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SE 300B Custom Amp Build


Curious_George

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  • 1 month later...

Thank you! BOM makes life easier for the diy'er.

 

Question about the 51 ohm resistors in series with the rectifier plates. Did  you find with the 47uF capacitor the surge current was too much without them? I know some builders just add them no matter what even if the surge current is within the limit which I believe for the 5U4GB is 1 amp.

 

Is it possible if someone uses a different power transformer they may need to raise/lower/omit these?

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Thank you for your well defined explanation.

 

I use the 5U4GB types a lot  and I have similar findings when using 50uF (two 100uF in series). I don't hear any changes when using the resistors, but wouldn't think so with Class A single ended. Push Pull I try and avoid adding extra impedance into the power supply so use SS.

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36 minutes ago, captainbeefheart said:

Push Pull I try and avoid adding extra impedance into the power supply so use SS.

Yep, PP definitely should have a low impedance power supply. I know you don't care for the Ultra-Linear amp config, but my pair of Williamson clone mono-blocks use SS rectification and they have a very solid bottom-end. 

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22 minutes ago, Curious_George said:

Yep, PP definitely should have a low impedance power supply. I know you don't care for the Ultra-Linear amp config, but my pair of Williamson clone mono-blocks use SS rectification and they have a very solid bottom-end. 

 

I'd be a bold faced liar to say I haven't liked the sound of some UL amps when done well, it's just over time I have found I personally had better results just going full pentode and the tubes seem to last a lot longer.

 

For push pull AB amps I was very serious at one point and wouldn't use anything unregulated or at least a choke input filter was easy and had good regulation. The last few PP amps I have made I didn't go fully regulated or choke input filter, instead I just went with a simple C multiplier circuit, basically a solid state ripple filter if you haven't used one before and they work extremely well.

 

Something about Williamson circuits that just sound great, either UL, triode, or pentode the circuit is remarkable even to this day. I think if I had to live with one it would be the original triode wired output stage Williamson.

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