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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, 09:21 AM   #1
ginetto61 is offline ginetto61  Italy
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Are you really fine with IC voltage regulators ?
Default Are you really fine with IC voltage regulators ?

Hi ! looking for some information about dual voltage power supplies for preamps in an interview with the Conrad Johnson designer he states that they prefer to realize voltage regulators with discrete parts and not using single chip voltage regulators. In their opinion they can have an impact on the sound ... and not for the good.
Looking then at some preamps schematic i see that in the late '70s and early '80s many of the TOTL solid state preamps actually used voltage regulators made out of discrete parts.
I guess the reason was that this IC regulators were not available ?
They are clearly handy ... but are they also completely fine to use in preamps ?
i would like to get some opinions ... i have a feeling that i was looking at the wrong part of the story ... the preamp circuit ... instead the secret of good sound could lie in the power supply design and construction
I am attaching one schematic just to explain what i have in mind ... more or less
Attached Images
File Type: jpg regulated dual power supply.JPG (99.5 KB, 1276 views)
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Old 3rd September 2020, 09:28 AM   #2
dreamth is offline dreamth  Romania
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I think you read too much of the "esoteric audio" press instead of good engineering books.
There's really high end audio equipment using op-amps in regulators of all sorts.You can't use them easily in high voltage regulators, but there are a lot of good engineers who don't give a damn on what Conrad Johnson said...By the way...in the late 70's and early 80's there weren't many op-amps on the market, if any...now we have high voltage op-amps too...IC regulators have some op-amps inside...you can use external op-amps too. I used TL783c with valve preamplifiers with no problem:
Gyraf Audio - G9 DIY
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File Type: png gyraf gyratecreg.png (139.5 KB, 1271 views)

Last edited by dreamth; 3rd September 2020 at 09:35 AM.
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Old 3rd September 2020, 09:30 AM   #3
Vovk Z is offline Vovk Z  Ukraine
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Objectively if we'll look at some parameters we can easy measure (filtering and regulation effect) then IC regulators (like 78xx or LM317) are of cause much (order or two or three orders) better then simple Zener regulators. But there are other parameters like output impedance (frequency and load dependent) and others which are harder to take into account when design (they are non-linear etc).
Possibly unfortunately bad designed IC regulators may worsen the sound I don't know.
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Old 3rd September 2020, 10:23 AM   #4
dotneck335 is offline dotneck335  United States
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I think if you'll look through this thread, you'll find that Elvee has come up with a brilliant solution for taming three-pin regulators (LM317/337). It performs nearly as well as the hot-shot regulators found elsewhere and it is easily RETRO-FITTABLE to existing designs:
D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.
It features a 30 db improvement over the stock LM317/337 design in terms of noise ripple rejection, and output impedance.
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Old 3rd September 2020, 10:31 AM   #5
dreamth is offline dreamth  Romania
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Yeah...technics style , which can be improved further by adding a zenner to the faster lm 7805
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File Type: png technicsregoriginal.png (78.9 KB, 1233 views)
File Type: png technregmod.png (83.0 KB, 1205 views)

