Alpha Nirvana 39w 8ohm Class A Amp

[xrk971]

But surely, X - if the very clever red 'clip LEDs' on the AN never flicker on - even on transients, when listening louder than normal - 100w will be of no benefit with my current spkrs?

Andy

It depends on the sensitivity of your speakers. Mine are 82.5dB and occasionally clips on crescendos with 40w. Your Satori array speakers are probably way more efficient so you might not need 100w headroom. After all, it’s just a bit more than 6dB above 40w. It is 60% efficient at full power though but that just because there is a choke loaded output which boosts voltage swing.


@Aksa:

I realised that replacing the lower output device with a pmos rather than a nmos you could define the voltage output at a far greater linearity than the original Aleph J. I recognised Nelson designed his Aleph for musical colour, but it had quite distortion, and the output voltage accuracy was set by the negative feedback loop. With a pmos in place of the lower nmos, you could reduce thd by maybe 10 times and simplify the swinging CCS so it could adjust to any load. These are eureka moments in our lives

This may be arrangement of existing ideas, and such is the basis of most inventions, but Hugh, you are much too humble and I’ll say that it was pure genius on your part. Bravo and thank you for giving us this amp!

 

[Samuel Jayaraj]

Wow Hugh. My respect and appreciation to a fine Amp Designer and a Master Wordsmith, ever so gentle, kind and never condemning. You have captured your entire Audio Life Journey, so succinctly in a couple of paragraphs, paying tribute where due, to the great Nelson Pass.

All that has been said of the AN by you and others in the last few comments, inspires me to build the amp. I have a few Pass and Juma amps. I have one pair of Tokins and LU1014s from the Pass giveaway group buy with X's aluminium PCBs. I turned down the second lottery VFET amp, due to shipping/customs hassles and 10watts being low power for my needs.

I use Fostex FE168ESigmas in ML TQWT cabs and they sound great on my system. All my amps are Zero NFB and resultant low DF.

Question is, would the ANs do well where low DF shines? Thanks in advance.

 

[xrk971]

I ran across this silent PC chassis that can handle up to 95w of dissipation. Perfect for an Alpha Nirvana monoblock. It’s not bad looking either. At $155 is well priced. You would just need to make a panel on back for binding posts and RCA’s.

I do wonder if the 95w rating is for continuous run though as most PCs run lower power and shorter periods run peak power. Needs more investigation.

Streacom FC8 ALPHA Series Fanless Home Theatre Aluminium Chassis

 

[thorstenlarsen]

Your Satori array speakers are probably way more efficient so you might not need 100w headroom. After all, it’s just a bit more than 6dB above 40w.

Hi X!
No! It’s a bit more than 3db above 40w. Two times the power is 3db. Two times voltage is 6db. But two times voltage to a loudspeaker gives two times current too, which gives four times the power.
Just a reality check.
Thorsten

 

[xrk971]

Yep, my mistake. 40w to 100w is 4dB increase I think.

 

[andyr]

Hi X!
No! It’s a bit more than 3db above 40w. Two times the power is 3db. Two times voltage is 6db. But two times voltage to a loudspeaker gives two times current too, which gives four times the power.
Just a reality check.
Thorsten

Yep, my mistake. 40w to 100w is 4dB increase I think.

Irrespective of the maths, I suggest that if my clip LEDs never go on with transients - even when listening louder than I normally do - it shows that my spkrs do not need any more headroom than what is currently available to them.

So a more powerful amp is simply not necessary.
Andy

 

[wirewiggler]

X, those cases look look pretty sweet, are you going to try and squeeze a power supply in with those? For my next project I will be putting a sit and mosfet on this, and this power supply.

 

[Vunce]

Super cool Bill!
I like your outside the “Box” thinking.

 

[xrk971]

Nice Wirewiggler. I just got a pair of SMPS like those from Sami today.

I’m looking for a compact and cost effective fabless Class A chassis. Not sure if this is the one yet. But it looks promising.

 

[wirewiggler]

Vunce,
Thanks, this case and my Yarra preamp will be hand made with wood to match. The front panel will be machined from aluminum anodized red, with a headphone amp to match. X that is a par metal case, I cut those heat sinks down to fit in as well but it is so tight I think airflow would be so restricted, probably the thick frame Sami uses is plenty good. I wish he would put more holes in it.
Bill

 

[xrk971]

I think you can ask Sami to add extra holes for you on the next one. He doesn’t charge extra for little things like that. These SMPS are always semi-custom in that way.

 

[Cresnet]

Vunce,
Thanks, this case and my Yarra preamp will be hand made with wood to match. The front panel will be machined from aluminum anodized red, with a headphone amp to match. X that is a par metal case, I cut those heat sinks down to fit in as well but it is so tight I think airflow would be so restricted, probably the thick frame Sami uses is plenty good. I wish he would put more holes in it.
Bill

In the future, there will be a nice black heatsink with holes underneath the heatsink for mounting.

Also, a future model will be a little bit bigger carrying 2 * 10000uF capacitors onboard

You don't need that much of airflow into your chassis, just low speed fan on top of the power devices to cool down the transformer mainly

Thanks!

 

[wirewiggler]

Sami,
Nice to hear from you, they are some sweet looking power supplies. With them being in there own case I am glad the extra caps will be in the amp case. Now with a set of one linear (X’s SMLB) and this SMPS in their own cases I am done building power supplies for a while.

Bill

 

[twocents]

Busy compiling my DigiKey cart while waiting for the pcbs. I am pleasantly surprised that almost all components are still available and in stock. But I have difficulty in finding a suitable part for C1260 - 11pF NPO. Largest package is 0805 (2mm) - a bit tiny for my liking. Can I use slightly different values (10, 12, 15pF) here, without rocking the boat?

 

[xrk971]

If this is on the main board, it should have optional through hole silver mica cap C1250 on the top side. Don’t populate both.

 

[pinnocchio]

Toroidy transformer should finally show up next week! Then I can resume my build.

Do

 

[twocents]

it should have optional through hole silver mica cap C1250 on the top side.

Thanks X. I was searching for a NPO (as built). There are more options from Mouser.

Then I can resume my build.

Do - looking forward to your build and listening impressions. You have an impressive line of amps to compare with.

 

[Vunce]

Hi Do,
If your Toroidy’s show up next week, what was the approximate time you had to wait from ordering until they were delivered?

Thanks

 

[pinnocchio]

Hi Vunce,

It’s usually 3 weeks for North America. But because I already had an open order with them that had been sitting 2 weeks, I was able to add this transformer before it shipped. They made it in 4 days but probably because they had the other two to make.

All the best!
Do

 

[poseidonsvoice]

What are you guys using as a substitute for the connectors on the MOSFETS and main board? Both Digikey and Mouser are out of stock:

Digikey

Wurth Electronics, mfg # 64900421122

Best,
Anand.