anybody tried a LM4780?

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Well, I gave it a try and it's pretty easy to P2P even with conecting all the voltage pins, I did however, snap of the NC pins. I'll just finish wiring it up and put together a couple of regulators for it and see how it works.

It's a nice little chip, having everything compact and all, but I wish they wouldn't include that mute feature...
 
Yup, bent a couple, but the trick is not to bend them at the base. If you bend them too much at the base they'll just snap right off. I bent a couple at the base just slightly to get easy acess on the underside to solder the feedback resistors to, but none others. Well, I'm gonna try and finish it off tomorrow mostly and I'll get a few pictures up, just to show it's not so hard to P2P these suckers... ;)
 
Well, I P2Ped the sucka and it worked out fine, easier than I thought, but it's not too pretty (but still, not as bad as I thought). I built the voltage regulators for it and mounted all this on the heatsink, all that's left if an equlisation and motion feedback circuit since half the amp will power a woofer (biamping, one LM4780 per speaker).

I've got an almost identical circuit built with LM3875s, so once I get a chance I'll compare the sound to those. Sorry about the pictures, it's not finished enough for me to "show off" :( heh
 
grrr...... +-38 volt rails is too high for these chips to run 4 ohms... hmm.... I guess there would be 1.2 volts drop due to the bridge, so its 36.8 volts.... say 37 volts, but thats still too high... I wonder how much the transformer voltage will drop under load... I am however planning on using 9400uF per chip, per rail..... hmm... my transformers are really underpowered for the amount of power I could expect with these high voltage rails... and I'd rather not parallel the chips... I'm looking at 750VA of transformers.. for 4 of these amplifiers ICs... so 8 channels... should be able to get 120watts of music power per channel I guess.... anyone have anything to say about the high voltage rails?? thanks.. :)
 
see... the idea is to run each of my towers off of 2 channels... (so, one woofer and tweeter off one channel, and the other woofer and midrange off the other channel) and then bridge/parallel the other 4 channels to run a 15inch, 4 ohm subwoofer.. :) I would like about 100 watts per 8inch woofer, and the subwoofer should be getting like 400watts... lol (its rated at 250, but who really cares) thats the idea.... what do ya think? :) the 15inch won't be able to keep up with 4 8inches for SPL... but that doesn't really matter.. :)
 
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You could always try half-wave rectifiers. That will definitely drop your rails. They will also need to be smoothed extensively, and will be not very efficient.

*Incomplete sentence deleted at request of poster* :cop:dhaen

I got my samples today, 3 4780 and 2 4781. I already have some 4766 from a previous order, now I can get down to business and design my HT amp, using just one of each chip. 4766 for the fronts, 4781 for the center and rear, and 4780 for the sub. 30-32 volt rails throughout, and just one transformer. Should be enough for a decent HT setup.
 
what is the complete schematic fort he P/S. and why 4ohm speakers? IIRC most of the 47xx line doesn't appreciate 4ohm loads as much as the 38xx line. and it also makes a BTL subamp just that much harder.

that miniPCB idea of mine hasn't been milled yet. but it's a PCB thats' like 1.5" by 0.5" or so. the +V pins are all connected as are the -V.
 
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