Amp HUMMMMMMMMM

[Doc W]

I finally got my 50s-style custom tweed working. The amp itself was built by a friend and is sort of like a 50s Tremolux. I had a cabinet made and tolexed it myself (first time!). Pics will follow soon, I promise.

In the meantime, I have a few questions about hum. I live in an old house with old wiring and all kinds of new lighting gizmos so ALL my amps hum, or rather, my single coil guitars hum through them. This new amp is very quiet, even cranked, as long as you don't plug in. But with my Strat, it buzzes like a bee hive, except in positions 2 and 4. I realize that this is a perennial problem, so let me be specific. I notice in old tweeds that there is almost always a sheet of metal, screen, foil or some other metallic material in the cabinet somewhere. Does this reduce the hum somewhat? Any suggestions on what to use. Also, does it help to rewire the guitar at all? I am not looking for super quiet.

Noiseless pickups are not an option since I really like the pickups I have.

[NTBluesGuitar]

Whenever I build a tweed, I put foil tape shielding on the back panel that contacts with the chassis. Not a smoking gun solution, but a piece of the puzzle.

Old houses tend not to have the best AC supply vs. ground, but alone won't be the main issue.

I'd look at your Strat directly...does this specific Strat exhibit the same characteristics in other environments?

[phantomman]

I can't speak to the issue of tweeds directly but I know that all of Leo's later designs (brownface and blackface) relied on metal-screen shielding stapled to the underside of the top of the amp's cabinet. On the later silverface editions, the screen was changed to a thin aluminum sheet (approximately .010" thick).

T.J.'s idea is likely a good one and the least intrusive insofar as actually modding your amp. Basically, the hum is the "nature of the beast" when it comes to traditional SC pickups. It can be ameliorated but never completely eliminated.

A power conditioner may also help.

[yankeerob]

I can add a piece of wisdom to this having also been a custom installation engineer... switch your lighting and other gizmos off one by one and see if that makes a difference. Dimmers are right pains in the arse as are compact flourescents... I've never had very much luck solving these issues by adding shielding and the other problem that you may have is just to do with your house wiring in general...

As your Strat P/Us seem to be noise cancelling in the 'juggled' positions that pretty much tells me that your middle P/U is RW/RP and that this simply a case of hum being generated by an external device/circuit...

Further and finally - I've had stuff come back fried because of a lack of earth (especially in CTed filament supplies) etc... Not to be a smartarse.... but I personally couldn't live somewhere where I knew there were wiring issues - let alone plug an amp in. Please remember - earth is your safety net. Without a proper earth you become the next best source of free moving electrons... If you happen to touch something with a better source of FMEs whilst holding your guitar you coud become the next Gary Thain...

Best of luck with that

[Old Ranger]

Understand the house wiring being a mess. My place is an ancient single-wide MH out in the woods. It's a wiring nightmare! Had an issue when using my pedals. Running into the amp w/o them it was fine. Put a RAT and something else in front of the amp and it was buzz city! Now of course going through the standard checklist of things I first thought it was cable related. After tests I found the cables were fine. I tried the outlets that were available in the room I have my stuff in, but none were any different. All caused a hum. Finally I just gave up trying to use my pedals and played amps that had built in effects at home.

Later I found that I had a circuit breaker that was on the verge of dying and that was the culprit right there. And I would have never found that was the problem other than when I would be making coffee and toasting something at the same time that breaker would pop. Changed it out for a new one and the next time I went to hook up my pedals all was well. That breaker was allowing some odd feed of current or something, I think? Like I said, my place is a real mess and I'm no electrician either. I don't mess with household wiring. I can go into the guts of an amp without fear, but I was trained how to do that. A house? Nope, not my cup of tea.

[yankeerob]

I don't mess with household wiring. I can go into the guts of an amp without fear, but I was trained how to do that. A house? Nope, not my cup of tea.

yer a hoot Old Ranger... welcome to the club

[yankeerob]

Rewired my whole house into a new consumer unit - didn't take much once I worked out what the previous guy had done... then again I do live in a tiny two up/two down end of terrace cottage in West Yorks... bit hairy wiring live tails in from the road but a bit of common sense and cupful of courage got the job done and safely...

I seriously think that it's just old school 50/60 cycle hum and if you have light dimmers or any other extraneous transformers then that is the problem... DO NOT screen your guitar... capacitance will kill your top end. Screening the amp will do little if anything. Find the source of interference.... dimmer... CFL... whatever it is.

I have a good circuit diagram for wiring a guitar cable with microphone cable that will greatly reduce capacitance and therefore greatly reduce high frequency losses... the better the cable - the better the preformance...

[Doc W]

yankee, the wife loves those dimmer things. We get 'em all over. I think I am stuck with hum. I can reduce it somewhat by standing exactly in a specific position. I look stupid but maybe I did already.