BPA-200 w/ six chips working w/ pics!

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carlmart

Member
Joined 2001
preciseaudio.com
Mattyo5 said:
I have a .22uf cap across AC mains, 250vac... doesn't help any. One amp has it, the other doesn't. Does it need to be closer to the switch? (there is no room for me to get in there)...doh. Higher voltage needed? again doh, just put in an order to digikey...
Click to expand...

What Hugh Dean was talking about was switch bypass to reduce arching, not cap bypass. And not bypass between input pins, but between input and output pins.

It doesn't need to be closer to the switch: it has to be ON the switch.

This is nothing new, really. Most commercial units already have such cap, usually a ceramic.


Carlos
 
M

Mattyo5

Member
Joined 2002
I see, so let me get this straight. I have a DPDT switch, total of 6 pins, i'm only using 4... ac 2in, ac 2out to trannys... so, i put 1 or 2 caps between in and out? .01uf? 1000v? ceramics?
not that i can actually get in there, but it's useful to know. later :)

-Matthew K. Olson
 
C

carlmart

Member
Joined 2001
preciseaudio.com
Mattyo5 said:
I see, so let me get this straight. I have a DPDT switch, total of 6 pins, i'm only using 4... ac 2in, ac 2out to trannys... so, i put 1 or 2 caps between in and out? .01uf? 1000v? ceramics?
not that i can actually get in there, but it's useful to know.
Click to expand...

Yes, you should have two rows of three, each row corresponding to one AC cable. One of them, the input AC, is probably in the middle and the output AC just by it on same row.

You simply connect the caps between adjacent pins in same row.


Carlos
 
S

SuperAudioBuff

Member
Joined 2004
Schematics, that'd be great!!!

Hey I was just curious if you wouldn't mind sharing some schematics of what you've built, and maybe what you plan to build.

Just a note also, i've tried building a BPA amp with building all of the typical application amplifier that National builds using their LM3886. In explanation, build (4) separate amplifiers, run (2) sets of 2 in parallel with 0.1 current sharing resistors on the output, and then use a double op amp inverter for the signal. Feed the non-inverted signal to one and the inverted signal to the other set. Thus running two in parrallel on top and on bottom, then configure them in a push/pull configuration. Sounds good. I'd run off of appx. 26 to 28 VDC rails if possible. I run 29 VDC, regulated this is the hairy edge of where you'd like to be.
 
M

Mattyo5

Member
Joined 2002
As stated before, i use the BPA-200 schematic from page 12 of the application note. The only thing that I changed is I added 2 more chips per channel (3+3 config) and I also added 100k resistors referenced to ground at each chip input. I'm running approx. 27 volt rails although I should have gotten trannies that run higher. Still, there is quite a bit of power. I am currently working on a pcb, but lately, school has just killed the ammount of time I have. Sorry guys. Later!

-Matthew K. Olson
 
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Mattyo5

Member
Joined 2002
Thanks for necro this thread. I haven't posted in many years.. life... etc. But I happened to come back to this and wanted to mention to folks that these amps are still running..often... with no issues nearly 20 years later. They power my line arrays in my theater room. Can't honestly say that I've run the amps at their limit but they certainly have nice range. Anyway.... to anyone thats been here a while... howdy :)
 
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