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-   -   TDA7294. . . help! ;) (http://www.diyaudio.com/forums/chip-amps/121272-tda7294-help.html)

danielwritesbac 13th April 2008 10:56 AM

TDA7294. . . help! ;)
 
Hi, I'm making a circuit board for the TDA7294. . . in barely over an inch of space. The question is about the mute and standby circuits and what is the minimum support necessary to operate them.

ST mentions that they are two, seperate cmos operated switches. Okay.

On the bridge application chart, the ground returns for these two switches, pins 1 and 4, are shown jumpered together. That's half a clue.

The mute and standby, pins 10 and 9, do function if they are jumpered together. Now, the support can be providing them power with a single 10k resistor--eliminating a huge mess.

Despite that being undocumented, the amplifier has been running this way for 38 hours so far. There are no clicks, pops, burps, or noises at power on or power off.

Here's the question:
The amplifier "seems" to sound slightly different that way, than if two seperate resistors are used to feed power to pins 10 and 9. I can't measure that. Does anyone have any news on it?
Thanks!!

EWorkshop1708 13th April 2008 05:24 PM

It makes no difference. However, if you want to eliminate clicks and pops on startup/shutdown, you would ground the mute lead before turning amp on/off with the standby lead. You don't have to run them apart though. Connecting them together, and powering them at the same time is fine.

danielwritesbac 14th April 2008 07:14 AM

2 Attachment(s)
Quote:

Originally posted by EWorkshop1708
It makes no difference. However, if you want to eliminate clicks and pops on startup/shutdown, you would ground the mute lead before turning amp on/off with the standby lead. You don't have to run them apart though. Connecting them together, and powering them at the same time is fine.

It makes no difference? Oh, that's good news. So the slight audible difference that I observed between these two can be assumed to be an audible difference of the power circuit (removal of RC networks from the power circuit)--and not caused by the mute and standby switches themselves?

How do you like this circuit then?
Edit: its for double-sided PCB

danielwritesbac 19th April 2008 06:58 AM

Hey, did you guys know that this thing gladly does 100 watts?
I gave it a 4 ohm load, and, welll!!


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