Off topic: Mysterious hum on acoustic guitar pickup

D107

with that wire around your wrist. So you became the ground, as long as you didn't jump up with both feet. you may already know this but you can check http://www.mandolinbrothers.com in staten island ny for tech questions and their site also has comparable guitars/basses/prices. If you have any plans to sell the bass i'd be careful about replacing anything, though I guess you could keep the old parts in storage.

Interesting that you say some buildings didn't have '100%' ground. didn't realize that was possible. How do you measure degree of ground? I assume my cheap little three-pin tester doesn't do that. Of course there's also crosstalk out there....

Thanks,

David

D107

Doesn't have problem in other locations

I know many of you guys are into electronics and audio, so I'll throw this out there:

Have an acoustic guitar with a fishman under saddle pickup. A year or so ago I noticed when I'm hooked up to my home recording/monitoring setup or a guitar amp in my house, I get a low freqency hum. only with this guitar, no others. I've brought it into the city to check it out, and never a hum. If I plug into a battery operated amp, no hum. At home, hum increases if I touch the strings, and disappears if I touch one of the metal components. sometimes the hum disappears for awhile, without any identifiable reason. Tech told me it could be the pre-amp within the pickup, or that I"m too close to a computer, rheostat, etc. but it only happens with this guitar. I've switched out all the variables, cords, inputs, preamps, etc. It's my main performing and recording guitar so I'd like to resolve this.

any ideas?

Thanks,

David

Paul Fredricks_9

In my experience it has always been a grounding issue. Make sure your outlets are properly grounded and the polarity is correct at the wall. Maybe the preamp needs a ground too. I'm no expert and haven't had a hum problem for a long time so this is just a guess.

Since it does it when you are plugged into the monitor or the amp, I'd guess the problem is either on the house end or the guitar end.

ScottMP

Humming

Simple

It dosn't know the words !

I'd say grounding also.

Scott

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D107

Ha--well at these prices it darn well should know the words--

and I keep having to tune the thing too....

well it must be the sensitivity of this particular pickup in this setting. the outlets check out fine with the tester. I assume there's no such thing as a 'partial' house ground. a loose connection could give you intermittency, but it's either grounded or it's not, yes? When they installed new 200 amp service two years ago they did a double ground outside and then attached to the water line inside.

This pickup is powered by a 9 volt battery that is reachable via the soundhole, the pickup presumably has shielded wire running to the jack/hole at the bottom of the guitar where the 1/4" plug connects from the sound system. While there are alot of screw-in fluorescents in my basement, the noise happens even when I plug into a dedicated outlet.

thanks,

David

Bruce M_2

More Info Needed

What is the make of the pickup and where is it made? Did the acoustic guitar come with a pickup or is it something that was installed afterwards?

michael_34

michael_34

my guitar gently weeps...

Or Hums.

Lee_8

Does it occur wwith lights off ???

Does it occur with the lights off?
Is it 60hz hum?

You may have high frequency noise on your ground

D107

installed about 5 years ago

I spoke to Fishman; seems like it's a Fishman Natural 1 or 2, installed on my old dreadnaught. Their current matrix infinity series is supposed to be better. His advice was to pull up the saddle and check the red tin foil, which is the pickup itself. sometimes a tear develops which compromises the unit. Some people have corrected by addint a sliver of tinfoil over the tear. Or a component of the internal pickup could be going bad. As for why only at my place, each environment is different in terms of crosstalk, interference, etc.

and yes Lee I did turn out the lights and check that angle

Thanks,

David

Bruce M_2

Amp

Are you using the same amp at both places? Is it a tube amp? If so, do you have a tube tester?

Timco

My vintage Hy-Watt and new Carvin tube amps both have a ground selector switch. (pos / neg) if it humms on one setting, I just flick the switch and it is fine. I also use expensive shielded cables. I had a guitar shock me hard while playing in a light rain...and it was buzzing when I wasn't touching the strings before I got bit...

Tim

[Deleted User]

David, you might try posting your question over at
www.audiokarma.org/forums/index.php?

They have both a general audio and a musical intruments section.

The general audio post will be seen by many knowledgeable people. I am not familiar with the instrument section.

bruhl

D107

Thanks Tim, Bruhl

thanks for the audio site...I'm amazed at how many Wallies are not only audiophiles, but musicians as well. Yes, playing in the rain is a definite risk, I think some well-known guitarists have died that way. And to answer someone's prior question, for this acoustic guitar it's not a question of which amplifier, it only happens at home (so far). I've checked all the variables.

The interesting thing that came out of my inquiries is that I've had confirmed what I recall from some years ago, is that the best acoustic pickup setup is having one soundhole pickup--which picks up the string sound, and one undersaddle pickup, mixed together to the performer's taste. (Of course one can throw a fortune into this with condenser mikes inside the guitar, 12 band equalizers, etc.)

For recording though, the best sound is usually achieved with two condenser mikes, one near the soundhole and one at an angle pointed at the fretboard --somewhere near the 12th fret I believe. (FYI)

Thanks,

David

Steve Ebels_3

My old Fender Jazz bass

Does the same thing. What I found was that the winding in the bridge pickup is beginning to break down. It shows a resistance that's a bit off from factory spec. (had quite a time tracking down that bit of info for a 1966 guitar)
The only solution is to change the pickup but I haven't as of yet because everything is original. I bought it used when I was 12. Two years worth of paper route money IIRC. I just hate the thought of the old girl not being 100% original but one of these days I'll have to get a new set from Fender and give it a heart transplant.

