Need Advise on Amp with +/- 20Vac

[naldy]

Greetings to Everyone !!!

I just acquired the FF from a friend and planing to build a class AB amp out of it:

Xformer: sec. output 21-0-21Vac rms @ 10 Amp sec. rating
Reservoir Caps: 18,000 uF 45 V


This would yield to +/-30 V DC rail.

with 8ohms load, maximum RMs power I can get from this is =(30-2*30-2)/8 = 100W

Current needed = sqrt(110/8) = 3.7 Amps which the xformer is capable of delivering.

Are my computation correct?

Any suggestions on the circuit I need to build???

Can I use this on Leach Amps? M250? I appreciate any help or any diagrams you can share!!!

Thanks,
Naldy

🙂

 

[planet10]

Xformer: sec. output 21-0-21Vac rms @ 10 Amp sec. rating
Reservoir Caps: 18,000 uF 45 V

LM3875 gain clone -- caps are perhaps a bit big. More like 40W/channel thou.

dave

 

[elizard]

lol .. funny how one of the universal solutions to "what amp i should build" is gainclone 🙂

but seriously .. that seems like a good xformer for a gainclone 🙂
almost the 22V prefered by Peter ..

 

[peranders]

Greetings to Everyone !!!

I just acquired the FF from a friend and planing to build a class AB amp out of it:

Xformer: sec. output 21-0-21Vac rms @ 10 Amp sec. rating
Reservoir Caps: 18,000 uF 45 V


This would yield to +/-30 V DC rail.

with 8ohms load, maximum RMs power I can get from this is =(30-2*30-2)/8 = 100W

Current needed = sqrt(110/8) = 3.7 Amps which the xformer is capable of delivering.

Are my computation correct?

Sorry,

100 W is correct if it was DC power you're talking about. You have forgotten a "2".

28^2/(2*8) = 49 W in theory! The amp can't deliver 28 volts peak if the supply voltage is 28 V! You will loose some voltage depending of amp design.

Power in is approx. 70-80 W

 

[moamps]

This would yield to +/-30 V DC rail.
Any suggestions on the circuit I need to build???

Hi,

RMS power on 8E is P=Veff*Veff/Z,
Veff=Vmax/1.41 = ca Vcc/1.41

P=ca 50W

look this amp too; http://sound.westhost.com/project3a.htm

Regards

 

[naldy]

Thanks for all the inputs!

forgive my math...
so indeed I can have >40W of power from this PS.

I'd like to try IC gain clone but I've got 3 pairs of motorola
xsistors MJ15015/16 for the output stage. 😕

I like moamps recommendation though it lacks some short protection circuit.