LME49810 1200RMS into 8 ohms amp possibility? - diyAudio
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Old 26th October 2012, 07:05 PM   #1
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Default LME49810 1200RMS into 8 ohms amp possibility?

Is it possible to build a 1200RMS into 8 ohms power amp with lme49810? what are the things to be done to the existing sample schematic from National? one of my friend wanted it for PA purpose but he wanted good class AB..
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Old 26th October 2012, 07:22 PM   #2
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I will give you some home work:

How many volts can you feed LM49810 with?

How many volts do you need for 1200 W into 8 ohm?
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Old 27th October 2012, 07:03 AM   #3
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200v max for the lme49810
if the output voltage is 100 then we need 12 amps to get 1200watts..

considering v=IR so for voltage of 100 i= 100/8 = 12.5amps..
P=IV makes 12.5 x 100 = 1250watts
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Old 27th October 2012, 07:28 AM   #4
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Almost right. 100 V peak is 71 V rms = (71*71)/8 = 625 W!

Notice that you should have maybe ±70-80 V max as supply voltage. The difference between 1200 and 625 watts is only 3 dB, mind that.

Have you checked that prices for new or used PA amps? They are not particularly expensive.
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Old 27th October 2012, 11:09 AM   #5
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so how many output transistors is required to get that much of power?
can I have more max supply voltage like 100 or more?

i am thinking of using this one or build everything from scratch...
Connexelectronic

if im using two of this modules then can I use them at 2 ohms?
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Old 27th October 2012, 11:12 AM   #6
jaycee is offline jaycee  United Kingdom
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If you really want 1200W RMS, you do not want class AB. At the very least you want Class G. Really you want Class D.

You won't be able to build anything as cheap as you can buy it, unless you're recycling parts.

edit: No, those modules will not work on 2 ohms, especially if you were driving them bridged. Either protection circuitry would activate, or you would burn them out as each one would see a 1 ohm reactive load. There are not many amps that will drive such low loads.

Last edited by jaycee; 27th October 2012 at 11:19 AM.
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Old 27th October 2012, 11:31 AM   #7
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Maybe you should consider 2500 watts module?
http://www.hypex.nl/docs/UcD2kOEM_datasheet.pdf
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Old 27th October 2012, 01:15 PM   #8
AndrewT is offline AndrewT  Scotland
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Typical of the many questions asked by R.
He has not got a clue and despite many Members coming in with assistance, R appears to have learned nothing.
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Old 27th October 2012, 02:01 PM   #9
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Quote:
Originally Posted by rhythmsandy View Post
i am thinking of using this one or build everything from scratch...
Connexelectronic
I work with electronics since decades back. I think that it requires high competence to design a good 1200 W 8 ohm amp. This is nothing I would do with my left hand exactly.

My advice is to look for a couple of used PA amps.
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