Soul sister question

[fitz]

Would like to build a Soul Sister pre from the Valve magazine(vol.5 issue 4) to go with my Paraglows. Would like to use the 5670 tube that calls for a B7-15k transformer, would a B7-10k work ok ?   

[Paul Birkeland]

That particular schematic I think got revised at some point.

For a 5670, 9.5mA of current and 150V on the plate would be 1.5V of bias and a cathode resistor of about 160 ohms.  You could use an HLMP-6000 diode here for this.

With 3.2V of bias and 9.5mA of current, you'll have more like 225V of B+.  That's OK too if you want.

In either spot, rp is about 6K, so the 15K output transformer makes a lot more sense than a 10K output transformer.

There are a great many other 15K:600 output transformers available, many of which are still in production.