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Another question for MicroStack owners--Power

post #1 of 10
5/18/06 at 12:21am
Thread Starter 
Do most of you use batteries or DC? I really can't hear much difference, except when the batteries start to die and then--yuck. It is a major pain to change the batteries when using the MicroStrap/bag.

I'm not crazy enough--yet---to spring for a Desktop Power Supply, but I am considering ordering a second pair of power cords/wall wort so I can just plug in at home or office without doing the battery switch.

Caveat: I have been using cheezy 9 volt batteries so far. My Powerex charger w/ good 9.6 volt rechargeables just arrived today, so I may notice more of a difference with these than I did with the rat shack batteries.

Just curious what the rest of you do for power.

BTW, i wasn't sure which sub-forum to post this in, but there are more MicroStack owners who check the amp forum than any other, so that's why I posted here. If it should be posted elsewhere, oh great and powerful moderator, please feel free to move me. Thanks.
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post #2 of 10
5/18/06 at 12:47am
I use good Accupower 270 mAh batteries and have no problems. I did buy a second power cord which I use in my car with a converter that plugs in the cigarette lighter, so I save battery power because I use my rig while driving and use the battery when walking around.
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post #3 of 10
5/18/06 at 1:36am
With standard disposable alkalines, I find that fresh batteries sound very clean, but don't seem to have enough push to drive my HD600s to their fullest. To be specific, they can't drive extremely bass-heavy songs as cleanly as DC power can (e.g. 50 cent). DC power is pretty quiet, all things considered. I'd be interested to hear how much improvement the desktop PSU affects, but I'm not interested enough to thrown down the $300 needed to run the experiment.

-Angler
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post #4 of 10
5/18/06 at 3:36am
Quote:
Originally Posted by angler31337
With standard disposable alkalines, I find that fresh batteries sound very clean, but don't seem to have enough push to drive my HD600s to their fullest. To be specific, they can't drive extremely bass-heavy songs as cleanly as DC power can (e.g. 50 cent). DC power is pretty quiet, all things considered. I'd be interested to hear how much improvement the desktop PSU affects, but I'm not interested enough to thrown down the $300 needed to run the experiment.

-Angler
I did this comparison a while back. Fresh batteries = 90% of a DPS. The best sound without a DPS is to use lithium 9V (not LiPO rechargeables, lithium) which have more than twice the capacity of standard alkalines. Batteries are 90% of a DPS as they supply less voltage than a DPS, however in terms of clean DC power batteries are unbeatable. The brick supply gives more voltage, however a much less clean source.

Best to worst: DPS > Lithium 9V > Alkaline 9V > Brick, in terms of absolute refinement of sound, though there is more power in the brick than 9V batteries. Hope that made some sense.

Btw angler, you are confusing terms a little bit. All amps use DC power internally, whether it comes from a DC source such as batteries or an AC source converted into DC like the brick or DPS.
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post #5 of 10
5/18/06 at 12:08pm
Quote:
Originally Posted by TheSloth
Btw angler, you are confusing terms a little bit. All amps use DC power internally, whether it comes from a DC source such as batteries or an AC source converted into DC like the brick or DPS.
Certainly, it was late and I was tired. Of course I meant AC->DC power.

My understanding was that audio unpleasantries were cause (1) by unintended voltage drops, themselves caused by rapidly changing demands for current and (2) by noise and distortions to the local AC power resulting in clipped/low voltage power being supplied to (in this case) the PSU. To some extent the DPS should correct both problems (less so the second one) relative to the supplied power-bricks.

Good batteries do not suffer from the aforementioned line-noise problems, but should still be sensitive to the first problem, in addition to being potentially voltage limited as stipulated in my previous post.

If I've got this right so far (and I'm not an electrical engineer by any stroke of imagination), then it seems somewhat strange that batteries should so much outperform power-bricks, unless the incoming power is truly noisy/heavily distorted. In that event, even the DPS might be performing below capacity (as one would need a true power regulator to solve the problem). Of course, this all depends on the quality of power one has to work with, which varies significantly on even a house-to-house basis.

