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Old 7th May 2012, 01:04 AM   #5181
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Quote:
Originally Posted by dvv View Post
their 627, 637 and similar op amps were always damn expensive, at least in Europe. And consequently, EXTREMELY hard to find.
Not so.

$30 each in 1991, if ordered at a local electronics store.
$17 each, if ordered at Thel audio in Germany, had an ad with prices and phone number in several magazines for years, e.g. (Holger Barske's) Klang & Ton.
Couple of years later, followed by Mr Rother's Schuro mail order business, still before the www days.

(1991 US$ exchange rate, AP type)
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Old 7th May 2012, 07:23 AM   #5182
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Originally Posted by scott wurcer View Post
I might add a great period for the British film industry. They pushed the envelope. Oliver Reed, Richard Lester, Linsay Anderson, Peter Sellars etc. were involved in so many great films.
Yes, and that, as well. Lindsay Anderson made his "If", Ken Russel made "Tommy", "Women in Love", etc, even my favorite war movie (I'm generally not very fond of war movies) "Battle of Britain" was made then. As was Tony Richardson's "The Charge of the Light Brigade", and so on and on.

It was a time of an intellectual awakening, and we all so naively thought we could change the world for the better.
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Old 7th May 2012, 07:30 AM   #5183
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Originally Posted by scott wurcer View Post
I was thinking mainly of the current noise, MM really wants FET's.
I figured that was what you were getting at, Scott. I certainly won't say you're wrong or unreasonable, but if memory serves, there weren't too many Burr-Brown FET front end op amps in the economy class at the time - remember, that was published in 1990.

And quite obviously, it had to a Burr-Brown op amp, which rules everybody else out.

Personally, I'm glad they didn't. My most hated op amps are from BB, their 134 family; it has come to the point where I can actually pick them out by their sound signature inside some device say 7 or 8 times out of 10. They sound shrill and irritating to me.

Oddly enough, one of my most favorite op amps is also from BB, the venerable 2604 - now, that sounds really sweet, it stands apart quality wise, and I use it gladly.

Go figure.
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Old 7th May 2012, 07:39 AM   #5184
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Quote:
Originally Posted by jacco vermeulen View Post
Not so.

$30 each in 1991, if ordered at a local electronics store.
$17 each, if ordered at Thel audio in Germany, had an ad with prices and phone number in several magazines for years, e.g. (Holger Barske's) Klang & Ton.
Couple of years later, followed by Mr Rother's Schuro mail order business, still before the www days.

(1991 US$ exchange rate, AP type)
$30 is cheap to you?

And remember, $1 was worth more then than it is today. And we had less of them then.

Also, I said "hard" to find, not "impossible".

What I was getting at is the fact that when talking to Americans, you need to point out that they pay for these parts at worst 1/2 of what we do, more typically 1/3 or even 1/4.

The same is true of you, for example. At the time, that may have been a viable option for you, but not for many of us - on its way from say Germany to me, its price would go up by 10% customs duties and 18% for VAT, or simply multiply its cost plus shipping by 1.29. So, what cost $30 in Germany would cost me say $35 with shipping, and ultimately $45 at home.

That's DAMN expensive even today, let alone those days. To me, at least.
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Old 7th May 2012, 07:59 AM   #5185
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Originally Posted by bcarso View Post
Modest-power tube amps and horns. Check out the history of Western Electric, among others. My refs are buried in storage or I could be more specific.

One problem with all film optical audio tracks, even relatively recent ones: they wear out in a hurry. That's one of the reasons DTS is a continuing success, supplying audio that merely has to be synchronized to the film. And the "flywheel effect" of their servo system is significant, so some fairly large dropouts can be readily accomodated.

Thanks for that . Lee de Forest started working on it about 1923 . Kellogg of Corn Flakes fame also ( Paul Voigt ) . My feeling is all hi fi is dirived from cinema . The man from Star Trek may be related .
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Old 7th May 2012, 08:47 AM   #5186
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Default Booster

Click the image to open in full size.

I took the liberty of lifting this from basic amp design thread running now item 31

This idea is often in text books . I have tried it with feed forward cap . Anyone ever succeeded with this as a booster ? 51 R is the usual text book feed forward .

Last edited by nigel pearson; 7th May 2012 at 09:01 AM.
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Old 7th May 2012, 11:29 AM   #5187
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Originally Posted by nigel pearson View Post
Click the image to open in full size.

I took the liberty of lifting this from basic amp design thread running now item 31

This idea is often in text books . I have tried it with feed forward cap . Anyone ever succeeded with this as a booster ? 51 R is the usual text book feed forward .
What liberty? Everything posted here by me at least is public domain.

Question - does it HAVE to be a single line power supply?
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Old 7th May 2012, 11:55 AM   #5188
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Originally Posted by dvv View Post
... remember, that was published in 1990.
...
There was an earlier version with two OPA37s and passive RIAA published
in a now defunct austrian electronics magazine in the 80s. (I know because
that´s what I used at that time). The OPA627, 637, 606 and the likes did not exist yet.
Ronald Reagan was president in the US back then and it was not allowed
to sell such stuff to the eastern block. That´s probably why Burr Brown and
similar companies had representatives in Vienna ;-) (The OPA37s I have are "military grade" because these where the only ones they had in stock...)
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Old 7th May 2012, 12:28 PM   #5189
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Quote:
Originally Posted by dvv View Post
What liberty? Everything posted here by me at least is public domain.

Question - does it HAVE to be a single line power supply?
Hi D V V . It is split supply but that's his idea not mine . I was thinking use feed forward but not global feedback ( one can use it naturally as belt and braces ) . Here is a good version of feed-forward .

Single darlington line preamp.
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Old 7th May 2012, 02:02 PM   #5190
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That circuit is a 'dog' that was first used in the Studer A80 line amp, and measures with LOTS of Xover distortion. The normal R5 is 100 ohms. I made a 'current dumping' version of it that measured 10 times better, and offered it to Studer, in fact Willi, himself, in 1975, but they ignored my measurements, that were backed up with Polaroid pictures of the distortion.
Haven't any of you tried a good, clean, but easy enough to make, discrete design for serious recording?
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