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Old 28th November 2011, 05:47 PM   #1
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Question 45 TSE desired tube current? Acceptable B+?

Reached the checkout stage, and must confess a bit nervous. Read and re-read the checkout/bias sections of the manual, a couple of questions ...

Near the end I do the "slowly adjust pots R12 R23 to raise output tube current to desired."

What is the desired output tube current for 45s?

What is the acceptable range for B+ in a 45 TSE?
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Old 28th November 2011, 06:08 PM   #2
evanc is offline evanc  United States
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The 45 should be biased in the 25 to 30 mA range. I use 28 to 30 mA on 280 volts, and 26 or 27mA if operated at 320 volts.

right out of the manual.....
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Old 28th November 2011, 06:49 PM   #3
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Ta,
Yeah, found it now. Blush.

One more question. I have breadboarded the amp at present. I have Electraprint OPTs - do I need to ground the outputs from these?
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Last edited by Alan Hope; 28th November 2011 at 06:52 PM.
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Old 1st December 2011, 11:32 PM   #4
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Quote:
Originally Posted by Alan Hope View Post
One more question. I have breadboarded the amp at present. I have Electraprint OPTs - do I need to ground the outputs from these?
Grounding the speaker negative assures nothing is floating, and at my house, I sometimes run vintage Polk SDA speakers (with an umbilical between them) that requires the speaker -ve to be grounded.

I'm no expert, but IIRC it's also important to ground the speaker -ve when running gnfb (not the case here, of course)......

Last edited by boywonder; 1st December 2011 at 11:34 PM.
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Old 2nd December 2011, 06:24 AM   #5
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There's also a safety issue in that if the primary shorts to the case or the secondary, you'll have full B+ on the case or secondary. Speaker negative and the transformer case (at one of the mounts) should always be connected to earth.
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Old 2nd December 2011, 06:47 AM   #6
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Not in all the OPT. Silk transformers are designed to have the secondary floating. The case should be grounded.

D.
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Old 2nd December 2011, 09:27 AM   #7
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Thanks ...

The Electraprint transformer legend says of the negative output - "this to ground if needed"

Will start with negative ungrounded, case grounded.
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Old 5th December 2011, 11:45 AM   #8
jrobson is offline jrobson  South Africa
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You should ground the grey wire, there is a thread on here where George states that you should ground them.
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Old 5th December 2011, 12:07 PM   #9
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OK, will do.
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