-Angler
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post #6 of 10
5/18/06 at 1:06pm
Don't mean to bash, but I find my portable amp running on 2x9V doing it very well compared to my home amp, the Marantz. It has just as much as slam (=dynamics) compared to the latter one. Even my very old AGK (600 Ohm) gets the juice it needs. I'm starting to like this little guy more than his big brother, even though it can only run on batteries.
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post #7 of 10
5/18/06 at 1:51pm
Quote:
Originally Posted by angler31337
Certainly, it was late and I was tired. Of course I meant AC->DC power.

My understanding was that audio unpleasantries were cause (1) by unintended voltage drops, themselves caused by rapidly changing demands for current and (2) by noise and distortions to the local AC power resulting in clipped/low voltage power being supplied to (in this case) the PSU. To some extent the DPS should correct both problems (less so the second one) relative to the supplied power-bricks.

Good batteries do not suffer from the aforementioned line-noise problems, but should still be sensitive to the first problem, in addition to being potentially voltage limited as stipulated in my previous post.

If I've got this right so far (and I'm not an electrical engineer by any stroke of imagination), then it seems somewhat strange that batteries should so much outperform power-bricks, unless the incoming power is truly noisy/heavily distorted. In that event, even the DPS might be performing below capacity (as one would need a true power regulator to solve the problem). Of course, this all depends on the quality of power one has to work with, which varies significantly on even a house-to-house basis.

-Angler
All regulated voltage outputs are by nature 'voltage limited', however you are correct that the Micro operates at a lower voltage of batteries. However, a fresh set of batteries (especially lithiums in the case of 9V) is a pretty perfect DC source, in terms of voltage stability (assuming the current load is within spec), output impedence and an overall very smooth DC line.

The DPS, through excellent design mimics the performance of a battery in most of the senses, except with significantly higher voltage (+/-15V instead of +/-9V). It may have a slightly lower output impedence as well due to banks of storage capacitors.

That lower voltage is not that relevant unless it is causing clipping, which is unlikely in most usage scenarios. The only real sonic difference caused by that voltage, when compared to an equally clean AC-DC design such as the DPS is a slight reduction in 'headroom' around the sound. It's very hard to describe, but it's just not quite as effortless and smooth.

Overall, I always found lithium 9V to be a very good price/performance compromise to get the best sound when I briefly owned a Micro.
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post #8 of 10
5/18/06 at 3:48pm
Thread Starter 

Update

I tried the Powerex 200mah "true 9.6" rechargeables from Thomas Distributing last night and am using them today on A/B testing vs. the wall wart. The Powerex rechargeables are working better than the radio shack 9 volts (they were SERIOUSLY on sale, and may well have been old/defective).

I do think these batteries produce a subtle improvement over the wall wart, but it could be my imagination. The perceived difference is very slight, and I need to try this with different kinds of music to see if it is real or perceived.

If I had to describe the difference, it would be that there is more clarity. It's almost like there is a low level of noise using the wall wart that is too low to be consciously heard, that is absent with batteries---you know it was there only when it's gone. This is very hard to articulate, and I'm probably doing a poor job of it. Let's just stick with "subtle." Thus far, the difference is certainly not significant enough to me to justify the hassle of messing with the batteries when the wall wart is readily available.

I'll pick up some lithiums later and see if they change the sound significantly ( I kind of hope they don't, because knowing me I'll wind up buying them in bulk for awhile, and will then buy a DPS).

Thanks to all for their input.
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post #9 of 10
5/18/06 at 4:25pm
Quote:
Originally Posted by ComfyCan
I'll pick up some lithiums later and see if they change the sound significantly ( I kind of hope they don't, because knowing me I'll wind up buying them in bulk for awhile, and will then buy a DPS).
They won't 'sound' different to your rechargeables, but each set will last over 20 hours with the desktop module.
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post #10 of 10
5/18/06 at 5:14pm
Thread Starter 
Quote:
Originally Posted by TheSloth
They won't 'sound' different to your rechargeables, but each set will last over 20 hours with the desktop module.
Thanks; 20 hours would be handy indeed.

Lithiums are pretty pricey for disposables, however.
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