Retrieved from this perhaps dodgy lot of material - http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/contents.htm ...
If it's the same Jim le Surf that I think it was,MIT explains a lot.
Secondly, it's one thing being an electronics engineer and another bring a solid state physicist working in a fab. There are few that straddle both fields confidently and knowledgeably. Le Surf I doubt is one of them.
As Scott has pointed out, the band gap reference would not be possible without accurate and repeatable v/I characterization.
Secondly, it's one thing being an electronics engineer and another bring a solid state physicist working in a fab. There are few that straddle both fields confidently and knowledgeably. Le Surf I doubt is one of them.
As Scott has pointed out, the band gap reference would not be possible without accurate and repeatable v/I characterization.
No need to get too serious about all this - just a light-hearted pointing to the fact that things can be looked at at simple levels, or to a depth and complexity almost without bounds. It's just been my experience that taking the latter approach yields real, audible benefits in the audio game - which runs counter to what many believe ...
What are you complaining about, I see you're doing well from your latest preamp effort. I read it cover to cover yesterday, and I am impressed indeed by the amount of sane thinking behind it. The exact opposite to art for art's sake, very straight down to business. Kudos Andrew.
I do have a few questions, but I'll get in touch via the supplied home link rather than pollute this thread.
The reason why Studer stood tall in any company in Europe, his only near equivalents in other subfields of recording being another two Swiss companies, Kudelski's Nagra and Stellavox, was because they were supremely reliable (mechanics to die for) and were backed up by a service network second to none, in addition to being a "home grown" company.
Because I agree with your comment regarding sonics, I have owned a reVox integrated amp and now a reVox tuner, but never a tape machine. Instead, I started out with a German made Uher portable (Report Stereo) and continued again with an Uher Royal de Luxe (at the time, their top model), finishing up with a 60 lb(28 kg Philips N4530 monster. They all sounded better to me than reVox A77 and B77.
In my admittedly limited experience with professopnal studios, MCI beat Studer on sound basis, which is why Radio Belgrade, a bastion of Studer, bought the MCI for their presitigious Studio 5. Others used Telefunken machines, which also sounded better to me.
And it goes further. I had their A740 professional amp with me for a while. I bet 99% of us here would drool and slobber over the mechanical construction and the general approach, and it was very load tolerant (3 pairs of 250W Motorola power devices per side in a nominally 100/175W into 8/4 Ohm amp), but somehow, its sound was lacking. Precise, stable, detailed but lacking emotion.
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In professional Analog recording studios, the two main providers of tape recorders, (both stereo and multitracks) were Ampex and Studer.
The main difference with their multitracks was about the magnetic heads.
While Studer used different magnetic head, different for recording (large gap) and reproducing (thin gap), Ampex used the same heads in the two positions.
While the Studer was a better performer, due to those better heads, i used to prefer the Ampex.
Let me explain why.
Most of the recording sessions are made in 'playback'. Means you add instruments tracks on previously recorded ones. To get them synchronized, you are obliged to *read* the previous recorded ones with the recording head. With the Studer, it produced a very degraded sound, for the sync 'play back'. It means you were building your new sounds on a degraded signal, not ideal to get a well balanced result. You just recover perfect sound during the mixing session, reading on the playhead. Often strange surprises !
While, on the Ampex, the playback was very close to what you will have during the mixing session, reading everything on the playhead.
dvv, i don't agree with you about Stellavox. Looking good, some kind of copy of the Nagra, but very fragile. By example, the magnetic heads were very subject to constant misalignment (base too thin) . The national french TV station (FR3), with production centers in all the regions of the country used a lot of them. They were always in the maintenance centers, and the guys in charge of the maintenance were always protesting against this choice: "Why the hell did-they had not buy Nagras, like everybody else in France ? "
Nagra, on the contrary was incredibly solid and good performers.
The main difference with their multitracks was about the magnetic heads.
While Studer used different magnetic head, different for recording (large gap) and reproducing (thin gap), Ampex used the same heads in the two positions.
While the Studer was a better performer, due to those better heads, i used to prefer the Ampex.
Let me explain why.
Most of the recording sessions are made in 'playback'. Means you add instruments tracks on previously recorded ones. To get them synchronized, you are obliged to *read* the previous recorded ones with the recording head. With the Studer, it produced a very degraded sound, for the sync 'play back'. It means you were building your new sounds on a degraded signal, not ideal to get a well balanced result. You just recover perfect sound during the mixing session, reading on the playhead. Often strange surprises !
While, on the Ampex, the playback was very close to what you will have during the mixing session, reading everything on the playhead.
dvv, i don't agree with you about Stellavox. Looking good, some kind of copy of the Nagra, but very fragile. By example, the magnetic heads were very subject to constant misalignment (base too thin) . The national french TV station (FR3), with production centers in all the regions of the country used a lot of them. They were always in the maintenance centers, and the guys in charge of the maintenance were always protesting against this choice: "Why the hell did-they had not buy Nagras, like everybody else in France ? "
Nagra, on the contrary was incredibly solid and good performers.
