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Old 2nd November 2009, 07:46 PM   #1
Bengali is offline Bengali  United States
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Default Aleph J Front End for Pre

Hi,

I have some IRF644's. I would like to build a mini-AJ(stock AJ circuit) and use it as a preamp to drive an Aleph J.

What would be a reasonable bias current? any reason not to try this?

thanks.
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Old 2nd November 2009, 08:13 PM   #2
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Run it at whatever current your heat sink allows.

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Old 2nd November 2009, 08:18 PM   #3
Zen Mod is offline Zen Mod  Serbia
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naah - just look for Jfet BOZ

way better , and you can also have balanced feed between preamp and amp

edit:

just realized that Papa already answer ...... anyway - what he knows .......

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Old 2nd November 2009, 08:44 PM   #4
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I was thinking of the same thing, but using it as a preamp to drive the F5.
The other alternative is using the F3 topology as the preamp.
I have a B1 so I will use that first, if I don't need the extra gain then I will leave it at that.
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Old 2nd November 2009, 09:43 PM   #5
Bengali is offline Bengali  United States
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Thanks Mr. Pass.

would changing R27 from 68K to 680K lower the bias too much? there a minium bias current to keep it from distorting? would like to
use standard to-220 heatsinks if doable.

Hi Zen Mod,

I've built the single ended JFET BOZ, sounds good. just wanted to perhaps try another variation.
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Old 2nd November 2009, 09:51 PM   #6
Zen Mod is offline Zen Mod  Serbia
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sorry - my typo ;

I meant - Jfet XCCS BOSOZ , or whatever that shorty ( XCCS) is ......
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