Burning Amps

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Today the six month mark of BA2008 passed quietly (which might be just as well considering all the OT stuff triggering email notifications).

Rather than twiddle my thumbs, I'm making a dual LED holder to fit our chassis.

That's all....sniff.
 

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By adding that round tube to the heatsink the airflow through
the sink will slow down so the benifit of more heat disipating
area will be lost. Wakefield enginerring had a short article on
this in one of there old catalogs and the conclusion was in a
properly designed heatsink the volumn of the sink was a better
indicator of thermal resistance than total heatsink area.
 
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I need someone to hold my hand.

One thing that has already been built in that chassis is the PLH amplifier. See the article.
I have looked the PLH article up and down (as well as 'The Class-A Amplifier Site') and can't reconcile how all those amp schematics show only NPN devices in the output, but my chassis has complementary pairs of NPN and PNP...

I think I've worked out a nice front end which will accommodate everyone's needs with regard to this chassis. The all N channel guys will get something, the complementary Mosfet guys will get something, and even the Bipolar guys can use their output stages.

With lots of options to keep you busy until the second coming...

So stay tuned.

"...and even the Bipolar guys can use their output stages."

Now THIS is the part that interests me, as I am in the awkward position of having taken on custodianship of a SECOND Pass prototype chassis, No.27 (I also have No.34), which also has 4 pairs of complementary BJTs. What do I do?
 
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Would that make it related to the Pass A40? This is the only amp of yours I've seen that has pairs of complementary pairs of BJTs. (And in the A40 article you said it even sounds good driving ESLs, which is what I need it for.)

I'm mostly in over my head about many electronic terms (like 'followers'), but I can build from a complete schematic. If you draw something on a napkin using these BJT output devices, I will probably try to put it together. On the other hand if you think it won't sound nearly as nice as your MOSFET amps, then I'll gut the output boards in both chassis and make two stereo BA2's for bi-amping (or two monobloc BA2's?). I just don't understand what the possible variations are...
 
I would suggest going to passdiy.com and checking out the enlightning articles by The One And Only. Start with the Zen 1 I guess it's called. You will be introduced to a simple is better philosophy that can be very rewarding, not to mention delightfull reading.
Or, you can jump over all that and I think;
http://www.passdiy.com/pdf/zen-v5-hires.pdf decribes quite a bit about whats going on here :)
 
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I did it!

Did what? I pretty much demonstrated the extents of my electrical knowledge by putting a resistor in series with the LEDs and a tired 9V battery to light up my two chassis. And they look very impressive with the lights on!

Um, thanks flg for trying to be helpful, but I've already built the Zen (and NP has signed it), and I've read all those articles, but unfortunately they didn't suddenly gift me with mad electronics skills...

So the deafening silence about the BJTs means I think I'll be building two of the BA2 instead (if only I could source 16x IRFP9240 in TO3 cases to go along with the 20x IRF250 Nelson gave me).
 

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I guess this would be the right place to post...
I am part of the fortunate group that has chassis from Mr. Pass he generously donated for the 2008 Burning Amp. The very case this Burning Amp BA2 is intended for. Case was originally used by Mr.Pass as a test bed, and who knows what great amps came out of it. Just for that reason and the fact that Master worked on it, I treat it as a very special item.

So what best use for the case than using it again for what was meant for? While I am waiting for the BA boards to be produced I wanted to test few amps and hear what they do. My planned line up include F5, F5 balanced, F5 with cascode drivers and two output pairs (schematic designed by Zen Mode) balanced, F3, Aleph J and Aleph JX, Babelfish by Zen Mode, BA1 and BA2... I also have huge transformers that Mr. Pass donated for the first BAF 2007. Those are real monsters, originally used in X1000. I do not know exactly, but I believe they are something like 3 KVA each, potted, center tapped with dual primaries (220 and 120V) and with equal secondaries: 45 - 35 - 0 - 35 - 45
Between two of these I could get any dual voltage that I could have ever dream off. From 18 V to 90V and anything in between. I have Peter Daniel's boards and Zen Mod's Babelfish boards, so all that was needed were parts for the boards which I just ordered and received last week.

Case has already installed N and P channel MOSFETs, 6 pairs on each side. That gives me the opportunity to test any type of amp just by wiring needed output fets. I could even have two different amps in the same chassis. Since I do not know where I am going to end up I didn't mount anything permanently and everything is wired so that I could easily exchange input boards, add more output devices... Obviously trannies are outside of the case, as well as rectifiers. Here are the pictures. Obviously everything is mess, wires are everywhere, much longer then needed, but it provides me with an opportunity to test.
Here is the shot of the chassis in front of my test line up.
 

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