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Chip Amps Amplifiers based on integrated circuits

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Old 25th February 2005, 08:02 PM   #11
Ropie is offline Ropie  United Kingdom
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So for a few hours of listen time, 4 12v 5ah batteries would be 20ah.

Looking over the data sheets at nat. semi. it looks like 48v is a little much?
Not quite - you use 2 batteries per channel (for a stereo gainclone) to give +/- 24V per channel. Each battery will still give 5 amps per hour.

Have a look at this thread for a quick start:

click here

I have used batteries in a phono stage and they do give a very smooth sound.
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Old 25th February 2005, 08:14 PM   #12
colinc is offline colinc  United Kingdom
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That's not right is it? 4 @ 12V x 5Ah is 48V when wired in series but it is still 5Ah capacity.

Wired in parallel it's 12V and 20Ah, but you wouldn't want to do that.

regards, Colin
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Old 25th February 2005, 08:20 PM   #13
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One properly charged cell will produce approx 13.6V DC. So the max you can do is 3 of them in series per rail. I did some brief comparisons and it seemed like higher voltage produces better sound, but running 6 batteries is not as convenient as 4.

And using AC power with 100u BG N caps (only) is still better.
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Old 25th February 2005, 08:22 PM   #14
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I was talking per channel. So with only 24v, we're only running these chips at like 30watts, is that right?
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Old 25th February 2005, 08:25 PM   #15
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This graph shows available power levels:
Attached Images
File Type: gif graph.gif (21.9 KB, 439 views)
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Old 25th February 2005, 08:29 PM   #16
DonoMan is offline DonoMan  United States
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I have a 48V UPS. It takes 4 12V batteries in series. It would work. Though I have no interest in doing this project for myself...

Note: APC UPS' won't work, they're 24V. My good one is an online UPS from Liebert.
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Old 25th February 2005, 08:37 PM   #17
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I used an amplifier with a battery powersupply once.
A Metaxas clone, with a powersupply setup that Fred Gassman in Switzerland made for the original power amplifier.

Dont know if there is still some info on Gassman's site.
Nice ones for power amps are sealed maintenance free batteries.
For my boat i have used AcDelco's, in 5 AmpHour theirs should be great too if they make 'm.

I used a charger circuit from elektor that selected the battery it charged, that way you only need one charger, with a drop charger.
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Old 25th February 2005, 08:38 PM   #18
DonoMan is offline DonoMan  United States
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12V 12Ah UPS batteries are quite cheap on Ebay, you know.
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Old 26th February 2005, 12:12 AM   #19
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Try the batteries. In a direct comparison I found them different sounding from AC but not necessarily better.

In my setup I could do hot switching between AC and battery supplies. I used a heavy duty DPDT switch (rated for 10A) that switched between rectifier bridges and batteries. The caps were 1000uf Panasonics soldered at the chip pins, so they were always in circuit. I don't think the switching would be friendly without some reservoir caps in circuit all the time. It was important to find a switch that changed contacts on both poles at exactly the same time, otherwise a pop was heard through the speakers when switching.

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.
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Old 26th February 2005, 12:23 AM   #20
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Ok, so I want around 5-10ah thats fine, and I'll be using SLA type, thats decided with individual chargers.

So now I need to determine the voltage I'm gonna run. I will be bi-amping these speakers, with the top end being a 4ohm Raven R1, and the bottom as yet undecided, but some form of TL, maybe an Adire Extremis. So I'm thinking 4 mono amps, two of which would be at 24V, while the other two would be at 36V? So I could run 2 12v's on the 4 ohm one, and 3 12v's on the 8ohm amp. Does this sound logical?


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

thanks for the advice!
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