hI,
I am building a TDA7294 AMP. Help me on DC volt limit. I have a 35 0 35 rail and after regulated it gives +47 0 -47 v. May I use it for 7294??
Thx
I am building a TDA7294 AMP. Help me on DC volt limit. I have a 35 0 35 rail and after regulated it gives +47 0 -47 v. May I use it for 7294??
Thx
Hi!
In practise, I would not go to the maximum limits of a TDA7294. For a stable operation, I would recommend a transformer with 22-0-22 V rails for both 8 ohm and 4 ohm loads, and perhaps 25-0-25 V (up to a mximum of 30-0-30 V) for 8 ohm speakers only.
But that's quite allright. I build amps using TDA7294 and TDA7293 and these chips do perform very well with a 22-0-22 V transformer (around +-30V after rectification and smoothing caps).
Regards - martin
In practise, I would not go to the maximum limits of a TDA7294. For a stable operation, I would recommend a transformer with 22-0-22 V rails for both 8 ohm and 4 ohm loads, and perhaps 25-0-25 V (up to a mximum of 30-0-30 V) for 8 ohm speakers only.
But that's quite allright. I build amps using TDA7294 and TDA7293 and these chips do perform very well with a 22-0-22 V transformer (around +-30V after rectification and smoothing caps).
Regards - martin
No.
The TDA7294 cannot operate safely with such high rails, it is specified for maximum operating voltage of 40V in high-efficiency mode or 35V in Class AB (normal) mode.
Since you have a regulated supply, I would advise you reconfigure the regulators to 35V rails. This should be relatively simple.
The TDA7294 cannot operate safely with such high rails, it is specified for maximum operating voltage of 40V in high-efficiency mode or 35V in Class AB (normal) mode.
Since you have a regulated supply, I would advise you reconfigure the regulators to 35V rails. This should be relatively simple.
Ive got a TDA7293 running off of +/-42v DC and it runs fine but I believe it is the upper limit that the chip should be run at , I"m running my next Stereo TDA7294 off of +/-34v DC .....
CHeers
CHeers
I want to build TDA7293, how to use the Clip detector with LED? just simply add a resistor and LED?
for mute and standby function, should it be powered from external supply(low voltage) or connect it from the +Ve main power?
for mute and standby function, should it be powered from external supply(low voltage) or connect it from the +Ve main power?
For safe operation I changed the rail as per the advice and it works fine now with 25 0 25 rail. Sounds good.
If anybody have a nice mosfet or transistor circuit which is very stable with 35 0 35 rail (DC RANGE OF 50 V).. I want to build a subwoofer amp..
thx..🙂
If anybody have a nice mosfet or transistor circuit which is very stable with 35 0 35 rail (DC RANGE OF 50 V).. I want to build a subwoofer amp..
thx..🙂
My TDA7293 have +/-35V rails without any problem and the St.By/Mute is connected to +35V.
If you dont want a plastic box TV sound (Schematic in data is made for that use) :
replace the 22uF between 680 Ohm and ground by a jump and increase the 22uF bootstrap cap to a good 220uFcap (Elna Silmic)
Philippe
If you dont want a plastic box TV sound (Schematic in data is made for that use) :
replace the 22uF between 680 Ohm and ground by a jump and increase the 22uF bootstrap cap to a good 220uFcap (Elna Silmic)
Philippe
Tda7293 and TDA7294
I have over 7 years built amps with these chips and my suggestion is to use power supply with not over 34 volts per rail.For bridge application i used phase-turner with opamps and the power i got was higher than with manufacturers suggestion (see the datasheet,it`s not good solution).With +/-
34 volts power supply (+15000 mkf ellytes per rail) i `ve got starting limiting sinus at 32 volts rms on 8 ohms.Remember that 0,1-0,5 mkf capasitors on power supply are needed as near as possible to chip to avoid self-oscillating and for low thd.Heatsink i use is allways with bigger surface area than suggested and allways with automaticaly powered ventilator.Never burned
any chip.And allways satisfied with sound.
Regards,
Hannes from Estonia..
Hi,there somwhere!
I have over 7 years built amps with these chips and my suggestion is to use power supply with not over 34 volts per rail.For bridge application i used phase-turner with opamps and the power i got was higher than with manufacturers suggestion (see the datasheet,it`s not good solution).With +/-
34 volts power supply (+15000 mkf ellytes per rail) i `ve got starting limiting sinus at 32 volts rms on 8 ohms.Remember that 0,1-0,5 mkf capasitors on power supply are needed as near as possible to chip to avoid self-oscillating and for low thd.Heatsink i use is allways with bigger surface area than suggested and allways with automaticaly powered ventilator.Never burned
any chip.And allways satisfied with sound.
Regards,
Hannes from Estonia..
It'll work on +/-42v but use only 8 ohm speakers if you choose such a high rail voltage. Bridge mode is also out of the question.
Larger value bootstrap cap
So using a larger value bootstrap cap is an improvement. With say 30 volt rails, how much voltage will it see?
I was thinking about raising it to 47 ufd. But 220 ufd caps at 35 volts are not that large.
My experiance is the LM chips are cleaner sounding. But that is with 22 ufd bootstrap caps. It do put 22 ufd FM right on the power pins to ground and a 0.04 ufd rail to rail. This is in addition to decoupling that is a short distance away.
George
So using a larger value bootstrap cap is an improvement. With say 30 volt rails, how much voltage will it see?
I was thinking about raising it to 47 ufd. But 220 ufd caps at 35 volts are not that large.
My experiance is the LM chips are cleaner sounding. But that is with 22 ufd bootstrap caps. It do put 22 ufd FM right on the power pins to ground and a 0.04 ufd rail to rail. This is in addition to decoupling that is a short distance away.
George
for the bootstrap cap, I measure the voltage on it, it's only half of the supply rail, I use 100uF/25V for +/-35Vdc. It's a small cap isn't it...😉
No, not really. It has a max voltage input of +-40V under load. I would recommend using what I used:
24-0-24 3A or more transformer. After rectifying the ac and with the appropriate filter caps you should have a nice +-36V
24-0-24 3A or more transformer. After rectifying the ac and with the appropriate filter caps you should have a nice +-36V
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