Ultimate Amplifier

[7N7]

Originally posted by Andrewbee
quote:
"Comprising" or according to context, "Comprised" is enough; the "of" is superfluous - indeed tautological!

Somewhat akin to "foot pedal". English is indeed a strange language, even for the the native speaker. Imagine learning it as a second or third language.

Andrew

Sometimes this is only apparent when someone makes a mistake.

For example, I cannot imagine anyone saying "including of", but it is just as incorrect as "comprising of".

"Foot pedal"! An excellent example of a "howler" acceptable to all!

7N7

[ray_moth]

My objection here is that the article is supposedly a learned piece, written by an educated person to whom English is not a foreign tongue. He should know better. 'Composed of' is 'OK; 'comprised of' is not.

I agree that English is strange, but the reasons stem from the inability of the natives to defend their shores from invaders over hundreds of years. This led to corruption/pollution to which no language should be subjected. But please don't get me going on this - I was born in the English Midlands, where the accent is difficult for outsiders to understand - too much high-order odd harmonic distortion, I suppose.

[SY]

Never take advice from someone who thinks 'comprised of' is English!

It's actually a very common phrase used in patents.

[Dave Cigna]

It's actually a very common phrase used in patents.

So don't take advice from lawyers!

[DF Plummer]

Hi there!

OK, I give up! I didn't know my little question could spawn such lengthy debate about the intricacies of the English language.

If anyone wants the rest of the article and the circuit diagram, drop me an email: pdf3@comcast.net.

Regards,

Dave P.

[7N7]

Originally posted by DF Plummer
Hi there!

OK, I give up! I didn't know my little question could spawn such lengthy debate about the intricacies of the English language.

If anyone wants the rest of the article and the circuit diagram, drop me an email: pdf3@comcast.net.

Regards,

Dave P.

Thanks for the offer; I have emailed you.

7N7

[tmiller11147]

Originally Posted by DF Plummer

Hi there!

OK, I give up! I didn't know my little question could spawn such lengthy debate about the intricacies of the English language.

If anyone wants the rest of the article and the circuit diagram, drop me an email: pdf3@comcast.net.

Regards,

Dave P.

I know this is a very old topic but I built one of these amplifiers while in High school in 1964. If you still have the article, would you mind sending it to me?

Regards,
Tom

[Miles Prower]

Feedback in itself is no panacea for a poor design. True, it helps to cover up the frequency response of a cheap amp on the test bench, but a respectable job can't be done without a well designed amplifier comprised of the best components. Only then is the addition of feedback impressive...

...There is a certain amplifier design philosophy based upon the type of logic that assumes if 100HP in a car is good, then 200HP must be twice as good. If 20db of feedback in an amplifier ia a salubrious thing, then let us by all means make it ten times as healthy and use 40db.

I definitely agree with their design philosophy. This is what I do myself. NFB should not be abused to cover up a bad open loop design, although that happens all too frequently, and is what gives NFB a bad reputation.

I also agree that you don't need esssssssss-loads of NFB. In this case, 20db is probably too much. Perhaps this has to do with the speeks they had available in 1954? May be needed better damping than more modern designs?

In the designs I've done, 12db of gNFB is definitely headed for that great transistor sound, and with 20db, you can't tell the difference between the hollow state amp and any Big Box solid state amp.

[LinuksGuru]

Hi, DF Plummer,

Thanks for posting so interesting article! Since magazine this article taken from is very old, copyright is expired, you can freely scan and post it on net.

Schematic is really very interesting, it uses 2 feedback loops from pre-amp stage#1 and #2 straight to the output transformer. To be able to replicate this amp, one will need either original Langevin 316A output transformer (an unobtanium today), or at least data sheet for it, in order to get turns ratio for tertiary windings used in feedback. Reconstructing such output transformer will be no ordinary task, it had to have very small phase shift and leakage inductance <= 20mH or may be even 15mH in order to avoid oscillation. Probably it would be a best approach to wind this trafo on grain oriented silicon steel toroid core with large inner diameter to kill 2 birds with one stone. Needless to say, making these custom transformers will cost a fortune.
I re-engineered and built Sansui AU111 output transformers (with separate winding for cathode feedback), and have to say it was very time consuming and very expensive enterprise. And I have no idea how all this stuff will work and sound since I'm waiting for some other parts to arrive.
Yesterday measured
frequency response - 10Hz-100KHz +/-1db (my generator with 5 Ohm output impedance provides only this range)
leakage inductance - < 20 mH
primary-secondary capacitance - 4.3 nF.

One more thing - this amplifier is very inefficient in terms of power consumption, it uses a quad (!!!) of 6550/KT88/6L6GC per channel, yet producing only 40W of output power. 2 monoblocks will be huge and heavy beasts indeed. This is only half of output power possible with classic UL design (e.g. Mullard 520). IMHO it will be even less costly to build a replica of Marantz 8/9, or Sansui AU111 (all these amps also used very complex output transformers).

PS. If you have more issues of this magazines - would you please share them? As I said before, due to the age of material there will be no copyright violation.

[jfsprague]

The last I heard, Emory Cook's own "ultimate" amp was languishing in a corner of his shop. I haven't run across an obituary, but I suspect he is no longer with us. I visited him in Connecticut about 20 years ago, but didn't ask about this amp. I bought a batch of LP's at the factory price of only $5 each. He gave me one of his demo CD's. He had done the A-D conversion using a TRS-80, presumably not in real time.
There was a follow-up article written by David Hafler (Dynaco) using a pseudonym, titled "The Post-Ultimate Amplifier", apparently as an "April Fool's" joke.