Don't you dare! I just got done with this one, I don't even have the covers on it yet. I have to build the AN now, I I I I......
Is it going to use the Semi FETs?
Nope.
There are two optional output stages: one with off-the-shelf $2 IRFP240/9240 verticals and the other with slightly harder-to-find $8 2SK1058/SJ162 laterals.
You do need 24 for a stereo amp so the laterals start to get a bit pricey, but nothing like the SemiSouths and it has roughly 4x the output of the J2.
Initial listening report
I have my first 10 or so hours on the J2 in my system, and am very happy so far.
Very quiet background, more so than my Aleph Js I have built.
There is an accuracy but yet, smoothness, I like.
Good balance through the frequencies with a nice midrange.
More to come in the near future, but first impressions are very positive.
I have my first 10 or so hours on the J2 in my system, and am very happy so far.
Very quiet background, more so than my Aleph Js I have built.
There is an accuracy but yet, smoothness, I like.
Good balance through the frequencies with a nice midrange.
More to come in the near future, but first impressions are very positive.
The J2 is very good... I like the sound of it better than anything I have built so far. The bigger trrans has made it even better. Now that it's daytime and I can give it a little volume, I can for sure hear more depth and better mids and lows. Taking the rail from 22 to 24 is noticeable, I didn't think it would, but after just a couple hours I can tell with no question. The soundstage is wider and deeper. The speakers disappear and there is just a wall of music there. If I close my eyes I can't locate the speakers.... me likes that.
Seriously thinking about banking 4 more of those Semisouths for another build, or in case something blows down the road. $320 for 4 of them though... ouch.
Seriously thinking about banking 4 more of those Semisouths for another build, or in case something blows down the road. $320 for 4 of them though... ouch.
Jeff,
thank you very much for your reply
best regards
what bias are you using
thank you very much for your reply
best regards
what bias are you using
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I took another look for you... The bias is steady at .777V or about 1.55mA
Temps are great, highest is about 61C If one wanted to push it, I think you could take it much more at those temps, and one of the reason Papa used those FET is they can take some abuse and sound amazing. Temp wise, I thin I could push them a lot harder, but with my speakers... nit needed, and they are about 4-6R crazy, but it sounds very good .
JT
Hey Jeff,
Interested to build a J2, where do I get the heatsinks that you have?
Ed
Interested to build a J2, where do I get the heatsinks that you have?
Ed
Front plate drilled and tapped for diodes:
Heatsink prepped (FET footprints polished and brass fulcrums installed for the power resistors):
Note that it appears that the Ohmite leads are long enough to mount the resistors directly in the holes, but I used the fulcrum method on my F3 (the Lovoltechs don't have holes at all) so I'm sticking with it.
Less then optimal for the amp... A highly modded pair of Tekton DIs with external crossovers. They are factory rated at 4R, but with my external crossover they are running about 6R. These are the speakers in my lab, but the amp will soon be moved to my dedicated listening room where it will drive a pair of PAP Horn1s.
Both the Tektons and the Horn1 will have no problem being driven by 25W.
This is by far the most pleasant easy to non fatiguing SS amp I have ever heard. My ears are very sensitive to... forward upper frequencies. I find I'm most sensitive in the 3k range and have, at times, reduced that range -3lb.
I'll be putting some finishing touches on it today and will post a few images later. I have, what I think, is a cool idea for the front of the amp.
Will love to get one of these so that I can mount the boards horizontally. Any links to it?
You can always mount a piece of angle aluminum on the vertical sink like I did. Seems to run cooler too at about 58-61C where as the one he used gets up to about 68C.
Just put the covers on and the finishing touches. I still have a couple things to do with the face, but I like it fine now too.
Attachments
You can always mount a piece of angle aluminum on the vertical sink like I did. Seems to run cooler too at about 58-61C where as the one he used gets up to about 68C.
Just put the covers on and the finishing touches. I still have a couple things to do with the face, but I like it fine now too.
I tried doing that for my Sissy SIT and the thermal coupling wasn’t good as the aluminium L bracket wasn’t flushed to the heatsink, in the end I had to abandon the idea.
I am officially"in", have some semisouths coming.
Have the boards and the 109s.
Not the cheapest way to do this but, I would like to keep it as close to original as possible.
After hearing my F5 and seeing what others have posted on there experiences with the J2 and wanting to hear one.
You only have 2 options buy one or build one.
My budget will only allow me to do the latter.
Looking forward to it though.
Have the boards and the 109s.
Not the cheapest way to do this but, I would like to keep it as close to original as possible.
After hearing my F5 and seeing what others have posted on there experiences with the J2 and wanting to hear one.
You only have 2 options buy one or build one.
My budget will only allow me to do the latter.
Looking forward to it though.
