SemiSouth power Jfets .......... FW J2

[Tea-Bag]

turn back R25 to zero , increase value of R26 for max 220R ( from 390 to ,say, 610-620 (whatever you have in drawer) ) ;

turn R25 up , to have 0 offset

set both Iq and offset - fiddling iteratively with R12 and R25

Tea - these are simple things

if you can't do it easily on Sunday afternoon - leave it for tomorrow

These are simple things

So I am at 680R for R26, and best offset so far is achieved with R25 at max, R12 at min.

Are you suggesting I try 220R for R26?

Sorry if I am coming across as dumbass. (true nature)

[generg]

good news...after half an hour the optocoupling device tracks the current precisely and offset is stable around 1mV plus minus 5mVeven at 1,4 A and 6 times o,25 Ohm!@tea-bag: good luck and I hope the sound will change in the direction you want!

[Zen Mod]

........

So I am at 680R for R26, and best offset so far is achieved with R25 at max, R12 at min.

........

completely logical and in line what I'm writing all the time

....

Are you suggesting I try 220R for R26?

...

nope - that will increase negative offset

what I said is " increase R26 for 220R"

......

Sorry if I am coming across as dumbass.

not dumbass , but you're obviously working today without enough concentration

[Tea-Bag]

nope - that will increase negative offset

what I said is " increase R26 for 220R"

This still doesn't make sense to me. You mean R25 to 220R (max for it)??

My thinking tells me to use 1K instead of 680R, should get more wiggle room with R25 pot. 680R improved over 470R, which was improved over 390R original. OR I should try to swap R25 to 1K pot. This makes sense to me....

More resistance here has been dropping the offset, but not enough room to get near 0v.

[Magura]

nope - that will increase negative offset

what I said is " increase R26 for 220R"

This still doesn't make sense to me. You mean R25 to 220R (max for it)??

My thinking tells me to use 1K instead of 680R, should get more wiggle room with R25 pot. 680R improved over 470R, which was improved over 390R original. OR I should try to swap R25 to 1K pot. This makes sense to me....

More resistance here has been dropping the offset, but not enough room to get near 0v.

Let me translate: Increase R26 for 220R = Increase R26 by 220R, as in "add 220R to R26"

Magura

[generg]

One pair of SemiS sound much better than two pairs, maybe not closely matched enough........I am still a little bit fascinated by 6x 0,25 Ohm and 1,4A@sp300b I am too lazy today to change to your values ..... tomorrow......and the Aleph 3 has 60W on my 4 Ohm box and Babelfish J2 13W, of cause Aleph 3 seems in some aspects more impressive....I now change to the Sonidos and compare both amps (but only channel, I have no two complete amps)

[Tea-Bag]

Let me translate: Increase R26 for 220R = Increase R26 by 220R, as in "add 220R to R26" Magura

Got it!!

[sp300b]

Got it!!

Very good. Any impression about the sound after this change?Thanks in advance

[Tea-Bag]

Very good. Any impression about the sound after this change?Thanks in advance

Well, still working on getting it right, need to add a little more R to get offset lower.Then will need to work on the other channel. So I am not sure I will get a good listen for a few days now.

[sp300b]

Well, still working on getting it right, need to add a little more R to get offset lower.Then will need to work on the other channel. So I am not sure I will get a good listen for a few days now.

OK. Easy - take your time.

[generg]

Hi sp300b,Only for your information, I was reading many sides about mufollowers, the one tazzz recommended gives the lowest value to the upper resistor, but most sides advice to make the resistor in the middle the highest.That was your preferred constellation. Tomorrow I will choose 0,25/0,47/0,25 nearly the same like you and possible with the values I have.The second channel will have the original constellation so I can compare easily...I simply wish more body all other aspects are very good...

[sp300b]

...The second channel will have the original constellation so I can compare easily...

Excellent !This will be real-time comparison.Eager to hear about the differences between 0,25/0,25/0,25 and 0,25/0,47/0,25:cheers:

[generg]

dear Zen Mod, is it possible that C3 and C4 are in the signal path from the lower to the upper JFet?does that mean we can influence sound a little bit by choosing different caps or bypass caps?I yes and if we all took different caps, it may explain a bit the differences in sound impression between "wodka" or "champaign"......

[Zen Mod]

yes - they are in signal path , but not so much influential as you hope :Viannen_loungelizard:10n MKC is my preferred bypass

[generg]

can you give an estimated percentage of the contribution of the upper part to the total output?

[Zen Mod]

rephrase , please .which contribution - power or wellness of sound ?

[generg]

I meant contribution to the power..... what did you mean with wellness of sound (distortion cancelation?)

[Zen Mod]

wellness , fitness , well being , quality of life , mu , 42 , Tendon of Sound , whatever :buehehe:don't make that mistake again , and read seriously what I wrote :sarcastic_hand:you remember how's measured AC gain (of Aleph CCS) in Aleph output stage ?pretty much the same - feed it with 400Hz sinethen measure AC voltage across lower SS source resistor ( R37 // R31 ), then measure across upper SS source resistor (R22 // R29)compareI didn't ......

[generg]

thank you Zen Mod, you are really a good guy-de in electronics ......... I hope our many questions and trials of modifications do not bother you ........ these details are our playground .... and we all learn something ..........where are you playing along?

[Zen Mod]

........where are you playing along?

rest of my day-time I'm spending as a Teacher of Modesty and Flying ....... so - you can call me High Flying Modesty ZM:rofl:(pick today's lesson :http://www.diyaudio.rs/blog/6-zen-mods-blog/ )

[generg]

the rest of my day........ :buehehe: :buehehe: :buehehe:

[sp300b]

Is there anybody, or all of You have left