SWR TRANSFORMER HUM

[Makatak]

Does anybody have any quick fixes for reducing power transformer hum ? , when the amp is switched on the whole chassis is humming , I basically have to almost sit on it to quieten it down !! , really annoying in a quiet practice situation . Has anybody rubber mounted their transformers or similar and what results did you get ? Its the older square type [ american made ] of transformer , havent really looked at it yet , some of them are bolted together , one tech suggested a replacement transformer . Just curious if this is a SWR Trait .

[T-Bird]

Hi.

If a transformer is vibrating, there's either something wrong with it, or there's going to be something wrong with it in the near future.

The vibration comes usually from the loose windings, so vac. potting (preferably professionally ) is the recommended cure.

A good quality replacement i obviously an option, but usually more costly and more difficult one, especially if there's "custom" voltages/windings involved.

Regards
Sam

[Plays_For_Dog]

I have a pre-fender SWR Sm-500. No problems or noise once so ever. If it's a really hot day out side and I'm playing in the sun, the fan may kick on for a few minutes, but even then, that's a rareity.

[craig.p]

Originally Posted by Makatak

Does anybody have any quick fixes for reducing power transformer hum ? , when the amp is switched on the whole chassis is humming , I basically have to almost sit on it to quieten it down !! , really annoying in a quiet practice situation . Has anybody rubber mounted their transformers or similar and what results did you get ? Its the older square type [ american made ] of transformer , havent really looked at it yet , some of them are bolted together , one tech suggested a replacement transformer . Just curious if this is a SWR Trait.

Are you sure it's the transformer itself, versus sympathetic case vibration? How is the case held together? Is it folded and riveted sheet metal? You might be able to stand your transformer off from the case with stacked+compressed rubber grommets.

[Bassmec]

Originally Posted by T-Bird

Hi.

If a transformer is vibrating, there's either something wrong with it, or there's going to be something wrong with it in the near future.

The vibration comes usually from the loose windings, so vac. potting (preferably professionally ) is the recommended cure.

A good quality replacement i obviously an option, but usually more costly and more difficult one, especially if there's "custom" voltages/windings involved.

Regards
Sam

I am so lucky to live in Ipswich cos we have a fantastic local transformer company called Sowters they are really old school types and so you just ring Brian up say what you want
and he will do all sorts of potting and different fixtures all
in the utmost quality and charge very little for it considering
all the trouble he takes. Good old boy!
I have one of his output transformers in my Marshall DSL
Its a fantastic improvement in LF and HF clarity and extension over the undersize stock offering.
OH and a 240V remake power transformer in my RCA Pre Amp and various line and mic transformers in various kit around the studio over the years.