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Old 25th March 2008, 12:37 PM   #1
jrebman is offline jrebman  United States
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Default Calculating PS current for octal Aikido

I am slowly starting my Aikido octal stereo board and am wanting to learn how to calculate currenmt requirements for B+. just adding up the plate curremnt specs for each tube just doesn't seem correct as that would result in a PSU big enough to power a decent power amp. I'm going to be using a 6sn7 gain tube and octal 6h30 for the output buffer. I'm more interested in methods and procedures than an outright answer, but my B+ will be 300v.

Thanks,

Jim
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Old 25th March 2008, 04:13 PM   #2
Stixx is offline Stixx  Germany
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my turn to reply to your post...

You sure have Broskie's manual (Aikido.xxxxxx.octal.pdf) that contains a spreadsheet with possible tubes and component values. You take the numbers listed under Ik for the tubes you are planning to use and add them up...like 2 x 5mA (input stage) plus 2 x 15mA (output stage) = 40mA total current demand.

But: there is no octal 6H30 I can think of (I'm using the noval...), and they are not meant to be driven at 300V (150V respectively).??
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Old 25th March 2008, 04:23 PM   #3
jrebman is offline jrebman  United States
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Styx,

Thanks for the reply. Here's the tubecad blog entery talking about the 6h30pi octal:

http://www.tubecad.com/2007/08/blog0117.htm

The table on this page lists 10.8 mA for the 6sn7, and 112 mA for the 6h30pi, for a total or nearly 250 mA, but maybe that's with a lower B+. I thought both the 6sn7 and 6h30 would be ok at 300 v, but maybe I need to go to 250 or 200., or lower.

-- Jim
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Old 25th March 2008, 07:30 PM   #4
Stixx is offline Stixx  Germany
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jrebman,
OK, never saw the octal version before...

The value listed for Ik is in strong contrast to Broskie's manual, be it octal or noval. My headphone amp running at 210V has a current draw of about 20mA for the 6H30, so I can't comment on the value in your link. Looking at the datasheet for the 6H30 the max. value for plate current is 100mA (50mA continuous), and the octal version can't be much different or it would be two tubes.
You can probably run the 6H30 at a B+ of 300V (150V each half), Broskie's spreadsheet then lists 15mA current draw. My guess is that the value listed in the link refers to something else, but I am no expert to clear things up...
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Old 25th March 2008, 08:47 PM   #5
jrebman is offline jrebman  United States
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Thanks again. Seems there is a lot of either confusing or incorrect data and/or inconsistencies between various manuals and blog entries, so I wrote to the man himself to try to clarify.

We'll see what happens.

-- Jim
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