guitars versus flourescent lights!

[axismatt]

Hi, just wondered if anyone had any ideas or solutions to the problem of guitars with single-coil pickups transmitting hum from nearby flourescent light fittings. (Don't say remove the lights - they're in the offices below me!).
For the last 2 years I've had to send guitarists with Teles or Strats to stand in the corner of my studio live room as its the only place that doesn't pick up so much...not ideal!

Thanks, Matt

 

[NewYorkDave]

Um, outside of guitar modifications, which are obviously not feasible, perhaps a homemade Faraday cage of some sort?

 

[Scenaria]

carefully drill a hole in the floor and *disconnect* the offending lights :green:

 

[NewYorkDave]

I like Scenaria's suggestion best :grin:

However, you might want to consider trying to persuade your downstairs neighbors to fit special ballasts to their light fixtures. There are low-noise ballasts available for fluorescent TV studio lighting, an application where generated electromagnetic interference must be kept to an absolute minimum.

 

[axismatt]

I like Scenario's suggestion too, but I think yours has more chance of happening Dave!

It would be worth my while to buy the ballasts myself and pay for the fitting if it helped cure the problem...thing is I know zilch about lighting - whats a ballast(!) and any suggestions where I might source them? S'cuse my ignorance

 

[CJ]

You could get some single coil humbuckers.
There is a guy in Australia who is supposed to be making some killer pickups.
His info is at the Fulltone website.
:guinness:

 

[adrianh]

Going out on a small limb.

I know sheilding the guts of a guitar with copper foil tape soldered
to the bridge works wonders. Had a friend that I did this and compleately
shield all of the guts and now on the road the noise is much much better even with neon signs nearby.

Electronic ballast my be better in the lights below you.

If the field is purely E field connecting a very good ground #8 awg or bigger
driven into the ground using a seperate 10 foot ground rod then connected to your faraday cage may work. You could use copper or brass window screen
and build a booth kind of like a RF screen room.

If it is magnetic put thin 0.02" steel sheets on the floor to try to
break the magentic path connect this to the seperate ground also.

Try these 3 things for a test.
Cheap first pass test.
connect a good ground fat wire 312 or larger to your electrical panel run it into you tracking room.

get a isloation transformer and compleatly isolate the ground of the guitar amp. Guitar, cable, amp only!!!! not other junk. Use the isolation transformer and be sure to lift the ground completly for these tests.

turn amp up max. guitar up max, wrap gutiar in bubble wrap to protect it.
Wrap guitar compleatly in aluminium foil and ground the foil.

If unit is quiet it is E field "voltage" i.e. electrostatic fields.
So build a copper or brass cage for them to play in.

If not try some smaller sheets of steel grounded to the
grounded. try to shield the guitar with thin steel sheets. Even tin
i.e. air condition duct will work IF a magnet stickes to it.
Try to keep the field below from getting to the guitar.
Place Guitar in bad spot on floor turn amp and guitar up to max.
Repaeat with a shhet of steel below the guitar with the sheet grounded.

If this cures the noise it is magnetic and mu-metal would be best but trade in your car to pay for it.
I assume you may could add a floor with steel electrically connected together and grounded. Then add a new floor for looks.

If it is magnetic the electronic ballasts wll help but they may throw off hash
in the RF spectrum that you other equipment may pick up.
No way to know buy one test with guitar next to it.
A good ballast for TV and Radio will work great I hope.

What ever works go with it and run a seprtate clean ground directly to the earth.

I threw the isolation transformer in there to cover your butt as it may also help. The best kinds are for medical use and have LESS than 1 picofarad
between windings i.e. no noise will get into the ac line of the amp!

Have fun.

 

[clintrubber]

I'm posting this in a hurry so I'm not sure if this was already mentioned: how about a dummy coil inside the guitar. Was used for instance by the Blade active basses. The dummy coil (no magnet I thought) senses the disturbances and subtracts them.

There are disadvantages though: you'd rather get rid of the disturbnces at source, and not having to treat each 'receiver'.
Requires active circuitry - although I guess a passive version should be feasible.

FWIW,

Peter

 

[axismatt]

Hey adrian, thanks for the in-depth reply. I should say firstly that treating the guitar isn't the answer as bands bring their own gear in....
From what I've been told about Faraday Cages, I think I'll pass, as in my opinion the problem is not so severe to warrant ripping up my live room and spending a small fortune...unless I've overestimated the effort and cost involved? I'd rather just make them stand in the corner!!
The ballast idea is worth a try though....is there a particular type or manufacturer I should search for (as I said earlier I know zilch about these things)?
Thanks Again
Matt

 

[NewYorkDave]

I don't know of any brand names off-hand, but you might want to visit your local lighting specialist (ideally one who's familiar with lighting for television and film) and inquire about low-noise electronic ballasts.

 

[BYacey]

Might be worth trying some of the new high frequency electronic ballasts. As someone mentioned, you could also lay down on the floor an 8 foot square chunk of sheetmetal that is grounded well. You could also use the record tally output on your multitrack to activate a relay. The relay would simply shut off the neighbors flourescents when you go into record mode. It'll take them awhile to figure it out.