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Hummmmm in a Classical Guitar Transducer
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Author:  brady.jackson [ Thu May 15, 2008 10:56 pm ]
Post subject:  Hummmmm in a Classical Guitar Transducer
A client of mine who plays Brazilian music on a 7 string nylon classical has had a series of issues with his pickup. I was able to fix everything but a low hum that goes away when you touch the jack. This seems to be a grounding issue, but the pickup instructions (of European Origin) don't mention anything about grounding. HummmmmDoes anyone have any practical ways to reduce the hum in this situation?
Author:  David Collins [ Fri May 16, 2008 7:35 am ]
Post subject:  Re: Hummmmm in a Classical Guitar Transducer
Is this a passive saddle transducer, or is there any onboard or outboard preamp involved with the problem? Does this happen the same in all amps and outlets? That's what comes to my mind first, but I'm assuming you've tried different amps, cables, etc. It could also help if you could tell us the make and model of the pickup - or at least the style if it's a small maker we may not know. Solutions could be quite different if we are talking about something like a Fishman-style saddle transducer vs. a Schertler product.
Author:  brady.jackson [ Fri May 16, 2008 10:45 am ]
Post subject:  Re: Hummmmm in a Classical Guitar Transducer
Some more info: this is an active undersaddle pickup, made by a small Euro maker. I am not familiar with Schertler, but the pickup element is definitely not Fishman-style. The undersaddle component is a copper mesh wire material, and it does have a built in pre-amp at the jack. The hum occurs regardless of the amp or cable.
Author:  David Collins [ Fri May 16, 2008 8:16 pm ]
Post subject:  Re: Hummmmm in a Classical Guitar Transducer
I hate to say it, but I don't know what to tell you. If it was an issue with damaged shielding on the pickup or preamp the hum wouldn't entirely go away when you touch the jack. The fact that the hum does go away when touching the jack would normally indicate that the grounds are good, though you could pull the preamp and check the grounds point by point. On a well made pickup/preamp system I would first look to the amp or the ground in the outlets you're plugging in to. If it's not that, then it may be a problem in the preamp that I can't readily offer a diagnosis for. Do you know if the problem has always been there, or did it start suddenly?
Author:  brady.jackson [ Fri May 16, 2008 10:59 pm ]
Post subject:  Re: Hummmmm in a Classical Guitar Transducer
Thanks David. I think that the problem has been there since he installed the pickup, and on pretty much any amp. I'm not going to get into checking the preamp itself connection by connection, as this is supposed to be a higher end system and not only do I know nothing about it, but the manufacturer is German and has very poor English language support. I think that my client is ok just living with it. It is a very low level hum and not noticeable while playing. I was just trying to see if anyone had any obvious fixes I was overlooking.
Author:  Guest [ Sat May 17, 2008 1:10 am ]
Post subject:  Re: Hummmmm in a Classical Guitar Transducer
The shielding is inadequate.

Rick Turner
Author:  KeithM [ Sat May 17, 2008 8:20 am ]
Post subject:  Re: Hummmmm in a Classical Guitar Transducer
Check the connection to the pre-amp and make sure the ground and hot wires are not reversed.
Author:  Steve Brown [ Sat May 17, 2008 7:18 pm ]
Post subject:  Re: Hummmmm in a Classical Guitar Transducer
Humm that does not come from ac induction (lack of shielding) is can usually be eliminated by an isolation transformer. Old technology and expensive but very effective. PM me and i'll send you one. Include shipping address & email.

Steve
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