Last edited by dreamth; 3rd September 2020 at 10:36 AM.
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Old 3rd September 2020, 10:44 AM   #6
ginetto61 is offline ginetto61  Italy
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Are you really fine with IC voltage regulators ?
Quote:
Originally Posted by dotneck335 View Post
I think if you'll look through this thread, you'll find that Elvee has come up with a brilliant solution for taming three-pin regulators (LM317/337). It performs nearly as well as the hot-shot regulators found elsewhere and it is easily RETRO-FITTABLE to existing designs:...
Thanks ! what makes me think is the following comment
Quote:
Summary: low noise voltage regulator achieved using twelve electronic components, one of which is an integrated circuit
Instead i was thinking to something different but of course i do not know how to do it That is using a IC regulator as a voltage reference and leave the transistor to provide the ripple filtering. Can IC regulators be better voltage reference than zener ?
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Old 3rd September 2020, 10:58 AM   #7
bimo is offline bimo  Indonesia
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Usually for audio used, no need voltage precision at PSU voltage. For me, high PSRR at least until 100kHz, low noise, and good transient response are more important. I designed several discrete PSU regulator, series and shunt and I share to local audio community. They compared with LM317/337 or 7815/7915. They think my regulators sound better. But still I do not know why they sound better
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Old 3rd September 2020, 11:03 AM   #8
ginetto61 is offline ginetto61  Italy
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Are you really fine with IC voltage regulators ?
Quote:
Originally Posted by dreamth View Post
I think you read too much of the "esoteric audio" press instead of good engineering books
You found me out but please follow my reasoning
If there is an audio product that almost always get excellent reviews and its owners love it, people who listen to it for years ... it must have something good.
I am a solid state guy. While good power amps are not very rare good line preamps are. Conrad Johnson fet preamps series (also those under the Motif name) are a classic in the high end circle.
As you can well image the schematics are not available
From some descriptions it seems that the preamp circuit is very basic and that the power supply is made with discrete parts
So my idea is that maybe is the power supply the reason for the nice "sound" ?
For nice i mean low noise, great detail, dynamics and soundstage.

Quote:
There's really high end audio equipment using op-amps in regulators of all sorts
like ? could it be that they are use but in more complex design also using discrete parts ? i was referring to the very basic circuit

https://www.circuitstoday.com/wp-con...-regulator.jpg

clearly more in more complex circuits they could be just fine

Quote:
You can't use them easily in high voltage regulators,


Quote:
but there are a lot of good engineers who don't give a damn on what Conrad Johnson said...
still their product sound good ...

Quote:
By the way...in the late 70's and early 80's there weren't many op-amps on the market, if any...now we have high voltage op-amps too...IC regulators have some op-amps inside...you can use external op-amps too.
this is fine i understand that. As soon as they have been available they have been used They are very convenient and cheap

Quote:
I used TL783c with valve preamplifiers with no problem:
Gyraf Audio - G9 DIY
i would really like to stay away from tubes ... there are too many variables like tube quality

Quote:
Originally Posted by Vovk Z View Post
Objectively if we'll look at some parameters we can easy measure (filtering and regulation effect) then IC regulators (like 78xx or LM317) are of cause much (order or two or three orders) better then simple Zener regulators. But there are other parameters like output impedance (frequency and load dependent) and others which are harder to take into account when design (they are non-linear etc).
Possibly unfortunately bad designed IC regulators may worsen the sound I don't know.
that is my doubt
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Old 3rd September 2020, 11:10 AM   #9
ginetto61 is offline ginetto61  Italy
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Are you really fine with IC voltage regulators ?
Quote:
Originally Posted by bimo View Post
Usually for audio used, no need voltage precision at PSU voltage. For me, high PSRR at least until 100kHz, low noise, and good transient response are more important. I designed several discrete PSU regulator, series and shunt and I share to local audio community.
They compared with LM317/337 or 7815/7915.
They think my regulators sound better. But still I do not know why they sound better
Thanks ! your words confirm what was just a feeling ... now it is more than a feeling ... and I begin dreaming
this point is very important for me because it would change completely my approach
Someone blame for instance opamps for flat sound while instead is the power supply to blame, for not being able to provide a good response to current transients.
An evidence comes from increasing the output cap ... i have used 1000 uF on each rail close to the preamp circuit and it seems that the sound improves (i.e. less noise more dynamics)
Then i was told to stay below 470uF ... 1000uF being too much
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Last edited by ginetto61; 3rd September 2020 at 11:15 AM.
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Old 3rd September 2020, 11:23 AM   #10
bimo is offline bimo  Indonesia
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I am new in designing voltage regulator but I think the power supply is important. I designed capacitance multiplier for power amplifier. Even, the amplifier has high enough PSRR, but adding capacitance multiplier usually improve the mid and the high frequency. So, it give me feel that high PSRR at high frequency is important.

In the future, I will learn to find the relationship of PSU specification with sound perception. But for now, my approach is high PSRR at high frequency, low noise, and good transient response.
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