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Firstwatt Aleph-J clone build


henry4841

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This is an amplifier I built many years ago but in what I call my test wood box containing the power supply section and transformer. Most of the Firstwatt projects use the same voltage PS which makes this possible. I have been using a test box to determine if I want to make a complete amplifier from a new design with boards when a new project is introduced. If I like the sound of the new project I give the boards a proper home. After listening to this amplifier for many years in it's ugly wooden case I decided to fork over the money for a proper chassis. I bought this chassis almost 6 months ago intending to finish it then but other projects got in it's way. All I did is move the heatsinks with the boards attached into a newly built PS section and with an old 500VA 18v Antek transformer I had in stock. Overkill on transformer but workable. Some may consider even better. This SE Aleph J is one of my favorite SS amplifiers. 

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I have built all of the Firstwatt clones. Some are just boards now taken out and replaced with some other boards I like better. This Aleph J is one of my favorites, single ended which is also my favorite type of amplification. Very tube like sound. At the present time I have 6 complete up and running Firstwatt clones. The boards taken out and replaced just from memory are the F6, F5 and a version of the F7. Nothing wrong with these three, they just are not my cup of tea with horns. 

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I still have the F3, single ended single stage, and still one of my favorites. Also have the F5, don’t sell it short with horns, not at all.

Didn’t think it was all that until I sat down and really had a listen. Extremely clean, detailed, more robust bass than F3, a really really fine solid state amp. Had it for sale here for a while, glad everyone was too cheap to buy it which gave me time for a good evaluation. Probably the best amp that’s come for sale here in a long time - happy it’s still in play.

Had the M2, sold quickly, nothing special. Had the J2, very F5’ish as I recall. 

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The F5 and F6 are very good amplifiers just too unforgiving for me.

 

A lot of the Firstwatt offerings are much the same with different front ends and the same output configuration. Both the F5 and F6 have one pair of output transistors for each channel. In general terms the more pairs of output transistors an amplifier has the better the sound is going to be. Two of my favorites are the one just for diyer's called the BA-1 and BA-2 with the BA-3 front end. The BA-2 is basically the F4 with the BA-3 front end. The latest project is the M2X where you have the F5 follower end stage with multiple front ends one can build and swap in and out. Neat for those that like to play. What you probably did not like about the original M2 was the transformer coupled front end. It does add it's own signature to the sound but other than that very much like the F5 and F6 circuit wise. 

 

Just to set the record straight, there are no culls in the Firstwatt lineup. Perfect for Klipsch speakers if you desire a tube sound in a SS amplifier. 

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10 hours ago, babadono said:

Yes that's part of the kit I think. or equivalents.So they have the PCBs but no parts, I'm on the "we'll notify you" list.

I think you may be confusing the Firstwatt J2 with the Aleph J. The Aleph J uses the more common IRFP240 mosfet rather than power J-fets. Those semi-south J-fets, forget the number off hand, are unattainable unless you are willing to fork over more money than I am willing to pay for them. Semi-South went out of business years ago. I think you mean this kit being out of stock at the diyaudio store.  https://diyaudiostore.com/products/aleph-j-mosfet-and-jfet-kit?variant=39321292931145

The kit is a good deal for those that do not wish to match the parts themselves but it can be built buying the parts and matching them yourself from Mouser.com. That is all but the 2SJ74's will have to be bought at the store but they are in stock for $45.  https://diyaudiostore.com/collections/jfets/products/matched-jfets?variant=39335246954569  I buy my IRFP240's in quantity of 25 in a tube. That way you will have pretty well matched mosfets without any testing when they are from the same run. They come that many in a tube, 25. I have verified this many times with most of the 25 in a tube, close enough matched for most builders. 

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I have built the Aleph J using the same diyaudio.com boards shown in the thread photos. In fact, I built the Aleph J at the height of the pandemic, and I connected with a couple audio buddies via weekly Zoom calls to coordinate three simultaneous Aleph J build projects in 2020 across the country. It was a great project to build together while everyone stayed home to work. 
 

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I used balanced connections from my Schiit Freya+ line stage, and when I run the Freya+ in tube mode, the sound quality is very good. 
 

My other Pass DIY amp uses Sony VFETs, and this amp sounds fantastic as well, but like henry4841 stated before, the single-ended Aleph J has a tube amp-like presentation. My build uses the Toshiba JFETs as the First Watt builds used, but the JFETs that are included in the diyAudio.com store kit are equally good. 

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