Aleph J MOSFET and JFET kit
All of the critical semiconductors to complete two channels of the Aleph J amplifier.
- 8 x N Channel MOSFETs (Matched for the Aleph J)
- 4 x P-Channel JFETs (Matched for the Aleph J)
- 4 x ZTX450
- 2 x ZTX550
This amplifier is a direct descendant of the legendary Pass Labs Aleph 3, the amplifier that turned the audio press upon it's ear, brought single-ended amps to many people, and catapulted Pass Labs into the forefront of specialist audio engineering and construction, where it still resides today.
Circuit description
The Aleph J is a single-ended, Class-A, MOSFET power amplifier, with a Jfet driver stage. It utilizes the Nelson Pass 'Aleph Current Source' to greatly increase the overall efficiency of the output stage, with the benefits of more linearity, a higher damping factor, and greater stability into tough speaker loads, doing all this with less negative feedback than it's predecessors. The Aleph J is a regular kind of amp - a voltage source amplifier, requiring nothing out of the ordinary from the preamp or the speakers.
Power supply requirements
A bipolar power supply of (+/- 24V) is required. The PSUs for almost all First Watt amplifiers including the F4, F5, F6, M2x, Aleph J, and Aleph Jzm are identical. The same PSU can be used for all of them.
There are three PSUs to choose from:
- Nelson's Bipolar Power Supply is the least expensive and easiest to build. It was designed to compliment the beautifully simple and inexpensive "minimalist" F5m.
- The Simple Linear Bipolar Power Supply is the choice for DIYers that prefer a higher performance power supply, but enjoy the convenience of a full kit. For builders that prefer to choose their own parts, the PCBs are also available.
- The Universal Power Supply PCBs allow the experienced DIYer to choose every part of their PSU or use what they have in their spare parts bin.
Chassis suggestions
The 3U Deluxe is an excellent choice. For builders that want more space and/or may want to build a bigger amplifier in the future, the 4U Deluxe or 5U Deluxe are great choices. We also have a back panel parts kit to make life easier, and don’t forget the Keratherm.
Key Information
- Power Amplifier Project
- Designed by Nelson Pass
- Intermediate Difficulty
- Only PCBs Available
- Basic Build Guide
Highlights
- Possibly the most popular First Watt for DIYers
- It's an Aleph. "Everyone needs an Aleph" - Jim Tiemann (6L6)
Links, Discussion & Files
I made mono blocks with the superb pcb you are selling and the fets.
i am astonished by the results. they have only few hours and they start to open up!
Thanks Mister Pass and DIY audio store, what you do is revolutionnary.
I just completed my build and testing of the Aleph J amplifier. It’s occupying the 4U chassis of the F6 amplifier I built and have been enjoying for the past 18 months. I liked the F6 a bunch, but at times I wished for more authority over my speakers. The Aleph J certainly has that! It sounds great. It’s detailed, has a nice soundstage, and packs a punch. So far I’ve tested it with B&W 686 S2’s and a vintage pair of ADS 1230L’s. The Aleph boards were top notch, and the build guide was very helpful. I’m grateful to the DIY Audio forum for for the great service and products it provides! Keep up the good work:-)
Just finished my Aleph J in a 5U case (big and heavy sitting on my bench) and the sound is just beautiful with my Focal Sopra 2 speakers. Those demanding beryllium tweeters just sound sweet as honey with the Aleph J and the low impedance dip in the base region is a piece of cake for this monster.
Only added the excellent Neurochrome speaker protection to be feel more on the safe side.
Before this I made me the F6 that is also one excellent amplifier to keep.
P.S. the service from the DIY -store is world class!
Great Kit it all worked first try. It's a great price and you know you get genuine parts. So highly recommended!!!
It came nicely packed and I actually bought this FET Kits separately and bought the other parts to complete the whole Aleph J Amp. The sound signature of this design, thanks to the very generous Mr. Pass is so unique with holographic and engaging sound stage, well controlled lows and very sweet mids and highs.
This is my reference DIY amp now after building the ACA and the F4. Its is just a cut above all the ones I built. So worth the time and money and I am delighted I decided to build it.
My Aleph J