It's the same type of problem that you have in that it shows up occasionally when I play at different places. Seems like the ground on a particular circuit in a building may not be 100% and that's when it hums. I can often plug it into a different circuit and the problem will disappear.

I had to wrap a bare copper wire around my wrist and terminate it under a screw on the metal plate surrounding the volume and tone controls in a studio once. If I lifted both hands off the strings or bridge cover at the same time it gave me a little tickle.

Paul Fredricks_9

Steve

What year is your bass?

I like the copper around your wrist. I can just picture you trying to explain circular burn marks after the coil starts glowing.

When I first started playing with my current band I had an issue getting shocks while playing bass and using a mic. Very distracting trying to remember the words. Found out they had cut the ground off the plug on a power strip. Had to give them an education.

I suppose a poor ground connection could be noisy, but I'd venture to guess noise on the line that is affecting a problem pick up.

Steve Ebels_3

According to Fender

The serial number on the neck plate indicates it was made in 1966.

The copper wire was interesting. On one particular song there was a passage played with a lot of open string work. Playing it was...... shall we say exciting......until I figured out that I had to stay in contact with something metal on the guitar.

D107

1966 is just one year late....

I believe 1965 is the cutoff date (for guitars at least) to be considered an original pre-CBS Fender, which is of higher value, but in your case by how much who knows and it sounds like you'll want to keep this baby anyhow...

Bruce M_2

Steve

You can keep your bass original by having your present pickup rewound to the original specifications (same number of turns).

Paul Fredricks_9

Of course...

If you thought it was in the way and you wanted to give it to someone who would take great care of it and made sure it got the exercise it needed and would even let you visit it from time to time and.....

Steve Ebels_3

From what I have read

According to S.P. Fjestad in his Blue Book of guitar values, there is virtually no difference in the jazz basses produced in the years shortly after the CBS buy out of Leo Fender. The only noticeable clue is the lack of the cloverleaf tuners. The old girl plays like a dream yet. I still haven't picked up another bass of any brand that plays as nicely.

Steve Ebels_3

That thought has crossed my mind and will probably be the way I go when the time comes.

D107

check out this site steve

this gets very technical and I have no idea about the veracity of this; some is subjective too I'd think.

http://www.provide.net/~cfh/fender.html

Bruce M_2

Steve, Look at This

http://www.provide.net/~cfh/pickups.html

mtfallsmikey

Another good source

www.danerlewine.com

I get e-newsletters from Stew-Mac featuring some of his repairs,rebuilds,etc. He pulls off some difficult stuff. Me, I keep it simple by sticking to my Gibson Mastertone banjo!

Steve Ebels_3

I'm getting pretty good

Picking Dueling Banjos on my 12 string. When are we going to have a Wetstock featuring the WetHeads All Jug Band?

Unknown

Ground issues...

Can be very dangerous especially when it includes things like cut ground lugs on cords. It's not payed as much attention here in the states but in Europe where everyday voltage is 220 they are much more aware of the issue. It pays to carry a meter with you and check outlets for good grounding before using them for your amps.

Here's a link to a good discussion on the subject. This is a Brit website so the "English" is a bit hard to decipher. When they say "earthed" they mean "grounded".

http://www.soundonsound.com/forum/showflat.php?Cat=&Number=576976&page=0&view=collapsed&sb=5&o=&fpart=1#576976

Larry C_13

Home only ground buzz.

If the noise only occurs at the home studio, I would suspect an issue at the home location. Is the home studio in the basement on top of a concrete slab? If so, I suspect that the rebar in the concrete is not bonded to the rest of the electrical ground electrode.

Is the home setup being powered off of an "Isolation transformer"? If so, some people will deliberately not connect the Neutral to the earth in an attempt to isolate the system from an noisy neutral.
This can result in LETHAL voltages building up between the "Isolated" system and the earth.

I believe pick ups are sensitive to both Electrical fields and Magnetic fields. Are there any large power transformers or motors in the area? Pumps, generators, compressors, Air blowers, light dimmers, welders, etc. All of these can and do produce all sorts of interference. Do you have an in ground swimming pool? The pool makes an excellent grounding electrode and often if the power utility ground rods are failing, the current will flow thru the pool rebar and out thru your neutral connection. This can set up a voltage gradient across your property and can show up as a slight voltage difference between you and the neutral, if you are in contact with the ground.

Any other symptoms?

Larry C

D107

yes it's on carpet over concrete basement floor

Thanks Larry for your very interesting info. House is from 1924 so I don't know if they used rebar then or not.

I don't know what an isolation transformer is, but this is Westchester NY. Power line runs from the street pole to the house and then down the side and through foundation to 200 amp power box. The only nearby motors (10ft away behind a wall) are for washer and drier. Dehumidifier is 20 ft away, and the house also has a 3 ton Central AC. No pool.

Based on what I've heard from manufacturer and other music techs and that it's only a problem with one instrument, it sounds like it's just a combination of natural slight deterioration of the pickup and possible crosstalk issues.

Since this thread has delved into various issues--all of them interesting to me--I'll add another piece of info and a hope that any musicians out there playing rock and roll will protect their ears with earplugs while they're playing. Check out http://www.etymotic.com/ephp/er20.aspx

I intend to buy a pair instead of using the heavy foam ones that cut out too many needed frequencies.

Thanks,

David

Unknown

Have you,,,

determined exactly which song it is humming? Maybe it just wants more of a part in the act?