Aksa Lender P-MOS Hybrid Aleph (ALPHA) Amplifier

[Aatto]

Hi X, Hi Gable

congrats on 25,001, that is some dedication

Maybe I need to get out more.

Meh, been there, more fun inside

 

[zman01]

Just realized this is my 25,001 post.

Congratulations X on the milestone.

And thank you for all your contributions to the forum! Keep up the good work!

 

[Vunce]

That’s on average a post every 2.1hrs for 6 years.

Congrats X
I knew you never slept!

Thanks for all your help

 

[drpro]

Creeping up on Andrew T.

 

[alibear]

Congratulations X, great dedication and always helpful, many thanks for what you do.
Best regards
Alan

 

[AKSA]

Ditto, X, your dedication to the forum is incredible. I joined DIYaudio in Sep 2001 and have only 5,600 posts, almost 25 less than you.

I guess it is testimony to your amazing energy and your willingness to help others...

Hugh

 

[thimios]

Sorry about that. You can use any small signal NPN like BC546/547/550 and it should work.

Just realized this is my 25,001 post.

I see also 33pf smd for compensation,different values according to schematic,are these ok ?

 

[xrk971]

I see also 33pf smd for compensation,different values according to schematic,are these ok ?

You can try 33pF or 36pF, smaller if you can do it and not get oscillation. I have 36pF in silver mica but only 33pF in NP0 SMT. Both can work. You might even try smaller 28pF and get away with it. Hugh says best to use silver mica for sound quality. NP0 may measure lower distortion but silver mica probably best for SQ.

 

[xrk971]

Ditto, X, your dedication to the forum is incredible. I joined DIYaudio in Sep 2001 and have only 5,600 posts, almost 25 less than you.

I guess it is testimony to your amazing energy and your willingness to help others...

Hugh

Thank you, Hugh (and all the folks above) for the kind words. It's been a great community to be a part of and to have so many people I now know from all over the world. It seems like any place I travel to now, i can meet up with someone from DIYA for a cup of coffee/beer or a listening session.

 

[thimios]

You can try 33pF or 36pF, smaller if you can do it and not get oscillation. I have 36pF in silver mica but only 33pF in NP0 SMT. Both can work. You might even try smaller 28pF and get away with it. Hugh says best to use silver mica for sound quality. NP0 may measure lower distortion but silver mica probably best for SQ.

I have 2 pieces only 33pf Mica.
How critical is the 0.12ohm resistor?
Is it ok to use 0.1ohm for R132?

 

[xrk971]

R132 needs to be about 1/2 of R131 (0.33R). So 0.1 is a bit off. Do you have two 0.22R or two 0.33R is even better for a perfect 2:1 ratio.

 

[thimios]

R132 needs to be about 1/2 of R131 (0.33R). So 0.1 is a bit off. Do you have two 0.22R or two 0.33R is even better for a perfect 2:1 ratio.

Yes 0,22 & 0,33 are available.
So R131=0,33R
R132=0.33R//0.33R=0,16R.

 

[thimios]

Up to now...
Unfortunately not all resistors RN55.

 

[thimios]

Are R125 & R1270 optional?

 

[xrk971]

The pots are optional, just install the resistors and no pots. This amp doesn’t need any pots as it is adjustment free. Set R105 pot at 1050R or use 1k and 47R in series - again, no pot needed on this amp. You should look in the GB thread for more build tips as almost all of these questions have been answered there.

Aksa Lender P-mos Hybrid Aleph (ALPHA) Class A Amp GB

 

[thimios]

Thanks xrk, i have troubles posting photos...

 

[thimios]

Close to the end!

 

[zman01]

thimios,

Good to see you are close to completion with populating the PCBs.

Look forward to your listening impressions.

 

[xrk971]

Looking good Thimios. I assume you have a +/-24v PSU and Class A heatsink all ready to go?

Good luck with power up!

Usually goes well for this amp without a hitch. Monitor the bias current at switch on and turn off PSU if you get more than 2amps bias or >0.7v across R131 0.33R resistor.

 

[thimios]

Thanks guys but this is tested already!
Two variable bench power supplies used at first start up.
+/-21v , 1.8A idle current.
It is singing nice!
I have listen only for a few minutes as i feel very tired.