Early clipping with JX Amp

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I finished my second mono today. 100ohms current limiter resistors.
Fired up, same problem. So most probably no wiring or part error.

Than I removed the current limiting resistors (R13, R14) completely.

Slightly better
55 Watts into 8 ohms at 1kHz with 1% THD whereas 49W before.
35 Watts into 4 ohms at 1kHz with 1% THD whereas 25W before.

It's not the current limiter.

Is it the concept itself?
 
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Ok,

I ask in a different way:

Is it possible that the 2SJ109(BL) isn't able to drive the amp for higher current? BTW: I tried 2SJ74BL/2SK170BL too with similar result.
If so, we can't use the J-X for higher power, right?

So we can double the power into 4/8 ohms (compared to Aleph J) by building the X Version of Aleph J but that's it.

Can someone with a working amp confirm this?
 
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Sound

I should not only post problems but also the good things 🙂

These amps sound marvelous and as long as one don't start a party or drive low impedance speakers there is no problem with 50W/8ohm; 35W/4ohm.

The amps are not played in at all but the first impression was that the J-X sounds a bit fresher and "lighter" than the XA version. I can' tell about smoothness as I think the amps need to run for a few hours first.
 
the pdf enclosed describes the scientific way 😱 to do it right under "AC gain adjustment"

easier you hear what you want or need for R24😀

mind that R24 is called in this plan R115 😱

another source are the first three Zen articles at First Watt🙂

(pdf by curtesy of Zen Mod)🙂
 
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