[wsatia]

How does changing a battery in an amp change the sound quality? I've read here and there that changing the battery DOES change the sound quality, but what's the science behind it?

And also then, what would give the best sound quality? Connecting the amp to an external power source through a charger? Using rechargeable batteries? Using non-rechargeable alkaline batteries?

Oh and I'm talking about portable amps here, and specifically AAA batteries for my amp.

 

[El_Doug]

you might find this a very interesting read: diyparadise - Batts vs PSU

different batteries are more/less capable of a steady voltage and current draw. on idle, batteries are amazing, and look better than most power supplies. however, at full draw, you'll often see that batteries perform worse than very well regulated power supplies.

i don't know nearly enough about this to tell you why, or which setups are the best, however

 

[wsatia]

hmm wow thanks for the link, it's a pretty interesting read. and quite surprising to me, I thought using a PSU would actually be better than the batteries (disregarding any noise that the PSU might have?).

and what do you mean by "on idle"?

 

[Rempert]

If the battery is dead, changing it could improve the sound dramatically.

 

[krmathis]

When the battery are running towards its end of life (charge) it will loose power to drive the amplifier properly. Replacing it then sure will improve the sound quality. Or re-charge if its one of those batteries.

 

[wsatia]

Quote:

Originally Posted by krmathis /img/forum/go_quote.gif When the battery are running towards its end of life (charge) it will loose power to drive the amplifier properly. Replacing it then sure will improve the sound quality. Or re-charge if its one of those batteries.

but assuming two different batteries are at full charge, would their performance be the same? and wouldn't that make the PSU the best way of running the amplifier?

 

[trains are bad]

Quote:

Originally Posted by wsatia /img/forum/go_quote.gif Connecting the amp to an external power source through a charger? Using rechargeable batteries? Using non-rechargeable alkaline batteries?

Yes.

No.

To be honest, this is a silly question to ask in general.

What kind of amp is it? What kind of headphones are they; what is their impedence? How high is the volume? What is "an external power suppy" and what is a "rechargeable battery"? Is the PSU higher voltage than the batteries or less? Does it have less output impedence than the batteries' internal resistance or more? Does it have proper filtering and low noise? Is it regulated? How dead are the batteries? What's the temperature of the batteries?

I suggest listening to the particular amp and batteries and evaluating their relative sound quality. In a portable amp that uses AAA batteries, I would lean toward using primary cells because the voltage benefit over Nihm batteries is significant, and current draws are generally very low in such devices internal resistance shouldn't be an issue. Even better, would be lithium-chemistry AAAs which have even higher voltage and more capacity. When I had my Total Bithead as a home amp I ran it off a 9v unregulated wall wart and it sounded fine.

 

[krmathis]

Quote:

Originally Posted by wsatia /img/forum/go_quote.gif but assuming two different batteries are at full charge, would their performance be the same? and wouldn't that make the PSU the best way of running the amplifier?

Same voltage/ampere specs and identical charge, then I don't see how there would be an audible difference between batteries

 

[Jeff Guidry]

Alkaline batteries will drop in voltage over their useful life, with a fairly steep voltage curve. The longer you have used a battery of these kinds, the lower the voltage it can provide the circuit, resulting in declining audio quality. Rechargeable NiMH and NiCad have shallower discharge curves and are more predictable, thus being somewhat better for audio.

Lithium batteries have a very shallow voltage curve during their useful life, so they maintain their voltage throughout their lifecycle, which makes them the battery of choice for critical applications like pacemakers. Using them for flash cameras makes the brightness of the flash predictable, important for serious photo taking. However, these batteries are generally cost prohibitive for portable audio use.

A PSU has the advantage of being able to provide higher voltages and very even voltage production at all times for the circuit, making them the best choice for overall sound quality.

 

[berthoud]

It depends on the load drawn on the pack. For example, a 25c capable lipo will provide a very constant power output throughout its discharge curve if pushed below is max discharge rating (like 5c), once you start peaking higher, current wise, the ability to maintain the voltage under that load is less predictable.

 

[trains are bad]

Quote:

However, these batteries are generally cost prohibitive for portable audio use.

Depends how battery-hungry your amp is. My Total Bithead would last like 30 some hours of listening on a set of AAAs, and close to twice that with lithiums. The larger capacity of lithium primary cells nearly makes up for their price increase, and they perform better to boot. I still prefer primary cells for portable amps, because in this low-current application, 6v is significantly more than 4.8. The batteries can discharge a good bit before they have the voltage that rechargeables start with. And they don't self-discharge, like even low-self-discharge rechargeables do, and it is economical to have a spare set ready to go.

 

[NelsonVandal]

I think it depends on the amplifiers topology. Take the RA-1, where the batteries midpoint is used as ground, the effect of batteries is obvious. In a three channel (active ground) or four channel amp (balanced) the effect of batteries and capacitors are of very little importance. The same goes with class A amplifiers running at a constant current.

Batteries have impedance, and the smaller they are and the higher number of cells they use the larger the impedance. I guess the impedance varies between different batteries, and it's also possible the impedance varies with frequency differently.