JC-2 remembered

Fred Dieckmann · 19th January 2004, 06:02 PM

It is not many products that are still being reveiwed 30 years after thier introduction.........

http://www.theabsolutesound.com/news...emember.html#4

Da5id4Vz · 20th January 2004, 08:34 PM

I read the review on the airplane at Christmas. When I fly the DC-NYC shuttle flight, they "give" us complementary magazines and "The Absolute Sound" is often available (as is IEEE Spectrum and the WSJ).

The history of equipment manufactures and designers has always fascinated me. I've always loved the story of the Ampex engineer (Ginsburg?) who had a pesky intern while working on the first video tape recorder. Just to shut the kid up he told him to solve the problem of how to modulate the video signal onto the tape. When he came back from vacation the kid, Ray Dolby, showed him that FM modulation, which they had used in instrumentation recorders, would work great with the video signal and their heliacal recording stream.

If I could ask for anything more from the review it would be more about John Curl and his experiences with Mark Levinson and others. A review of this sort becomes really interesting when it highlights many interdependent relationships.

Bas Horneman · 20th January 2004, 09:04 PM

Quote:

The history of equipment manufactures and designers has always fascinated me.

Hi love stories like that as well...so I searched the internet to find if that story is just an urban legend...

Turns out that that is indeed what happend...sort of :-)

http://severdia.com/family_tree/tony/ampex.html

Cheers,
Bas

Da5id4Vz · 20th January 2004, 09:22 PM

Also a very good story. Ive read a few accounts, this one however is the only first hand account of events I’ve seen. Thanks.

I think Mr. Ginsburg, or one of the other team members, may have published a book on their experiences at Ampex. In spite of my enthusiasm for the subject material, I've never tracked it down. I suppose an Ampex query on Amazon would get me there, but not until I get rid of the Al wiring in the new house and the painting is done.

john curl · 20th January 2004, 11:36 PM

I did some of my best work when I worked at AMPEX, as well. What a place!
A wonderful technical library. I virtually zeroxed it for the audio info. Still have many obscure zeroxes going back to the '30's.
I worked in Instrumentation, Audio, and Research/video, when I was there. We even had a digital audio recorder: 12 bits/50kHz clock.
I independently invented the complementary differential input stage and learned low noise design while working there. In 1969, I developed a complementary differential, balanced bridge, 2000W power amp with current controlled output (high Z) for a motor drive application, while working in the Research Dept. Those were the days!

Christer · 20th January 2004, 11:41 PM

Quote:

Originally posted by john curl
We even had a digital audio recorder: 12 bits/50kHz clock.

Very interesting. What year approximately was that, and was it just
an inhouse lab equipment or a commercial product?

Da5id4Vz · 20th January 2004, 11:50 PM

Was John Watkinson involved in the digital audio product? I’ve seen him speak and read a few of his books. He is another interesting Ampex person.

Unfortunately just after I got my current job, they closed the library. For a while they left it open with all the books available free to employees. Apparently Google is the corporate surrogate for a good library.

So the 2 Kw amplifier was an MDA, does that mean you never measured it for audio performance or listened to it? Must have been for something like the tractor drive or the octoplex.

woody · 21st January 2004, 02:53 AM

(( Dr. Curl)),

I realy liked your JC-3 amp, your attention to detale in the circute
that you let The Audio Amateure print back in 1981 (specifing a
RCA 2n6178 -2n6180 could this be because the RCA devices
had a higher HEF ?, a 100uf low z power supply decoupling cap
in parrell with a 5uf poly cap and a selected ps for the high freq
feedback ect. besides the dang circuite looks pretty)

Regards,

Woody

john curl · 21st January 2004, 07:56 PM

I'm getting a lot of 'off the wall' questions on this thread:
First, I worked at Ampex in the years 1967-1969.
I did not work with Watkinson.
The RCA devices had lower distortion than most roughly equivalent transistors at the time.
Please don't read too much into the JC-2 or JC-3 designs. They are 30 years old! My newer designs, at almost any price-point are better.

Bricolo · 21st January 2004, 08:23 PM

Quote:

Originally posted by john curl
My newer designs, at almost any price-point are better.

Which ones?

20th January 2004, 11:36 PM	#5
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	! I did some of my best work when I worked at AMPEX, as well. What a place! A wonderful technical library. I virtually zeroxed it for the audio info. Still have many obscure zeroxes going back to the '30's. I worked in Instrumentation, Audio, and Research/video, when I was there. We even had a digital audio recorder: 12 bits/50kHz clock. I independently invented the complementary differential input stage and learned low noise design while working there. In 1969, I developed a complementary differential, balanced bridge, 2000W power amp with current controlled output (high Z) for a motor drive application, while working in the Research Dept. Those were the days!

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20th January 2004, 08:34 PM	#2
Da5id4Vz diyAudio Member Join Date: Feb 2003 Location: lost in america...	I read the review on the airplane at Christmas. When I fly the DC-NYC shuttle flight, they "give" us complementary magazines and "The Absolute Sound" is often available (as is IEEE Spectrum and the WSJ). The history of equipment manufactures and designers has always fascinated me. I've always loved the story of the Ampex engineer (Ginsburg?) who had a pesky intern while working on the first video tape recorder. Just to shut the kid up he told him to solve the problem of how to modulate the video signal onto the tape. When he came back from vacation the kid, Ray Dolby, showed him that FM modulation, which they had used in instrumentation recorders, would work great with the video signal and their heliacal recording stream. If I could ask for anything more from the review it would be more about John Curl and his experiences with Mark Levinson and others. A review of this sort becomes really interesting when it highlights many interdependent relationships.

20th January 2004, 09:22 PM	#4
Da5id4Vz diyAudio Member Join Date: Feb 2003 Location: lost in america...	Also a very good story. Ive read a few accounts, this one however is the only first hand account of events I’ve seen. Thanks. I think Mr. Ginsburg, or one of the other team members, may have published a book on their experiences at Ampex. In spite of my enthusiasm for the subject material, I've never tracked it down. I suppose an Ampex query on Amazon would get me there, but not until I get rid of the Al wiring in the new house and the painting is done.

20th January 2004, 11:50 PM	#7
Da5id4Vz diyAudio Member Join Date: Feb 2003 Location: lost in america...	Was John Watkinson involved in the digital audio product? I’ve seen him speak and read a few of his books. He is another interesting Ampex person. Unfortunately just after I got my current job, they closed the library. For a while they left it open with all the books available free to employees. Apparently Google is the corporate surrogate for a good library. So the 2 Kw amplifier was an MDA, does that mean you never measured it for audio performance or listened to it? Must have been for something like the tractor drive or the octoplex.

21st January 2004, 02:53 AM	#8
woody diyAudio Member Join Date: Jan 2002 Location: Tyrone Ga. U.S.A.	(( Dr. Curl)), I realy liked your JC-3 amp, your attention to detale in the circute that you let The Audio Amateure print back in 1981 (specifing a RCA 2n6178 -2n6180 could this be because the RCA devices had a higher HEF ?, a 100uf low z power supply decoupling cap in parrell with a 5uf poly cap and a selected ps for the high freq feedback ect. besides the dang circuite looks pretty) Regards, Woody

21st January 2004, 07:56 PM	#9
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	I'm getting a lot of 'off the wall' questions on this thread: First, I worked at Ampex in the years 1967-1969. I did not work with Watkinson. The RCA devices had lower distortion than most roughly equivalent transistors at the time. Please don't read too much into the JC-2 or JC-3 designs. They are 30 years old! My newer designs, at almost any price-point are better.

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