New Sure TDA7492

[rikkio]

recently I ordered this amp sure to electronics.

2 X 50Watt Class D Audio Amplifier - TDA7492_Special Offer_Sure Electronics' Webstore

In the past I had a customized (reduced input resistance) TA2024 and TA2020 in my boombox.
Given the small price difference, I have now chosen an amplifier in a cabinet so that I can easily swap it different setups.

On my laptop its fine, but on my ipod the power is dissappointing.

Unfortunately, there is no schematic online. Mail to Sure Electronics not been answered (yet)


http://imageshack.us/photo/my-images/705/adsc06250med.jpg/
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Anyone know if it is possible to reduce the input gain (reducing a resistor) to increase power?

advice is greatly appreciated.

 

[rikkio]

Schematics

The guys at Sure Electronics send me the schematics after some mail traffic.

With the TA2024 I had to lower the resistor in front of the line-in to the processor from 20k to about 6k.

I have looked for resistors in front the processer. C25 C26 seemed logicalI to me. have resistors c25 and c26 lowered from 10k to 5k but that did not work.

Still trying to figger it out.

here's the schedules they sent me,

 

[Mooly]

Its in the data sheet for the TDA7492

 

[rikkio]

I think that datasheet belongs to this amplifier

2 X 50Watt Class D Audio Amplifier Board - TDA7492_Class D Amplifier Board_Audio Amplifier and other Audio Boards_Audio_Sure Electronics' Webstore

discussed in this topic

http://www.diyaudio.com/forums/clas...board-adding-standby-volume-pot-bass-amp.html

i can't find any switches on my board
or am I wrong?

thanks

 

[rikkio]

Or did you mean

"the gain is set by changing the feedback resistor of the amplifier" ?

I'll have to find de feedback resistor

 

[Mooly]

You have to measure the logic level on pins 30 and 31. It is possible that yours is already running at the maximum gain if both those pins are at 3.3 volts. If you need still more gain then you are going to have to add a simple gain stage (preamp) in front of the amp.

 

[Saturnus]

Or did you mean

"the gain is set by changing the feedback resistor of the amplifier" ?

I'll have to find de feedback resistor

There is no external feedback resistor. The feedback resistor is set with the gain pins (pin 30 and 31) as mentioned above. It's in the chips data sheet.

 

[rikkio]

That did the trick!

Gain pin 30 en 31 where at 0 Volt.

VDDS at 3.3 Volt.

Gain pin 30 was connected to the Ground through 0 (!?) Ohm resistor (nr. R6).
I removed this resistor and shorted the Gain to VDDS throug (nr. R10) which was blank.

The amplifiers power increased a lot using the ipod.
Maybe even more of I do the same trick with pin 31 which is called Mode instead of Gain2 in de schematics.


Thanks Mooly and Saturnus

 

[52592]

photos

Just to add a couple of photos of the fix for lowest gain / low volume problem on this board - see attachments.