AMB Laboratories DIY Audio

[brucethehoon]

Here we have my first, second and third attempts at the op amps (in order from left to right). Honestly at this stage, I'll be grateful if they WORK.


And here we have a back and top view of the powercon jacks against the Hammond case (note the model number on the label in the top pic)




Hope this gives you an idea of the space you're working with!

[gumleguf]

You are using the AD861 which is SOIC-8 based. I am going for one of the DIP-8 based opamps which will fit straight into the 8-pin socket. As long as the soldering works, who cares how it looks, right? I won't tell.

Thanks for the pictures of the PowerCon/enclosure. Very helpful. I still think the PowerCon looks kind of cool. Maybe I Should just go ahead and use it!

[fishski13]

even though it's a less common 4-pin XLR, an XLR is for connecting signals in commercial audio applications, not power. for safety reasons, you could argue it's the wrong widget for the job. since i have no intentions of selling my M3, and i prefer the look of a black or nickel jack, it's a non-issue for me. the Neutriks are excellent though.

[hagak]

even though it's a less common 4-pin XLR, an XLR is for connecting signals in commercial audio applications, not power. for safety reasons, you could argue it's the wrong widget for the job. since i have no intentions of selling my M3, and i prefer the look of a black or nickel jack, it's a non-issue for me. the Neutriks are excellent though.

I had the same internal debate with myself when choosing to use SpeakOn connectors (PowerCon did not provide enough contacts for my application) for my power connections on my beta22. I justified it with the fact that SpeakOn is not exactly a common connector in the home space and that I have the jacks clearly labeled as being DC power.

[gumleguf]

Alright! PowerCon it is!

[xt0rted]

Here's a couple pictures of mine

[DorkVader]

xt0rted, is that one of those really nice miniplug female jacks on the back of your m^3?

Looks very good.

[xt0rted]

Yea it is. I ordered it by accident (thought it was one of the locking jacks like I used on the front) so it ended up as an input. I thought about using it on the front but I didn't really like the look of it since it's not all black.

[gumleguf]

amb > A little sanity check here, please.

I'm planning for the following upgrade parts. Looks ok?

Sigma 11:
---------
R10: 1/8W 1% metal film resistor 4.99KΩ

D5: BZX55C12 (12V)
http://search.digikey.com/scripts/DkSea ... ZX55C12-ND

Amveco TE62064 - Amveco 25VA 2+18V (388 grams or 0.8 pounds) = $34.40
http://search.digikey.com/scripts/DkSea ... 64&x=0&y=0

Heatsink - TO-220 Extruded heatsink Aavid 529902B02500 2” = $2.61
http://search.digikey.com/scripts/DkSea ... 00&x=0&y=0

M3:
----
Opamp - Analog Devices AD843JN (no adaptor) = $9.66
http://search.digikey.com/scripts/DkSea ... D843JNZ-ND

Heatsink - TO-220 Aavid 531202B00000G 2” = $0.93
http://search.digikey.com/scripts/DkSea ... 0G&x=0&y=0

One additional question about the heatsinks. I plan to build an open enclosure much the same way that meat01 has done it. Is it still recommendable to upgrade the heatsink to 2" insted of the 1.5"?:

[amb]

D5: BZX55C12 (12V)
http://search.digikey.com/scripts/DkSea ... ZX55C12-ND

Digi-key no longer stocks this, but you could substitute with 1N5242B, or get BZX55C12 from AMB audio shop.
The rest looks ok. Beware that AD843 has a tendency to output a thump noise at power-on.

One additional question about the heatsinks. I plan to build an open enclosure much the same way that meat01 has done it. Is it still recommendable to upgrade the heatsink to 2" insted of the 1.5"?

Depends on how heavily you will bias the MOSFET output stage. Larger heatsink will never hurt, you should also drill some holes on the bottom of the case to allow air convection around the heatsinks.