Twenty years or so when these regulators were introduced Evans claimed that the Lithos 6 pre regulator in front of the 7 significantly improved the latter's performance. Does that seem to be true from what you can see?
How does this circuit combo compare to a Jung-Didden Super Regulator? Would a Super Regulator benefit from a Lithos 6-style pre-regulator?
How does this circuit combo compare to a Jung-Didden Super Regulator? Would a Super Regulator benefit from a Lithos 6-style pre-regulator?
The generic name for those is Foam-in-Place Systems. Apparently you can buy the stuff in bags that mold to the item. Example: https://www.uline.ca/BL_7708/Instapak-Quick-Room-Temperature
Tom
Cascading regulators sums their power supply rejection ratios (PSRR). So, if the PSRR of a given regulator is, say, 60dB, cascading two of them, in theory, gives a net PSRR of 120dB. In practice, however, at some degree of doing that, parasitic coupling on the PCB must start to degrade the improvement. Long chain cascading also probably requires careful attention to the dynamic stability of the chain. I’ve not experimented with such a chain, though.
The bipolar Lithos regulators could, I think, be fairly considered a super-regulator implementation. It’s closer to a Sulzer type than to a Jung-Didden type. The most uniquely identifying feature of a Jung-Didden, to me, is its boot-strapping. Which helps to shield the voltage-reference, and the error op-amp from incoming supply noise. Improving the regulator’s PSRR.
Last edited:
Well, Mike Sulzer's 1980-81 regulators were not too shabby. They performed well in the comparisons that Walt and Jan did in 1995 as I recall. It is clear that over the decades they did extraordinary work to advance the design beyond the Sulzer design.
Evans didn't just cascade two regulators... he evidently designed the one to precede the other so that might qualify as an attempt to apply "careful attention to the dynamic stability of the chain"... amongst other things.
Evans didn't just cascade two regulators... he evidently designed the one to precede the other so that might qualify as an attempt to apply "careful attention to the dynamic stability of the chain"... amongst other things.
Please don't enter a spelling bee.
I won't press too hard on the details because now I'm only basing my argument on what I remember from the video, but wasn't Mark only selling his method of how to trace and back-engineer?
And let's for argument sake say that Mark was trying to sell the schematics then I have a hard time seeing how the schematics could even infringe on his copyright . A partly discrete bipolar series regulator isn't really anything remarkable and neither is cascaded linear regulators.
- C
If you are using decent opamps, these fancy regulators are just fluff. They bring zero to the party when the opamp has 100 dB PSRR. If the supply rail ripple from the regulator output using say a 7815 is 30 mV worst case it’s a lot, and decoupling says it’s going to be at LF. Further, on a preamp, there are no big load changes.
Better to spend the time and effort on good layout, metal housing, high quality transformers etc.
Well, he hasn't yet...........
He's obviously trying to stop the spread of information on his "design" and poor workmanship.
True, but not all op-amps feature such good PSRR across the audio band, especially against the negative supply, where I’ve seen PSRR spec’d. as low as 40dB for one current production op-amp. The PSRR is always best at rejecting power line frequencies and its harmonics, not wide-band noise, hash and signal stage crosstalk. Also, of course, not all gain paths utilize op-amps, whether good or bad performing. Simple discrete common-emitter/source gain stages, as you know, feature a 0dB PSRR, and very low PSRR if utilizing a triode common-cathode stage. Those circumstances make, so-called, super-regulators more useful. Though, with a great disparity in relative circuit complexity between the regulator and the gain stage it is supplying.
Last edited:
I don't remember that, but the copyright only extends to the actual publication.
For instance, I have copyright to a schematic in Linear Audio. You're not allowed to copy it and show it without my agreement.
And you cannot publish a Linear Audio article without my agreement.
But nothing stops you from re-drawing that circuit and publish it. In fact, you now hold copyright to your drawing and I cannot reproduce it without your agreement.
It has nothing to do with being new or old or whatever. That's a patent, and basically a patent is nothing more than the right to sue anybody who uses it.
But if the guy you sue has deeper pockets than you, don't - you'll lose and might have to pay all cost.
So if someone shows a redrawn circuit from a teardown, I don't think that is a copyright violation. It would be if it was a screen shot of the actual unit documentation. So if he summons the guy to take down the redrawn circuit, he's bluffing.
It would also not be a patent violation, because you are free to publish anything from a patent. You just can't build it yourself without an agreement.
Jan
@jan.didden
perhaps it was diyaudio who decided not to keep links to PDFs of articles that should have been purchased from your magazine rather than given away free here.
thanks for the elaboration on copyright.
perhaps it was diyaudio who decided not to keep links to PDFs of articles that should have been purchased from your magazine rather than given away free here.
thanks for the elaboration on copyright.
i did this once with a kit phono amp, decided to use 7815/7915 first and then down to 12 or whatever it was with another set.
It made zero difference 😀
PSSR isn't an issue anyway on a pre or phono amp, if it's important then batteries with offline charging is reasonably cheap and easy.
What is interesting is that it seems YouTube takes down material simply upon the "claim" of copyright infringement. "This video is no longer available due to a copyright claim by Tom Evans".
Was Tom Evans required to substantiate this "claim" to YouTube? Doesn't YouTube have lawyers? Is YouTube that cowardly... or entirely motivated by profit? What motivated their actions?
With all of the workarounds, patents and copywriting seem to be of little consequence. That is nothing new I suppose since the invention of fire.
@Hierfi, from what I’ve heard about YouTube regarding entertainment industry infringement claims, it doesn’t take much to get them to block a video. It seems that the mere whiff of copyright infringement is enough to have them take action. No doubt, they’re wisely following the advice of their legal dept. to quickly avoid getting held even liable by association, in any copyright infringement suit. After all, having, by far, the deepest pockets of any party defending a lawsuit, they would become the prime target.
The important thing here is to consider how much noise is actually on the rails in a small signal amplifier stage which is what a line level preamp is. The load is virtually constant so you are not getting any load transients and the regulator input ripple suppression is typically 50-70 dB (see below). Its relatively cheap and easy to build a preamp supply with 200mV ripple at 500mA load on the raw DC supply. I was pathological about wideband noise and on some earlier preamps decoupled each and every opamp with a 22 Ohm + 220uF capacitor. Later when I got my QA401 I decided to measure it and set an opamp up with a gain of about 20x and looked at the output noise floor with the + input to the opamp shorted. There was no difference, so I ended up ditching the HF filter on the opamp supplies so don't use them any more.
I have used an LM4562 to build a +-10mA front-end power supply running off 7815 regulated rails. The wide band noise output of the regulator is 7nV (~50pV/rt Hz). It's much better to solve the 0 dB PSRR problems you mention like this than to try to build ultra regulators designed to feed the whole circuit. The problem with power supplies is there's a whole folklore around them in the same way there is around feedback or tube amps. The end result is you get $62 000 phono amps with a separate power supply box that probably weights 30 lbs.
LM4562 PSRR:
OPA1641/2 PSRR - not as good, but quite adequate (~50 dB on V+ at 20 kHz)
YMMV
Last edited:
If I was Youtube I might too... though this doesn't prevent questioning the extent of their cowardice...
- Status
- Not open for further replies.