amp guts

[d0n]

I bought this acoustin control corporation amp recently. It's 200wpc. Dual mono design with a power switch for each channel. I've never seen 2 power switches on one amp before. She's a big heavy beast!

I thought you all might be interested in seeing the guts. If anyone happens to have a rocker power switch let me know! The outside measurements are 1.5" high x 1.25" wide.

[ostripper]

Hi, Don. I just seen a rocker like that in the radio shack parts drawer. Worst case , if you know the dimensions , mouser definitely has it .

What a classic (looks like 70's) separate driver boards,each channel forms one half of the "tunnel". (does it work?)
Also , this amp seems to be single supply (no + - , just positive)
with capacitive coupling (blue caps in rear). Just 1 cap per channel.

BTW , worry not ..the stealth is open and on the table. (did you get my email?)
OS

[d0n]

Pete, Good eye! It was made between 1974 and 1979. I have powered the amp up but not hooked it up to a source or speakers yet. It does turn on and the fan starts running. No magic smoke came wafting out... so that's a good sign.

I looked through the mouser site at about 50 different rocker switches but couldn't find one with the right dimensions. It's a strange size... 1.5 inches high and 1.25 inches wide (outside bezel size). The switch is a snap in type so the dimensions have to be exact or it won't work. I'll keep looking.


I did get your email. I am not too worried about the stealth. I knew you were busy working on your amp. I just wanted to make sure you were able to get the cover off with those stupid and useless locks on it. The locks are strange. Why would someone put locks on a case to keep someone out? And, they don't even work.

[sakis]

1800w power consumption .....and 10 transistors per amplifier section your calculation about power is for sure wrong ...

id expect a minimum of 450 W rms at * ohms ...

[AndrewT]

I wonder if the model number (400) means 400W per channel?

5pair output stage could indicate 4ohm compatibility. 4A slow blow is just about right for this.

400W into 4r0 requires ~ +-70Vdc or +140Vdc (single polarity)

What's the voltage rating of the larger electrolytic capacitors?

[d0n]

I was originally told that it was 200wpc at 4 ohms.

Recently a collector tells me it is listed as being 375wpc at 2 ohms.

[firechief]

For the switch, try Antique Electronic Supply

[dangus]

200W into 4 ohms per channel is plausible. Some amp companies rate some of their amps that way. And in the '70s, more than 100 watts was considered high power, and darned expensive. If you have a local university library with back issues of Audio magazine, the Annual Equipment Directory issue may have a listing for those amps.

I'd look carefully at those Molex style connectors... I've had problems with those, like oxidized contacts that overheat and burn up the plastic.

[sakis]

Originally posted by d0n
I was originally told that it was 200wpc at 4 ohms.

Recently a collector tells me it is listed as being 375wpc at 2 ohms.

before posting ...... this is out of the question .... at the good times of 70's there was no such a term 4 OHMS or 2 OHMS all amplifiers were refered to power in watts at 8 OHMS

rating amplifiers in 4-2 ohms is >2000 fashion and doesnt mean that is possible or true ....

hypotheticly a today's amp that produces 100W @8ohm will produce 200 in 4 ohm and 400 @ 2 ohm but from existing amps only very few are capable to do that eventhough they state so

especially some of the amps have a new term which is called 2OHM stable ( meaning that is possible to operate in 2ohm but nobody say how much power they will produce )

today all these is mostly comercial tricks .....at the 70's the real power for class AB amps was rated in watts in 8 OHMS

now days we have class D amps that can do things like that but yours isnt any of those

[Steve Dunlap]

Originally posted by d0n
I was originally told that it was 200wpc at 4 ohms.

Recently a collector tells me it is listed as being 375wpc at 2 ohms.

The collector seems to be right. That amp was rated at 275W@4 ohms and 375W@2. That was at 5% distortion. This was a PA amp that listed for $899 in 1977.