of focus in part, but this shows the lead-bend required for the pre-punched Hammond case. There's barely enough to solder in the pads, but it results in the tube sockets slightly below the top of the case for the best appearance. Placing the PCB at this level won't fit the larger caps, but the ones shown here have plenty of clearance. Note the second screws holding each heat sink in place. The sharp bend on the MOSFET leads brings the heat sinks far enough forward that they clear the bezel - unlike with the silver case below.

Pics of the silver one using the prototype board. This one uses Stackpole carbon film resistors and Nichicon Muse FG caps for output couplers at 1000uf 63V. Everything else is pretty much the same, but the FG caps required placing the PCB at the 2nd slot. This version sounds much more bassy than the black one. I think the black one is the best combination of parts and sounds scarily good. However, as long as you bend the MOSFETs as shown for the black one, you should be able to use the pre-punched Hammond case to build this version, too (placing the PCB in the 2nd slot, iow).


Note the chunks I had to cut out of the bezel to make room for the heat sinks. This is why we're using the sharp bend for the MOSFET leads as shown above for the black one. It puts the MOSFET mounting holes and thus, the heat sinks, further forward on the top of the case. It's enough to clear the bezel and prevent the need for cutting them as I had to do here.




Done for now, but I'm going to try to get the Group Buy going for the case before the weekend is out.

Wow, that's incredible! +1 for the GB

Looks like you got the dimensions absolutely perfect.

Will the predrilled endplates come with the hammond case? If so, time to invest in some laser water-slide decal paper!

Yes, the endplates will be punched. All that's needed is wiring and assembly once the PCB is populated.

WANT!!

I must have one... or two

NICE. I want two!

i'd be down for one as well

Damn thats sexy. In for one!

Very elegant solution, Tomb!

perfect! very very nice tom... will these be open to orders from down under?

looks like a great amp!

Of course - I ship everywhere the US Post Office allows.

Updated BOM for the PCB SSMH here.

Friday, 5/29/2009 at 8:00PM EDST, the following will go live:

• Pre-orders for SSMH kits, only 1 ea per person (everything in the attached BOM, including the custom-machined Hammond case & guaranteed tubes)
• Pre-orders for the custom-machined Hammond case only (tube availability not guaranteed)
• PCB sales (tube availability not guaranteed, but will ship immediately)

I hesitated to display something like this up till now, but things are imminent at this point, so I took an inventory. We will definitely have enough tubes for at least 100 SSMH PCB's, with plenty left over to support rejects/losses from shipping or microphonics, etc.:



Please note that 95% of these tubes were obtained through wholesalers that did not deprive anyone from onesie-twosie purchases. In fact, I had specific conversations with one vendor to make certain that he had a stock remaining for individual purchases after my volume buy. At any rate, building this stock was needed to make the SSMH PCB a possibility.

I sent a few more questions to Hammond about their custom cases, but am prepared to order as quickly as possible, depending on how brisk the demand from you guys. I'm hoping that we can get at least 100, but remember that there's a 6 week lead time. So, the quicker there's some interest shown, the quicker we'll get them.

Kits will include everything on the BOM for at least the first 30 kits (Mouser column except for FC caps at C1/C6). I'll be contacting some vendors in the next few days about getting more power supplies. Depending on the results of those conversations, we may or may not include power supplies beyond the first 30.

It's been a long wait, but hopefully this will be worth it. Thanks for your patience.

Heh. Look's like Commons (my college cafeteria) got an upgrade.

That looks great. Excellent work.

I already have my tubes and components, I just want a PCB and perhaps a chassis.