John Curl's Blowtorch preamplifier part II

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Yesterday I promised more on the designer assigned differences in different power amps depending on price point. Here goes:

... loadsa good stuff from #31342 to #31346
JC, may I thank you on behalf of everyone on this forum for these posts. :)

I would all posts were as informative & useful. Respect.

They all have the SAME CIRCUIT TOPOLOGY
Would this be the topology you pioneered in JC-3 all those years ago?

The 250 W amp is fine for medium sensitivity direct radiators like my WATT or similar speakers with sensitivity hovering around 90spl @ 1W/meter. More power would just endanger the speaker, perhaps blowing a driver.
For example, if I put the JC-1 on my WATT's the peak power would be between 800 and 1000W, just too much.
Actually there are small speakers that CAN take advantage of 1000W/channel but the little WATTs aren't among them. I agree with your 250W as nearly optimum for them.

Of course, though I would like to use 1000W/channel if trying to fool .. I mean persuade Marshy of the benefits of mini-monitors in a Blind Listening Test, there's always the possibility that he'd play the Garage Door just to kill anything small I might sneak in. :mad:

For serious listeners, this is critical, because higher order harmonics virtually always appear when you reach Class AB operation. They may be low in absolute value, but they are plain as day with good test equipment.
JC, is this one of your most important criteria? How do you measure this? What test gear?

I dunno if the latest AP still allows you to look at the distortion residual. Or is everything shown as an FFT plot these days?

About the only thing we are disagreeing on this far is those pesky N and P JFET matched pairs.
JC, any recommendations for these which aren't Unobtainium?
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JC, if I may have the temerity to ask a humble question .. Would you ever consider using a Regulated SMPS in a high quality power amplifier?
 
A project that I think might be challenging! '-) They use good wire too!
 

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And to sell your products: Invent evils and make believe YOU have find the turnaround.
(Of course, it is an artistic process, because if not, you would be asked for proofs).

Right, he mentions JC Morrison a perfectly fine guy, but his approach is more like a painter, there are still painters BTW that grind their own pigments some of which are fabulously expensive. He has a large gallery of schematics many realized in the flesh. I think the engineering as art angle is overstated in engineering it would be like the process is the point.

If yet another triode connected pentode and some MOSFET's makes good sound that's fine. I have a hard time seeing a learning process in this approach.
 
I use wires from Airbus for my sub. (a friend of mine, working for them) . They are semi-rigid twisted pairs, very strange looking and protected against vibration.
Does that give you the audiophile desired plenty of 'air' in the sound ...? :)

But seriously, semi-rigid is good, very good; we don't want anything vibrating, apart from the speaker cones ...

Frank
 
"All quiet on the western front." I guess we can move forward again. Unfortunately, what I am now working on, (improvements to power amps) is confidential, but I will say that I am sticking with the complementary differential jfet input that I have used for so many decades, now.
If anything, I think that RFI buffering is more important than ever. Heavy Class A operation is VERY IMPORTANT, as well.
I still have not found any IC that I would use in replacement for good discrete design.
They are just too compromised in idle current (too low) for me to be comfortable with them.
People are always asking me for cheaper and easier to build designs. Unfortunately, I don't have any. It is not what I do. I try to make the best, most elegant designs I can think of, in respect to the price point that I must work to. I'll leave IC's mostly to mid-fi, where people suppose that everything sounds the same, anyway, as they have been told by others. '-)
 
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