What's the reason you want to get down from +/-80V to +/-70V?
Because the transformer I have is 55v-55v ac and the amp I have maximum voltage is +/-70v
Because the transformer I have is 55v-55v ac and the amp I have maximum voltage is +/-70v
Don't you have 240V or 120V tap at the primary ?
That would be the most elegant way to drop about ten per cent of tension at the secondary .(i.e. , for a 220 V network ,you hook on 240V tap , for 110V network on the 120V tap .)
That would be the most elegant way to drop about ten per cent of tension at the secondary .(i.e. , for a 220 V network ,you hook on 240V tap , for 110V network on the 120V tap .)
http://www.ampslab.com/c300.htm
the transformer I have has both 240v, 120v primeries. whatis a tap ? should I hook it in series with the primary ?
the transformer I have has both 240v, 120v primeries. whatis a tap ? should I hook it in series with the primary ?
Hi leander,
The higher voltage may or may not be a problem. It is a good opportunity to install a voltage regulator for the amps. SOmething better than 317/337. Think of the Adcom vreg, or others.
-Chris
The higher voltage may or may not be a problem. It is a good opportunity to install a voltage regulator for the amps. SOmething better than 317/337. Think of the Adcom vreg, or others.
-Chris
Leander , all you have to do is the 220 on the 240 and you should have 70V at the secondary instead of 80V . Try and check.
Stringing diodes is a bad idea as their junction drop varies with current and temperature (they will get very hot at high output), plus you need loads of them per rail.
if you use a regulator make sure it is a very beefy one that can handle all the current the amp needs driving 4 ohms at 300W you will need a considerable heatsink for this too!
Or you could see if it is possible to run the power transistors at 80V safely and then use a lower current regulator for the rest of the circuit to run off 70V?
Guytou: sounds like he cant do that because he only has taps for 115V and 230V and nothing in between.
Craig
if you use a regulator make sure it is a very beefy one that can handle all the current the amp needs driving 4 ohms at 300W you will need a considerable heatsink for this too!
Or you could see if it is possible to run the power transistors at 80V safely and then use a lower current regulator for the rest of the circuit to run off 70V?
Guytou: sounds like he cant do that because he only has taps for 115V and 230V and nothing in between.
Craig
This circuit should work fine on 80V rails but you will need to use different output transistors, such as the MJ15024/5 or the MJ21193/4. I'd also change Q15/Q16 to MJE15032/3 if you can as these are higher current driver transistors.
You may also want to replace the small signal devices with 2N5401/5551 or MPSA42/92. I would probably use the 2N devices for the LTP, and MPSA42/92 for everything else.
You may also want to replace the small signal devices with 2N5401/5551 or MPSA42/92. I would probably use the 2N devices for the LTP, and MPSA42/92 for everything else.
I'd recommend the same for the output transistors: MJ21193/4 and Maybe the MJE15034/MJE15035 for the drivers
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