I have been talking a little bit about this amp on the What’s On the Bench Tonight thread, but thought it’s time to give it its own proper thread. It started as a 25W Class A amp, and now has progressed to 40W - mandatory Class A operation since the topology is SE Class A with a an active push-pull CCS based on the Aksa Lender P-Chan Complementary Aleph (ALPHA Nirvana) output stage developed by Hugh Dean and used here under license to Aspen Amplifiers PLC, Melbourne. The layout is by JPS64 which means this is a state of the art amp in terms of layout symmetry, low impedance traces, thousands of sticking vias, and careful attention to minimizing ground loops and noise immunity.
Some of the notable features that this amp will have includes:
We are exploring anodizing color options for the handles and heatsinks. All black is still a major contender.
The internals will be laid out like this with the amp and its PSU mounted together on each heatsink. The floor of the amp will house the dual toroidal power trafos and also a main board let’s the SSR’s for the soft start, the main IEC soft On/Standby, and speaker SSR’s.
Here is a closeup of one channel of the amp and on-board CRC PSU on one PCB assembly. You can see the temperature sensor on the heatsink. Keantoken helped with the construction and assembly of the amp PCBA.
Initial testing of this amp indicates it sounds superb and the latest work is expand the chassis an extra 50mm deep to reduce heatsink temperatures and permit full 50W operation.
You can listen to it here:
Vanguard speakers
XSD speakers
Some of the notable features that this amp will have includes:
- Dual Monoblock design with independent power transformers and amp boards
- Solid State Relays (SSR) for speaker DC protection similar to the RTR SSR designed by jhofland
- SSR Soft Start with soft mains On/Standby button in front panel similar to the SFP designed by jhofland
- Custom All-CNC milled and satin bead blasted hard anodized aluminum chassis with thick 5mm walls and massive 40mm heatsink plates. The chassis is a massive amount of aluminum on the order of 25 to 27lbs. Chassis look, shape, HMI and layout is all my own design and the 3D modeling and CAD is by Darko M.
- Dual analog meters for output power with backlight
- Premium Viborg copper binding posts
- Premium gold plated RCA jacks
- Front panel Mute switch via SSR enable
- Automatic over temperature safety shutdown with dual thermostatic switches that activate the SSR
- Maximum output power of 40W into 8ohms and the wonderful ALPHA Nirvana 2nd harmonic dominant distortion profile with relatively low THD of circa 0.005% THD at 2.83Vrms into 8ohms
- Beautiful classic lines for an enduring timeless visual look
We are exploring anodizing color options for the handles and heatsinks. All black is still a major contender.
The internals will be laid out like this with the amp and its PSU mounted together on each heatsink. The floor of the amp will house the dual toroidal power trafos and also a main board let’s the SSR’s for the soft start, the main IEC soft On/Standby, and speaker SSR’s.
Here is a closeup of one channel of the amp and on-board CRC PSU on one PCB assembly. You can see the temperature sensor on the heatsink. Keantoken helped with the construction and assembly of the amp PCBA.
Initial testing of this amp indicates it sounds superb and the latest work is expand the chassis an extra 50mm deep to reduce heatsink temperatures and permit full 50W operation.
You can listen to it here:
Vanguard speakers
XSD speakers
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We might be growing the chassis to 375mm deep now to really give it lots of breathing room and run cooler. Working on final CAD drawings. Also working on combination SFP soft start and speaker SSR protect main board. We will also have a single front panel PCB with IDC ribbon connector to main power control board for clean look and reliable operation.
In reviewing the bias current needed to drive 50w into a 6ohm load, it seems thermal output would probably be still too high. We will have to back down to 40W output again. It’s tough on a Class A amp to squeeze those last 10W out!
However, a larger chassis will run cooler. Hopefully I’ll be able to test the smaller chassis at 27v and see if it cools down enough. We may just go with a 375mm deep chassis for the 40W.
However, a larger chassis will run cooler. Hopefully I’ll be able to test the smaller chassis at 27v and see if it cools down enough. We may just go with a 375mm deep chassis for the 40W.
New SFPP soft start board installed, cleaned up wiring, connected VU meters, it’s all working now. I changed R value in CRC to drop voltage to 28.5v. Temps now at 55C on heatsink with cover on. This is 300mm deep heatsink. When we switch to 375mm deep it should be much cooler still. Nice to see VU meters dancing when the music gets rocking.
Listening to the A40 playing some classical music. Wonderful track here.
Brahms Cello Sonata No. 1 in E Minor
https://music.amazon.com/albums/B0B...0B2Y1CLSH&ref=dm_sh_Bu94aRdlvQs8unLW7VpCXVzeM
Brahms Cello Sonata No. 1 in E Minor
https://music.amazon.com/albums/B0B...0B2Y1CLSH&ref=dm_sh_Bu94aRdlvQs8unLW7VpCXVzeM
We are working on the fine details of making sure things fit, and that there is plenty of ventilation to keep the inside cool. Looking at taller 45mm rail smoothing caps so we can fit 22,000uF caps now if needed.
The large PCB on amp floor is the new combined SFP Plus or SFPP with dual speaker protect SSR’s. Front panel switches and LEDs will connect a large single PCB on the front connected to the main SFPP/SSR board via a ribbon cable.
375 mm deep chassis is a go!
The large PCB on amp floor is the new combined SFP Plus or SFPP with dual speaker protect SSR’s. Front panel switches and LEDs will connect a large single PCB on the front connected to the main SFPP/SSR board via a ribbon cable.
375 mm deep chassis is a go!
wouldn’t adding height to the heat sinks do more for the thermal headroom than more depth?
So which amp is this actually? Alpha nirvana?
The PCBs for the combined soft start and speaker protection SSR’s for the A40 just arrived.
Also, the front panel PCB to help integrate all the miscellaneous wires to the main soft start and speaker protection SSR board:
These boards really help to reduce the board to board wire assemblies.
Also, the front panel PCB to help integrate all the miscellaneous wires to the main soft start and speaker protection SSR board:
These boards really help to reduce the board to board wire assemblies.
Attachments
Thanks, I am good. Nothing to do with commercial banks in Si Valley.
We are moving forward with the pre production prototype with the deeper 375mm chassis and the new integrated soft start and speaker protect SSR’s.
I was wondering what a silver chassis looked like. Still like all black best. Redoing the front panel to have A40 name and correct markings on LEDs.
So this will change. But you can see what the depth looks like.
We are moving forward with the pre production prototype with the deeper 375mm chassis and the new integrated soft start and speaker protect SSR’s.
I was wondering what a silver chassis looked like. Still like all black best. Redoing the front panel to have A40 name and correct markings on LEDs.
So this will change. But you can see what the depth looks like.
It’s basically the same amp but with improvements for integrated PSU and has built in SSR soft start, SSR on/off with auto thermal protection, and speaker protect SSR’s.
I am running slightly higher rail voltages so probably a little more headroom for peak power circa 40w vs 39w.
One option on color scheme is gold heatsink and all black elsewhere. What do you guys think?
Or all black but silver corner handles:
Or gold corner handles:
I am running slightly higher rail voltages so probably a little more headroom for peak power circa 40w vs 39w.
One option on color scheme is gold heatsink and all black elsewhere. What do you guys think?
Or all black but silver corner handles:
Or gold corner handles:
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