PLEASE HELP-240 wpc LM4780 DESIGN

[Dominick22]

I just bought 2 LM4780 Mono Kits from Peter Daniel at Audiosector.com. Thats 4 chips total.

My goal is to create two Mono Amps that each contain two chips wired in Mono. So essentially, EACH SPEAKER will individually recieve 240 watts.

I just finished a single LM4780 kit (120 watts/2 channel)and it works great so I am familiar with the chips and how to wire them in Parllel. Now I want to bring 2 chips wired in parallel together!

I am not sure how to wire this however. Each Mono Amp will be running off of a dual 25 volt 330 VA torroidial transformer from parts express.

So how do I bring the Mono signals together through wiring? I am guessing that I could wire them in parallel again and then just bridge the two amps together somehow???? Would that work??

If it is right...does anyone have a clear schematic or explination on how exactly the wires need to be connected??

In case you are wondering why I need so much power, I will include a link to the speakers I am trying to push. Check out the Ohm load! 1.2 at 20K
http://www.martinloganowners.com/~td...hread.php?t=95

Is it as simple as using a sig out to from one amp and the sig in form other?? I would think that only one board is pushing current in this configuration??

Peter is a big help, but I already ask him too many questions!LOL
Please Help with these monsters!

Dominick in New Jersey

[tiltedhalo]

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

[Dominick22]

I am not sure that you understood my question.

I already made dual mono lm4780 amps that put out 120 watts each! They sound great!

I am looking to now combine the same type mono amps to produce 240 watts into ONE channel! Not 120 into 2 channels.

So in total, I will have 480 watts into the two main speakers.

I just dont know how to wire this. What do I change to bridge the two parallel Mono amp boards??

Thanks,
Dominick

[jasonva]

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/bunk...ingModule.html

http://guerrillaaudio.com/store/bunk...Amplifier.html

[sangram]

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.

[Dominick22]

OK--thanks guys,

I will buy the DRV134...But there are three that Burr-Brown makes!?????

Which one do I want for this project?
Pricing/Packaging/CAD Design Tools/Samples
Price Packaging CAD Design Tools Samples
Device Status Budget Price ($US) | QTY Industry Standard (TI Pkg) | Pins Top Side Marking Standard Pack Quantity Symbols Footprints Samples
DRV134PA ACTIVE 1.95 | 1KU PDIP (P) | 8 View 50 View View Request Free Samples
DRV134UA ACTIVE 1.95 | 1KU SOIC (DW) | 16 View 48 View View Request Free Samples
DRV134UA/1K ACTIVE 1.95 | 1KU SOIC (DW) | 16 View 1000 View View Purchase Samples

That may not have come out so well... Here is the link to Burr Brown.

http://focus.ti.com/docs/prod/folders/print/drv134.html

THanks,
Dominick

[sangram]

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.

[abid_rehan]

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.

[Dominick22]

I dont understand...One chip has 8 pins while the other has 16???

To bridge two mono amps, which do I need? They both carry the name of DRV164??

THanks,
Dominick

[jasonva]

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

Get one for each stereo amp you plan to bridge.