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Alpha Nirvana 39W SE Class A Amplifier GB
Alpha Nirvana 39W SE Class A Amplifier GB
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Old 1st December 2019, 11:05 AM   #1
xrk971 is online now xrk971  United States
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Location: Metro DC area
Alpha Nirvana 39W SE Class A Amplifier GB
Default Alpha Nirvana 39W SE Class A Amplifier GB

This is the Group Buy and Build thread for the Alpha Nirvana 39W SE Class A amplifier designed by AKSA. The technical discussion thread is here:

Alpha Nirvana 39w 8ohm Class A Amp

PCBs:
Click the image to open in full size.

Production ones will be 2mm thick, 2oz Cu, ENIG gold finish, and Blue solder mask.

Amp module looks like this assembled:
Click the image to open in full size.

Includes helper snubber boards to allow remote mounting of MOSFETs for flexibility and ease of installation by decoupling the installation of the PCB and the MOSFETs:
Click the image to open in full size.

Latest Schematics and BOM will be updated soon, but current version (very close to final) is below:

I recommend use of these Fairchild MOSFETs (higher power rating than IRFP's):

FQA40N25 ON Semiconductor / Fairchild | Mouser

FQA36P15 ON Semiconductor / Fairchild | Mouser

The SLB PSU is also highly recommended - proven to work with single SLB and Antek 600VA 24v (AN-6224) trafo. Should work as dual monoblock with dual SLB and Antek 300VA 24v trafos (or equivalent). Also, a ready to run (RTR) solid state relay (SSR) DC protection is highly recommended to prevent turn on thump and provide safety net for your speakers should something fail.

Also tested to work on DIYA Store Dissipante 4Ux300mm chassis. Board is UMS compliant and I did not have to drill and tap a single hole on my UMS heatsink. Chassis temp is 57C at hottest point in 20C ambient. A 5Ux400mm would be much more generous and allow higher bias current.

Pre-Orders are now being taken in my Etsy shop for the GB.

Pricing is $37ea (includes pair of snubber boards - which cost almost as much as the PCB, hence the higher price). Thus, a stereo pair requires two boards. Free shipping in USA. Etsy calculated shipping elsewhere - circa $23 via tracked and insured USPS First Class mail.

If you place a pre-order, please add your name to a running list below with name, qnty, country. Thanks!

A huge thank you to Hugh (AKSA) for the design and JPS64 for the superb professional layout.

Here is the schematic of my amp "AS-BUILT". These values should work and clears up any ambiguous locations where multiple values are possible.
Alpha Nirvana 39w 8ohm Class A Amp-proto-schematic-built-dec-3-2019-jpg
Attached Files
File Type: pdf ALPHA-NIRVANA_SCH_001.pdf (107.7 KB, 66 views)
File Type: pdf ALPHA-NIRVANA_PBA-TOP_001.pdf (51.2 KB, 24 views)
File Type: pdf ALPHA-NIRVANA_PBA-BOT_001.pdf (20.2 KB, 17 views)
File Type: zip ALPHA-NIRVANA_BOM_001.zip (3.1 KB, 24 views)
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Last edited by xrk971; 3rd December 2019 at 06:22 PM.
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Old 1st December 2019, 11:23 AM   #2
meanie is offline meanie  Singapore
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Alpha Nirvana GB

1) meanie : 1 stereo pair (Singapore)
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Old 1st December 2019, 12:09 PM   #3
AKSA is offline AKSA  Australia
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Location: Melbourne, Australia
Thanks X,

I think this is one of my best designs, and X has hugely prototyped, auditioned, measured, and documented it to an inch of its life! It has an even, consistent harmonic profile at all outputs and frequencies, delivering a classic Class A sound with very high efficiency (43%) at full output. It requires no adjustment to get it going, and with a couple of changes you can set it up for 8R or 4R speaker. It will drive just about a rusty nail.

