PLEASE HELP-240 wpc LM4780 DESIGN

240wpc lm4780

Yes you can parellel the two boards, mount boards directly together make sure of one common ground connection, connect your speaker outputs together as close two the output resistors as possible, same fore the inputs.
The Martins are a pretty difficult load to drive!!! the package dissipation of the lm4780 is 120w, taking in all the math that adds up to a SAO of about 80watts per package, DC offset can be a major incumbrance you can have an amp that sounds perfect but is wasteing 20 to 40% off its ouput power. I would check power out, DC offset ,idle currents ect..... just to make sure you are getting every bit of power to load.
DONT SKIMP ON HEAT SINKS

Use a DRV 134 from Burr Brown.

Go to their website and look at the application notes to see how to wire it up. You will need a +/-15 volt DC power supply to run the DRV 134. and simply connect one output to the left input of the amp, and the other to the right. and use your right positive speaker output as the "Bridged Positive" and the left positive as the "Bridge Negative" (yes, only the positives get used)

This will have the added bonus of giving you a higher input impedance, so your preamp won't be stressed out.

I used it to Bridge two pairs of LM3875s together. Here are some links below.

http://guerrillaaudio.com/store/bunker/BurrBrownDRV134LineDriverBridgingModule.html

http://guerrillaaudio.com/store/bunker/ParallelGainCloneAmplifier.html

I'm on this project as well, and the best way to do it is either a DRV134 or a dual opamp unity-gain buffer, one inverting and the other non-inverting. My monoblocks are completed and they work perfectly this way, with a 440 VA EI-core transformer.

As of now the amps are being driven by my delta 66 (which has a balanced output) and they sound awesome. Can't take the power above 3% (Yes, we can measure now) before my ears start to hurt from sound pressure.

the DIP is the regular 8-pin IC chip packages, both the others are surface mount, I would like to stay away from.

So it's the PA version you want.

technically there shouldn't be marked differnce between all three, choose the chip that suits ur needs, DIP or SOIC, one is through hole type chip and ther other is surface mounts both will have almost same noise character and same supply range.
Hope that fulfills ur querry.

get the 8PDIP one, that is what I used.

Get one for each stereo amp you plan to bridge.

Don't worry about some having 16 pins and some having 8. Internally they're exactly the same, execpt the surface mount chips are a little bigger for heat reasons since the DRV134 drives quite a heavy load. Surface mount packages usualy can dissipate less heat than their DIP counterparts, so an increase in area may have been needed to keep it within safe limits at short-circuit or full load conditions. The internal circuitry is the same, and there will be a lot of unconnected pins. So don't worry, use whatever you like.

The way it works is that almost all sources output voltage in one 'Direction' only, with reference to ground. For an amp to be bridged the two amplifiers need to see opposing voltages, so one amp is driven negative when the other is driven positive. The total voltage across the load then becomes twice the input signal + the amp gain.

The DRV134 takes an input signal, adds 6dB of gain, then supplies two outputs, one with the positive signal the other with negative signal (inverse polarity). Then these two outputs need to be connected the two amps, and the speaker connected to the output live terminals of the two amps (+ and + spkr outputs to + and - of the speaker). The speaker will not be connected to the ground at any time.

I'm using this scheme right now (as I said, I'm not using a DRV134 yet but am in the process, meantime using my soundcard with balanced output) and it works fine!

Dominick22 said:

Jason, Just to make sure I understand you correctly...

I will be taking 2 stereo amps wired in parallel which makes them two mono amps. Then I am going to use the DRV164 to bridge these mono amps according to you I think.

Is that what you are saying I can do??

Or are you just referring to a chip that bridges the stereo amp into a mono ONLY???

Thanks again,
Dominick

Click to expand...

If you do that you will be making one BIG mono amp, which is what I did with my 4 chip gainclone. 4 outputs, .22 ohm resistor on each positive output to force power sharing. now tie two outputs and inputs together. this results in two paralleled amps. now drive these two amps with ONE DRV 134.

on the other hand, if you just want two bridged amps, just drive each amp with a DRV 134.

Look at the BPA 200 and 300 threads for details.