1977 Martin D18 (surprise!) with an after-market pickup
Standard guitar cord
Electric guitar (1964 Rickenbacker, in case anyone is interested. The quasi-Telecaster with a single pickup. I forget the model.)
In lieu of an amp, an M-Audio USB device attached to a Mac computer. I’m using the direct monitoring feature on the M-Audio device with headphones attached to it, so it’s not running through the computer
The situation:
Running the cord from the Martin, there is a significant 60-cycle hum. I can still hear the actual guitar pretty well over the hum, but since in situ, the Martin will be plugged into someone else’s amp so am not sure how it will sound.
Running the cord from the electric guitar, no 60-cycle hum of any note and can hear the guitar fine. Takeaway: the cord seems to be fine.
Plug the cord back into the Martin. If I just hold the shielding of the jack on end of the cord plugged into the Martin, the hum disappears. However, if I hold the shielding of the cord on the end plugged into the M-Audio device, the hum also disappears.
Not enough information. What kind of pickup is in the Martin? Piezo? A single-coil in the soundhole? They’re prone to hum. Double-coil? Less so.
How about the Rick? I think (not sure) Ricks were generally single-coil pickups, but I don’t know what model you have. But even if it’s a single-coil, it could be well-shielded.
I’m guessing you have a single-coil pickup in the Martin, with poor or no shielding.
Then something in that pick isn’t shielded properly. Does the guitar have an internal pre-amp? That could be the culprit. Or the connection between pickup and pre-amp. Or to the jack. Somewhere in that chain, something is picking up the hum.
By output, do you mean the quarter inch female jack? (Huh. Do we still call the receptical “female”?) In any case, no, never soldered. OK, more accurately, never soldered successfully!
Soldering a quarter inch jack is fairly simple; everything you need to get to is very accessible. I’m sure there are videos on YouTube that demonstrate technique. If you are careful, you should be able to do it in one shot with no mess or waste. If you screw up you may need a solder sucker to help you clean up excess. These can be found very cheap (<$10) but you might want it on hand before you actually need it is why I bring it up.
Thank you, everyone! My immediate need is to have a guitar to plug into an amp tomorrow for one song, so I’ll use something other than the Martin. To solve the problem, I’ll look into some videos on jack soldering and figure out whether I want to give it a go or whether I’ll take it to the shop. In any case, my instinct when I don’t know what I’m doing is to fart around with it for far longer than I have time for, so it was really helpful to get your input so I could nip that in the bud!
One more thing you can try is to plug a different cord in and see if that makes a difference. It’s clearly a bad ground but that could be from a broken shield in the cord itslef. One possibility is that the plug in angle differs between the guitars and makes contact on the Rick but not on the Martin.
I had an Ovation six-string for decades. It had only a battery operated pre-amp with a single volume control (no EQ) and to replace the batt, you had to loosen all the strings, reach inside and remove the batt holder that was bolted to the side of the guitar from the outside–what a pain. Somewhere along the way, I started using pedals for “ambience” and, to my surprise, the pre-amp would howl like a banshee and make even more annoying sounds the closer you got to “11.” I ended up disconnecting the pre-amp, soldering the pick-up straight to the (female :)) output jack and, viola!, no more squeal. Go figger! The music store tech I asked about it said it must have been a very “hot” pick-up.
In addition, the output jack on this particular Ovation was just secured to the fiberglass bowl. The jack never really held on sufficiently and would rotate slightly each time a cord was plugged in/out. So every once in awhile, the “hot” lead or the shield would break off and require a soldering.
Not that any of this necessarily applies to you. Just another anecdote you can add to your file of frustrating facts–every musician has one.