This amp will consume 95W of electrical energy at idle, and at full output. This is a consistent power draw, though it drops the dissipation at audio levels, passing that energy to the speaker. Notwithstanding, the constant power requirement is 190W for two channel, heatsinking is CRITICAL and heavy use of this amplifier will be reflected in your power bill. BE WARNED CLASS A COST MONEY AND YOU SHOULD KNOW THIS BEFORE YOU DECIDE TO BUILD.

JPS's pcb layout is avionics standard, his pcbs are a work of art and his skills are the result of thirty years in the industry. If you build this amp you will be combining SOTA design (it's taken my 30 years to get to this point too!) with professional aerospace layout techniques. It is, in my and X's opinion, as good as any expensive Class A amplifier and in most cases better. You are getting a very high level product at DIY costs; but be aware building yourself is NOT the cheapest option. The cheapest option is always a Class D bought from China, but you choose your poison........

A big thanks to X for bringing my designs to reality, and enthusiastically explaining it to DIYers on this wonderful forum we all enjoy. We three offer this ALPHA Nirvana unreservedly - it is an incredibly good amp with the guarantee of years of music enjoyment for anyone with a bent for the Class A sound with a bit more power, efficiency and ease of build than the majority........... I really hope it becomes a classic into the future!

Ciao,

HD
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Last edited by AKSA; 1st December 2019 at 12:12 PM.
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Old 1st December 2019, 12:29 PM   #4
maty tinman is offline maty tinman  Spain
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190 watts x 6h x 30 days = 34,200 watts = 34.2 kwatts.

Spain: 1 kWatt = 0.12 - 0.14 (one of the most expensive countries in the EU, thanks to the corruption of our political class)

VAT: 21%

34.2 x 0.14 x 1.21 = 5.8 / month.

In other words, 1 hour, every day -> 1 / month.
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Old 1st December 2019, 12:33 PM   #5
maty tinman is offline maty tinman  Spain
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The real problem, to me, is the heat in the Mediterranean coast. And the need of speaker with higher sensitivity than my loved coaxials (true 85 dB, and minimum 3.9 Ohms).
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Old 1st December 2019, 12:35 PM   #6
jacques antoine is offline jacques antoine  France
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Alpha Nirvana 39W SE Class A Amplifier GB
Alpha Nirvana GB

1) meanie : 1 stereo pair (Singapore)
2) jacques antoine : 1 stereo pair (France)
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Old 1st December 2019, 03:20 PM   #7
xrk971 is online now xrk971  United States
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Alpha Nirvana 39W SE Class A Amplifier GB
Thanks for the show if interest Meanie and Jacques. Don’t forget to place the pre-order in my shop.
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Old 1st December 2019, 07:49 PM   #8
gary s is offline gary s  Australia
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Join Date: Nov 2002
Location: Australia
Alpha Nirvana GB

1) meanie : 1 stereo pair (Singapore)
2) jacques antoine : 1 stereo pair (France)
3) gary s : 1 stereo pair (Australia) - will place order in Etsy shop.
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Old 1st December 2019, 07:58 PM   #9
mordikai is online now mordikai  United States
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Alpha Nirvana GB

1) meanie : 1 stereo pair (Singapore)
2) jacques antoine : 1 stereo pair (France)
3) gary s : 1 stereo pair (Australia) - will place order in Etsy shop.
4) mordikai : 2 stereo pair (USA) - order placed in store
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Old 2nd December 2019, 02:44 AM   #10
Vunce is offline Vunce  United States
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Alpha Nirvana 39W SE Class A Amplifier GB
Alpha Nirvana GB

1) meanie : 1 stereo pair (Singapore)
2) jacques antoine : 1 stereo pair (France)
3) gary s : 1 stereo pair (Australia) - will place order in Etsy shop.
4) mordikai : 2 stereo pair (USA) - order placed in store
5) vunce : 1 stereo pair (USA)
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