Inspiration for future ZEN Versions - basic description of Italians 400.000 $ Amp

[tiefbassuebertr]

Hallo Mr. Pass
The Ultrasound design group wrote follow (about their integrated amplifiers) concerning the three basic driving methods of loudspeakers

1) VOLTAGE driving
The output impedance of the amplifier is very lower than that of the loudspeaker. In this way, we keep constant the voltage, while the current varies. It is the simplest system, used by all the solid state amplifiers, but it is the worst from the point of view of the musical result.
2) POWER driving
The output impedance of the amplifier is equal to that of the loudspeaker. The maximum transfer of power is achieved; such a system is used in tube amplifiers (through the output transformers).
3) CURRENT driving
The output impedance of the amplifier is very higher than that of the loudspeaker. In this way, we keep constant the current, while the voltage varies. It is a system never used because his complexity, but it is the best in absolute from the point of view of the musical result.

This very interesting statements you can read about the weblink
http://www.ultrasound-hifi.com/Us_wh...catori_en.html
also the output requirements, output peak current: 30A, output impedance 1 Meg-Ohm
(sroll down to the commercial integrated amplifier "Parsec") also to read by the above weblink

Current driving basics of this design group you find about the weblink
http://www.ultrasound-hifi.com/Us_wh...rrente_en.html

This could be also a revolutionary approach for ultimate sounding single ended amplifier, based one of the "ZEN" circuits. A variation of a nearly clean current controlled output stage version.

Instead of the tube based input-resp.driver stage I would even here prefer a solid state variation, perhaps a double cascoded voltage gain or buffer stage like the french brand Larvadin - for the weblinks about this go to
Aleph (Single Ended) + Larvadin (no Memory Distortion) = Ultimate Aleph?

Amazingly for me is the great simplify of the whole circuit of "Parsec" - i. e. only two stages, I think one buffer stage (tube based) and one voltage/power gain stage like the ZEN var. IV (Penultimate Zen) about the pdf-link
www.passdiy.com/pdf/zen-v4.pdf
But I don't understand, how the Ultrasonic design group make a output impedance of 1 Meg-Ohm by output peak current of 30A. However I think, that considerations could be helpful to create new projects

[Nelson Pass]

Perhaps they are counting on someone buying it to measure
that claim.

[tortello]

Originally Posted by Nelson Pass

Perhaps they are counting on someone buying it to measure
that claim.

Marketing strategy!!
I've seen this "misterious" object one or two times during audio shows, but always unplugged..

[Duo]

As Penn Jillette walks into the room and yells his favorite phrase.

[tiefbassuebertr]

The explanations about
The revolutionary Ultrasound amplifiers
sounds very interesting.
But is the follow explanation true ?
CURRENT driving:
The output impedance of the amplifier is very higher than that of the loudspeaker. In this way, we keep constant the current, while the voltage varies. It is a system never used because his complexity, but it is the best in absolute from the point of view of the musical result.
I would like to know the exact topology.

[Duo]

Search the term "Transconductance Amplifier" on google.

[Nelson Pass]

Yes, it sounds like a current source.

"It is the best in absolute from the point of view of the musical result"

That would be an opinion.

[Duo]

Most speakers not intended for high impedance amplifiers also go at least a bit, if not extremely, squirrely when driven by said amplifiers. Infinite output impedance rarely gives the desired result but having something in between that and zero sure is nice.

[john dozier]

I will bet that Mr. Pass has one of Paul Klipsch's famous rubber stamps and has used it on this amp.

[Nelson Pass]

Everyone is allowed a little "puffery" (actual US legal term) when describing
their product.

There are occasions (more than you might think) when a higher output
impedance brings something to the table, but I find as a rule that having
an output impedance greater than 16 ohms or so is too high for even those.

Keeping it at 16 or below also has the advantage of giving greater stability
in the real world.