fired it up and smoke comes out of PT

[wsaraceni]

Sorry Bill, I was in "default diagnostic mode"...lol. Have fun.

haha. it's all good . im sure ill need that info next time i build an amp.

[rdjones]

[img824]http://www.accusrc.com/objects/catalog/ ... mg3495.jpg[/img]

Nearly every shop I've worked in had a Sencore PR57.
I've got one of my own now.

The PR57 only does 3A continuous.
Another option is to use a Variac and the inexpensive Sencore PM157 power monitor, although you don't have the isolation of the Powerite.

rd

[KellyBass]

Based on your schematic, I would say the dc heater circuit is marginally useful. I would build a simple voltage doubler on that winding (use a couple of 6800 UF caps and strong diodes low voltage/high current), and regulate to 6 volts with a 7806 packaged regulator. That would be quiet and worth doing... imho.

I might give this a try on a noisy little SVTish preamp I built. Oddly, I'm using the same PT...Hammond 269ex (also laying around from a gutted ax84). The preamp sounds great...just like it's 90lb big brother, but I'm getting lots of hum. What would be a good diode to use for this supply? UF4007?

[FUCHSAUDIO]

I'd use something like a higher current lower voltage diode. We use a 6CA10 (I believe ?). It's a larger body diode, but works well on heater supplies and as low voltage rectifiers. The UF series (ultra fast) are good too.

1N4007's are higher voltage and lower current, which may work, but get warm and are not optimal.

As far as the SVT preamp check grounding, look at the DC supplies with a scope and check for ripple, and make sure the transformer is not too close to a tube...hum fields are not good....

[KellyBass]

Thanks, Andy! I'm gonna give that a shot.