Super Regulator

Jump to Latest
#2,462
safesphere said:
@johnego I am using the board from the DIY Audio Store. I don’t think it would work without D5 in place. Then how can I listen without LM440? Are you referring to some additional extension?
Click to expand...

Oh, so LM440 is a zener in place of the LM329. It has nothing to do with whether you can or cannot add pre-regulation. If you ask whether LM440 noise is good enough, I think yes. I have never compared the LM329 as I thought it is not critical. LM317 is a 3-leg independent regulator. It is used as pre-regulator so that the input to SR will be regulated.

safesphere said:
The second part of your post is exactly what I inquired above. What changes do I need to make to the circuit to make AD797 stable? This would be a great help. Thank you!
Click to expand...

There, the Master already answer you. I changed the circuit but I don't have the file right now (in an old harddisk, right now I'm using SSD).
 
#2,465
jan.didden said:
AP uses 47pF between pin 6 and pin 8 of the '797.
Click to expand...

The little Cedarburg card I designed for the M2x power amp, has an AD797 without external compensation capacitor. Pins 1, 5, and 8 are floating. And yet it's perfectly stable at unity gain.

attachment.php



916954d1612024563-diyaudio-watt-m2x-cb_photo2-jpg


_
 

Attachments

  • cburg.png
    cburg.png
    57.4 KB · Views: 823
#2,466
safesphere said:
@johnego Would a pre-regulator provide any improvement if my power source is a battery? I use a 13V 16AH LiFePO4 battery that I need to charge only once a month at most.
Click to expand...

I have no experience with using regulator with batteries. I guess the SR functions differently here because there is no ripples etc. from the battery itself, so it can be something like lowering impedance etc.

My experience with battery is with power amplifier (Hiraga). Most complain about battery used here is about bass dynamics. I think that's about high impedance of the battery. The battery should charge large capacitors with low impedance and let the capacitors charge the amplifier...

But your preamp (or is it DAC) current requirement is small and your battery is I think sufficiently overrated in current capacity and voltage. I'm not sure what is needed from the regulator here. Probably shunt type is better. If you use SR, play around with the series transistor (if you have the inventory). Will be better if the transistor drops more voltage (at least not too few). Find high hfe transistor to lower the output impedance. There are many medium transistors with crazy hfe.

Hope others or Jan can explain about the issue so you can get the best out of your SR without accidents or having to use the expensive AD979.
 
#2,468
@johnego The issue is the low output impedance of the power supply in the signal frequency range. Batteries alone sound horrible. Capacitors are better, but large ones have a low impedance only at low frequencies. A good regulator, such as the SR, drops the impedance dramatically in a wide frequency range. The USB audio signal is 480Mb/s (MHz) and the SR beats capacitors hands down.
 
Last edited:
#2,469
Mark Johnson said:
The little Cedarburg card I designed for the M2x power amp, has an AD797 without external compensation capacitor. Pins 1, 5, and 8 are floating. And yet it's perfectly stable at unity gain.
Click to expand...

Mark, thank you so much for your insight. I am not an expert and I wonder if you could please explain how your post translates to using AD797 specifically in the Super Regulator. Should I leave certain pins floating or try without a capacitor, etc.? Thanks again! -Alex
 
#2,471
Mark Johnson said:
The little Cedarburg card I designed for the M2x power amp, has an AD797 without external compensation capacitor. Pins 1, 5, and 8 are floating. And yet it's perfectly stable at unity gain.
_
Click to expand...

Scott would know best but I think the cap from 6 to 8 is the distortion cancellation cap (decomp when to GND), and it's actually harder to make the circuit unity gain stable with it populated.
 
#2,473
for dual 24v (positive) supply

Got a Naim Stageline phono pre, all discrete, that uses a PAIR of 24v supplies (one per channel).
If I want to use 2 of the positive superregs, each set to 24vdc, can I use a single (meanwell 27v)SMPS to power them both? What are the considerations?
Also, for the same application, can use the negative superreg, flipping the output polarity, to use it as a positive reg (to get my 2nd +24vdc)?

thanks.
 
Last edited:
You must log in or register to reply here.
Top Bottom