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Old 11th August 2003, 05:17 AM   #1
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Default anybody tried a LM4780?

its stereo 60 watts. 120 mono
http://www.national.com/pf/LM/LM4780.html

i want to try out the bridged mode.

think it could possibly sound good like a 3875?

i'm more sure its fine for PA uses which might be something i want to build.

this pdf is really informative.

what's the deal with 3 differenct cap values on the rails?

you guys hate built-in mute circuitry though.

i'm trying to think of a good way to set one up where its really easy to change components to try different stuff out.
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Old 11th August 2003, 05:27 AM   #2
JoeBob is offline JoeBob  Canada
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I was looking into the LM47xx line of chips, and am gonna throw something together to see how it sounds soon.

But it probably won't sound as good as the LM38XX line, they're listed as high-performance, and for a reason, the 47s seem to be more aimed towards ease of use and efficiency.

It's worth a try, one is a stereo p[art (only 11W though) that has a built in beedback resistor.
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Old 11th August 2003, 04:31 PM   #3
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Default Interesting voltage on rails

Interesting that is a 60watt amp but will take such large rail voltage +/- 42v, 92v max peak to peak... and given that it is two amps in one chip, it is like it is begging to have emmiter followers added on to a BTL. If it put out 75v (which it should) each, that is 150 volts p2p.
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Old 11th August 2003, 05:03 PM   #4
SY is offline SY  United States
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Why do you think this will sound less good than a 38xx? The specs here look pretty good.
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Old 11th August 2003, 05:07 PM   #5
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The specs look very good, unless it just has a bad sound "character" to it, it shuld be a performer. I am very tempted to try one of these paralleled. Using two of these chips in a BPA alignment could be very rewarding. Two chips, about a total of 12 resistors, 4 capacitors, and you could have a very high powered amplifier.

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Old 11th August 2003, 05:18 PM   #6
SY is offline SY  United States
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Do you know the availablilty of the chip and/or demo board? This is one I'd really like to try.
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Old 11th August 2003, 05:40 PM   #7
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Quote:
Originally posted by SY
Do you know the availablilty of the chip and/or demo board? This is one I'd really like to try.
Just done a quick troll around the UK small order distributors, and non of them have that chip up yet, but it certainly looks interesting.
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Old 11th August 2003, 05:48 PM   #8
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This does look like what a lot of us have been waiting for.
I want it for a PA amp so quality doesn't have to be absolutely the best-just a lot better thean those pig PA amps out there..
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Old 12th August 2003, 12:07 AM   #9
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Hmm... Interesting.. especially seeing I have a transformer that';; give +-45 volt rails with no load..

In Parallel mode with +-40 volt rails, it'll give 160watts into 4 ohms at 1% distortion... good for a sub..
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Old 16th August 2003, 02:41 AM   #10
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amybody tried this chip yet?? need a schematic for an inverted version...seems it will use less parts...easier to construct I guess...but the pdf does have some wuickie examples...
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