New 2204 Build Tube Question

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Brad H
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New 2204 Build Tube Question

Post by Brad H » Mon Jun 25, 2018 7:21 am

Hey guys, starting a new 2204 build. Going with Tung-Sol 6550's. Has anyone done this? Wondering if I should go with 220k on the bias feed resistors, and 150k on the bias input resistor? That's what the old schematic shows, but I've done 2203 builds where I dropped down to 150k on the bias feed, and 15k on the bias input. With only two tubes, should I stick with the 220k feed and 150k input?

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neikeel
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Re: New 2204 Build Tube Question

Post by neikeel » Mon Jun 25, 2018 12:51 pm

Hope you saw my response on Marshall amp forum

There are some 2204 experts here, hope they chime in?
Neil

Brad H
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Re: New 2204 Build Tube Question

Post by Brad H » Mon Jun 25, 2018 1:29 pm

Yea I saw it, appreciate the input. Like I said, I've done 2203 builds where I dropped to 150k on the feed (split) resistors, and 15k on the input. I figured with only two tubes to heat up, staying with 220k on the feed, and dropping to 150k on the input, that would be good. Also, with EL34's using 220k feeds, and 220k input, wasn't sure if anyone had tried the lower values. Again, original schematics from the JMP's are showing all three at 150k when using 6550's. Was going to roll with that unless someone had negative results with those values.

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neikeel
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Re: New 2204 Build Tube Question

Post by neikeel » Mon Jun 25, 2018 3:05 pm

Search here for pi output couplers or grid leak resistors and the author Novosibir
:wink:
Neil

Brad H
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Re: New 2204 Build Tube Question

Post by Brad H » Mon Jun 25, 2018 4:07 pm

:thumbsup:

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