Battery or mains?

tackleberry

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Would it be better, or is it even feasible to use a bank of batteries with a pure sign wave inverter instead of a mains conditioner?

My amp is a mf A1000 which pulls 215watts continuously.

???????

 

Clubsport911

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A mains conditioner might actually have batteries on the DC link (DCL) side but it would be unusual. I used to design PWM inverters for control systems and also, UPS systems. All of these have a DC link between incoming rectifier and inverter (the bit that generates the output vol;tage). In the case of a UPS, the DCL is battery enabled (hence power is maintained when the input is gone). Batteries are series / parallel arrangements to get the required voltage (600v for 415c output) or ~350 for 240v output.

As for HiFi ? Well, I have seen the topology of most mains conditioners and they do not appear to have a DCL.

Could you put batteries in ? Yes. The advantage ? Potentially lower EMC but of course depending on how much current us being supplied, you will need to charge them up from time time.

Don't forget, batteries have some diasdvantages as well.. weight / cost / life etc

What's behind the question ?

 

rabski

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The issue is always the impedance combined with current delivery potential. It's highly unlikely your amp draws 215W constantly, more likely it draws a lot less, but draws substantial peak current momentarily. And that is always the issue with mains filters, regenerators and the like. The National Grid has the capacity, even through household wiring, to deliver massive peak current momentarily, most power conditioners and regenerators do not. Nor do batteries, unless you massively over-spec the system.

The reason people often post about music sounding 'flat' when they add a power conditioner is exactly this issue. The inability to deliver serious transient current. No matter how massive the capacitor bank in a power amp, it will still need significant current to handle peaks in music.

Kevin at Definitive has his battery supply system, which works superbly. However, so it should. You would be advised to take a quick look at that setup to appreciate what is actually needed in order to deliver the peak current requirements of amplifiers. And then bear in mind that rig is designed to work with low power amplifiers...

 

rabski

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A1000 is class-A. Current draw will be pretty constant.
I don't entirely agree. Running class-A the idle current draw will be similar to the 'normal' draw delivering music. However, big transients will still demand big current draw, albeit momentarily. The response times of capacitors in power supplies may, the way I see it, mean that very short (millisecond) high current draw will still come from effectively the incoming supply.

 

AmDismal

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Class A is class A - full power is drawn whatever the signal, and it either goes to the speakers or heats up the room. So one would expect class A amps to benefit more from regenerators and the like.

 

rabski

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Yes they will.

Regardless of what 'class' of the topology, big transients will draw off the incoming supply unless the inbuilt PSU is capable of delivering in the time-frame. And they aren't.

 

i_should_coco

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Rong. True class A amps are current-invariant. The power supply has to be dimensioned to supply full power all the time. It cannot be class-A otherwise.

This is why they are large, hot and heavy.

 

speedysteve

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Are you considering this because your mains is so bad? Valid then I guess.

From an upgrade point of view I had a good listen a while back to a pro battery powered system. Nice hi-end system in Hampshire. The diff between isolated batt power and mains was MINIMAL or even just different. Would have been better off spending the money on better horn speakers:)

 

i_should_coco

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Just to prove it to Richard, this is a SPICE simulation of a 211 output stage being driven by 39V RMS at 1kHz into a 20 kOhm load.

This is the output voltage at the plate of the 211, swinging about

Scr002-2.png


This is the current through the 211

Scr001-5.png


This is the PSU current

Scr004.png


 

budgetblown

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I bought a couple of beefy 1300kva battery backup/mains conditioner units a while back for an absolute song (£5 each) - I've been meaning to do something with them, this debate makes me even more determined.

I'm buying bits to build cables at the end of the month, I shall be comparing direct feed from unfiltered mains to a basic filtering unit to these units to see what effect they have on my power amps.

 

SergeAuckland

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Rong. True class A amps are current-invariant. The power supply has to be dimensions to supply full power all the time. This is why they are large, hot and heavy.
I've always thought of a Class A amplifier as a current diverter.The current either goes from + to - of the supply and heats up the output devices, or some of it is diverted through the load, so less heats up the output devices. The total result is a constant draw from the power supply and hence mains regardless of what's going through the load.

S.

 

AmDismal

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Absolutely. Class A - easy on the ears, hard on the planet... but it would take an awful lot to make me change from mine.
Uhh, there's no way those Adcoms are going to be pure class A...

 

budgetblown

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Bet? There's a reason they've got hooooge torroidals and weigh 23kgs each, you know, and have the massive heat sinks besides. Even if they are biased into class a/b past a certain point on the dial (which I don't think they are, from the specs I've seen on them) I still love them. Post service, and with the new kit nicely broken in, they sound very, very good, even if they do make the leccy meter run faster than Usain Bolt.

[update]

Agh. Ok, they're "A Weighted" according to the only specs I can find. Does this mean class ab?

They still sound nice, and with the current setup I can now tell the difference between 256Kbit MP3s and FLAC files, so they must be doing something right.

 

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