Peavey Alphabass round two-troubleshooting

[catalin gramada]

This is the position should be put it in. It almost fit (almost meant 3/4"over).Think will be need to make a new top for it. The noise is still here but was reduced to almost none. Any thought ?

[glebert]

If the transformer is radiating to the amplifier I'm wondering if you could leave it in the original position and make a faraday cage around it.

[catalin gramada]

Hey,
It is not possible to do any cage around . This PT need a lot of cooling, it works hot as hell. This position I found to reduce the noise to almost none, unfortunately I have to cut a hole in the top of amp shell cause it have no chance to fit inside. Think Peavey did a compromise to align both transformers in same plan just from size reason. The noise is still acceptable in original position for a guitar amp. I will do a capture tomorrow with output scoped in both instances to do an ideea how much noise reduction it gain turning the PT upside down.

[Helmholtz]

If the transformer is radiating to the amplifier I'm wondering if you could leave it in the original position and make a faraday cage around it.

A typical Faraday cage won't help with LF magnetic fields.

Would require a high µ shielding material.instead.

[glebert]

A typical Faraday cage won't help with LF magnetic fields.

Would require a high µ shielding material.instead.

Moving a transformer 3/4" also shouldn't change much for the magnetic field of a 60Hz signal. Yet he is saying it does.

[Helmholtz]

Moving a transformer 3/4" also shouldn't change much for the magnetic field of a 60Hz signal. Yet he is saying it does.

3/4" can make a significant difference as the magnetic field rapidly decreases with distance. Just increase the distance between strings and a magnetic PU by 3/4".

But the main difference should come from rotating the PT and thus its magnetic axis as magnetic fields are directional.

[catalin gramada]

Moving a transformer 3/4" also shouldn't change much for the magnetic field of a 60Hz signal. Yet he is saying it does.

It was not moved 3/4" away, it was turned 90 degree which mean different thing of course. As consequence the end bell of the transformer is out 3/4" from the rack shell gabarit.

original and turned

[Helmholtz]

BTW, all touchable parts of a PT, i.e. core and end bells should be well grounded for electrical shielding and even more importantly for safety reasons.
That's not always a given with lacquered/varnished PTs.
So I like to make sure.

[catalin gramada]

BTW, all touchable parts of a PT, i.e. core and end bells should be well grounded for electrical shielding and even more importantly for safety reasons.
That's not always a given with lacquered/varnished PTs.
So I like to make sure.

Thanks. Yes, the lamination is welded to the base plate together with the end bells.This is fixed to chassis with the screws through. This was the big inconvenience to find an alternate position.
This is the best I was able to do: the top of PT will be out 1/2" from the shell

[catalin gramada]

Maybe not state of art, but effective