Aleph J Schematic

[Runcis]

Taking in account the last quote buy Qusp & that IPFP9240 has 125pF larger input capacitance than IRFP240, I must use 2 pairs of output devices for I have only 4Ω booomboxes right now.

 

[schultzsch]

Zen I need a little help from you

I want to change ac signal coupling caps of my dac and line pre, and I was thinking if I can replace input pot of my line pre from 100k with one of 200-250k so in this way I will need a cap of a lower value on the stage before him right?
correct me if I am wrong

what else will change along with pot value?

I use second schematic

 

[Zen Mod]

using anything more than 50K for volume pot will introduce cable talk

that will be much more important than any cap issue

whatever cap you have as output on preceding stage , bypass it with MKC , or make another config , which will be DC coupled

however - I'm resorting to DC just because I can , not because cap in chain is most critical link ...... looking at that toob stage , I'm finding it more critical than any cap

 

[schultzsch]

cable talk means?

 

[Zen Mod]

influence of cable capacitances yukyuk

 

[habsrock93]

Hello, I just completed my second Aleph J, but this time one channel is very quiet. Everything seems to be working fine ( still sounds great just doesn't have the gain. Any ideas on where to start?

Thanks

Dave

 

[habsrock93]

Could this possibly be related to a bad ztx450 @ q4? or would it most likely be the input jfets?

 

[Danger Mouse]

Could this possibly be related to a bad ztx450 @ q4? or would it most likely be the input jfets?

At my amp i can reproduce this by not grounding -input when using unbalanced input. Then the amp should have a gain of 1

look from your -input to the inputpair maybe there is a problem.

 

[habsrock93]

That was the first thing I checked...can't seem to find a problem there. When I unground the -in there is a slightly lower gain, but not by much. I'll have to check it again.

Thanks

Dave

 

[schultzsch]

Zen I`m planning to change all resistors in the circuit(rn55d) with cmf55-143 which are non magnetic.what do you think, it worth`s the try?
what non magnetic resistors do you reccomend for R16-R23?

 

[Zen Mod]

I'm not hearing difference between them

maybe in phono , but in power amp - pure fifi mist

 

[schultzsch]

k...got it
thanks

 

[schultzsch]

I have some 2.2k wirewound`s and I want to use them for bleeding resistors.
do they really serve to discharge those caps?

 

[Zen Mod]

yup

they'll serve as bleeders , if you connect them that way

 

[prakit]

Hi Zen Mod,
Would this work?
Aleph J with N-Ch JFET input and P-Ch MOSFET output. Reversed cap, diode, and supply polarities.
Thank you!

 

[Zen Mod]

nope

without going even further - drains are where you have signal amplified in LTP

search , and you'll find already posted schematic for Aleph turned upside -down

 

[didiet78]

Maybe this will help
www.diyaudio.com/forums/pass-labs/152379-mini-aleph-using-bf862-possible.html

Didiet

 

[hm4nine]

Hi Zen Mod,
Would this work?
Aleph J with N-Ch JFET input and P-Ch MOSFET output. Reversed cap, diode, and supply polarities.
Thank you!

Q2 has to be reversed, too....

 

[prakit]

Thanks ZM and Didiet

 

[schultzsch]

does it worth it to replace ordinary no name toroids from my aleph with these Transformateur R-CORE à fixation sur châssis 300VA - 2 x 18V - Transformateurs R-CORE pour châssis ?