John Curl's Blowtorch preamplifier part II

[scott wurcer]

Originally Posted by john curl

Richard is right. Both Charles Hansen and I use very low power supply rejection topologies. We have to make up for this by designing custom, super low noise/distortion power supply buffers to take the nominal DC to a really low noise DC.

This is a strange thing coming from someone who cherishes complimentary symmetry and balanced design. What do you gain with poor PSRR circuits?

[john curl]

I gain nothing but the optimum topology for the job at hand.

[morinix]

I heard the band War on a DD vinyl once. It was like taking a vitamin rather than eating a meal.

OOPS Sorry it was Tower Of Power Sheffield Lab. Still though

[john curl]

Well, that was just one record, and not necessarily their best offering. I have virtually 'fallen in love' with an unknown singer (to me) from listening on a set of quad electrostatics and Electrocompaniet electronics in Oslo, Norway, of a Sheffield direct disc record. That is HOW I could easily verify that these guys from Electro. were on to something.

[SY]

Actually, for that genre, it's a pretty good recording.

[scott wurcer]

Originally Posted by john curl

I gain nothing but the optimum topology for the job at hand.

That output stage is a throwback to things like Futterman OTL.

Here's one, the hot chassis is an added feature. Does anyone know if this predates Kaneda?

[bcarso]

Originally Posted by scott wurcer

Here's one, the hot chassis is an added feature.

[Wavebourn]

Originally Posted by scott wurcer

That output stage is a throwback to things like Futterman OTL.

Here's one, the hot chassis is an added feature. Does anyone know if this predates Kaneda?

If you mean that "practical schematic" that John had shown, it is quite different. There 2 currents were applied to resistors between gates and sources of each particular output device. Here triodes loaded on resistors supply voltage signals to grids of common cathode and common anode stages. Gross imbalance. John's version is much better.

[Chris Hornbeck]

When Yamaha brought out the giant-JFET-output model B1 amplifier (below) they had a good white paper about the output stage drive, but I can't find it online. I'll see if I can figure out a way if anybody's interested.

http://my.coolala.net/upload0713/201...1286557087.gif

Thanks,
Chris

[scott wurcer]

Originally Posted by Chris Hornbeck

When Yamaha brought out the giant-JFET-output model B1 amplifier (below) they had a good white paper about the output stage drive, but I can't find it online. I'll see if I can figure out a way if anybody's interested.

http://my.coolala.net/upload0713/201...1286557087.gif

Thanks,
Chris

I don't see the point, these circuits are bandaids when you can make only one good flavor of device. Topologically you can show the same crossover issues with low quiescient bias as if you had a class A/B output and the PSRR is do-do.