I stand beside John Curl....
Please show some respect for those who has spend a lot of time making the original designs.
You can't take someone design, mod it and then still call it the same name as the original!
If you tweak/mod it, then it's a design based on the original! Not the original....
Sorry but couldn't help it.....
I would be rather angry if someone took one of my designs and e.g. downgraded it, and then claimed that it behaves/sounds as the original!
Ahhhh! Feels better
Besides that, I like the simplicity of this circuit
Please show some respect for those who has spend a lot of time making the original designs.
You can't take someone design, mod it and then still call it the same name as the original!
If you tweak/mod it, then it's a design based on the original! Not the original....
Sorry but couldn't help it.....
I would be rather angry if someone took one of my designs and e.g. downgraded it, and then claimed that it behaves/sounds as the original!
Ahhhh! Feels better
Besides that, I like the simplicity of this circuit
Fwiw, John has pretty much spoon fed the process of reverse engineering his design, so proper courtesy is in order.
Do what you want in private?
My limited experience says that for reasons that are as yet unclear to me that the 1/4 watt size axial leaded MF resistors are to be avoided sonically - YMMV.
Cannot speak to SMT parts - yet.
In most applications it seems like paralleled resistors sound better than one single resistor. Not sure why that would be?
_-_-bear
Do what you want in private?
My limited experience says that for reasons that are as yet unclear to me that the 1/4 watt size axial leaded MF resistors are to be avoided sonically - YMMV.
Cannot speak to SMT parts - yet.
In most applications it seems like paralleled resistors sound better than one single resistor. Not sure why that would be?
_-_-bear
Bear and ACD The layout of this board was as true to the original as possible. I started this project because i wanted to compare this amp to the JLH, Pass Aleph, and ZV9. Maybe some other DIYer's also may want to build it. Dimitri has tested it, has data and has improved it quite a bit. Not downgrade it. He has the utmost respect for Mr. Curl and so do I. The data has been sent to John. Not posted as respect for him.
He has not fed me any information and I have not tried to pry any out of him. If he wants this project stopped just send me an e-mail.
I spent most of today trying to get the whole amp together. By next week I should do some listening tests. Depending how it goes it may be the end of this project.
He has not fed me any information and I have not tried to pry any out of him. If he wants this project stopped just send me an e-mail.
I spent most of today trying to get the whole amp together. By next week I should do some listening tests. Depending how it goes it may be the end of this project.
My version seems to work fairly well. It derives from the same topology, so I can't claim that I started with the proverbial "clean sheet of paper," but the basic form is still there. The only complaint I have is one I inflicted on myself--I chose MOSFETs for the folded cascode, which left me having to use pots in the first stage load to set the second stage bias. No one asked or told me to do so--I just wanted to do an all FET version, although I did cheat and use bipolars for the bias circuit. Yes, I used MOSFETs for a while, but the variable Vgs annoyed me enough that I went to bipolars to have the more-or-less predictable Vbe. That lessened the fiddle-factor of choosing resistors to match the Vgs of the bias devices.
John has seen the schematic and has asked that I change the nomenclature from JC-3 to JC-4. If anyone notices me referring to a JC-4 from here on and gets confused...don't...it's the same circuit. He feels that the circuit more closely resembles certain other circuits he's done over the years than the JC-3. No, I'm not aware of a public domain John Curl JC-4 schematic, but then I wasn't aware of the JC-3 until a couple of years ago when I found it on www.marklev.com; never had a subscription to Audio Amateur. The JC-4 may be out there, waiting for me to discover it. How closely my schematic resembles John's JC-4 concept is for him to say, not me. I just made a few changes to the JC-3 and then fiddled for a while until things looked about right to me.
As I have expressed to Mike, I am disappointed that his project didn't work out as I was looking forward to having complementary projects come out about the same time. I never felt that it was a competitive thing, although others seem to have gotten that impression. In fact, one of the reasons I've held back from starting a thread was to let Mike get in first. His project would have been more interesting to more people than mine, since mine reflects my desire for wide bandwidth and as low a feedback ratio as I can get away with--definitely a minority view. His was more of a mainstream version to my niche. Ah, well, we all pine for what might have been...just think, but for a twist of fate, Angelina Jolie could have been mine...
Grey
John has seen the schematic and has asked that I change the nomenclature from JC-3 to JC-4. If anyone notices me referring to a JC-4 from here on and gets confused...don't...it's the same circuit. He feels that the circuit more closely resembles certain other circuits he's done over the years than the JC-3. No, I'm not aware of a public domain John Curl JC-4 schematic, but then I wasn't aware of the JC-3 until a couple of years ago when I found it on www.marklev.com; never had a subscription to Audio Amateur. The JC-4 may be out there, waiting for me to discover it. How closely my schematic resembles John's JC-4 concept is for him to say, not me. I just made a few changes to the JC-3 and then fiddled for a while until things looked about right to me.
As I have expressed to Mike, I am disappointed that his project didn't work out as I was looking forward to having complementary projects come out about the same time. I never felt that it was a competitive thing, although others seem to have gotten that impression. In fact, one of the reasons I've held back from starting a thread was to let Mike get in first. His project would have been more interesting to more people than mine, since mine reflects my desire for wide bandwidth and as low a feedback ratio as I can get away with--definitely a minority view. His was more of a mainstream version to my niche. Ah, well, we all pine for what might have been...just think, but for a twist of fate, Angelina Jolie could have been mine...
Grey
bear said:MikeW,
No need to fold your tent and leave!
Curl may bark a bit, but he's actually a good fellow.
No need to quit now, just stay calm... run the ship steady on, old boy!
_-_-bear
I am not that sensitive. It's DIY. I can make any amps I want. If they don't work out I have no one to blame but myself. I have got to the point to know when to go in another direction. I may do some changes on these boards but nobody will know.
Thank to everyone for the input.
Mike W! As had been said, an awful lot of people would like you to see this through 
Is it not possible, further eval and tweaking etc., could get it to the performance level it is known for?
I find it hard to believe a quasi original style JLH is substantially better sounding?
It has also been suggested that the reproduction has been made possible by "spoon fed" assistance from JC himself?
Just what posts are those
Personally, I think the lack of the exact same semiconductors is enough to change the character to the extent you have experienced
This would be much easier corrected or avoided if the "spoon feeding" were actually happenning. But, like John said, it needs to be biased correctly and all Maybe correctly is a little different with these devices 
It also seems to me, even John wants to see it done as good or better than he did it
Is it not possible, further eval and tweaking etc., could get it to the performance level it is known for?
I find it hard to believe a quasi original style JLH is substantially better sounding?
It has also been suggested that the reproduction has been made possible by "spoon fed" assistance from JC himself?
Just what posts are those
Personally, I think the lack of the exact same semiconductors is enough to change the character to the extent you have experienced
This would be much easier corrected or avoided if the "spoon feeding" were actually happenning. But, like John said, it needs to be biased correctly and all
Maybe correctly is a little different with these devices It also seems to me, even John wants to see it done as good or better than he did it