The BA-3 as preamp build guide

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If One were so inclined, and wanted to get crazy and fancy with C3, and say that individual didn't care so much about cost (within some sort of reason, barely). What would be your suggestions for a fancy pants 10 uf capacitors.

Asking for a friend (Not really)

I like WIMA MKP10 ... have used them in all my preamps, also in M2.

Best regards, Claas
 
John, any specifics with the Russian PIO? I've read anecdotal things about the ones with "Ch" suffix are better suited to AC and have better frequency characteristics (for whatever that really means), and the "KBG" ones have been described as having aluminum foil - paper - aluminum foil - paper layered construction. The rest seem to be more generically described as "sputtered/metalized" ...
 

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Eric, I’m most fond of the sound from the rectangular can variety. The letters are not available on my key board. They are sometimes called MBGO. You won’t need high voltage ones. I used the 160 volt rated. I do give the sonic edge to the 630 volt rated variety but they get very big very fast - just pick a well liked seller from that famous web site :)

Do note that often you need to isolate the shell of these metal can pio from the chassis and ground :)
 
If One were so inclined, and wanted to get crazy and fancy with C3, and say that individual didn't care so much about cost (within some sort of reason, barely). What would be your suggestions for a fancy pants 10 uf capacitors.

Asking for a friend (Not really)

I user Janzen Audio Silver Z. Not cheap, but supposed to be premium quality. A bit too big for the boards but could manage to fit them.
 
Looks like 45mA per channel. See schematics on p5 here:

http://www.firstwatt.com/pdf/art_ba_3.pdf

Thanks for the ultra fast response!
I find puzzling that the overall consumption of the gain stage is so low! Can you please walk me thru why is 45mA?
I am thrown off by "The bias current here is about 50 mA,
and it will deliver peaks of approximately 100 mA. Q3 and Q4 require heat sinks
"
 
Thanks for the ultra fast response!
I find puzzling that the overall consumption of the gain stage is so low! Can you please walk me thru why is 45mA?
I am thrown off by "The bias current here is about 50 mA,
and it will deliver peaks of approximately 100 mA. Q3 and Q4 require heat sinks
"

....because it is a preamplifier. It will drive the input of a power amplifier. Let's say that the input impedance of the power amp is 10k ohms. 100mA pk from the preamp into 10k ohms is 1000 volts peak.

100mA is overkill if driving a 10k ohm input impedance.

If the amplifier has a 50 ohm input impedance, then the drive voltage will be 5v pk. If you need more than 5v pk inot 50 ohms, then up the bias.
 
BA3 pre up and running

Finally finished my BA3 preamp. I had lots of assistance from forum members including 6L6 and jwilhelm. Greatly appreciated. It is up and running with no problems(yet). Just need to tidy up the wiring in the preamp chassis. Will set bias later once I finish the Pearl 2 and the F5Turbo. Almost done the Pearl 2 but waiting on transistors from the diystore to finish the F5t.

Thanks
 

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