TDA2822M based bench amp: advice please

[JFX09]

For those about to binge on egg nog, I salute you

well, I finally have some quality time with my bench ahead of me and been wanting a little bench amp for a while.

I gutted some computer speakers and have a TDA2822M amp on the pcb with speaker connection and what looks like an input : red that goes to R, white that goes to L and black that goes to G.  So I put this thing on my protobard to test. It powers up nicely and the little led lights up. But I can't get anything to be amplified, the speaker goes  sshhh, no matter what.

I wired it red to tip, black to ground, white to nothing. I'm sure it's got to be something super obvious and you can all have a good laugh on my behalf, help yourselves , my treat

But let me know what it is, pretty please.

thanks in advance

[petemoore]

  How was it working before the jack was connected ?
  Have you tried the thumbuzz [only recommended for low voltages] test on the white wire and everywhere?
  There has to be an input that'll razzle the speaker somewhere.
  Also test for ground / resistance to Gnd. on the input signal wire.
 

[JFX09]

ok, it now seems to work. I have joined the white and red and also added a booster. So, I guess it's just a matter of it being not very powerful? I use the tiny speaker that came with the amp. I remember this to be way louder though. Is this where the bridging part comes in ?


Thanks for your time peter

[JFX09]

ok, when I feed a synth, I don't need a booster to hear it. Is the the result of impedance, the guitar loading the circuit ?

thanks

[petemoore]

   I imagine the synth has lower output impedance than the guitar.
  and that the synth puts out higher voltage AC signals than the guitar.
  The input impedance was mattering and the voltage output of the source too.
  I would 'fix' to where it doesn't matter, or determine the input impedance of the amplifier, perhaps there is diggable data for that model #.

[frequencycentral]

Sounds like what you have there is a line level amp - you will need a preamp too for guitar use.

[cab42]

I'm also working on an amp based on a tda2822. I got it from my daughters  broken toy microphone stand with build in amp and speaker.

I'm going to rehouse it with a new speaker and a better microphone for her. Testing it with a guitar cabinet, its pretty loud.

I did not bother desoldering the chip and make a new amp as it is setup exactly as the test circuit in the data sheet (bridged version).

I just need to find a suitable speaker. All the smaller speakers I have tried are no good and a guitar cabinet does not sound very good for singing.

Any tips on what to look for?

Regards

Carsten

[JFX09]

well, it works all right now. I guess I underestimated how much of the cabinet empowers the speakers, put them in a little wood box and bam. But yeah, it's a line level, so having a pedal in front is mandatory for guitar use, but i'll be using it as a bench amp and I debug with a synth, so it's all nice and dandy.
Thanks for you input guys.

ps: Carsten, I use the crappy speakers that came with the amp so I can't really help you here. But yeah, they sound crap allright. but all I need is a debugging amp that cant go TOO LOUD when something goes wrong