Fender Superchamp XD - Transformer Hum?

[andyd]

Hi

I believe these are quite popular amps amongst Shads players, so maybe someone can answer this?

Does anyone else notice quite a loud transformer hum from the Superchamps?

I have two of these and they both have the same thing.

It's a bit of a nightmare if you wanted to record using the amp, because as soon as you stick an SM57 near the grill, you pick up hum.

Doesn't really matter if there's not an answer, because I mainly seem to play acoustic these days but thought I'd ask anyway.

PS. It is the transformer humming, as it's humming even with nothing plugged in.

[ernie1958]

Hi Andrew,
It's got something to do with an unsufficient stabilised power supply I believe...
You should ask Amanda if you want to know the more in depth details about such things..
Hope this helps,
Regards,
Ernie

[JimN]

No such problem on mine...

JN

[AlanMcKillop]

I find mine ok as well, the only time I get a little hum is when I use my Copicat, but the other echo units are fine.

[RUSSET]

You can get a hum from any amp if you sit right in front of the speaker, or if you are in front of a TV/PC screen which emits radiation & gets picked up by the guitar. I have had no problem with my Super Champ for the two years I have owned it. If you have two of the same doing the same thing, it's rather a coincidence. It would suggest perhaps an outside source for the hum.

Tony.

[dave robinson]

I've had my Super Champ XD for over two years now and I use it on a regular basis on solo gigs. I haven't experienced the hum so far, in fact it's a great little amp.

[almano]

Hi Andrew,

Do you still get the hum with all the volume and gain pots turned right down?

The valves in this Fender amp are the (near enough) American equivalents to the Brit EL34’s and ECC83’s – so it should approximate to a standard Mullard type of circuit. These are good circuits and shouldn’t produce any hum as such – maybe the slightest of ‘hums’ if you place your ear right up to the speaker with all the pots turned to the “off” position, but nothing more.

If your hum only happens when you turn the pots (gain) up, then it’s something you are picking up. It has to be an induced signal from somewhere. Mains trannies do not hum as such – they buzz or rattle. If the hum is smooth sounding, it won’t be the tranny – and if it comes out of the speaker, then you can virtually eliminate the mains transformer from the list.

You say you pick it up on the mic when recording – this points to induced hum. It means you are picking it up from elsewhere. Have you tried moving the gear to another location and then seeing if it’s still picking up the hum? It’s worth trying as it will eliminate a lot of potential possibilities at one go.

Nice little valve circuits such as these Fender Super Champ XD amps are as clean as a whistle and don’t generally produce such nasties – especially in two identical amps in the same location! I think Tony (Russet) is definitely on the right path with his answer to this hum problem.

Cheers,

Alan.

[Didier]

The valves in this Fender amp are the (near enough) American equivalents to the Brit EL34’s and ECC83’s

The Super Champ uses a pair of 6V6 in the output stage, which are closer to EL84 than EL34.

Didier

[almano]

Yes, you're right Didier, I actually thought the 6V6 was an equivalent of the EL84 myself - but before I did that post I did a quick "Google" to make doubly sure - and it rather appears that the 6V6 is an octal base as opposed to the B9a base of the EL84.

Some valve data sites also list the EL34 as being the electrically closest - so I just "went with the flow" and opted for their info!

Hopefully they're right - but I do agree with you, I thought the EL84 would have been the right one as an equivalent myself.

Cheers,

Alan.

[Amanda]

It sounds to me like the clamp or laminations loose. If it's a drop through
type transformer, tightening the mounting bolts may help. If it's an upright clamp type
transformer then it's harder to silence!

Amanda