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Author Topic: TDA7294?Help, please  (Read 7877 times)

mensur

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TDA7294?Help, please
« on: January 13, 2008, 07:21:47 PM »
Is it possible to run a TDA7294 as poweramp,and as a preamp Randall RG100ES preamp?
TDA7294 is a 100W(hifi)poweramp,can i use it as a guitar poweramp?
Here is the sch. of TDA7294:
http://bp2.blogger.com/_noz8x6lNwLk/R3tEkXwg_WI/AAAAAAAAASM/FK6KJDXfPIw/s1600-h/01.jpg

Thanx

n9voc

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Re: TDA7294?Help, please
« Reply #1 on: January 19, 2008, 03:13:00 PM »
Mensur,

(The following is my humble opinion, that and $5.00 will get you a cup of coffee almost anywhere.)
As with any chip amp, I believe you can use this as the power amp stage of a guitar amplifier.  However, with a closed loop gain of 30-35 dB (per spec sheet) you will need a pre-amplifier for this unit.  I do recommend putting a 10k Log pot right up front of the power amplifer stage to allow for easy adjustment of amplifer level.  I am unfamiliar with the pre-amp mentioned, but in my little world - an electron is an electron is an electron.
Couple-three of things to be aware of:
1)  The rated power will only be developed across the rated speaker load (in this case, 2.7 ohms)
2)  Be certain and have more than sufficient heat sinking on the chip - or it's "fried chip time".
3) The rated power can only be achieved with the rated power supply voltage (in this case +/- 40 volts)
4) Make certain that power supply can supply at least 2 times the necessary current needed to run the amplifier at full rated output. (100 watts out, 80 volts (+/-40), is about 1.25 ADC - I would not try to run this circuit with less than a supply that can produce +/- 40VDC at a current level of 3 amps minimum - try for 5). 
5) I do recommend a voltage regulated supply for this - ABSOLUTE maximum voltage for the chip is +/- 50 volts.

The data sheet for the chip can be found here: http://www.st.com/stonline/books/pdf/docs/1057.pdf

Finally, below you will find a suggested schematic to interface the output of the pre-amp to the TDA7924

Hope this helps!

mensur

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Re: TDA7294?Help, please
« Reply #2 on: February 25, 2008, 02:13:00 PM »
Than you very much,
Finally someone replayed,this is very helpful.
I will post what i did.