Electric guitar problem, bad resonance?

Question

I've been facing this problem for quite some time now: some notes sounding bad with an overdriven amp. It's a 19 years old solid body Kaman GTX-33 (the maker of the Ovation acoustic guitar), made in Korea. Practically the same as this one, but with a better PING licensed Floyd Rose bridge.

I have found a good sound example in this youtube video. Approximately at 07:43, Jack (the guy on the right) stops playing for a brief moment, switches to the neck pickup and then you hear two weird, warbling/vibrating notes, they sound almost as if they were out of tune. My guitar has this exact same issue, it annoys me so much I lose concentration, sometimes. Except in my case, it happens on the 5th string, mostly, around the 6th - 9th frets, and the 6th, towards the end of the fretboard. Does anybody know what causes that? It could be similar to the problem mentioned in this question, possibly the same, but the question didn't make it clear and also no satisfactory answer was given, so I'm really not sure.

The string is absolutely not buzzing against the frets and I've double checked and ruled out everything I could about:

• loose parts
• old strings
• amp problem (happens on all of my 3 amps)
• excessive magnetic pull
• electronics
• bad pickups (had them replaced just for testing, problem remained)
• floating bridge springs vibration

Important: it only happens with overdrive. With heavier distortion, it tends to disappear. With clean sound, I can only notice it if I listen very carefully and in a very silent environment. Seems worse when using the neck pickup.

The only other possibilities I ended up with are:

1. a vibrating truss rod (unlikely),
2. something about my floyd rose bridge, its saddles or how it resonates, or
3. the neck/body junction, maybe the neck and body don't "like each other"?

My theory is that there is some bad resonance or frequency beating going on, either in the wood or the bridge. It's a solid body guitar, but it never had a fantastic sustain, so to speak.

I don't have many luthier options in my area, and the last time i tried one, the guy knew less than I do (I've been playing for 24 years). I will also post a more detailed sound sample ASAP.

EDIT: here are the sound files. Notes: the first one is the neck pickup, clean. I can't hear the problem in this recording.

The second one is the neck with overdrive. I let the background noise flow for a while to illustrate to @Yorik what I was saying about hum or RF. About the sound, If you listen loud with good speakers, the problem becomes quite evident: some warbling, some unwanted vibration, some additional noise under the note, making it sound weird. I feel like it could be an excess of bad harmonics as @Andy mentioned, but I'm just not sure.

The third recording is a trick I did just for this question: I've wired neck and middle pickups in series but inverted the wiring of one of them, so they go phase cancelling and kill the background noise (I know, it kind of kills the tone, too. It's not a real humbucker, after all). In this example we can hear the problem very clearly and this removes the hum/RF possibility. The hum is gone, yet the problem remains. The pickups are pretty far away from the strings to avoid magnetic pull and there is very, little fret noise in the recordings, it was my first guess, but I don't think it is the source. I'm running out of options! I still think it's a wood resonation issue or something with the floyd rose vibrating and interfering.

• Neck, clean
• Neck, overdrive
• Neck and middle, hum cancelling

Answer 1

Whether it actually is or not I have to say it really does sound like fret buzz to me! Listening to your clean recording I notice in looking at the waveforms produced when looking at the accompanying graphic on soundcloud, that it seems to occur more when you strike the string slightly harder, and as you know will know from experience when the string is struck harder it's vibrates more and at some point almost any string vibrating enough will contact at some point, especially with the thicker wound strings which have more mass. It's quite a familiar sound to me, as I use quite a lot of guitars with very low actions and this sort of harmonic content to the note seems to be added when some degree of contact is made with a fret - however little. On further consideration I do seem to remember hearing a similar sound produced on an electric guitar when a string seating in the saddle piece on tune-o-matic type bridge was not quite firm ie some movement of the string witinin the slot in the saddle. A simillar phenomenon can also occur when the actual saddle itself is not well seated, and can vibrate within the bridge in sympathy with a string - and this can happen at certain frequencies. I have a bridge that does this on a PRS copy at present. Hope this is of some help to you,

All the best, Dave.

PS Just listened to your Sound Cloud recordings again. The only one which is really useful is the first one without any effects on at all - adding distortion to distortion just muddy's the issue. Looking at the wave forms in detail it's very interesting to note that the distortion happens as the note starts to decay as it produces different harmonics and again this is a very familiar sound to me!

Answer 2

Could it be sympathetic resonance induced in the tremelo springs?

This tremelo spring is from either a Brian Moore or a Variax. Both guitars are fitted with piezo pickups and so are more sensitive to physical vibration. The illustrated precaution does however support the theory that there can be issues with spring noise. Have you tried dampening the tremelo springs?

Answer 3

Sounds like a classic case of Stratitus. Try lowering your neck and middle pickups (the single coil ones) further into the body cavity. That usually helps as the strong magnets won't effect the string vibration as much.