John Curl's Blowtorch preamplifier part II

[bogdan_borko]

Originally Posted by john curl

I'm back. This is just a test.

[john curl]

Much of the speculation is bogus. Not just mistaken, but irresponsible. I apologize for your actions to Bob Carver, a fellow designer that I have known for the last 35 years, but sporadically. This new design is just as 'crazy' as one of his, but he is not connected with it, in any way.

[Bob Cordell]

Originally Posted by john curl

Much of the speculation is bogus. Not just mistaken, but irresponsible. I apologize for your actions to Bob Carver, a fellow designer that I have known for the last 35 years, but sporadically. This new design is just as 'crazy' as one of his, but he is not connected with it, in any way.

Hi John,

Welcome back. I for one have always enjoyed Bob's thinking out of the box and his innovative designs. I look forward to hearing about what you are up to.

Cheers,
Bob

[john curl]

Unfortunately, I am not in a position to say much, at the moment, about this design. We hope to have a working example at the Rocky Mountain Festival, but I can't promise at this point. It is out of my hands, so to speak.
We should find something else to 'discuss' on this thread

[Bob Cordell]

Originally Posted by john curl

Unfortunately, I am not in a position to say much, at the moment, about this design. We hope to have a working example at the Rocky Mountain Festival, but I can't promise at this point. It is out of my hands, so to speak.
We should find something else to 'discuss' on this thread

Hi John,

I plan to be at RMAF.

Cheers,
Bob

[stinius]

Originally Posted by john curl

Unfortunately, I am not in a position to say much, at the moment, about this design. We hope to have a working example at the Rocky Mountain Festival, but I can't promise at this point. It is out of my hands, so to speak.
We should find something else to 'discuss' on this thread

Hi John

It’s good to see that you are back.
I hope your eyes are ok now.

Could you please tell a bit more about the class d amp.
I’m not interested in details, just some ideas about the topology you are using, is it a self oscillating design? Are you using opamps and class d drivers or is it a discrete design? What kind of output filter, feedback, comparator etc. are you using?

Cheers and all the best.

Stinius

[john curl]

The new amp is not a class D amp. It uses class D power supplies. This amp itself, is linear.
However, the amp uses patented concepts, has a very high effective open loop bandwidth, and is hard to make without serious engineering, for stabilization, since it is relatively complex as a system.
We are thinking of selling pre-potted portions of it to other manufacturers and individuals, but it will take a serious engineer to make it go together properly, and it is more advanced than many amateurs should try.
The fellow who mostly designed it has multiple degrees in physics and engineering and is one of the best designers that I have been privileged to work with, in many years. We don't want to fix anyone else's mistakes, so we can't just offer something, half way.

[anatech]

Hi John,
Well, the class D power supply is the same concept that Bob Carver used in the Lightstar. The linear amp portion is also the same. Looks like aside from the details, my speculation is in fact, spot on. You can quibble about the details, but the concept is still the same. This is something I am really familiar with.

I think the potted components are entirely silly. If you are worried about being reversed engineered, don't sell any - ever! The potting will only make service impossible and the only people that get hurt are the consumers who supported your circuit ideas. The copy professionals will remove the potting and will successfully copy your circuit. There is zero doubt of that. They can even reverse engineer some ICs these days.

If the circuit is special, most people will not understand the schematic. They sure will not know of any component types or pre-selections to use. The details are still protected in that case. If you are using surface mount components, there is enough trouble trying to look that stuff up to the original type numbers. No basement attempt will be made, and a corporate effort has too much to lose in court.

I think that far too much is made of the secrecy of a circuit. If it's novel, people have to get their head wrapped around it. Now, if it's only a rehash of something done before, you had better pot it. Otherwise it will be seen as it really is. It's telling that Bob Carver didn't pot or hide anything. He had novel circuitry and concepts. If anything, he had reason to protect his intellectual property. He didn't have to.

A question for our members here. Who of you have encountered a potted circuit that was a secret? Now, once the secret was known, how often were the details truly a new concept or circuit arrangement?

I'll answer from my own experience. Every single time the contents of a potted circuit became known, it was just a standard circuit arrangement. I have never seen anything new that was potted. In fact, the only purpose of potting a circuit has been to tie a consumer to the mercy of a parts department.

I have reverse engineered a few potted circuits that were no longer available from time to time. I have been successful in replacing them. John, fear me if you are hiding a normal circuit. Fear me and everyone else like me who won't put up with that stupidity.

-Chris

[KSTR]

@John:
So, this is a rail tracking amp, or is it something different?
Care to share the patent numbers?

@Chris: You're not alone with your experience with potted circuits. At least the more clever guys additionally grind off the device markings from the semi's before potting to make us work harder

- Klaus

[anatech]

Hi Klaus,
True, but that won't stop us! Been there, done that.

Rail tracking is exactly what Carver was all about. I'm dying to hear what makes this different to the Carver concept in the Lightstar and Sunfire.

Only people with something to hide bother potting anything. They are only hiding normal circuit designs and passing them off as something different.

John, I forgot. When did you say you developed the complimentary differential pair? I may have seen it somewhere else.

-Chris