Would a battery powered stereo be good?
Subscribe to Ask Paul Ask a QuestionNothing can be quite as clean and noise free as battery power and without the noise and hash associated with AC supplies. So, how about battery powered stereo equipment?
COMMENTS
Leave a Reply
You must be logged in to post a comment.
As Paul says impedance is a problem with batteries. But there are also safety and environmental concerns that need to be considered as well… Many batteries –particularly lead acid types– can give off gasses that are are outright harmful to humans and other types are harmful to the environment when we try to dispose of them.
Batteries are generally not a good idea unless the gear is to be portable.
Another problem Paul alluded to is that a power amp will modulate a power supply. This problem is often worsened by the output stages being on unregulated voltage. Conventional pass through regulation for even a modestly powerful output stage is going to require some very beefy components and will generate a ton of heat… and since they run at 50 or 60 hz it’s likely modulation would still occur in any case.
So, of late I’ve been experimenting with medium power class D amplifiers in the 80 to 150 watt class that run off of external switching power supplies (SMPS) that look like the power bricks used with laptops. These are typically 24 or 30 volt supplies rated at 5 and 6 amps. This method has a few advantages: First it removes any AC components from the amplifier’s chassis, getting rid of any sources of hum. Second, since these things switch at close to 100khz there is no hum from the supply itself. Finally, since the supplies are very tightly regulated at such high frequencies, it is possible to have a regulated voltage on the output stage’s high current sections.
I am currently using two setups with these SMPS bricks and in both cases the supply voltage is stable as a rock right up to the maximum output of the amplifier. The brick’s internal regulator circuit is fast enough that it automatically compensates for any tendency of the high current output stage to modulate the supply which has an audibly beneficial effect on the final sound of the amplifier. Even class AB amps hooked up to these rock stable power sources sound better.
Now I’m aware of the reservations stated by many that some of the switching transient’s may get into the final output of the power supply and be conveyed into the amplifier itself. That simply has not been my experience. The DC from these things is easily as clean as battery power would be. Moreover; even if it did leak a little bit of the 100khz signal, it’s at a frequency so high that we’d never hear it anyway.
Perhaps Mayrab (sp?) could investigate switching power supplies instead of batteries.
“The brick’s internal regulator circuit is fast enough that it automatically compensates for any tendency of the high current output stage to modulate the supply which has an audibly beneficial effect on the final sound of the amplifier.”
Due to some issues with my AC wiring (too far to the panel and too thin of gauge), I recently tried my luck at taking my system mostly off-grid with the use of large SLA batteries and a dual mono class D car audio amplifier setup. I have to say I am very impressed with the result. It’s not what I was expecting. Your comment really resonated with me because I have the amps directly connected to the batteries with no DC regulator and yet it sounds fantastic. I believe what is happening is that even on large power draws where the battery voltage dips a little bit, the switching power supplies inside the amplifiers are “fast enough to automatically compensate” for any voltage variations on the input. This DC powered concept is something I will explore in greater depth. There seems to be a lot of promise here.
I agree with Blake above. Switching mode power supplies, and Class D amps, are the future, even for high end products.
This is why I find the Stellar and Sprout lines so attractive. I’ve recommended them to several of my friends.