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Aleph P v1.7 Build from Wisconsin
Aleph P v1.7 Build from Wisconsin
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Old 13th May 2021, 12:41 AM   #1
Chris In Milwaukee is offline Chris In Milwaukee  United States
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Aleph P v1.7 Build from Wisconsin
Default Aleph P v1.7 Build from Wisconsin

Oh no, not another “from Wisconsin” build!

This time I will be documenting my build of the Aleph P v1.7 from Jim’s Audio in HK. Now before you start giving me grief for this (as some no doubt may be so inclined), let me lay down some groundwork.

I first learned about the Aleph P during a preamp discussion in which I was curious about a variety of technologies. Specifically, I was intrigued by the multiple “flavor” options of the Schiit Freya+. Mr. Pass suggested I look at the Aleph L which has both a passive and active component depending upon the position of the volume control knob. While researching that product, I ran across another conversation that discussed the Aleph P. Similarly intrigued, I kept reading about that one and Mr. Pass made comments that he preferred the sound of the P over the L (paraphrased). Given that I have built an Aleph J amp -- and it is a balanced device -- it seemed natural that the balanced nature of the Aleph P would be a good companion to it. So off I went on a mission to learn as much about the Aleph P as possible.

Search revealed several folks who had built and provided board sets for this design once upon a time, but at the current time there aren’t any folks in this community who do so. A web search revealed Jim’s Audio had a design as well as matched semis for it, so I placed an order.

Disclaimer: New to DIY, I was unaware of the conflict that brewed within the community for those who develop products based on Pass designs who are not members of DIYA or aim to make a profit off of his work. That's not lost on me. So call me ignorant for not making the connection. I’ve already had the IP discussion with others in the community, so no need to bring it up again. I did attempt to contact Mr. Pass through a couple of channels to discuss the status of this design, but it’s possible my message didn’t reach him. I realize he’s a busy man with hundreds of emails to go through daily, so no hurt feelings on my part. There are no other options for purchasing boards for this design, this version of the product is available, I bought it, and it’s my goal to complete it. This is the tale of that project and is meant as an educational experience. I don’t expect assistance from community members who are opposed to this particular version of the Aleph P preamp, only humbly ask that they allow others to follow along with the build. If I fail (or it fails), then that’s on me and I take responsibility for my actions.

So let’s get the show on the road, shall we?
__________________
~Chris In Milwaukee
Aleph J | Muses v2 Volume Control | Aleph P v1.7 | WHAMMY | Bucket Subs

Last edited by Chris In Milwaukee; 13th May 2021 at 12:57 AM.
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Old 13th May 2021, 12:43 AM   #2
Chris In Milwaukee is offline Chris In Milwaukee  United States
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Aleph P v1.7 Build from Wisconsin
The Jim’s Audio (JA) version of the Aleph P v1.7 (AP) is a combo board that contains the amplifier stage and an onboard power supply. Each board supports one channel of audio and therefore requires two boards for stereo. After analyzing the JA schematics and comparing them to the official service manual for the AP, I found that the amplifier stage was the same as designed in the service manual. There is an addition of two 50-ohm variable resistors (VR2, VR3) on the drains of the CCS FETs, parallel to the 22-ohm drain resistors (LR2, LR3 on the JA boards – R44, R59 on official), used to compensate for biasing differences between each side of the amp. According to the folks at JA, the following was stated about them:

“VR2 and VR3 are to adjust the biasing current on the mosfets. When power up, measure the voltage across LR2 and LR3 respectively. If the voltages are almost the same, then no adjustment is needed. If the voltage differs by over 20%, then adjust these two VRs so that the voltage are close to each other. It is not necessary to make the two voltages the same though as there is always a tiny difference. Normally a small adjustment of the VRs can do.“

In addition, JA chose to not use the switches to offer selectable change of gain with the AP, opting to fix the gain at its lowest setting of 1.3dB. It may be a blessing in disguise, however. With the AP having a max gain setting of 15dB and the Aleph J having 20dB gain, it’s a lot of gain. Perhaps potentially too much for the AJ inputs. So I’ll go with this configuration first. If I need more gain, I’ll add/remove/short resistors as needed.

