Current draw with 9v Amp32

[Greg]

Just finished the last few things off and tested ... in sleep mode .286mA and 52.9mA awake, does this sound about right with 9v battery [?], I'm using 500mA fast blow fuse (could find slow blow in the right value).

I only have my good Aria bipole with CSS WR/FR125 full range speakers at the moment, no cheap test speaker, it read .02 / .05v DC at the speaker outputs does sound about right [?]

No input connected

Thks Greg

[V-bro]

Looks good, you can protect your speakers with some very large capacitors. If you use bipolar 100uF caps or larger (don't use electrolytic caps!) you can protect your speakers against DC. This does degrade the audio quality, but is good for testing purposes.



------X-max. can be several meters on any driver, too bad it can be done only once...------

[Greg]

Thks V-bro,

Looks like a restless night and a long day tomorrow until I test this thing with music ... to late to play now 11:20pm fresh mind tomorrow after work ... fingers crossed

Greg

[Greg]

Well got it going seems ok on output 2 but starts to break up if I up the volume to 30+ (max is 50 = 37mw I've used 22/47k combo)

Output 1 had to crank the volume up more than double to get any volume, re-soldered the speaker outs no change to 2 but 1 is worse now.

Also should the LED be on when playing [?]

Greg ...

[V-bro]

Led should be absolutely on...

Can you show some very detailed pics of the top and bottom?



------X-max. can be several meters on any driver, too bad it can be done only once...------

[Greg]

No ... no camera anymore

At least I don't need to worry about the LED

Would you think that volume from MP3 would clip the input [?] didn't seem that loud.

Greg

[V-bro]

It should be louder than expected from such a small amplifier.

Here's what it says about gain in the chip datasheet:
"TA2021B Amplifier Gain
The gain of the TA2021B is set by the ratio of two external resistors, Ri and Rf, and is given by
the following formula:

Vo/Vi=-12*Rf/Ri

Where Vi is the input signal level and Vo is the differential output signal level across the speaker.
Please note that OUTP1 and OUTP2 are 180 out of phase with their corresponding input
signals.
20 watts of RMS output power results from an 8.944 Vrms signal across a four-ohm speaker load.
If Rf = Ri, then 20 Watts will be achieved with 0.745 Vrms of input signal."

With the resistors you used you should get 20W output from about 0,4Vrms input. Most MP3 players are capable of giving this...

------X-max. can be several meters on any driver, too bad it can be done only once...------

[V-bro]

It seems to me like you've got some bad soldering...I would have another good look at it, maybe give the chip another go with some extra flux...

------X-max. can be several meters on any driver, too bad it can be done only once...------

[Greg]

Well once again V-bro suggestions paned out ... I re soldered the chip ... and now have music from both channels ... still cracks and pops at higher volume but I only have it wired for testing hopefully once in a case and all is finalized it will be ok, and driving 8omh spkers with 9v battery isn't helping.

Thks again V-bro for your help

Now I have to decide on a case

Greg ...

[V-bro]

The cause is the 9V battery...it doesn't have enough peak current capability....

Have a look at hammond, eddystone or multicomp cases, they're very nice for the price...you can give a custom look by adding a nice thick aluminium front plate

------X-max. can be several meters on any driver, too bad it can be done only once...------