100W+ amp needed desperatly!

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Elkaid

Elkaid

Member
Joined 2003
Ok i've tried to build a tda7294 based amp using 2 different pcb's and all i got is to burn 3 of these IC's. I need a 100W amp which uses a 60+60V PSU
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In fact, the TDA7294 is +/-50V when no signal is applied. It's +/-40V Max when signal is applied.

Last time I played with TDA7294, I had to unwind my 30+30V toroidal transformer because once rectified/filtered, the supply was too high and the chips were blowing up.

TDA7294 has a little brother with slightly higher specifications. The TDA7293 can go up to +/-50V with signal applied.
According to the datasheet, you'll get 100W for a 8ohm load with a 10%THD. I would go for 80 Watts instead in order to keep THD value at an acceptable level.


If you absolutely need 100W+, maybe you should consider for bridged/parallel LM3886 amplifier. National semiconductor has a whitepaper describing it.
AN192

However, even the amplifiers described in the application note cannot withstand +/-60V
 
M

Minion

Member
Joined 2006
Why Not just drop the +/-60v Idea and Build PSU of more reasonable Voltages to run a Chip amp?? Or maybe you can Mod your PSU to put out lower Voltages....

If you don"t want to drop the +/-60v idea then you will most likely have to drop the Chip amp Idea and go for a Discrete Solid state amp useing BJT"s or Mosfets which should allow for a +/-60v PSU.....

It is sad But True.....



:D
 
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hernanstafe

Member
Joined 2007
well i'm trying to find a solid state amp, i seriously don't care about the amp type (chip, solid state, etc) i just want it to work properly. The PSU is made using a 110V transformer, with a "fake" ground rectifier to have about 70 +70v...i wonder if i can like downgrade the voltage to 50+50? i can think of resistors but they'll be HUGE! I don't have any other transformers to do a better psu around, so i have to fix the problem with that one
 
A

AndrewT

R.I.P.
Joined 2004
hernanstafe said:
...........The PSU is made using a 110V transformer, with a "fake" ground rectifier to have about 70 +70v...i wonder if i can like downgrade the voltage to 50+50? i can think of resistors but they'll be HUGE! I don't have any other transformers to do a better psu around, so i have to fix the problem with that one
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if this is a single secondary transformer than buy a dual secondary transformer.
A "fake ground" sounds like you are using some kind of passive/active rail splitter to generate a dual polarity supply.
This is very unlikely to work for a power amplifier. The Power amp must see a low impedance on it's ground connection and that ground connection must also be capable of sinking sourcing the peak current of the power amp, even in fault conditons.
If I have read "fake" correctly then I fear your proposal is doomed.
 
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