Scheme for regulating power amp rails down for IC's

[jackinnj]

I simulated the circuit you posted in #13 and it should work really well! Really good PSRR, decent (not great) output impedance, negligible noise contribution. (I simmed with an On-Semi transistor of which I have a couple tubes.)

I think that while a Maida type regulator could also fit the bill -- it has some real issues with respect to noise AND the error amplifier in the LM317/LM337.

 

[synonymous]

Thanks for the input Jack

On the board that I intend to have the DAC and line receiver, there will be appropriate ceramics/bypass for the LDOs. I'm thinking that they wouldn't offer much in the scheme that I drew in that this part of the regulator is already a highly filtered linear power at it's input. If it were SMPS, I would incorporate a variety of alternate filters, but not needed here. I didn't label them, but the resistors are also MELF, which should be good low noise.

Thanks
S

 

[SyncTronX]

Jack,


Which transistors did you sim with, that you have tubes of?
What are other recommended transistors?



synonymous, which LDOs are you feeding? with the post313 boards?


Cheers

 

[jackinnj]

Jack,
Which transistors did you sim with, that you have tubes of?
What are other recommended transistors?

I sim'd with D44H11 and 45H11 -- the ones used in WJ's super-regulator. 70 volts would stretch them, however.

I also tried this scheme but it didn't work as well although the impedance was lower:

 

[synonymous]

Jack,
synonymous, which LDOs are you feeding? with the post313 boards?

Cheers

LT1761 and LT1964

You can use others of course, just make sure they handle the voltage and that they have a low quiescent and low current draw. Choose efficient regs. You can modify the scheme some to get the voltage down further if you need to. I prefer to feed the regulators near their high spec so that they do the efficient regulation themselves, freeing up the rest of the circuit to work less. So far as the regulators themselves, I do prefer low part count necessary and easy to solder onto the PCB. Some that are potentially better are more difficult to work with and I favor simplicity.

What may you be using such a regulator for?