John Curl's Blowtorch preamplifier part II

[kgrlee]

Originally Posted by john curl

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.

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?
_______________

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?

[dennis h]

For a change of pace....
(new adventures in) ultra‑fi: from design to audio design
dennis

[RNMarsh]

Originally Posted by dennis h

For a change of pace....
(new adventures in) ultra‑fi: from design to audio design
dennis

Makes you think... good stuff. Thx-RNMarsh

[dennis h]

Originally Posted by RNMarsh

Makes you think... good stuff. Thx-RNMarsh

I knew you and some others would like this...
I have heard some boom-box systems (set up as an equilateral triangle) sound better than a lot of multi thousand dollar systems, because they worried about which resistor (or you fill in the blank) instead of the overall picture.
dennis

[gpapag]

Originally Posted by dennis h

For a change of pace....
(new adventures in) ultra‑fi: from design to audio design
dennis

Dennis, thank you for sharing
Peter Sikking speaks the language of common sense (that’s what it is in the end) fluently.

A great “open source” contributor too.

George

[gpapag]

Originally Posted by 1audio

And they come in qualities ranging from Platinum to lead. . . Like audio a lot of the performance comes from design and execution. The components aren't too expensive, but getting the performance is a lot of work and experience.

May be this one is a helping hand

http://www.ti.com/lit/ds/symlink/lmk04906.pdf

George

[john curl]

A project that I think might be challenging! '-) They use good wire too!

[Esperado]

Originally Posted by dennis h

For a change of pace....
(new adventures in) ultra‑fi: from design to audio design
dennis

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).

[fas42]

Originally Posted by dennis h

I have heard some boom-box systems (set up as an equilateral triangle) sound better than a lot of multi thousand dollar systems, because they worried about which resistor (or you fill in the blank) instead of the overall picture.
dennis

Yes, ...

Frank

[Esperado]

Originally Posted by john curl

They use good wire too!

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. While my room do not vibrate so much.