Wiring Amplifiers PSU

[Stinger]

Hi guys,
I've build a speaker for my notebook using three TDA2030's. With one amp connected to the PSU the sound quality is very good, but the quality drops as I connect other two amps to the PSU.
It gets hum...noise.
Could you plaese guide me how to wire multiple TDA2030 amp boards to a single power supply?

Thank you in advance,
Stinger

 

[Rainwulf]

What current capacity is your power supply?

 

[Stinger]

What current capacity is your power supply?

3A 12V-0-12V

 

[Rainwulf]

Sounds like something isnt wired correctly.

Do you have a circuit diagram?

 

[drummer_Dave]

do the other two amps work if you just connect them individually?

Dave

 

[Stinger]

I don't have any at the moment. But I will draw one asap I can in a few days.

regards!
Strynger

 

[Stinger]

do the other two amps work if you just connect them individually?

Dave

Yes, Each amp is working with no problem, If it's connected individually.

 

[Stinger]

Here's a digram of my wiring:

As you see each amp has two grounds. one is for signal-gnd and the other is for decoupler and bypass capacitors.

Where's the problem with my wiring?

I have another question about the diode pole;
Can they cause any problem?

 

[Stinger]

An externally hosted image should be here but it was not working when we last tested it.

 

[Rainwulf]

no picture there...

 

[Stinger]

no picture there...

Sorry, but I can't see my post for several hours...

 

[Rainwulf]

Responded to your email.

Do you have a diagram of the actual modules?

 

[Stinger]

I don't know much about electronics. I'll draw a schematic asap.

Thanks for the reply!

 

[Rainwulf]

You didnt include signal wiring in your diagram you sent me either.
I think you have some earth loops.

When you say its not as good, what degrades?
Do you get more noise? less volume? Hum?

 

[Stinger]

Here's a sample sch of my amps; all have two grounds:

There's a little Hum at my speakers, especially the subwoofer.

 

[Stinger]

You didnt include signal wiring in your diagram you sent me either.
I think you have some earth loops.

I'll draw a signal wiring diagram too. maybe the problem is there!

 

[Rainwulf]

Definately sounds like earth loops.

You signal coming in will consist of two wires, earth and sig.

Disconnect the signal earth from your star mains earth, and connect it to the signal earth coming in.

Thats how i got zero hum in my amp, and i have 6 modules, with 2 different power supplies!

Also your power supply, is it regulated? What size filter caps do you have?

 

[Stinger]

Thank you very much!

Done; No Hum at all!

Ther's still a little Hiss sound at the moment; Is that normal?

 

[Rainwulf]

Do you get the hiss with the signal line disconnected?
It could just that amp module may hiss a little bit.

One of the reasons i love LM3875 chips, sooooo little hiss its amazing.

 

[Stinger]

Yes, Without connecting signal... .The hiss is not much, So it's normal.
Anyway thanks for your helps!

Best regards!
Stinger