How to get a clean/noise free unbalanced hook up?

[thekid777]

Hi,
I have a organ connected to a Leslie 147.

The 147 got a unbalanced input and I would like to know how I could
while keeping things unbalanced, be noise free? (mainly hum)

What could be the solutions?

Many thanks, best regards

 

[sahib]

Use a line transformer.

 

[thekid777]

Use a line transformer.

You mean for the main AC? isolation transformer to feed both the organ and the leslie?
Thanks

 

[Rob Flinn]

A leslie takes it's input from the speaker terminals on the hammond so it's not an ordinary hook up

 

[abbey road d enfer]

Hi,
I have a organ connected to a Leslie 147.

The 147 got a unbalanced input and I would like to know how I could
while keeping things unbalanced, be noise free? (mainly hum)

What could be the solutions?

Many thanks, best regards

The main isue is that the 147 is unbalanced (the 122 is balanced), and the audio connection is in the same cable assembly with the mains voltage. In addition, there is no earth connection.
So you have to power the cabinet with a 3-prong cable, with the earth connected to chassis, and you must take the audio signal in a separate shielded cable.
You may also want to modify the input section and make it similar to the 122; it's not that hard to do.
The most difficult part is changing the connectors. I've replaced the 6-pin connection with IEC for mains and XLR's for audio. I have mounted the connectors in the wood panel.

 

[thekid777]

A leslie takes it's input from the speaker terminals on the hammond so it's not an ordinary hook up

Hi Rob, it take the signal from the G and ground terminals of the AO28 preamp (A100)

 

[Michael Tibes]

I have split the mains from the audio in my Leslie (251, similar to the 147) and also added a solid state relay for the motor switching. My Hammond is a C3 which has a balanced output, so I built a separate transformer box to unbalance the signal going into the Leslie. So now I need just normal power leads for the Leslie, not the horrible multi-core they used originally and I can use a simple footswitch for the motors and I can plug in a keyboard or guitar stuff directly and balanced stuff via the transformer box.
It was a lot of work, but it was really worth it.

Michael

 

[abbey road d enfer]

Hi Rob, it take the signal from the G and ground terminals of the AO28 preamp (A100)

I think you are mistaken; the internal amp indeed takes its input from the preamp's output, but the Leslie receives its input from an eavesdrop on the internal speaker.

 

[Rob Flinn]

I think you are mistaken; the internal amp indeed takes its input from the preamp's output, but the Leslie receives its input from an eavesdrop on the internal speaker.

That's what I understood to be the case.

 

[thekid777]

I have split the mains from the audio in my Leslie (251, similar to the 147) and also added a solid state relay for the motor switching. My Hammond is a C3 which has a balanced output, so I built a separate transformer box to unbalance the signal going into the Leslie. So now I need just normal power leads for the Leslie, not the horrible multi-core they used originally and I can use a simple footswitch for the motors and I can plug in a keyboard or guitar stuff directly and balanced stuff via the transformer box.
It was a lot of work, but it was really worth it.

Michael

Excellent Michael!
Which transformer do you use?
Because the output is quite loud on these G terminals.
I guess it solved all the noises problem.
I'm thinking to put the combo preamp circuit in the organ (which is a Bertram portable) to feed and control the 147 sending the whole via a regular 6 pins connector/ cable.
I could even put the low/fast switching on the expression pedal then and use another switch for the stop position!