Combo amp Project - Noisy Cricket or Tiny Giant

[vigilante397]

Have you tested the Tiny Giant by itself? That's where I would start. And I would never object to pictures and voltage readings.

And as for the question about leaving out the regulator and preamp (which I kept thinking "I'll answer that when I have more time"), if you leave out the voltage regulator then you can omit the 120R and 1k resistors and the middle regulator pad is a good spot to be your new 12V input. As for the preamp you can leave off a bunch of parts (everything except the TDA, 2.2R's, 220n's, 22u's, 470u, and the 100n on the power rail) and put your signal in on the leg of the 1u that connects to pin 3, just like you said previously.

[PRR]

[Jebull]

Excellent!! Thank you!! Hopefully soon I can mess with it again between packing boxes haha

But yeah I have not tested it alone, I was unsure if that would work or be okay (or not incredibly loud) without the preamp.

[Jebull]

Okay, finally got to work on it some more! Update: I now have sound, but it is very quiet. While biasing the j201s, I get 0 at G of q3 and 12.35 at D of q4. Any idea what I have wrong here?

What other measurements would be helpful?

[Jebull]

It SEEMS to me like something is wrong with my sunn preamp, which is odd, because it worked fine before. All I did was resolder the output wire.. :/ hmm. Maybe I screwed something else up in the process.

[PRR]

[vigilante397]

Do you have an audio probe? I would recommend running through everything before the amplifier with an audio probe to make sure all the signal that's supposed to get into the amplifier is getting there.

[Jebull]

I do not! I've been meaning to make one for ages, ill try to do that when I get home!

Also, I added a jumper there PRR, that's what finally got me sound. Just incredibly quiet sound haha. So I've obviously still got something wrong somewhere. Maybe the probe will show me!

So I just need to follow the signal with it to see if it stops somewhere, and that would be where my problem probably is, correct?

Also just for more info: I couldn't figure out which 100n I needed on the TG board, so I just added both, could that somehow cause an issue?

[bluebunny]

Also just for more info: I couldn't figure out which 100n I needed on the TG board, so I just added both, could that somehow cause an issue?

There are three.  Having all of them probably won't hurt.  You could conceivably omit one of the two by the non-existent regulator (with Paul's short, they're equivalent).

Re-purpose the one you don't use in your audio probe!  All you need in addition is a 1/4" plug.   

[Jebull]

Ah, I may have added all 3. Either way I couldn't figure out which to omit and I'm not sure, I don't have it in front of me sadly but yeah that's not a bad idea! Hopefully I can work on it after work today!!

The way it's acting, it doesn't seem to be a problem with the Tiny Giant, it seems like it's the Sunn preamp. I have no idea though haha

[vigilante397]

So I just need to follow the signal with it to see if it stops somewhere, and that would be where my problem probably is, correct?

Exactly. It doesn't necessarily rule out anything after the point at which signal cuts out, but it's generally safe to assume that the circuit is good until you lose signal.

[bluebunny]

The way it's acting, it doesn't seem to be a problem with the Tiny Giant, it seems like it's the Sunn preamp. I have no idea though haha

You can plug a guitar directly into the TG.  This would likely rule it out.

[Jebull]

You can plug a guitar directly into the TG.  This would likely rule it out.

Ahh okay cool, that will be helpful! thanks!!