Dear All,
I am looking to build SS class A amp from what ever left with my B&K ST-140
Here what I got
1. Case 16x13x5.25 inch
2. on the back there is a heat sink size 7.5x4 inch
3. Transformer with secondary wiring 46x2 (I measure it)
and there is writting on the transformer
-904 wattage 300 W
Any suggestions ??? I like to make Amp with heavenly sound.....
I am looking to build SS class A amp from what ever left with my B&K ST-140
Here what I got
1. Case 16x13x5.25 inch
2. on the back there is a heat sink size 7.5x4 inch
3. Transformer with secondary wiring 46x2 (I measure it)
and there is writting on the transformer
-904 wattage 300 W
Any suggestions ??? I like to make Amp with heavenly sound.....
Weird
Because +/- 46V DC is right for a 70W/8r per channel amplifier (ST140 specs), while 46+46VAC means around +/- 63V rails, good for 180/200W/8r
Big mystery there.
You are right
When it still used on B&K ST-140 the DC rail was 63V
so what Class A amp I can use?
Not recommended for class A amplifier.
Why? because Class A passes a lot of continuous current, always.
The necessary current for an 8 ohms load will be very high, pull more power from the PSU than it can deliver.
As Jay said in post #2, class A amplifiers use relatively low +/- rails, to keep power dissipation at bay.
Not the case here.
The original PSU was designed for a class AB2 amplifier, you can't veer away from that, unless you get a 300VA transformer but at a quite lower voltage.
So all you could use is the case and heat sink, mut notmuch more.
Personally I would rebuild or clone an ST-140 or build there a standard power amp (your choice) , which is happy with +/-V rails.
AB class, of course.
*If* you insist on a class A amp, fine with me, but pick any suitable schematic (lots of them here) and get a *new* transformer, which is more suitable.
Good luck.
Why? because Class A passes a lot of continuous current, always.
The necessary current for an 8 ohms load will be very high, pull more power from the PSU than it can deliver.
As Jay said in post #2, class A amplifiers use relatively low +/- rails, to keep power dissipation at bay.
Not the case here.
The original PSU was designed for a class AB2 amplifier, you can't veer away from that, unless you get a 300VA transformer but at a quite lower voltage.
So all you could use is the case and heat sink, mut notmuch more.
Personally I would rebuild or clone an ST-140 or build there a standard power amp (your choice) , which is happy with +/-V rails.
AB class, of course.
*If* you insist on a class A amp, fine with me, but pick any suitable schematic (lots of them here) and get a *new* transformer, which is more suitable.
Good luck.
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