De-Lite grounding

[Puffin]

It hums with or without source connected and it hums if the input is grounded.

 

[Puffin]

^ second that. Also, are your audio input cables not screened? Looks like 2 individual wires, but I could be wrong...

They are single wires. I have made many amps and never used screened cable and never had a hum problem. As this sounds like 50/60Hz hum, would screened cable make any difference?

 

[cochleus]

Try positioning the tx facing up instead of toward the circuits.

 

[Lazybutt]

Just as long as the wire isn't passing too close to the xformer magnetic field. In my case it was only a matter of about one inch farther away from xformer. I have an F2J clone.

Exactly same experience here!
I had hum on an F2J clone. The amp is dead silent when moving the Transformer about 1 or 2 inches back, or by turning it a few degrees. It can be tricky as the "silent zone" is very slim .. just a few degrees wide.

Fred

 

[stefanobilliani]

Hi there ,

How is your capacitance filtering bank ?
In that amp I needed 150000 u F for a good S/N ratio ( almost unaudible ) .

 

[Puffin]

Exactly same experience here!
I had hum on an F2J clone. The amp is dead silent when moving the Transformer about 1 or 2 inches back, or by turning it a few degrees. It can be tricky as the "silent zone" is very slim .. just a few degrees wide.

Fred

OK, I will give it a try.

I built a Pass F2 using Peter Daniels board. The tx was orientated as normal (on floor of case) and there is a lot of air around it as the case is a lot bigger.

Rob.

 

[Puffin]

Hi there ,

How is your capacitance filtering bank ?
In that amp I needed 150000 u F for a good S/N ratio ( almost unaudible ) .

About 18,000uf per channel. I didn't want to spend zillions on caps only to find that the amp sounded crap. 100v caps are expensive (mind you so were the nice heat sinks) Nelson's schematic shows 25,000uf.

 

[Puffin]

http://www.diyaudio.com/forums/diya...udio-component-grounding-interconnection.html

Blimey, loads to read. I always hope for the simple fix

 

[cochleus]

The amp is dead silent when moving the Transformer about 1 or 2 inches back, or by turning it a few degrees. It can be tricky as the "silent zone" is very slim .. just a few degrees wide.

Instead of changing tx location perhaps just rotating will do the trick.

 

[Puffin]

OK, have put the tx outside the case and what I would consider is a reasonable distance. Result - the same....Hummmmmm

I re-routed the cable from the tranny to the bridges, but no fix.

 

[tauro0221]

Hi,
Attached it is drawing of the star ground that I used to fix a hum problem in my amplifier. It may help you fixing your problem.

 

[cochleus]

Well, if no change at all in buzz after moving tx then at least that is one thing you can cross off the list.

 

[Puffin]

Well, if no change at all in buzz after moving tx then at least that is one thing you can cross off the list.

Yes, i'll try anything!

Thanks for your input.

 

[Puffin]

Hi,
Attached it is drawing of the star ground that I used to fix a hum problem in my amplifier. It may help you fixing your problem.

Yes, I was going to make a ground breaker circuit as per Elliot Sound Projects.

 

[generg]

With similar circuits I could get them only (nearly) humfree by connecting all ground cables from one side directly at the source or if you use a source resistor of course under the source resistor....

 

[Zen Mod]

well - I wrote that one proper pic is worth as zillion words

problem can be wiring , but also physical layout of ripple currents in your C bank

how's that made ?

it's easy to make pics today , to shrink them and post them

don't use flash but some other source of additional light

anyway - look here - maybe you'll learn trick or two ( same as I was doing long ago before internet , first read , look , think ........ and ask only if you're in deep drek)

Babelfish J2 , ongoing ; Part Four - diyaudio.rs