Why not batteries instead of power supplies?

@erik_squires 

This is fascinating stuff. I must admit that I don’t understand the link between output impedance of batteries and more cross talk and dynamic range. 

You clearly know this stuff inside out. if you could give me a pointer or two to help me get it I would be totally grateful. 

Hi Defiant,

Power supplies provide a (hopefully) fixed voltage to the circuits which does work for us. Say, +15VDC, Ground and -15VDC is typical for a solid state preamp / CD player, etc.

A "perfect" power supply has no output impedance. No matter what the circuit it feeds does, the voltage remains rock-solid.

As the output impedance of the supply goes up, the voltage sags and surges as the demands go up and down respectably. So, instead of exactly 15VDC, it will start to look like 13V to 15V, tracking the output signal somewhat.  The higher the PS output impedance, the more this happens.

Once this happens, your power supply has a "copy" of the music. This is where cross-talk happens, as well as weak bass and reduced dynamics. If the L channel is moving the power supply V, the R channel will be influenced, and vice-versa.

One of the best Ideas I ever read about was a designer who would listen to his power supply. He would treat the + and - rails and hook them up to headphones or speakers, so he could literally hear the noise or cross talk in the power supply itself. Pretty brilliant.

Best,


E

@erik_squires

Awesome explanation, many thanks. I think I am beginning to get it.

Technical discussions are always fun, but it is important to keep an open ear and buy what you like to listen to.


Best,

E

defiantboomerang
 Why not batteries instead of power supplies?

Easy to do for preamps, phono stages, ect using single rail power supplies.

But to do for poweramps with positive CT negative rails is harder, back in the 80/90’s (as you can tell by the ad) Nelson Pass was said to be the designer of one for a company called N.E.W. A20.1
http://www.canuckaudiomart.com/details/649334581-new-p3-new-201/images/1459271/

Two Nelson Pass designed tow box models for memory N.E.W. DCA-66 and DCA-33 had a bank of those black rechargeable brick shaped alarm system type batteries arranged in series/parallel to give +24v 0 -24v this way you get a 0 centre tap to ground.
https://tangentsoft.net/elec/bitmaps/vgrounds/ctap-battery1.png
When working properly it did sound very good to me.
The only problem I believe with it was if there was more current draw on one side more than the other or the battery lost more charge on one side than the other, the battery rails became unbalanced with age, which then results in higher distortion and can lead to dc offset problems.

Cheers George