Amplifier noise

[bogdan_borko]

It's good thing you haven't burned the transformers... Now is all good?

 

[Sancho49]

I'm back with some news of the build of my dual mono PSU F7
First, Thank You for you many replys !

I've remove the "short" between the two transforers, and ... yes , now no vibrating transformer, but 50hz noise still present on speakers.

With no input connected : 50hz Noise ~ -30db

With input connected (Fictive Load) : 50Hz Noise ~ -40db

I've try to remove the RFI/EMI Filter, same problem.

Any idea to resolve this issue ?

 

[Bonsai]

Ok. 1st step to solve is what is causing the hum. With no input plugged in does it hum?

 

[Sancho49]

Hi Bonsai
Yes, without inputs plugged, humm on the output.

 

[Bonsai]

Please click on the Ground loops link below. Towards the back of the presentation is a debug process you can follow (not exhaustive but will point you in tne right direction).

Look carefully at the ‘how to do it practically’ section for wiring up.

Is this a dual mono design BTW?

 

[synonymous]

Look into possibly using input transformers in your design.
They work wonders
S

 

[Bonsai]

Correction - I see it is a dual mono design.

How have you connected the amplifier side to the chassis?

 

[Sancho49]

Bonzai,

The connection to the chassis is make by the IEC connector (Earth)

No connection between amplifier and chassis.

And yes, it's a dual mono

thank you for the link about Ground Loop ! I read that

 

[Sancho49]

Bonzai

If I add TWO ground loop breaker (connected between 0v PSU and Chassis Earth) this for both PSU (Recall it is a Dual Mono Power supply) ?

 

[Sancho49]

Bonzai

If I add TWO ground loop breaker (connected between 0v PSU and Chassis Earth) this for both PSU (Recall it is a Dual Mono Power supply) ?

 

[Sancho49]

I've adding CL60 between 0V and PE for the two power supply, and ... IT'S OK
Silence .. and sweet Music
Thank you again community ( And Bonsai !!! )