New ES hum issue

[pieterh]

Here's the problem: I have just played a lunch time gig in the smaller venue at the theatre where I work (first occasion to use it live since sending it away in February). On the assumption that the ES is supposed to be balanced and so on I plugged into the stage box (multicable) without using a DI. There was a noticeable hum in the PA and monitors which didn't disappear when I connected using a regular guitar cable to my Radial Pz-pre, even when using the ground lift button. For reference I also had my Guild with its Fishman Matrix Natural II (which is why I had the Radial with me) and that was noise/hum free via the Radial.

In order to try and localise the problem we tried connecting the guitar direct to the mixer (a Yamaha 01v96), and the signal then was clean and hum free. Note that the phantom power was switched off on channels 1-4, my guitars were on channels 1 and 2. To be fair what we didn't do was try a regular cable into a DI into the stage box as there wasn't time before the audience came in, but as the Radial pz-pre is a preamp with a DI plus ground lift I doubt there would have been a difference.

Could it be an issue with long cable runs despite the claims that no DI is needed? The hum didn't disappear when we cut the stage and house lights either so it isn't due to bad shielding. Or maybe the issue is battery power, although the light was shining and the guitar hasn't been plugged in (by me at least) more than 3-4 hours max.

I've sent the same question to Taylor Europe (they'll be getting sick of me soon...) so we'll see what we collectively come up with...

[Edward]

Hmmm...ground lift should have taken care of it if it were a 60-cycle (or ground hum, since you're in europe and have no idea how your AC is phased).  And of course, check your guitar's battery just in case.

OK, so you are using a proper TRS-XLR cable, correct?  If so, then cable length does not degrade the signal ...that's only an issue with unbalanced (regular) guitar cables (tip-sleeve). 

Phantom pwr has no affect on the ES.

The key is that you had zero noise when going straight into the board.  So your ES is likely fine.  Perhaps it is your stage box/snake that is causing it?  Did you try a different channel on the snake?  Your ES perhaps is reacting to a ground fault within the snake.  And with a TRS cable through the Radial, the ground lift "should have" killed the hum. 

Yet another possibility is that Ground Fuse on the ES may have blown.  Dunno about this, though, as I've never had a ground fuse go on me, ever.

Try working backward: go straight from the Console to your ES with a proper balanced cable: check for noise.  Then through one channel on the snake using the same cable: check for noise.  Try another channel on the snake with the same cable: check for noise.  And everywhere in between, insert/delete the Radial to see if it makes a difference, making sure you try both ground lift on and off when the radial is in your chain.  Yeah, troubleshooting sucks, but methodical with one variable at a time is the only way to chase these buggers down.  Let us know what you find.

Edward 

[Big DB]

Are you by any chance originally from Canada, Pieterh?

If so, perhaps this can explain your dilemma...

http://abcnews.go.com/blogs/headlines/2012/05/mysterious-hum-only-canadians-can-hear-is-debated/


Just kidding! 

[pieterh]

Ha ha, thanks Big DB, but no I'm not from Canada. I'm from London but live by the ocean in Sweden, about an hour's drive south of Stockholm!

I had this question on the acoustic guitar forum and we may well have localised the problem (and partly the solution):

In the venue in question there is a hearing loop for the hard of hearing. And of course the amplifier and loop were on. The Guild didn't react as it has a piezo UST with (repaired!) shielding. What clinched the conclusion is that the guitar screamed high-frequencies when we were at the mixer (very near the active part of the induction loop) when we turned the volume up but was otherwise hum-free. As the guitar has only last week come back from ES upgrade and ding work we were concerned that something might not have been installed correctly or that a fuse had been damaged somehow in transit. Having eliminated all the variables by being consistent with mixer channels, cables used and inputs on the stage box, and lack of difference with the Radial preamp/DI, we were pretty sure it was the guitar that had a problem.

What's embarrassing though is that we are both experienced sound guys who automatically suspect the hearing loop when electric guitars howl on stage (especially SC pups with a valve amp) but this time it didn't occur to us. Of course, it is the guitar that is the culprit, though not at fault - and for future gigs in venues with a hearing loop I'll have to weigh the advantages of using the Taylor with potential induction interference problems against using the Guild which is noise free but less of an all-round guitar (for me anyway). Ideally I'd like to use both, keeping the Guild for harder strumming work and the Taylor for more subtle, often fingerstyle tunes. A little more research I think on my part to see what others have experienced.

A few weeks ago I was playing a church gig where I played a high-gain overdrive solo on my G&L ASAT on one song. Afternoon's rehearsal - no hearing loop. Actual gig - hearing loop on, guitar howled like crazy...

[Edward]

Glad you got it ironed out!

Edward