John Curl's Blowtorch preamplifier part II

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I have seen some of the old Telefunken, etc. master recorders. They were beautiful in mechanical design and construction.
Now, imagine this: Take a modern Studer transport, put all discrete electronics in it, phase compensated, Class A. Use the same width tracks and tape speed as the Germans did in WW2, but with modern tape and perhaps 5 times higher bias frequency. What do you get?
 
The tapes had probably deteriorated quite a bit by the time they were transferred. I'm under the impression that some of the tapes were steel ribbon. A lot of that stuff was stored after the war in an Army warehouse in Cincinnati. I friend of mine acquired a Magnetophon machine from that facility (as well as a rocket motor from an Me 263!) and he said it was pretty awesome.

John
 
Take a modern Studer transport, put all discrete electronics in it, phase compensated, Class A. Use the same width tracks and tape speed as the Germans did in WW2, but with modern tape and perhaps 5 times higher bias frequency. What do you get?

Something which works almost as well as a $600 Fostex recorder that's not based on stone knives and bearskins.
 
John,

Here are similar circuits but with low and almost matching values.
 

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Oh man!
Having serviced Studer, Revox, Otari, Tascam, Fostex (horrible crap!), Scully, Ampex and MCI - I'm wondering why the question was even brought up?? Much of the earlier Studer was discrete. Thank god they got into IC's so they could EQ the head bumps out! Doing that the old way would have consumed ridiculous amounts of power.

Anyway John, all pre-IC electronics were "class A" until you got to power output stages. I'm pretty sure the industry had a great understanding of how to squeeze the last bit of performance out of a discrete circuit.

I've always wondered how good a machine Nakamichi would have produced had they gone after the open reel market though. Those guys really understood low noise signal amplification, perhaps more than people are generally aware.

-Chris
 
I've always wondered how good a machine Nakamichi would have produced had they gone after the open reel market though. Those guys really understood low noise signal amplification, perhaps more than people are generally aware.

They used a very elegant approach to *eliminate* ground contamination caused by the (series) power supply regulators too. And lots of Toshiba FETs!

Thanks,
Chris
 
I've always wondered how good a machine Nakamichi would have produced had they gone after the open reel market though. Those guys really understood low noise signal amplification, perhaps more than people are generally aware.

-Chris

I got to meet one of their chief analog guys in 1988. The usual response from friends when I made them a tape on my Nak. was, "What did you use, I can't make my tapes sound like this?" The tapes sounded good on even much lesser machines (I noticed the same effect with video tapes make on my prosumer Panasonic machine ~1982). Never needed Dolby, either.
 
Two different designs. One SS the other glow Fet. The response similar and low noise floors on both. The feedback was about about 20 dB in both cases. The point being one had distortion an order of magnitude higher. I would say nothing new here but both were very good. Speakers 100 dB also.

John is quite correct to use known good components and they are audible but what can we measure to move forward?

Thanks for the info, I was hoping that it was a more apples to apples comparison of different designs that yielded similar musical qualities. Although 100db is a good listening microscope! You can really hear well into the part of the music/recording that makes it sound real.

I believe measuring for differences at -100db and below to be in question; when I hear one preamp sound real and another sounding not real, the differences are well above this level. Trying to measuring this would require a bit of sideways thinking.

What is a glow FET? Never heard of this device and it doesn't seem like a typo. Thanks!

Mike
 
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