neat Toroidal power tf's- Antek Inc.

[Gregg]

Though the data sheet says it has two 6 volt windings both PT's that I purchased ended up with a 6 volt and a 12 volt winding.

The 12V winding is handy for feeding preamp tubes' heaters with regulated DC.

[Ptron]

The B+ voltage was a little lower than I was hoping for but I used the extra winding on the PT to bump it up a bit.

Can you elaborate on this a bit? Are you saying the secondary isn't actually 300V for whatever reason or just that you're losing more than you hoped in the subsequent filtering?

[imaradiostar]

Can you elaborate on this a bit? Are you saying the secondary isn't actually 300V for whatever reason or just that you're losing more than you hoped in the subsequent filtering?

Yeah, sorry I wasn't more specific. I was shooting for the exact values listed for cathode biased class AB ultralinear operation on the 7591 datasheet. With the secondaries in parallel and bridge rectified everything was fine- with a cap input filter and the output tubes idling around 90ma/pair the voltage at the first stage was around 400 volts- somewhere between 1.3 and 1.4 * 300. I just thought I'd take advantage of the 12 volt winding and try to get closer to the textbook 425 volts. I had a 6600 ohm ultralinear output tf so why not?

The new production 7591's sound great but it sure seems like they require a little extra voltage to bias up correctly. I've been meaning to try them on my tube tester and compare them to my old 7868's but haven't taken the time. I've read that the ones I'm using (the Russian ones) don't look or fit like a true 7591 but behave like them in circuit. I'm not knowledgeable but they seem to require less grid drive than a 6L6 so I'm content.

In retrospect the amp sounded more interesting when it wasn't ultralinear. I think I'm going to remove the reverb circuit and switch back to the larger Bogen output transformer. I tried the ultralinear output hoping to achieve a sound similar to a Dr. Z route 66 but ended up in more Voxy territory so I'm going to embrace that vibe.

On that note- now that 6973's are back in production (and I have a few old ones stashed away) I think I might try that Triode Elec Deluxe output tf as a 13k ultralinear output tf as listed in my RCA book. I have a few old PT's that should make around 350 volts with a choke input filter. Once again I'm going to see if I can get a little bit of that kt66 vibe without all the excess volume and power draw.

jamie

[TWANG]

easy question.
what is that 'static wire' and where do I connect it?

front star ground? looks like.