Hi Jon, How musical and involving (goose bump factor) is J2 compared to several amps you had used before? How is the J2 compared to typical SET like 300B, 45, 845, etc?
Still thinking about how J2 output works.
...one difference with aleph j is that te voltage across the sensing resistor is phase opposite. I guess there is to reverse this phase before being able to trive the upper power Jfet.
...one difference with aleph j is that te voltage across the sensing resistor is phase opposite. I guess there is to reverse this phase before being able to trive the upper power Jfet.
Mhmmmm... So the ALEPH was papas first child. The J2 is the simpler is better approach... Maybe we'll see that the aleph current source will be replaced with a j2 like output... Maybe Nelson explains the benefit of th Aleph compared with the j2 arrangement...
Jfets and Mosfets are different beasts ;
they have somewhat
different transfer characteristics , along with different range/scale of Ugs ..... so SRPP/Mu Follower is more adequate for Jfets , than mosfets
they have somewhat
different transfer characteristics , along with different range/scale of Ugs ..... so SRPP/Mu Follower is more adequate for Jfets , than mosfets
Do you mean J2 cannot work with mosfets?
It could have been an exiting exercice to try.
http://www.tubecad.com/may2000/page9.html
It could have been an exiting exercice to try.
http://www.tubecad.com/may2000/page9.html
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I believe Nelson mentioned the can drop into an N-Channel MOSFET place and get improved distortion figures. I assume some tweaking of the gate and source resistors is needed to optimize. I will let the big guns speak to this...
I have built the J2 with Mosfets. The nature of the biasing
results in more open loop gain (more feedback) , and the
distortion is higher. That's where I got those comparative
numbers.
😎
results in more open loop gain (more feedback) , and the
distortion is higher. That's where I got those comparative
numbers.
😎
certainly is 😉
but look - Papa is lately pretty generous , especially when Holidays are near ...
he'll reveal J2 schematic much before 100 pcs are sold ....... or - in worst case - they'll be sold in next 10 days , and you'll see schematic ;
Sound of the J2
Goosebumps? Not a problem. Assuming the rest of the system is up to it. We played a lacquer from DirectGrace recordings of a guitar at RMAF. The common comment - it did not sound like a stereo, it sounded like a guy in the room was playing guitar. And it was (almost) that good.
Comparing it to an SET is difficult because you run into the whole PP vs SE thing. They simply do things differently. Not to degrade SE (I often listen to one, and have a number of them), but in comparison to PP it is time for the Rose Colored Glasses (or beer googles if you prefer). Everything sounds a little more romantic, but not necessarily more accurate. And before you SET guys jump all over me, a good SET is a very lightly shaded rose colored glass, or just a very mellow beer buzz. A touch of flavor that you may love, or your system may prefer, or certain recordings sound better with.
That being said, the one thing I SET fans rave about is low level detail, sometimes referred to as harmonic development of the instruments, or the texture of the music. That which keeps you from believing it is real. The J2 rivals anything I have heard in that regard.
Someone asked what the J2 replaced in my system. Most recently the F5 and a 2A3 SET. Both very nice amplifiers. I have heard all of the First Watt amps in my system. The F1 is perhaps a little more accurate, the J2 has just a touch of that sweetness (like an SET) that makes it better to my ears.
Goosebumps? Not a problem. Assuming the rest of the system is up to it. We played a lacquer from DirectGrace recordings of a guitar at RMAF. The common comment - it did not sound like a stereo, it sounded like a guy in the room was playing guitar. And it was (almost) that good.
Comparing it to an SET is difficult because you run into the whole PP vs SE thing. They simply do things differently. Not to degrade SE (I often listen to one, and have a number of them), but in comparison to PP it is time for the Rose Colored Glasses (or beer googles if you prefer). Everything sounds a little more romantic, but not necessarily more accurate. And before you SET guys jump all over me, a good SET is a very lightly shaded rose colored glass, or just a very mellow beer buzz. A touch of flavor that you may love, or your system may prefer, or certain recordings sound better with.
That being said, the one thing I SET fans rave about is low level detail, sometimes referred to as harmonic development of the instruments, or the texture of the music. That which keeps you from believing it is real. The J2 rivals anything I have heard in that regard.
Someone asked what the J2 replaced in my system. Most recently the F5 and a 2A3 SET. Both very nice amplifiers. I have heard all of the First Watt amps in my system. The F1 is perhaps a little more accurate, the J2 has just a touch of that sweetness (like an SET) that makes it better to my ears.