Alpha Nirvana 39w 8ohm Class A Amp

[Gill.T]

@danny_66 Congratulations! Thats a strong endorsement! Glad for you!
Which first watt amplifiers were in contention?

 

[poseidonsvoice]

@danny_66

Glad you built it and am always happy to see your tricked out CCLC supplies! Hopefully my measurements posted earlier and subjective review completed way back when were helpful! Thanks again for posting!

Happy New Year!

Best,
Anand.

 

[xrk971]

Hi Danny,
That is a wonderful build and a monster of a PSU there! Thanks for sharing and so happy that you love the sound.

I have heard similar anecdotes from others comparing to similar heritage very high end amps ($80k range).

Happy New Year everyone!

 

[danny_66]

Hi Gill,
The amplifiers that we used in our listening sessions during the last years were:
KT88 IT PP, First One 1.4, Juma Cubie2, First Watt F5, DartZeel clone, Alpha 20, FirstWatt Sony vFet PP, USSA3, LM-608IA 845, Alpha Nirvana

Hi Anand,
Yes, CLC is so much better than CRC, easy to compare in Duncan PSU Designer.
I had read your subjective review and that gave me the encouragement to finish this amplifier before starting another project 🙂

Hi X,
Yes, don't skimp on the power supply, after all, an amplifier is a modulated power supply 🙂
This Alpha Nirvana is a keeper!

Happy New Year!

 

[Nikos]

As feedback resistor I used 1.8K instead of 825r, this lowers the gain and when using 4 ohm speakers you get about the same FFT profile as with 825r and 8ohm speakers

Thank you Danny for all these information and the presentation you gave to all of us. What is the operating voltage and bias you chose for your 4R? amplifier?
Happy New Year to all of you.

 

[danny_66]

Hi Nikos,
My DC rails are about 25vdc, output transistors biased at 1.8A.
My speakers are 4ohm and about 93db sensitive , so I don't need large output voltage swings.
I'll post my Ltspice files tomorrow.
Regards,
Danny

 

[Vunce]

Awesome Alpha Nirvana build Danny!!
Your dual CLCC psu is a work of art.
Great start to 2025, Enjoy!

Happy New Year Fellow DIY'ers! 🥳

 

[maximax77]

The power supply is a dual mono with Toriody transfos, LT4320 bridges and CLC.

What chokes are these? Do you have a preferred supplier?

 

[AKSA]

And thank you Danny for building that AN!
This is very encouraging news....
Perhaps I should accelerate the next AN version!
Happy New Year to, to Bernard, your families and indeed the entire DIY family!
Let us hope 2025 is a good year, or perhaps we avert war...

Hugh

 

[Gill.T]

Perhaps I should accelerate the next AN version!

Loads of wishes to you!
Now thats a great news! When can we expect the next version? Would be accessible to DIY people?

 

[danny_66]

What chokes are these? Do you have a preferred supplier?

The chokes are from AE Europe, they're located close to me.
The specs are:
10mH 0.07 Ohm
5A DC
WxDxH 80x70x60mm

Another good candidate is the Hammond 196Q2, with the dual coils in parallel you have 10mH 0.12R
single: 20mH 2A 0.24R
parallel: 10mH 4A 0.12R
series: 40mH 2A 0.48R

Grts,
Danny

 

[xrk971]

And thank you Danny for building that AN!
This is very encouraging news....
Perhaps I should accelerate the next AN version!
Happy New Year to, to Bernard, your families and indeed the entire DIY family!
Let us hope 2025 is a good year, or perhaps we avert war...

Hugh

Happy New Year everyone!

Greetings, Hugh. A new Alpha Nirvana variant? Very cool. It already sounds wonderful I am not sure how it can be improved.

 

[viltsone]

Perhaps I should accelerate the next AN version!

What would be the main difference compared to this version? 🙂

Happy new year!

 

[danny_66]

And here's the LTspîce sim,
it's all standard except for the feedback resistor I used 1800 instead of 825:
lowers gain and better 4ohm compatibility:
FFT on 1800 with 4ohm load is the same as 825 with 8ohm load
Output transistors are FQA40N25 and FQA36P15

 

[danny_66]

I've been able to set the DC offset to 0mV, thanks to the great PCBs of X that have place for a trimmer parallel to R113.
In my case R113 is in fact a 680R resistor with a 5K trimmer parallel to it, trimmed for about 500R that gives 0mV DC offset.

 

[danny_66]

I'm impressed with this Alpha Nirvana amplifier 😯
It's an open 3D window on the recordings, therefor you need good recordings.
Bass is controlled and detailed, even low bass 20-30hz is amazing,
Instruments and voices layered, easy to pick or follow one.
When there's holographic info you'll get it n spades,
Perfect, except for some recordings 🙂

 

[emailtim]

...
The power supply is a dual mono with Toriody transfos, LT4320 bridges and CLC.
For the Alpha Nirvana I used bulk foil resistors for the critical positions and Isabellenhutte PBH as source resistors, other resistors are cmf60/rn60
Input caps are Clarity cap PUR, the rest Muse ES, Elna Simic and Jupiter Cosmos wet capacitors.
...

Happy New Year !!!

Please excuse the ignorant question, but what is the purpose of 6 transformers in what appears to be 2 stages ?

TIA

 

[danny_66]

The black round donuts are the two transformers, one for each channel,
the four square ones are chokes, one for each DC rail, left+25dvc -25vdc, right +25dvc -25vdc

 

[AKSA]

Sadly I cannot identify the differences between the present AN39 and my concept for a 'better' mousetrap.
Certainly it would be great to have a Class A develop more power and reduce dissipation, that would be nice.......
Unfortunately most of my great ideas come to me while standing under the shower in early mornings; but tragically a couple of weeks ago my hot water system collapsed so my bright ideas are on hold..........

Happy New Years to DIYers, I owe you all gratitude for so many of you building my designs. Danny, those inductors very likely make all the difference to the sound. Very well done!

Hugh

 

[danny_66]

Hi Hugh,
I've used those inductors also in my other amplifier builds, but it's the Alpha Nirvana that has the best sound.
So kudos to your design !