Bottlehead Forum
General Category => Technical topics => Topic started by: fitz on April 22, 2020, 11:23:28 AM
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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 ?
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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.