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Old 22nd February 2017, 07:21 PM   #1
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Default Point of Diminishing Returns; B+ Caps

I'm on my second SSE. This time it's all motor run oil caps for the power supply. No electrolytics. 40uF after the tube rectifier. Then a 5H choke. And then, how many uF for the second position? I have lots of 70uF caps left from an earlier project. At what point is enough enough?

thanks for any input.
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Old 23rd February 2017, 12:34 AM   #2
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Never. Run with it. My next will be all out also even though most of the time I haven't got a clue.
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Old 23rd February 2017, 01:07 PM   #3
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There is a point of diminishing return. That point would be different for each build / person. The main reasons would be the speaker system's sensitivity and low frequency response. You can tolerate more absolute hum output with speakers like mine that are 87db sensitive at 1Khz and are lower than that at 60 and 120 Hz.

For an average system a pair of those 70 uF's wired in parallel for the second cap should suffice. Super sensitive speakers with 15 inch woofers, use 3 if you have the room.

There was a builder on this forum several years ago that used off board non electrolytic caps for every cap in the amp. I can't remember all the details, but it was a big amp.
Tubelab, it's 5 year mission. To explore strange new tubes, to seek out new circuits and topologies, to boldly go where no tube has gone before......
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Old 23rd February 2017, 02:41 PM   #4
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I am now repairing this amp as a project. 6 100uF motor run cans.
For the love of music.
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Old 26th February 2017, 09:37 AM   #5
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Default thanks for the replies

Three it will be.
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Old 26th February 2017, 10:21 AM   #6
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You could model it in PSUD? I've found it helps.
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