Aleph P v1.7 Build from Wisconsin-img_4626-jpg

Aleph P v1.7 Build from Wisconsin-amp-schematic-jpg

The Power Supply section of the JA AP contains the rectifier, storage caps, zeners, and power FET with supporting circuitry. Because there are no input switches, there is no need for the relay power supply section, nor is there any accommodation for the mute circuits. The only difference I noted between the JA PSU and official is the two 1000uF caps after the bridge were combined into a single 2000uF cap for compactness. The shaded area below is what's included on the board.

Aleph P v1.7 Build from Wisconsin-psu-schematic-png
Attached Images
File Type: jpg Amp Schematic.jpg (648.0 KB, 922 views)
File Type: png PSU Schematic.png (163.4 KB, 935 views)
File Type: jpg IMG_4626.jpg (1.03 MB, 511 views)
__________________
~Chris In Milwaukee
Aleph J | Muses v2 Volume Control | Aleph P v1.7 | WHAMMY | Bucket Subs

Last edited by Chris In Milwaukee; 13th May 2021 at 12:59 AM.
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Old 13th May 2021, 12:50 AM   #3
Chris In Milwaukee is offline Chris In Milwaukee  United States
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Aleph P v1.7 Build from Wisconsin
Starting with the usual low-profile components, I started with the resistors and diodes, followed by small capacitors and potentiometers (set to center prior to install), and then large capacitors. I opted for the WIMA caps because they fit the spot, the sound nice in my AJ (to me – I don’t know the difference yet), and they aren’t horribly expensive at a few bucks apiece. And the red just looks cool. I finished up with the small transistors up in the CCS.
Attached Images
File Type: jpg IMG_4663.jpg (707.4 KB, 55 views)
File Type: jpg IMG_4664.jpg (817.3 KB, 39 views)
File Type: jpg IMG_4660.jpg (979.6 KB, 37 views)
File Type: jpg IMG_4661.jpg (869.6 KB, 34 views)
File Type: jpg IMG_4662.jpg (841.8 KB, 23 views)
File Type: jpg IMG_4665.jpg (813.0 KB, 25 views)
File Type: jpg IMG_4666.jpg (712.4 KB, 29 views)
File Type: jpg IMG_4667.jpg (872.6 KB, 35 views)
File Type: jpg IMG_4676.jpg (988.7 KB, 70 views)
__________________
~Chris In Milwaukee
Aleph J | Muses v2 Volume Control | Aleph P v1.7 | WHAMMY | Bucket Subs

Last edited by Chris In Milwaukee; 13th May 2021 at 01:11 AM. Reason: Photo addition
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Old 13th May 2021, 12:52 AM   #4
Chris In Milwaukee is offline Chris In Milwaukee  United States
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Aleph P v1.7 Build from Wisconsin
Next step are the amplifier and CCS FETs. These were matched at JA and sold as a set. After installing and aligning them, I installed these really cool low-profile heatsinks on the FETs. The nice thing is they have friction/pressure clips on them that keep the devices pressed tightly against the heatsink. They have lots of cooling area, but they’re not so big they get in the way of components around them. Many of the AP creations that I’ve seen have a piece of L-shaped aluminum stock screwed to them. This is a lot sexier in my opinion. A dab of compound on the back of each FET, slide the heatsink over the top, clip it in place. The heatsinks had locating pins at the bottom, but since there are no holes in the PCB to support them, I removed them and allowed the bottom of the heatsink to rest on the board held up by the FETs they cool. It’s a solid mounting arrangement.

