best sounding 78XX/79XX drop in Regulator Replacements?

[jean-paul]

Please NOTE that the pinout according to the Nat Semi datasheets is EXACTLY THE SAME as 78xx/79xx, so they ARE exactly replacable.

You're right, I was thinking of my experiences with the LT regulators which have a different pinout I've edited my post immediately in embaressment. BTW I used only the 5V fixed SMD variant which was OK, never tried the TO220 version. Still have the SMD variant in stock.

LM2940 is not the best sonically/specwise, LM2937 is better but the 0.5 A max. can be a problem. I can't comment on the LM2990 as I've never used that one. There is no real complementary version of the LM2937. This counts for other nice types as well, probably because they're originally designed for automotive applications.

It is time for real good complementary 3 pin regulators and/or real good symmetric IC's ( remember the XR4195 ? ). Nevertheless 78xx/79xx have become better and better over the years. I wouldn't be surprised if it turns out that the particular ones the factory in question uses will give better results than the LM regs you plan to use Use the ears as always !

[ThorstenL]

Konnichiwa,

Originally posted by Bricolo
Are you telling that a DAC has to have low noise power supplies (and opamps) in order to keep its full resolution (obvious), but that other stuff don't necessarely need low noise?

Well, some DAC's (like the TDA1543 with 50db) have not got much PSRR and also share the PSU pin between digital and analog supplies. They are obvioulsy much more critical to PSU noise. Others (like the PCM1074 with > 90db PSRR on all supply lines) manage very high supply noise rejection.

As always, horses for course. The same reg on the TDA1543 will result in 40db more noise in the output than for the PCM1704.

Originally posted by Bricolo
If your preamp has noisy regs, you'll also loose precision in the sound.

That will need a lot of noise if you use standard Op-Amp's.

Originally posted by Bricolo
An audio rig with a, say 24 bit player, will need a player with 145dB SNR,

Good luck finding one that does not need a lot of liquid nitrogen to work....

Sayonara

[Fred Dieckmann]

"Well, some DAC's (like the TDA1543 with 50db) have not got much PSRR and also share the PSU pin between digital and analog supplies. They are obvioulsy much more critical to PSU noise. Others (like the PCM1074 with > 90db PSRR on all supply lines) manage very high supply noise rejection."

Gee...... what happen to all the data above 1KHz I wonder.

[fmak]

Not in this thread. Let's review the FACTS:

1) Peter wrote:

"Recently, in ML38 preamp, I replaced 78XX/79XX regulators with low dropout type from National, LM2937ET and LM2990T, and those are much better sounding than the other ones. This was also a recommended upgrade from 38 to 380 version."

Note that Peter write about a Mark Levinson preamplifier, not a DAC with TDA1543 or a Tent Clock.

3) I wrote:

"Hmmm. I have on previous occasions noticed that regulators that are "poor" on the Datasheet can sound rather good. Often "good" regulators have such a low output impedance that they swamp any bypass capacitor sonics and determine the sound, usually in a negative sense."


Would I use these regulators in a DIY DAC using a Tent Clock and a TDA1543? Not likely. But as replacement of generic 78XX/79XX regulators in commercial gear they look the piece, which is what I originally asked for.

---------------------------------------------------------------------------------
Peter used the AN800x regulator which is not brilliant spec for the TDA1543/Tent Clock, which are what I was referring to.

[Fin]

Originally posted by Kuei Yang Wang
Konnichiwa,

And no, commercial drop in regulator PCB's like those from Audiocom are not an option here.

Any thoughts and experiences are very welcome.

Sayonara

Has anyone tried those Audiocom regulator PCB's?
Do they provide a significant improvement over traditional 3 pin regs?

[jbator]

Originally posted by Kuei Yang Wang
Konnichiwa,
Look at this:
http://www.wenzel.com/documents/finesse.html
This basic idea can extend to give excellent low noise levels and very low PSU node impedance designed into equipment, but it really is "design in" not "after market".
Sayonara

How to make negative supply from that? Change transistor (2n4401) to PNP (2n4403) and reverse base capacitor at Clean-up shunt part (of cource with lm337)?

[jksmurf]

Sorry to drag up an old thread, but turning to the original question, what "is" consiered the current "Best sounding 78XX/79XX drop in Regulator Replacements?"

Is it still the LM2937ET and LM2990T as above?

Basically I am looking at alternatives to the ones in my Marantz CD76SE for the +5V, +/-12V (the ones Audicom Replaces with their "Sulzer?" Super-regs, which I "might" still purchase.

I'd like to play around with something cheaper first AND I know there are other DIY super-regs e.g. Per Sjostrom's, ALW's, the PFM Flea plus half a dozen others, as well as a few nice simple LM317/337 or LT1085 based ones like the "Raygulator" (search the CD63 Mods Forum for that).

Cheers

k.