The Aleph Jango

[6L6]

So can you use a diff pair of j74? Or does it have to be the j109?

[buzzforb]

I paralleled the sj74's in my AJ monoblock's FE. I was running three output pairs. 109 is better of course, if you got them. ZM is always talking about liking lots of current. I believe Nelson says more current allows reduction of Rl and gain and better linearity. Don't quote me though, bad memory.

[6L6]

Here is a copy of the schematic that Nelson drew out for me at Burning Amp (well, he modified and made notes on an Aleph J schematic) Not significantly different than the original.

[buzzforb]

Looks great and plus, he drew it. No current limiting stuff on bottom end. I think the extra current/paralleled inputs in the J2 was for optimization of that circuit, so go with what he gave you. Cant get any better than a personalized schematic by the guru. You can use one matched pair of SJ74 unless you have and want to use a single 109. Phenomenal build diary on your other stuff. Very helpful for other interested in the DIY game.

[qusp]

Originally Posted by Nelson Pass

You can run enough current through the 2SJ109 to do the job - I paralleled
them just because I can.

cool, thanks, i selected some matched high idss j74 quads so i'll probably parallel them too

Originally Posted by 6L6

So can you use a diff pair of j74? Or does it have to be the j109?

you can use either, i actually think thermally bonded well matched singles are better, j109 arent always a great match.

[DUC985]

would you have any voltages, how to bias the PowerJfets correctly ?

[Sweetsweetback]

would the data sheet be helpful for establishing vgs?

judging from the curves (please forgive me if I am wrong), I'd say between 1-1.5V. (?)

[Zen Mod]

more like 1V4 - 1V9 ;

at least from my experience .

but - nothing really to worry about .

it will work in any range of Ugs , if they are reasonably close matched inside one channel

[digits]

Looking good.

[6L6]

The saga continues...


Here are my Peter Daniel boards I bought from a member in Holland. The only ones that anybody had for sale were stuffed, with tightly-matched 240's, and neat parts like Silmics and such. Saves me a digi-key order, I like that.

I will have to remove a few components (limiter circuit, the power Fets) and replace a resistor with a pot in order to match it to the schematic that Nelson drew.

Then it's off to chassis fabrication, I have the important parts, and am hopefully going to meet with a machine shop today.