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The Nagra 4S is probably the most impressive and beautiful piece of technology some can see in his life. Inside and outside. I had never seen equivalent, may-be in aviation or space crafts ?
It used the best parts some can find at this time, was designed like a watch, build like a tank, everything perfectly handcrafted with military grade components.
A master piece of the 20th century.
You can still get one for ~ 3000€ ;-)
It used the best parts some can find at this time, was designed like a watch, build like a tank, everything perfectly handcrafted with military grade components.
A master piece of the 20th century.
You can still get one for ~ 3000€ ;-)
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Howdy, did you pop out for a smoke or something ... ?
Very easy not to get lost ... know what you're after in terms of SQ, as far as the ears are concerned - they must always be the final arbiters as to whether real advancement is taking place...
Not really Frank, but on the plus side, I am now 4 days away from kicking out the damn builders, hopefully for good. Which means I get to wait for the New Year in a totally reworked apartment, from a in new in apartment power distribution board (I rerworked the floor distribution to my apartment connection using 6 mm2 wiring 11 years ago), brand new wiring using 2.5 mm2 triple wire connections, double and triple 3 wire distribution so I can assign almost anything to almost any phase, to new paint jobs all over the place.
As for getting lost on the way, it's actually easy to do. You start with a theory and try to boil it down simple facts, just one wrong turn in one place could throw you way off the track.
I've actually seen and touched a Stellavox tape deck only once in my life, unfortunately I haven't used it, so I cannot comment on its sound and/or build quality. However, it was the considered to be the only worthwhile competitor of Nagra.
Both had been expelled from most radio studios by that time anyway, and it was Uher's Report series which did that. They were not of similar sound quality, or the build, but were exceptionally portable, had a long run on one battery charge and did offer 4 speeds, 3 heads with full monitoring using the inbuilt speaker, and most important, they cost like 10% of what Nagra cost. To gather comments from people on the street, it was way more than most radio stations really needed.
But even this didn't last long, as there appeared even smaller cassette recorders from Sony, Panasonic et al., so in the end Uher produced their CR240 cassette deck, which was sturidier than any other competitor. I saw and heard it in action during my stay in USA in March-April 1991.
Today, I imagine fully digital devices, recording in RAM, will have taken over completely, these days even cell phones can be beefed up with 16 GB cards which are really cheap.
Even if I refuse to rid myself of my Sony TC-K 808 ES cassette deck, although I sold off my Philips N4520 open reel deck. No sense any more, yes it does great music, but finding new tapes is a chore, and a very expensive one at that. The Sony is a fine cassette deck, very wll built like most models from their prestige ES series, has 3 heads and 3 motors, Dolby B and C, HX headroom extensions, etc.
I am one of them. Well, the confident part anyway..
I used to be able to deal with the physics aspect of semiconductors, but lost most of that ability at least 25 years ago..
Now, I'll ask the more knowledgeable people I've met on this forum.
jn
Calling Is a "fudge" factor is rather starting off on the wrong foot. Not that what was said is wrong just that yes every diode is different unlike the fact that every mass has the same escape velocity. OTHO the diode equation can be reduced to a complex formula and the parameters measured, it's just more work.
Agreed. It sets up the belief that semiconductor physics is not well understood by those who do it for a living.
jn
Folks, I am not interested in comparing different (now obsolete) analog recorders, although I worked with most of them decades ago. In any case, we found, even 40 years ago, that Studers could be improved, that MCI electronics was just a copy of the Ampex AG-440, that Stellavox was delicate and added a slight edge to the recording, while Nagra sounded softer, yet not perfect. We were searching for more quality, something that would be comparable to direct disc recording. This is where we found our sonic challenge.
Regarding the OPS of anything -- including IC amps ---- anyone done work on furthing the reduction of switching distortion in AB amps? This is an interesting way which I wonder has it been used/refined somewhere..... Oct 1980 AES preprint 1683 (D-4) by G.Dodson of JBL. "Quasi-Class A/Improved Class AB Bias Loop"
View attachment OPS Bias.pdf
THx-RNMarsh
View attachment OPS Bias.pdf
THx-RNMarsh
Looks like yet another spin on the Blesser circuit. BTW I consider the CFP part of this general family of circuits involving tight local feedback around only a couple of devices.
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Does that include one or more of many sliding bias schemes, Richard? If so, I can dig up for you a particular solution as used by Nikko many years ago, which I unashamedly swiped from them and tried it out just for the kick of it. It seemed to work very well indeed. I think I also have the same idea but from Technics, probably derived from the JVC original idea, because by then Matsushita had already bought out JVC.
I must add I did not experiment with it much, I simply took it as is from them. I suppose that was a mistake, but there's still time to correct it.
If you're interested, just let me know.
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I don't know is it for AB. It's from Scotch attachment in other thread. I think !
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