Well, Folks. Forgive me for not contributing to this thread recently. I acquired a case of food poisoning, and until this morning, have not had the 'energy' to do much.
However, a few matters have found some resolution in the meantime.
I will, indeed seek to obtain a newer distortion analyzer. It is not that these old horses that I have in the lab are not useful, but they have become inconsistent and unreliable enough (all 4) that I can't show any consistent data, except for personal use, and this can be problematic with my clients. For the record, 1 ST is mine, 2 are Demain's (Audio 1) and one is Constellation Audio's. Every one has little 'hiccups' that drive me bats. Just getting older, I guess.(both me and the ST's '-)
Demian has taken over making the measurements of my own latest phono design with his AP system, in fact.
However, I don't really want an AP for my lab at the moment. It is just too alien to my daily work to be useful, and I just don't have the time or patience to learn it. It is expensive too, AND it will not solve the dilemma of the wire test, as it has an artificially floating oscillator, that I believe is 'unnatural' in a typical audio environment.
However, Parasound has just switched over to a different analyzer, the Panasonic VP7723. Does anybody here have any experience with it? I downloaded the owners manual and I think it will fill the need, and replace the ST's in the lab. It just might answer the 'wire test' dilemma, as well.
However, a few matters have found some resolution in the meantime.
I will, indeed seek to obtain a newer distortion analyzer. It is not that these old horses that I have in the lab are not useful, but they have become inconsistent and unreliable enough (all 4) that I can't show any consistent data, except for personal use, and this can be problematic with my clients. For the record, 1 ST is mine, 2 are Demain's (Audio 1) and one is Constellation Audio's. Every one has little 'hiccups' that drive me bats. Just getting older, I guess.(both me and the ST's '-)
Demian has taken over making the measurements of my own latest phono design with his AP system, in fact.
However, I don't really want an AP for my lab at the moment. It is just too alien to my daily work to be useful, and I just don't have the time or patience to learn it. It is expensive too, AND it will not solve the dilemma of the wire test, as it has an artificially floating oscillator, that I believe is 'unnatural' in a typical audio environment.
However, Parasound has just switched over to a different analyzer, the Panasonic VP7723. Does anybody here have any experience with it? I downloaded the owners manual and I think it will fill the need, and replace the ST's in the lab. It just might answer the 'wire test' dilemma, as well.
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No experience of the Panasonic, but I do have two of the old Sound Tech's. It's a full time hobby keeping them flying right, but sometimes I've limped along using the combination of the two. (I don't do anything so important that they *must* work.)
Makes me think that a pair of these old guys between 'em has isolated grounds between oscillator and analyzer.
Much thanks,
Chris
Makes me think that a pair of these old guys between 'em has isolated grounds between oscillator and analyzer.
Much thanks,
Chris
We tried a Shibasoku before AP was around, very nice instrument that should be very cheap used. I agree that the AP can be very non-user friendly at times (you actually have to RTFM).
(*) In lew of Scott. Most probably he is messing around with SY, excusing themselves they are doing some live recordings again.
Hedonists
Sorry George it's known as full court press time, you sent your designs to fab and surprise, surprise they work. It's 24/7 work right now, not audio but good stuff. I think others have capture the gist, there is a transition from lumped to continuous models that requires judgement based on several factors. Importantly the skin effect is fractional f in nature and does not plug into a normal simulation environment.
Prism Sound DScopeIII is about $7.000 for the analog only model and would be my first choice, I find it a most excellent instrument in both perfomance and usability. It is operated from a PC, though (as is any AP -- and the software/operation of the AP27xx is major PITA, and buggy, too. The DScope is very much better there, IMHO).
For standalones, there's the Panasonics, the Stanford Research SR1, and Rhode&Schwarz UPV and older models. Except for the UPV I don't have experience with them.
For standalones, there's the Panasonics, the Stanford Research SR1, and Rhode&Schwarz UPV and older models. Except for the UPV I don't have experience with them.
In lew of Scott. Most probably he is messing around with SY, excusing themselves they are doing some live recordings again.
Hedonists
I wish.
He's working, I'm packing up house for a move.John:
I can fix you up with a Boonton 1120, no PC required and it does a lot. Everything works from front panel controls and it has pretty low distortion. (I use one daily, have 4.) Or I can lend you the Shibasoku 725 analyzer + AC12? generator (all harmonics greater than -120 dB). The Shibasokus are really rare and more expensive than they should be. But they will be immediately useable and understandable (with autoranging to boot). They also have a harmonic analyzer, up to 5X. A manual may give clues to changing the last step to 7th harmonic. But they are big, the two boxes are 10" of rack space.
