anybody tried a LM4780?

travis · 11th August 2003, 05:17 AM

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.

JoeBob · 11th August 2003, 05:27 AM

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.

Sawzall · 11th August 2003, 04:31 PM

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.

SY · 11th August 2003, 05:03 PM

Why do you think this will sound less good than a 38xx? The specs here look pretty good.

PaulHilgeman · 11th August 2003, 05:07 PM

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.

-Paul Hilgeman

SY · 11th August 2003, 05:18 PM

Do you know the availablilty of the chip and/or demo board? This is one I'd really like to try.

pinkmouse · 11th August 2003, 05:40 PM

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.

Variac · 11th August 2003, 05:48 PM

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..

SkinnyBoy · 12th August 2003, 12:07 AM

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..

li_gangyi · 16th August 2003, 02:41 AM

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...

11th August 2003, 05:17 AM	#1
travis diyAudio Member Join Date: Apr 2002 Location: orange ca	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. __________________ donuts

11th August 2003, 04:31 PM	#3
Sawzall diyAudio Member Join Date: Jun 2001 Location: Alexandria, VA USA	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.

11th August 2003, 05:03 PM	#4
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	Why do you think this will sound less good than a 38xx? The specs here look pretty good. __________________ If there's a sucker born every minute, where do the rest of them come from?

11th August 2003, 05:18 PM	#6
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	Do you know the availablilty of the chip and/or demo board? This is one I'd really like to try. __________________ If there's a sucker born every minute, where do the rest of them come from?

11th August 2003, 05:48 PM	#8
Variac diyAudio Editor Join Date: Dec 2001 Location: San Francisco, USA	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.. __________________ 2013 Burning Amp Festival announced: Sunday, October 6th in S.F. We need Volunteers & sign-up's for what you're bringing!


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11th August 2003, 05:27 AM	#2
JoeBob diyAudio Member Join Date: Nov 2001 Location: Montreal, Canada	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.

11th August 2003, 05:07 PM	#5
PaulHilgeman Account Disabled Join Date: Dec 2002	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. -Paul Hilgeman

12th August 2003, 12:07 AM	#9
SkinnyBoy Banned Join Date: Nov 2002 Location: Adelaide, Australia	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..

16th August 2003, 02:41 AM	#10
li_gangyi diyAudio Member Join Date: Jun 2003 Location: Woodlands Circle	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... __________________ Kids in the back seat cause accidents...Accidents in the back seat cause kids...

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