This thread is for bringing back a classic with a modern twist.
Recently I rebuilt a pair of Rawson Aleph 5 monoblocks and the sound took me right back to the Aleph 3 I bought 15 or so years ago. That was my first Pass amp, and it was glorious. Since I fired those A5’s up I knew I needed to make a classic Aleph amp. Every day after shipping the A5's to their owner I craved that Aleph sound. Thinking back – why did I sell that Aleph 3? It’s the one that got away. It’s why I’m on this forum. As always, Blame Pa, right? And a big THANK YOU to Pa for the green light on this!
Right after the A5’s I was working on the layout for Aleph 2 front end boards and MOSFET Daughter boards. I also got to talking with Jim "6L6" about the classic Aleph circuit. We discussed the concept of a single board Aleph with some options… Some brainstorming brought this concept forward:
I started with the Aleph 30 schematic and added some updates based on DIYAudio threads over the years:
I built a prototype pair of Aleph 30 monoblocks last weekend for testing, using the 2SJ313's in the front end. The amps sound fantastic, as expected. Very authoritative lows with beautiful mids and highs. These went into a pair of monos that I rebuilt a few years ago. They had 20V donuts, not 18V – close enough.
During the build, I noted changes that would make the next rev more user-friendly. Most changes were to pads and details on the silkscreen. Those changes are done in a new revision. The built boards are my V0.0c Prototypes. The render of V0.0d will become V1.0a
Highlights of the changes on the new revision include:
C5, C9, C10 (220uF) updated footprints with 5.0 and 7.5mm LS pads
Updated C6, C7, C8 footprints for 5.0, 7.5, 10mm LS pads.
Updated silkscreens details on PCB: V+, V- , Output/Current Source, etc
Add AC Gain Test Jumper
Changed ZTX450 footprints - spaced out and larger pads
Updated trimpot footprints for triangle / straight line pins
Updated pads on most component footprints to be larger
Added part designators / IDs on silkscreen so they can be seen when parts are populated
Moved power MOSFET positions with respect to UMS - moved inboard.
Updated daughter board connections
I’ll make a run of these updated boards with a group buy if there is interest. I’ll follow up with details of BOM, AC Gain setting notes, build notes, etc.
To-do – does anyone want to chip in?
Build Notes at Post #72
https://www.diyaudio.com/community/...er-for-modern-ums-chassis.379571/post-6874343
Recently I rebuilt a pair of Rawson Aleph 5 monoblocks and the sound took me right back to the Aleph 3 I bought 15 or so years ago. That was my first Pass amp, and it was glorious. Since I fired those A5’s up I knew I needed to make a classic Aleph amp. Every day after shipping the A5's to their owner I craved that Aleph sound. Thinking back – why did I sell that Aleph 3? It’s the one that got away. It’s why I’m on this forum. As always, Blame Pa, right? And a big THANK YOU to Pa for the green light on this!
Right after the A5’s I was working on the layout for Aleph 2 front end boards and MOSFET Daughter boards. I also got to talking with Jim "6L6" about the classic Aleph circuit. We discussed the concept of a single board Aleph with some options… Some brainstorming brought this concept forward:
- Build a Classic Aleph circuit on a PCB for UMS heatsinks – Front End + Outputs & Current Sources
- Make it Flexible / Expandable - the "Swiss Knife Aleph". Include the ability to add additional PCB(s) for more semis. Want an Aleph 3/30? How about a 5/60? Got enough heatsinks for an Aleph 2? Want to try an Aleph 40? Be the first in your town to make the Aleph 1 million? The base PCB will handle 4 output and 4 current source MOSFETS, add board(s) as needed.
I started with the Aleph 30 schematic and added some updates based on DIYAudio threads over the years:
- Aleph Reloaded: 2SJ313 optional / updated R13 https://www.diyaudio.com/forums/pass-labs/267857-aleph-design-reloaded.html
- Bypass cap by zener Z5
- Added some trimpots for tweaking, added a jumper for AC Gain test (newest PCB rev)
- Added SE Only jumper by inputs – a tip of the hat to CSample on his F1 boards for that idea.
- Added an additional pair of MOSFETs on the base PCB
I built a prototype pair of Aleph 30 monoblocks last weekend for testing, using the 2SJ313's in the front end. The amps sound fantastic, as expected. Very authoritative lows with beautiful mids and highs. These went into a pair of monos that I rebuilt a few years ago. They had 20V donuts, not 18V – close enough.