Heatsinks (Mouser):
567-OMNI220-18-25-1C
567-OMNI220-18-50-2C
567-OMNI-220C
Attached Images
File Type: jpg IMG_4678.jpg (778.3 KB, 109 views)
File Type: jpg IMG_4679.jpg (902.7 KB, 92 views)
File Type: jpg IMG_4684.jpg (797.3 KB, 126 views)
File Type: jpg IMG_4686.jpg (704.4 KB, 129 views)
__________________
~Chris In Milwaukee
Aleph J | Muses v2 Volume Control | Aleph P v1.7 | WHAMMY | Bucket Subs

Last edited by Chris In Milwaukee; 13th May 2021 at 01:04 AM. Reason: Photo addition
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Old 13th May 2021, 12:54 AM   #5
Chris In Milwaukee is offline Chris In Milwaukee  United States
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Aleph P v1.7 Build from Wisconsin
Installed the capacitor bank with Panasonic 1000uF electrolytics. The open position is for the 2000uF cap noted a couple posts up. At the time I ordered parts I was having trouble finding 2000uF caps at 100V. Iíve since located them (Nichicon 2200uF caps) and theyíre on order.

I ordered a 100VA, 40V(x2) transformer from Antek to provide the 80VAC juice required on the input and should be able to test out the board when it and the larger PSU caps arrive. This preamp will be used in conjunction with the Muses volume control project in my other build discussion, so I have to coordinate the testing of this and Muses as well (which I also have transformers coming in for).
Attached Images
File Type: jpg IMG_4696.jpg (881.8 KB, 142 views)
__________________
~Chris In Milwaukee
Aleph J | Muses v2 Volume Control | Aleph P v1.7 | WHAMMY | Bucket Subs
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Old 13th May 2021, 02:47 AM   #6
dBel84 is offline dBel84  United States
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Beautifully laid out and clean work as always..dB
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Old 13th May 2021, 04:07 AM   #7
manniraj is offline manniraj  India
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Beautiful as usual Chris, eagerly waiting for next steps as I am building my J2 so the balanced preamp is in my mind
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Old 13th May 2021, 04:53 AM   #8
Nelson Pass is offline Nelson Pass  United States
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Aleph P v1.7 Build from Wisconsin
As it.is my practice to answer all emails, it is possible that yours got lost.

So you understand, I don't get upset about diy cloning for several reasons:

1. It's DIY

2. I don't need the money.

3. Could be worse - they could be cloning someone else.

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Old 13th May 2021, 11:04 AM   #9
Chris In Milwaukee is offline Chris In Milwaukee  United States
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Aleph P v1.7 Build from Wisconsin
Thank you for your reply. I'm appreciative of your consideration and your designs. Sorry we didn't connect, but very happy to have the opportunity to bring another of your devices to life. I'm truly looking forward to listening to it.

Respectfully,
Chris

Quote:
Originally Posted by Nelson Pass View Post
As it.is my practice to answer all emails, it is possible that yours got lost.

So you understand, I don't get upset about diy cloning for several reasons:

1. It's DIY

2. I don't need the money.

3. Could be worse - they could be cloning someone else.

__________________
~Chris In Milwaukee
Aleph J | Muses v2 Volume Control | Aleph P v1.7 | WHAMMY | Bucket Subs
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Old 13th May 2021, 12:48 PM   #10
Chris In Milwaukee is offline Chris In Milwaukee  United States
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Aleph P v1.7 Build from Wisconsin
Thanks! There are a lot of great choices out there in this community. This is the direction I chose, but there are others that fit the bill as well. Looking forward to seeing where this one goes. I chose it because it's unique and doesn't follow the "usual path".

Quote:
Originally Posted by manniraj View Post
Beautiful as usual Chris, eagerly waiting for next steps as I am building my J2 so the balanced preamp is in my mind
__________________
~Chris In Milwaukee
Aleph J | Muses v2 Volume Control | Aleph P v1.7 | WHAMMY | Bucket Subs
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