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RADFORD SC2 TUBE PREAMP POWER SUPPLY HELP

Subchannel

Subchannel

Active Member
I´m a lucky owner of a Radford SC2 preamp, but this runs of the powersupply from the power amp, which I don´t have.
Anyone here have a drawing/ schematics/ suggestion on building a standalone PSU for the SC2?
Thanks!
 
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don't know anything about this specifically, but this schematic for the STA15 power amp has supply schematics

Radford STA15 Power Amplifier Manual | HiFi Engine

should be able to work out needed voltages from that. Looks like 375 vdc and I'm assuming a 6.3vac heater winding but it may be higher to allow for rectification.


that is a really odd use of a 6U8. Looks for all the world that its being used as a long tail pair inverter. Not sure I've ever seen an LTP that used dissimilar tube sections before, and certainly not a pentode paired with a triode like that.

not sure how similar the SC2 and SC22 might be, but this one has a supply schematic for the SC22

Radford SC22 Stereo Preamplifier Manual | HiFi Engine
 
Thanks for replying Gadget73.
But I was hoping someone had an easier way than construct out of the amp´s PSU.
I think it´s a simple PSU, but still, need some help.
 
It can be done but you would need some reference info, tube data sheets, resistor tolerances and a power supply of at least a minimum of 250 volts.

Usually you would only need 4 wires or more simply put, two 6.3 volt heater wires for all the tubes, one 250 volt DC wire for the high voltage, and one wire for the ground.

Most preamps using the basic preamp tubes such as the 12AX7 will need a minimum of 250 volts DC to start working then you have to tweak the circuit from there.

Honestly, you really need to know electronics if you are going to want to tackle this.
 
I wasn't really suggesting to copy the amp's power supply, but from the amp schematic you can figure out the needed voltages and socket config.

Looks like the preamp I linked has a schematic for a supply for that. Could do a lot worse than to clone that. Thats probably about as simple as it gets, transformer, bridge rectifier, and a cap. The only trick is that it doesn't give the voltages, but the amp schematic does.
 
Thank for the input. I have experience with electronics, have the parts for a 250V PSU (250v/ 6.3V secondary) and have an electronics workshop, so the problem is not to build it rather than how to do it closest to the original. I´m not that experienced in building tube amp´s but can build one if I had a schematics. And to my knowledge, tube amp PSU´s have a big influence on the sound (as in all audio) so I would like to get the voltages right (the filament is not a problem). As you mention Cademan there´s only four wires, two of the six original are just for power switch.
Preferably I would like a tube rectifier, but will probably use bridge for simplicity. And the fillament is not rectified originally? There are different opinions on the latter, and there´s not a big problem to rectify and regulate this.
The part where bought for this schematics:
 

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Subchannel said:
Thank for the input. I have experience with electronics, have the parts for a 250V PSU (250v/ 6.3V secondary) and have an electronics workshop, so the problem is not to build it rather than how to do it closest to the original. I´m not that experienced in building tube amp´s but can build one if I had a schematics. And to my knowledge, tube amp PSU´s have a big influence on the sound (as in all audio) so I would like to get the voltages right (the filament is not a problem). As you mention Cademan there´s only four wires, two of the six original are just for power switch.
Preferably I would like a tube rectifier, but will probably use bridge for simplicity. And the fillament is not rectified originally? There are different opinions on the latter, and there´s not a big problem to rectify and regulate this.
The part where bought for this schematics:
Click to expand...

You could get one of these. John Broskie makes nice little supply kits for his preamp kits.

https://glass-ware.stores.yahoo.net/pstuposu.html
 
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