During the build, I noted changes that would make the next rev more user-friendly. Most changes were to pads and details on the silkscreen. Those changes are done in a new revision. The built boards are my V0.0c Prototypes. The render of V0.0d will become V1.0a
Highlights of the changes on the new revision include:
C5, C9, C10 (220uF) updated footprints with 5.0 and 7.5mm LS pads
Updated C6, C7, C8 footprints for 5.0, 7.5, 10mm LS pads.
Updated silkscreens details on PCB: V+, V- , Output/Current Source, etc
Add AC Gain Test Jumper
Changed ZTX450 footprints - spaced out and larger pads
Updated trimpot footprints for triangle / straight line pins
Updated pads on most component footprints to be larger
Added part designators / IDs on silkscreen so they can be seen when parts are populated
Moved power MOSFET positions with respect to UMS - moved inboard.
Updated daughter board connections
I’ll make a run of these updated boards with a group buy if there is interest. I’ll follow up with details of BOM, AC Gain setting notes, build notes, etc.
To-do – does anyone want to chip in?
- Figure out any changes of component values for “Aleph 40” using 4 up/4down MOSFETs on a single PCB. What rail voltage? What resistors need to change? Anything else?
- Build Aleph5/60 or Aleph 2 with 2PCB’s per channel. The connection points are there. Populate the front end on one board and spread the MOSFETs on the 2 PCBs. I thought of making UMS compliant extension/daughterboards with 3up/3down or 6up/6down MOSFETS, and 6L6 asked “why not just use the same board without the front end?” Does anyone care to beta test it?
- Who will make a “Turbo” version?
Build Notes at Post #72
https://www.diyaudio.com/community/...er-for-modern-ums-chassis.379571/post-6874343
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It's great to see the Aleph line coming back into focus for Diyaudio. It's a large part of the Pass Labs history that been missing from the site for some time. Congratulations to Papa and Randy for getting these amps updated and available!
It sounds like there's a lot of flexibility with the boards, so builders can try out their favorite Alephs. I've been running my Alephs (A2) almost everyday and I enjoy them as much as my FW amps.
It sounds like there's a lot of flexibility with the boards, so builders can try out their favorite Alephs. I've been running my Alephs (A2) almost everyday and I enjoy them as much as my FW amps.
This wonderful. Thank you for doing this Randy.
Couple quick questions:
For the ztx450, can the silkscreen also include the "CBE" pin designation (like in the store Aleph J board)?
Have you considered adding Allen Newby's clipping mod?
Aleph Clipping Mod
It'll be great to see more Alephs built...
Cheers,
Dennis
Couple quick questions:
For the ztx450, can the silkscreen also include the "CBE" pin designation (like in the store Aleph J board)?
Have you considered adding Allen Newby's clipping mod?
Aleph Clipping Mod
It'll be great to see more Alephs built...
Cheers,
Dennis
Are the transformer requirements similar to the other builds? Looks like it should be. I have a 20v x 2, 400va donut in the closet catching dust. I may be down for the group buy
Brings back memories 17 some years ago of the HotRod Aleph. It's still here somewhere if you do a search. I still have the only stereo set of boards I had made and I plan to build it in retirement 
I was the proud owner of one of the last pairs of Aleph 1.2 mono blocks built by Pass Labs. They were sensational amplifiers, powering my main system for about 15 years. Kudos to Randy (and the esteemed Mr. Pass) for bringing the Aleph series back!
Regards.
Regards.
CBE - done.
Clipping Mod - I can't see the pix on that thread. Does anyone have schematics?
That should be perfect for an Aleph 3/30 build!
I haven't seen that one. Google got me here, and I love it!
https://www.diyaudio.com/forums/pass-labs/51924-aleph-3turbo-hotrodding-a3-3.html#post596909
Nitrous top fuel dragster!
In the coming days I'll set up a group buy and post a link on this thread. I'll put together some options including power supply boards and matched MOSFETs, too.
Awesome work, Randy! My first truly great amp was an Aleph 30. Funny enough, I sold it to fund my first DIY amp, an Aleph J! I’ve always missed that A30 and this will be a perfect excuse to build one. Though mine is definitely gonna be a Volksamp 😀
*edit* I genuinely LOVE the Volksamp branding. I’ve always wanted to make a t-shirt!
*edit* I genuinely LOVE the Volksamp branding. I’ve always wanted to make a t-shirt!
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Nope. All parts are readily available (assuming you don't use 2sj313 for the input stage)
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Nice! Count me in on some boards. I’ve been scatter brained lately so pm me when things get finalized since I may miss the developments. Thanks for doing this!
It certainly helps, you've got the offset trimpot there, so maybe not as critical. I'm in for some boards, the world needs more Alephs!