Why not batteries instead of power supplies?

I think we'll see more of this and Powerwall is just the tip of the iceberg.

But a DC power supply will not get rid of noise problems that originate from inside your house.

@erik_squires, "The negative side of battery power supplies is the supplies themselves have inherently high output impedance compared to their AC counterparts, leading to higher cross-talk, and potentially weak bass and dynamic range."

Well, put.  Weak bass and dynamic range definitely plagues the majority of these products.

@whart, "The Veloce lacks for nothing in the areas of bass or dynamics."

Vytas is a buddy of mine, and your point is absolutely correct.  As a basshead and power focused guy in general, he would NEVER build anything that didn't meet that mark, and took a different tack than what I've encountered in many other products.  As we mentioned Erik pointing out, this really shows up as a problem for most other battery powered products

@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.