F2J mostly assembled. Neither long skinny nor Peter Daniels boards fit the original chassis. So I opted to build up PD boards for another Rawson chassis I have. So the original parts that remain are donut and output devices. Amp boards are Peter Daniel’s design. PSU board is by Chas Sample. I really like this board! AC cap and all thermistors are on the board, it’s a really nice design. He is doing a group buy on F1 including this board. If you need a stereo single rail supply I recommend this board! My F1 kit by Chas is stuck somewhere the USPS logjam... I did the rectifier / snubber boards.
I tested the amp on dummy speakers and it’s singing. Left to do: add LEDs and front panel, final cooking and set trim pots. Then test in my main horn rig. Then send to the owner.
Pix show original vs new board, new psu board, and assembly for initial test.
I tested the amp on dummy speakers and it’s singing. Left to do: add LEDs and front panel, final cooking and set trim pots. Then test in my main horn rig. Then send to the owner.
Pix show original vs new board, new psu board, and assembly for initial test.
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Thanks! The "frame off" on this one is because the 2 sets of boards I got my hands on didn't fit the old chassis. I thought I could squeeze the "long skinny" ones in, but I made a mistake on dimensions. So this project got swapped into an old chassis on my shelf. The original chassis may get some old Aleph Mini J boards put in. But I'm not in a rush because I have Aleph J monoblocs, too.
I shake my head every time I look at the pic of the original board next to the Peter Daniels board. Night and day different.
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Thank you to everyone for the kind words!!
This F2J is now done. Blue LEDs installed. Cooked & biased. Gain checks out. Distortion looked as expected. Sound is great on my bench speakers.
My SissySIT will take a break a few days while I run the F2J in my active horn rig. It will run 500Hz and up into JBL 375s and a Fostex superwteeters.
Now I can get back to my Singing Bush build. I also got really nice F1 boards today from the Chas group buy. The good news is that the F1 boards fit in the F2J chassis I swapped out. Plus I have a donut and a pile of matched mosfets on the shelf. So the F1 will be a low cost build when I use what’s on the shelf. Maybe I can get the caps and resistors I’ll need for less than the cost of one SIT. I’ll say it again - Great job on the F1 boards Chas!
This F2J is now done. Blue LEDs installed. Cooked & biased. Gain checks out. Distortion looked as expected. Sound is great on my bench speakers.
My SissySIT will take a break a few days while I run the F2J in my active horn rig. It will run 500Hz and up into JBL 375s and a Fostex superwteeters.
Now I can get back to my Singing Bush build. I also got really nice F1 boards today from the Chas group buy. The good news is that the F1 boards fit in the F2J chassis I swapped out. Plus I have a donut and a pile of matched mosfets on the shelf. So the F1 will be a low cost build when I use what’s on the shelf. Maybe I can get the caps and resistors I’ll need for less than the cost of one SIT. I’ll say it again - Great job on the F1 boards Chas!
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This just arrived. Aleph 5 with a dead channel. Other channel died a few years before and it appears the transistors were replaced with mismatched ones. I dug in a little last night.
We have the classics here - no safety ground, bare mains exposed on the CL-60, gnarly PSU PCB.
Any ideas on what model donut this is? It is 25vct, 120v input. No idea of vendor or VA rating.
The owner gave up on this amp. I’m at a crossroads. Rebuild as A5 or use chassis for another project...
We have the classics here - no safety ground, bare mains exposed on the CL-60, gnarly PSU PCB.
Any ideas on what model donut this is? It is 25vct, 120v input. No idea of vendor or VA rating.
The owner gave up on this amp. I’m at a crossroads. Rebuild as A5 or use chassis for another project...
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Good question. I looked at hi fi shark for "Rawson" and see 74 old listings. I imagine that's only a portion of them. About a dozen have come across my bench over the past 2 years. I've seen: Aleph J, Mini J, F5, F2J, F3, Gainclone, and now Aleph 5. They all have the same grounding and PSU issues.
At some point I'm planning to put an ad up somewhere to fix these. Bare minimum is total power supply revamp. Even if the request is to fix something broken, the mains wiring, grounding, and PSU PCB will need to be upgraded if it's coming across my bench. Audio related upgrades optional (caps, etc.)
It has been said that "The Plural of Anecdote Is Not Data" but...
I have a feeling many owners have held on to these for quite a while. I imagine the allure of a low price is what drew people towards buying them. And when they work, they sound fantastic. And why not, they're based on famous designs. Mostly Pass, but there also are Icepower amps, gainclones, and probably others, too. The ones I have purchased or fixed have been in the prior owners' hands for quite some time. Sometimes original owners, sometimes not.
Of course the thing that's not obvious to the buyer is the build quality. The chassis looks VERY DIY. I'm sure it's easy to justify the look based on the price. I imagine very few buyers pop the top until something breaks. I would also guess that many who do open the chassis may not understand what they're looking at once the top is off.
Yep 50VCT. I'm used to thinking 25+25
Physical size is about 145mm Diameter x 65mm height.
Tim Rawson (Rawsonte) Aleph J Nelson Pass DIY Clone - Audio Asylum Trader
Up for sale is an Aleph J clone (Nelson Pass design) built by DIY master Tim Rawson. I don't know if he is building these anymore, but they are without a doubt one of the best buys I've found in audio. Industrial-looking on the outside, quality sonics from the inside. Vampire connectors installed by Tim. When Tim built this amp last summer he said it would "smoke" all the other Aleph J amps he made before it.
Found this on Audio Asylum Trader, probably right about the last part, but probably not the way he meant.
Up for sale is an Aleph J clone (Nelson Pass design) built by DIY master Tim Rawson. I don't know if he is building these anymore, but they are without a doubt one of the best buys I've found in audio. Industrial-looking on the outside, quality sonics from the inside. Vampire connectors installed by Tim. When Tim built this amp last summer he said it would "smoke" all the other Aleph J amps he made before it.
Found this on Audio Asylum Trader, probably right about the last part, but probably not the way he meant.