We can't leave John hobbled with antiques.
I can fix you up with a Boonton 1120, no PC required and it does a lot. Everything works from front panel controls and it has pretty low distortion. (I use one daily, have 4.) Or I can lend you the Shibasoku 725 analyzer + AC12? generator (all harmonics greater than -120 dB). The Shibasokus are really rare and more expensive than they should be. But they will be immediately useable and understandable (with autoranging to boot). They also have a harmonic analyzer, up to 5X. A manual may give clues to changing the last step to 7th harmonic. But they are big, the two boxes are 10" of rack space.
We can't leave John hobbled with antiques.
On other subjects: There has been a hi end show in Newport Beach at the first of this month. I did not go, but I was 'represented' there by a number of products.
Besides phono, analog tape appears to be coming back, especially at these hi end shows. I am not really surprised, and I might outline, just as a tutorial, what analog tape reproduction entails, in future inputs.
Besides phono, analog tape appears to be coming back, especially at these hi end shows. I am not really surprised, and I might outline, just as a tutorial, what analog tape reproduction entails, in future inputs.
R&SUPV Audio Analyzer (Rohde & Schwarz USA - Products - Test & Measurement - Audio Analyzers)
They are affordable if you don't insist in the newest Version and work stand-alone.
I had an ap2712 in a mixed signal wafertester, that was NO fun.
Gerhard
Susceptibility to external influence is generally broken into two categories, when the victim has an impedance below 377 ohms, and when it is above 377 ohms. That is the free space impedance for planar wave propagation.
Above, capacitance is generally the domimant, below magnetic dominates. I believe that was also included in the Tom Van Doren link I provided earlier.
I kind of think it's more for dissipation. These puppies are getting harder and harder to keep cool, and the capacitive energy storage of the gates goes as the voltage squared. (cmos)
Hey, I'm gettin old. I read it back in the early 80's when I did chip and die stuff. And honestly, I've no idea how they measured it, nor where the return path was. I had to characterize bonds for capacitance out to .025 pf, but not inductance at that time..
Very cool. What size/speed?
jn
My AP System 2 came with a quick start guide. Useless, had to read the manual to start. Then played and reread it. Still have to look at it.
Before the System 2, I used my own dual oscillators and notch filter. By selecting components I was able to do better than 10 PPB! But as it was a very tweaked one off, it was not suitable for sharing results.
The Panasonic is popular because you can get one for under $2000!
But the freak'in issue is still what is it that you need to measure!
Affordable is relative. The cheapest R&S I have seen was in the $5K region. There is a "broken" one on eBay for $2500. And while self contained its still not John's idea of knobs.
At that price I would stretch a little further and get the SRS SR1.
The Boonton is similar to the Panasonic in operation. The Boonton generator is completely isolated and the control input is via optoisolators. Essentially the equivalent to the transformer isolation of the AP.
I though the best of the tape manufacturers had pulled the plug long ago, especially when VHS vanished.
If it were commercially practical it would not be interesting to audiophiles. If hard to find raw material is required and there are lots of moving parts its irresistible. I still don't understand the appeal of vinyl transfers of digital files when the original file is available. But phono and tape head preamps are interesting intellectual exercises.
There are - at least here in the UK - quite a few first generation master-tapes doing the rounds.
For exhibition purposes a good tape coupled with the visual impact of a big reel to reel will draw a lot of interest which - if a silver disc were playing in a transport - may well go to another exhibitor!
So, if any would be exhibitor wants a few master-tapes (at collectors' prices or a top MC cartridge or arm) for the up-coming shows, then just send me a PM!
For exhibition purposes a good tape coupled with the visual impact of a big reel to reel will draw a lot of interest which - if a silver disc were playing in a transport - may well go to another exhibitor!
So, if any would be exhibitor wants a few master-tapes (at collectors' prices or a top MC cartridge or arm) for the up-coming shows, then just send me a PM!
Not quite accurate, KBK. The story was about the late Stanley Kelly, whose first job was working in the UK's radar team in the 1940s. Yes, he was tasked with hitting copper bus bars with a hammer. But this wasn't to tune them to a transmitter, but simply to increase their conductivity to the specified figure.
Stanley was a superbly imgainative engineer. I remember him showing me how a ceramic capacitor could be very microphonic.
John Atkinson
Editor, Stereophile
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