Well, I was asked, and I stated my reasons WHY I did not have an LED. I got 'jumped on', stating that I did NOT know electronics design, that I had the WRONG friends, and that it would have been relatively easy for me to put in an LED, and the only reason I didn't do it was to make some sort of 'fashion' statement.
I believe that I have shown otherwise.
I believe that I have shown otherwise.
PMA has often brought forward an OVERSIGHT that Bob and I made with the back panel.
It can be shown that using the chassis as a primary ground, is possible, but not necessarily the best way to do things. For example, the Levinson JC-2 preamp was wired that way, as the RCA jacks were actually screwed into the back chassis. From an RFI, point of view, this probably worked fairly well.
For the Vendetta, however, the (much improved) RCA jacks were floated off the chassis, and the 2 input wires went direct to the closest place to make a clean connection. The chassis was connected separately at one point.
The Blowtorch created another dilemma. The back chassis was too thick to easily mount the RCA jacks, so we mounted them on a Teflon back-plate and drilled holes in the rear chassis to allow the RCA jacks to be addressed. This could let in RFI, but how much, if and when, is it important ?
It must be remembered that 5 of 6 sides of the chassis are pretty much RF proof, as they have no holes or slots at all. But the back panel only has partial shielding, especially at very high RF or microwave frequencies. What should we have done differently?
It can be shown that using the chassis as a primary ground, is possible, but not necessarily the best way to do things. For example, the Levinson JC-2 preamp was wired that way, as the RCA jacks were actually screwed into the back chassis. From an RFI, point of view, this probably worked fairly well.
For the Vendetta, however, the (much improved) RCA jacks were floated off the chassis, and the 2 input wires went direct to the closest place to make a clean connection. The chassis was connected separately at one point.
The Blowtorch created another dilemma. The back chassis was too thick to easily mount the RCA jacks, so we mounted them on a Teflon back-plate and drilled holes in the rear chassis to allow the RCA jacks to be addressed. This could let in RFI, but how much, if and when, is it important ?
It must be remembered that 5 of 6 sides of the chassis are pretty much RF proof, as they have no holes or slots at all. But the back panel only has partial shielding, especially at very high RF or microwave frequencies. What should we have done differently?
Nothing, really, unless someone has their system set up under a microwave tower or likes to talk on their cell phone while listening to music critically. I also have my preamps' grounding set up that way, and they're dead quiet. Never had a single RFI issue in the half dozen places I've lived nor with the half dozen versions of my phono and line amp stages built as you describe.
Oh, and they all had LED indicators.
Quote: "Moreover, the SCP-2 (Vendetta Research) was by far the quietest phonostage ever produced." Bob Harley editor, TAS May/June 2012, p.44.
Think you can beat that, SY?
That is an INDEPENDENT opinion from someone I know even less than I even know you.
And I have NOT produced one for the last 20 years.
By the way, my NEW stuff is as good or better (pp.94-98 ibid), as was the CTC Blowtorch.
Think you can beat that, SY?
That is an INDEPENDENT opinion from someone I know even less than I even know you.
And I have NOT produced one for the last 20 years.
By the way, my NEW stuff is as good or better (pp.94-98 ibid), as was the CTC Blowtorch.
If I had to, sure, since I'm not limited by fashion. My goal for my last two phono preamp designs was not to produce something that gave the best possible measurement on a lab bench, but one whose noise was within 1dB of the inherent thermal noise of the cartridge. It may not be as quiet with a shorted input as the Vendetta, but with a cartridge hooked up, you'd be hard pressed to hear any difference in noise performance. It's certainly one of the quietest tube phono stages out there.
Anyway, since I was agreeing with your approach, I'm not sure why that outburst.
Anyway, since I was agreeing with your approach, I'm not sure why that outburst.
Where, SY, does this 'fashion' come from? I have for the last 40+ years, tried to make the best designs possible. I STARTED with bipolar transistors, steel chassis, ceramic coupling caps, carbon resistors, etc., etc.. I moved AWAY from these approaches as I learned more and more.
Everyone, think about an F-1 race car. Would the design that you thought was 'best' 40 years ago, still be what you would 'race' with today. Perhaps, you would have learned a few things, found a few mistakes or dead ends, and moved to make something even more 'special'.
Everyone, think about an F-1 race car. Would the design that you thought was 'best' 40 years ago, still be what you would 'race' with today. Perhaps, you would have learned a few things, found a few mistakes or dead ends, and moved to make something even more 'special'.
Yes, I have, great stuff. There's some really excellent stuff from the nuclear researchers as well (e.g., Elmore and Sands). Scott cited a really nice paper from Rev Sci Inst a few days ago which allows voltage noise density limited devices like tubes and FETs to achieve much lower noise levels, but probably not useful for impressing the technical ignorami who write for TAS and the like and "listen" with their eyes and preconceptions.
In any case, when you get to the point where the cartridge Johnson noise is the limiting factor, you've done your job.
In any case, when you get to the point where the cartridge Johnson noise is the limiting factor, you've done your job.
"Special" in what respect?
With an F1 race car, its meaningful performance is easily determined.
But I don't see that this relates to high end audio where no one seems to be able to demonstrate a design being "better" in any meaningful sense beyond marketing. Would your latest design be able to be audibly distinguished from your previous designs using bipolar transistors, steel chassis, ceramic coupling caps, carbon resistors, etc. etc.?
So-called "high end audio" seems to be about little more than creating Bogey Men to scare people and get them to obsess over meaningless things and offering solutions in search of problems.
se
It depends.
IMHO, the blue LEDs are out. Bad taste.
I associate blue LEDs these days with chinese gear, computer gadgets, PC tower enclosures and pimped-up cars.
Yuck!
It's about time designers go back and play with other colors.
If absolutely needed to be, what about 2mm LEDs, flush mounted and operating at minimum current as not to be too bright to distract from listening in darkened room?
On the other hand, John, if "no LEDs" is your design philosophy, so be it. If your customers aren't complainig, everything is fine, your products speak for themselves. What other EEs are saying is irrelevant.
Best,
Attachments
Where? Your main point seemed to be DC imbalance in a semi-floating power supply, which only raised the issue of why the supply is semi-floating. A subsidiary point was the apparent need for two series resistors, for unstated reasons. There was also a suggestion that the forward-biased LED might generate RF problems (it won't, but the wires might).john curl said:
If this is how you explain something, what would it look like if you decided instead to be deliberately vague, mysterious and superior?
Yes, I know of Kingbright and several others who make that style LED. But Panasonic made an "amber" one that looked much better than the "yellow" that the others offer.
Thought perhaps the one you showed was from another maker of those that I wasn't already aware of to see if I could find the Panasonic "amber."
se
That's the high output version. The one I want is the normal one.
LN422YPH Panasonic - SSG | P546-ND | DigiKey
Only one in stock and they ain't gettin' no' mo'.
se
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