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Are you really fine with IC voltage regulators ?
Are you really fine with IC voltage regulators ?
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Old 3rd September 2020, 02:57 PM   #21
Mark Johnson is offline Mark Johnson  United States
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Are you really fine with IC voltage regulators ?
I always thought that John Curl's approach to voltage regulation for preamp circuits, was brilliant. However it does possess characteristics which some people really don't like
1. It requires a higher "raw DC" input voltage. In most cases this means a different power transformer with a higher AC output voltage. So instead of a [2 x 15VAC , 10VA] transformer, Curl's regulator needs a [2 x 18VAC , 10VA] transformer. If you are familiar with the line of transformers made by Antek, this means you buy "AN-0118" instead of "AN-0115". They are the same size and the same price.

2. It uses at least 2x as many electronic components and at least 2x as much area on a printed circuit board. These additional components also add to the parts cost of the final audio equipment

3. It contains twice as many carefully designed circuits and offers twice as many opportunities for the assembler or the copy-and-paste "re-designer" to make mistakes which degrade the sonics

4. It requires you to know in advance, the total current drawn from the regulated supply voltage, by all loads.

5. It dissipates more heat inside the chassis and draws more current from the AC mains
Curl's idea is to connect two, carefully chosen, voltage regulators in series. RawDC ---> Regulator_1 ---> Regulator_2 ---> DC Output

Regulator_1 is a plain ordinary series regulator made from a low cost IC: LM317 or LM337. Its job, its only job, is to reduce mains ripple by 66dB.

Regulator_2 is a shunt mode regulator, built with discrete transistors. It consists of a constant current source, driving an active constant voltage shunt.

Eureka! Notice that Regulator_2 draws a constant current from Regulator_1. Another way to say this is: Regulator_1 sees a constant load current. The ideal and perfect arrangement for best operation of Regulator_1.

Eureka! Notice that Regulator_1 provides a constant output voltage. Another way to say this is: Regulator_2 sees a constant input voltage. The ideal and perfect arrangement for best operation of Regulator_2.

Eureka! Notice that the cascade has wonderful line rejection (aka PSRR aka ripple rejection). 66dB from Regulator_1 and plenty more from Regulator_2.

Eureka! Notice that the audio circuits (the "loads" upon the regulator) are fed from a shunt regulator, so they get all the benefits of shunt regulation that Walt Jung and many other researchers have praised.

My conclusion: I like it. I think it's brilliant.


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Old 3rd September 2020, 03:05 PM   #22
edbarx is offline edbarx  Europe
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Quote:
Originally Posted by dreamth
anything between 5.1 and 6.2 will do the job.
they used CRD in the past for zener regulation:
Thanks for the information. It means, I was mistaken. Probably, I learnt it from a book written by F.A. Wilson when I was 16 years old many many moons ago. The series was "Elements of Electronics". The intended readers for this series were 'inquisitive adolescents asking awkward questions'.
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Old 3rd September 2020, 03:35 PM   #23
dreamth is offline dreamth  Romania
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Quote:
Originally Posted by Mark Johnson View Post
I always thought that John Curl's approach Curl's idea is to connect two, carefully chosen, voltage regulators in series. RawDC ---> Regulator_1 ---> Regulator_2 ---> DC Output
Curl or Jung Didden?
The previous post had some parts of a schematic that used a +-20v dc series reglator after another series +-24v reglator in order to spply a phono preamp...
i understand the beneffits of Jung Didden reg yet it looks like they are made for circuits with no PSRR of their own...

some very advanced phono preamps used some of these circuits, but their lowest noise stages had it all sorted out straight from their own internal current sorces...
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Old 3rd September 2020, 04:04 PM   #24
Pano is offline Pano  United States
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Are you really fine with IC voltage regulators ?
In the listening tests published in Linear Audio, the LT1963A/LT3015 did very well indeed. In fact ranked near the top.
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Old 3rd September 2020, 04:10 PM   #25
dreamth is offline dreamth  Romania
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i have a successful semi-professional recording soundcard using Linear technology switching regulators for +-12v of all dacs and op-amps inside and the switching chip is actually designed in the 90's while the soundcard was made in 2016, best sales on Amazon for a sondcard in 2017 and still in production for a higher price than in 2017 when i purchessed mine...Audient ID22
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Old 3rd September 2020, 04:25 PM   #26
wiseoldtech is offline wiseoldtech  United States
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I see no benefit to going crazy and complex over power supply designs, particularly to power line-level circuits, and RF stages.

A simple cap-multiplier filter before an LMxxxx regulator, and voila, a nice, clean, stable, noise-free DC output is the result.
I've been building supplies like this for years, with no ill effects.
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Old 3rd September 2020, 04:32 PM   #27
ticknpop is offline ticknpop  Canada
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Are you really fine with IC voltage regulators ?
Mark,

In addition to Mark’s description in his best products JC also uses carefully constructed cap multipliers at the local load with selected low noise Toshiba jfets for phono stages or Hitachi mosfets for line level (and resistors matched to the idss of the jfet) and film caps (usually Relcaps) to bypass the output to load. Non magnetic components are preferred.
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Old 3rd September 2020, 04:40 PM   #28
dreamth is offline dreamth  Romania
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Marantz CD-5000 a classic among good old days cd-players have no regulator at all for the analogue circits just 220ohm-220uf capacitors...
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Old 3rd September 2020, 04:47 PM   #29
dreamth is offline dreamth  Romania
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if yo don't like having no regulator at all yo can simply go with the L version of 78/79xx regulators and an additional rc filter for the most sensitive parts.OP-amps have their own PSRR which isn't really bad most of the times.
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Old 3rd September 2020, 05:25 PM   #30
jjasniew is offline jjasniew  United States
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Are you really fine with IC voltage regulators ?
30 years ago, in another audio forum where you used a VT100 terminal to participate, we discussed such power supply strategies. One guy said he deliberately injected pulses on the power supply lines to test the PSRR of a popular audio opamp; said he couldnt hear a thing until the pulse was raised to "ridiculous" levels. They also were designing and discussing discrete shunt regulators at the time.

Unsure why no one uses a power op amp for a linear regulated voltage. At Intel, we had these to-220 devices with an amp continuous output, 1 GHz bandwidth. That could have some flat impedance looking back into it - at least through the audio range.

Since it's an amplifier, it should have both series (source current) and shunt (sink current) capabilities. (I forgot to take any with me, when they threw out all the entire engineering component stock from the power supply lab as they let us all go, then closed the place for good)
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