Grey, please don't confuse the issue, even in jest. IF you want to make a JC-4, go for it, just don't call it a JC-3. For everyone else, the JC-4 is just a balanced version of a JC-3, utilizing the same input stage and just adding out with an inverted complementary differential 2'nd stage.
Almost any size amp can be made in the JC-4 configuration. I have made 2000W motor drive amps, several 100- 250W amps, (Gale, Symmetry, VMPS), and it is used in general by Nelson Pass, and Charles Hansen with various improvements and compromises.
For some reason, Grey wants to call a JC-4 a JC-3 with improvements. I think that it confuses the situation, because the JC-3 is a SPECIFIC circuit that I did for Mark Levinson, and I would prefer to keep it intact.
You probably KNOW the problems I am having already with the JC-2 circuitry. Every engineer and his brother wants to second-guess me, potentially effecting the circuit in a negative way.
IF it has MY initials on it, I would appreciate it if you would all keep the schematic intact.
You are perfectly allowed to make your own designs, I will even help, if it is deemed useful.
Almost any size amp can be made in the JC-4 configuration. I have made 2000W motor drive amps, several 100- 250W amps, (Gale, Symmetry, VMPS), and it is used in general by Nelson Pass, and Charles Hansen with various improvements and compromises.
For some reason, Grey wants to call a JC-4 a JC-3 with improvements. I think that it confuses the situation, because the JC-3 is a SPECIFIC circuit that I did for Mark Levinson, and I would prefer to keep it intact.
You probably KNOW the problems I am having already with the JC-2 circuitry. Every engineer and his brother wants to second-guess me, potentially effecting the circuit in a negative way.
IF it has MY initials on it, I would appreciate it if you would all keep the schematic intact.
You are perfectly allowed to make your own designs, I will even help, if it is deemed useful.
john curl said:
Two things:
1) I'd never even heard of a JC-4 before a private e-mail from John this past Saturday, so how could I know of its existence? This may be a case of "everybody knows except Grey," simply because I don't get out much. I was calling the circuit I was working on a JC-3 by default, even though I'd cascoded it in places and built it out on the other side for balanced/bridged operation. If there's a JC-4 schematic out there that everybody knows about but me, please tell me so I can go have a look at it. It never occurred to me to call it anything other than a JC-3 because that's the only amp schematic I'd ever seen from John. It would be the height of presumption on my part to call it a JC-4, with the obvious implication being that 4 trumped 3 and hence mine was better. Unh-uh. No way. I was just going with JC-3 because that's all I knew to call it.
2) As far as I can recall, I've not used the term 'improvement' in any context in relation to my version of this circuit. If I have, I apologize. I just set out to build an all FET amp. I later saw that I might be able to get the circuit to exceed my original design targets, so I ended up with no feedback, balanced, and wider bandwidth than I had originally shot for. Improved? How would I know? I've never even heard a JC-3 (or the ML-2 derived from it). I've always tried to be scrupulously honest about this sort of thing; not having heard the original circuit, the absolute most I can say is that I have no opinion. I just loved the concept.
John and I may be misunderstanding one another or something, I'm not sure. I had intended to start a thread here about my version of the circuit. Since Mike is/was working on a direct, literal adaptation of the JC-3 and since I was assuming that he was going to call it exactly that--JC-3--it would be confusing for me to start another thread about another amp with the same name at the same time. Especially since my version isn't a straight translation with more modern parts, like Mike's. That would confuse everyone, including me. We'd never know whose amp we were talking about; John's original JC-3, Mike's JC-3 with modern parts, or my oddity. So, being the (not so) clever young lad that I am, I hit upon the idea of calling mine the JC-3(gr) with the capital letters being John's initials and mine being in lower case at the end so people would know who to blame if the thing was just too weird for words. It would at least get mine out of the nomenclature fray, leaving John's and Mike's sharing the same name. All being very appropriate since Mike's is/was the same topology.
So I sent John the schematic and he responded, asking me to call it the JC-4, which I'm happy to do if he wants me to. I then asked him if he wanted me to call it the JC-4(gr) so as to distance the critter from anything he has done. I understood his reply to mean that I should just go with JC-4...no (gr). No problem. Glad to do it.
But now I'm wondering if one of us misunderstood the other.
In case John, or anyone else for that matter, has any question as to how I handle intellectual property, I only ask that they read the opening post of any thread that I have started here. My track record is unblemished. If I use someone's idea, I give them credit. Period. First time. Every time. Always. Even to the extent that Ian MacMillan lapped me by posting the DC offset correction resistors for the Aleph-X (which is maximally embarrassing to me because I had considered the exact same idea but discarded it because I convinced myself that the phase was wrong and it wouldn't work), whereupon I immediately dubbed them the MacMillan resistors (to keep me humble, cuz I blew it that time) and that name has stuck to this very day. He posted it, so he gets the credit.
If there's a misunderstanding, I hope this clears it up. If it's an April Fool's day joke, I ain't laughing. If John wants me to call the circuit Cinderella, then Cinderella it shall be (or maybe not...does Disney have a lock on that name?). If he wants me not to post it, then I won't post it.
I'll do what I can to make everybody happy--or at least as many bodies as I can--if only I can sharpen my machete and hack my way out of this thicket I seem to have blundered into.
Goodness gracious, what an unfortunate mess!
Grey
Grey, I don't publish everything, but what you sent me was NOT a JC-3. It more closely resembles what I call a JC-4, but you can put your own Id on it as well. In fact, I think that you should, because what I might do will be different from what you might do, in the details. Don't take it so personally.
MikeW said:
Sorry to hear that!
Looking at your photos, it looks like there is no regulated PS for the JC-3 power amp boards. John said that he used regulated PS for the JC-3 if I recall correctly.
If you did not use regulated PS, maybe this is part of the cause for your sonical dissatisfaction?
How about biasing? How did you bias the different stages?
I am curiuous, what output devices did you use?
Just to make sure how much the input cap affects the sonical character of your amp, I would short the input cap, and do a re-listen.
Sigurd
