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.
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.
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.
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.
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.
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.
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
-Paul Hilgeman
nice 27 pin to220 case.
"what's the deal with 3 differenct cap values on the rails? "
-distance i think. i think the 1000 uF cap is more for supply decoupling, and the 10uf and 100nf caps would be located much closer to the chip then the 1000uF.
there is a section in the pdf http://cache.national.com/ds/LM/LM4780.pdf
about this. application info - supply bypassing. page 16 of 24.
the chip is listed as ready for samples. there is a demo PCB layout in the pdf file.
"what's the deal with 3 differenct cap values on the rails? "
-distance i think. i think the 1000 uF cap is more for supply decoupling, and the 10uf and 100nf caps would be located much closer to the chip then the 1000uF.
there is a section in the pdf http://cache.national.com/ds/LM/LM4780.pdf
about this. application info - supply bypassing. page 16 of 24.
the chip is listed as ready for samples. there is a demo PCB layout in the pdf file.
It is TO220 package, so no SMD stuff required. But i cannot do cheap two sided boards, so i have to redesign the PCB as single sided.
I did not get the samples directly from National (i did get samples direct from TI). They said i must ask local distributor. From the company list i find for example Farnell. Wish me luck ordering samples from there...
I did not get the samples directly from National (i did get samples direct from TI). They said i must ask local distributor. From the company list i find for example Farnell. Wish me luck ordering samples from there...
got my samples today... p2p I DON"T THINK SO!!! the chip is abit bigger than the LM38**'s but there is twice as many pins, they are thinner, and smaller together... anyway designing a PCB? 
would I be able to bridge the amp into a 4ohm speaker with +-25volt rails? I need 80 - 120watts from +-25 volt rails.. hmm.. lol
would I be able to bridge the amp into a 4ohm speaker with +-25volt rails? I need 80 - 120watts from +-25 volt rails.. hmm.. lol
Using a LM4765
I'm using a LM4765 - sister chip to the LM4780 with 30Wpc for a whole home audio system where I use these as local amps for each room controlled by a touchscreen. When I prototyped these up last year using 1000uF power supply caps I was very pleased with the sound quality, it was able to reproduce dynamics better than my much more expensive DIY discrete MOSFET amp. The design uses the non inverting mode, when I tried inverting I could not stabilise the amp although I suspect trying this on breadboard was not optimal.
Dean
I'm using a LM4765 - sister chip to the LM4780 with 30Wpc for a whole home audio system where I use these as local amps for each room controlled by a touchscreen. When I prototyped these up last year using 1000uF power supply caps I was very pleased with the sound quality, it was able to reproduce dynamics better than my much more expensive DIY discrete MOSFET amp. The design uses the non inverting mode, when I tried inverting I could not stabilise the amp although I suspect trying this on breadboard was not optimal.
Dean
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