I did a search on battery power supplies, but...

[carlosfm]

Originally posted by jeff mai
With batteries, the bass was more defined and the music held together better through complex passages. Unfortunately, it was a little wiry sounding in the midrange compared to AC. I went back to AC simply because I had borrowed the batteries and had to return them. In the long term I'm not certain which I would have decided was better.

With batteries, you should have tried much lower caps (like 10uf~33uf).
And (not or) you could snubberize the batteries.

[jeff mai]

Originally posted by carlosfm
With batteries, you should have tried much lower caps (like 10uf~33uf)

I know, but it would have meant building another amp circuit and I only had limited time with the batteries. Taking apart the existing p2p amp would have destroyed it. I spent a lot of time getting everything as close together as possible. The leads on the 1000uf PSU caps are only a couple of mm long and attach directly to the chip pins.

[Peter Daniel]

Originally posted by Septimus
Peter "And using AC power with 100u BG N caps (only) is still better." In what sense, convenience or sound?

Better sound.

I was using batteries for close to a year with my GC amp. Direct comparison with a same amp connected to AC PS (and 1000u caps in both cases) was showing that batteries were better (although not by much). With batteries the sound was well behaved, with nicely defined bass and smooth highs (the AC power glare was not there). The midrange was fine too, but for some people the sound may seem a bit mellow and too polite. With AC power it was more lively (it also depends on the quality of your mains). However, I prefered bateries.

Up to recently, I was using 1000u caps with the amp (BG N type). For the last mont or so, I was experimenting with baterry powered DAC, and both the type of bateries and amount of capacitance after batteries are important. So, Panasonic cells sound differently than Yuhasa and from the caps I tried directly after bateries ( 4.7u, 10u, 33u, 47u, 100u 1000u, all of them BG N) I preferred 47/50 the most, that value was critical for best sound. Now, in my system I preferred batteries (on a DAC), but when I took it to a friend of mine with really well tuned room and active speakers (soundfusion.com), we both came to conclusion that AC powered DAC sounds much better.

Recently, I tried to experiment with different value caps in my GC amp, and by accident (as this was the only remainder after snubber) I tried the amp with 100u BG N only, directly after rectifiers. To my surprise, it sounded completely different to what I was used to so far: the sound was very harmonious, coherent and was completely free from the veil associated with bigger caps. It just sounded right, and I cannot go back to bigger capacitance now.

BTW, I also tried 100u with batteries, and the effect was similar to what I was getting with bigger caps and AC power: sort of veiling and lack of clarity ( clarity I now know is possible with such small caps).

Regarding capacitance on the amp with battery power: 10u sounded much worse than 100u and 100u sounded better than 1000u (same type). I still didn't check 47u

[Septimus]

You know, its almost funny you said this. I was looking into batteries originally, esp. because I'm such a noob I was a little hesitant because I don't understand transformers all that well (the whole secondaries, primaries etc), and didn't want things to be any more complicated than need be. However, looking into it more deeply, we're talking about 6 batteries for like 40 bucks a pop, crazy weight, charging system. Translation: complete waste of resources and utter defeat of my original intent. SO, I guess I'll just look deeper into a proper PS

[Peter Daniel]

To give you some more insight into comparison between battery and AC power, here's a summary of Stereophile's review (1997) of Jeff Rowland BPS-2 battery PS used with Model 2 amp. It's pretty close to what I experienced in my setup.

[Peter Daniel]

And here's the next page.

[jacco vermeulen]

I built an Elektor preamp in the high 80s and wondered why none were battery operated as that looked simpler for diy purposes, and was so much better.
After finishing it with lots of trouble on the voltage regulation circuits i figured i might try battery operation later.

At the time that rechargeables became more available at fair prices i added a battery supppy chassis to the preamp.
Much later the first battery feds came on the market.
After reading on battery operated Metaxas power amps i built one myself.
That took 12 batteries for twin channels, the cost was far less than 40 the piece, unless you buy filthy expensive ones in electronic stores.

It took 10 years before manufacturers with a higher market share catched up.
The idea is so simple, yet it was the DIY sector to go first, as so often.
I understand that manufacturers need to look at costs first, yet it seems that the majority is very conservative.

I would like to add a battery powersupply for my Stokes class A headphone amplifier one day.

Panasonic rechargeables i still use for my preamp, any suggestion for an improvement ?

[protos]

Having played around with battery power a lot the past two years for preamps and power amps -including the Aleph x!--
I always preferred the battery sound by a long way.It just seemed to me a big differnce in terms of harmonic and spatial righteousness.AC sounds at first more dynamic than battery power until you realize that this dynamic quality is more of a type of distortion you get when music is compressed digitally such as by radio stations and in some pop cd´s in order to sound louder and with more ``pop´´.Even the bass at first sounds bigger with ac until you realize it is a boomy type of bass while with battery you hear it is tighter with better note definition.In all these cases ideal capacitance with batteries may vary.Sometimes some film caps sound best , sometimes you might need some low value good electrolytics depending on the amp and current draw.
But as they say , YMMV or in other words it´s up to you to decide ion the end.
By the way as somebody mentioned earlier a battery PS is not necessarily that expensive.You can get a lot of offers on batteries for less than 20usd a piece.

[mourip]

As long as we have a nice battery thread going here perhaps I can pose one more question.

I have a Sonic Impact amp that I have moved to a more spacious chassis and am running on a 12v 3.4AH battery. It works great and powers my AKG K-1000 phones really well. Right now I have a DPDT switch which allows me to choose between "amp on" and battery charge. I see two problems with this. If I forget to turn off the amp and let the batteries run out the SLA will not like that. Also I cannot leave the amp running all the time as I do my gainclone. To my ears most equipment sounds better if left on and if not then requires at least 20 minutes to get to even 90% of what it can do.

My question: is anyone out there wiring their charger to simply be on all the time? In other words, amp is on with charger working while music is being played? Is there a technical downside to this? Obvously I will have to decide for mysef if there is a sonic tradeoff.

BTW. Give the Tripath SI amp a try. Battery power is a cinch since it runs from a single 12v supply. The sound will surprise you...

Thanks a lot.

Paul

[blip]

Might as well add my own battery question as well.

When building a battery supply do you just feed the voltage to your amp directly or do you still need to put power reservoir caps in between? If so, how much should you adjust the values by?

I ask because I'm thinking about doing a BrianGT amp with battery supply.

Thanks.