How to silence an acoustic electric

[jaylow]

I have an acoustic electric that I picked up in the Philippines. It came with a single coil pickup that was permanently placed in the sound hole. I added the Don Tillman preamp to it hoping that it might help me out when I plug it into a PA system. However, it has a bit of buzz/hum, typical of single coil pickups on electric guitars. I've shielded my electric guitars in the past to lessen the humbuzz but they're pretty easy to open up. Is there anything I can do to my acoustic to lessen or even eliminate humbuzz? I'm thinking that maybe I should install a dummy coil but I was wondering if anyone had any other suggestions.

[newey]

If the noise is coming from the SC pickup, the choices are really only two in number:

1) Shield around the back and sides of the pickup itself, by wrapping with copper tape, or

2) a dummy coil set-up.

I suppose replacing the pickup with a noise-free model would be a third option, but I don't think that was the type of answer you were seeking.

Wrapping the coil is probably not the best idea, as it will affect the field of the pickup's magnets, and probably adversely so. It tends to dull the tone and cut highs. At least, that sort of problem has been reported by some members with semi-hollow bodied electrics who tried coil wrapping.

There is a thread around here on experiments with a dummy coil. Placement seems to be key, and that may be a problem with an acoustic- the areas you can gain access to in the body may not be the optimal places to put the coil.

But, before you do any of this, you should probably try to minimize other possible noise sources besides the coil first. That means the wiring.

If the guitar has an endpin output jack, the wires running to the heel of the guitar where the jack is located travel quite a ways. Noise can come from lengthy wire runs, too, if shielded cable was not used. You should double-check to see if that cable run is shielded; if not, replace it with a shielded cable. This may reduce the noise to a tolerable level; if not, then the other options with the coil can be explored.

If there are other components besides a straight connection to an output jack (Vol pot, perhaps?), then other possible noise sources there should also be considered.

[reTrEaD]

I silenced an acoustic guitar but the results weren't reversible.



I think newey's ideas seem better.

[4real]

I suspect the biggest problem with a cheap guitar like that is that the internal wiring which could be quite long, is that the wiring is not shielded.

I tend, and especially in this case, to use shielded cable from close to the pickup (if it is not shielded) all the way to the jack socket. By shielded cable, I'm talking about the kind of stuff that guitar lead/cables are made of.

If this is the case, think about it, you would not use a non-shielded cable on an electric guitar (which is what this is) for noise, but potentially the last 1'1/2 inside there is unsheilded if this is the case.

Dummy coil (ie another non-functioning pickup effectively) wont help much if this is the case.

Shielding the pickup, perhaps...but minor if the wiring itself is unshielded. It might be worth looking in to see if it is shielded, many of these super cheap pickups are...potentially though the hot might have been wired to it rather than ground...could be worth looking into.

I tend to use shielded cable throughout my guitars which generally do not use cavity shielding and they can be dead quiet as a result.

The tillman preamp design is a little boost and makes it active, it also provides a 'warm' distortion...not sure if that was the intended effect...likely to make it more electric. Not a bad idea though to use something like that into a PA or with long cables as it might be happier being a low impedance and to prevent loading effects.

However, again, if there is noise in the pickup, or more likely internal wiring, this thing will be amplifying this noise and making things worse...plus, the light distortion may be compressing the signal a little a and so raising the low noise level.

...

Other than that...rather than experimenting with dummy coils or wrapping foil about.

What I would suggest is buying a stacked single coil sized 'noiseless' stacked neck pup design and simply replacing the existing pup...
There are more around and not that expensive...such as this..

www.guitarfetish.com/55k-True-Coil_p_1964.html

Something of a fairly low resistance value (not hot) is likely preferable in the neck position and for the acoustic thing (could lose the preamp too perhaps...or keep it) such as this example. I've not tried these, but $31...looks like a WCM(?) rebranded asian thing to me, if so I've tried that and while not a 'magic' sound or anything, they are indeed silent.

Effectively these designs have a 'dummy coil' directly below the main coil. I've become quite a fan of these kind of things fenders Scns and noiseless...if you had a heap of money, kinmans...etc...these have another layer of technology to make them sound more 'authentic'.

Check the dimensions of the single coil to your replacement, bridge pickups are often slightly longer due to the 'slant' on strats and allows more wire to be used to make them hotter, on an acoustic, less 'hot' is likely better. Stacked pups are often a little 'deeper' but perhaps not a problem on an 'acoustic'.

My last project is an acoustic like instrument and all cabling is done with shielded stuff, it has an HB pup and is silent as a result.

You might consider losing the preamp and battery (saving money and hassle...and circuit noise and distortion) or at least when wiring, try it with and without with the new pickup. If you decide to keep it, wrap it in PCV tape, then shielding foil (grounded) then tape again...or stick it in a small metal box and ground that making sure not to short anything!

For access, stick your hand through the sound hole or, use a coathanger wire to pull the wires through if necessary to the jack.

To do the dummy coil, you are likely to need another pup for the coil anyway and they wont be as easy to do nor as effective and a pickup designed to kill the noise like a stacked.

hope that helps... shielded cable, better than shielding much of the time!

[ashcatlt]

Do you know if there's a string ground? Does the noise get better when you touch the strings? If not, then adding a string ground might be just enough, at least while you're playing.

A single wrap of a thin, nonferrous metal can't have any meaningful effect on the magnetic field. What it will do is capacitively couple the signal in the coil to ground and suck tone in much the same way that cable capacitance does. There's a thread around here where somebody did some pretty extensive testing and found that this effect could be reduced or eliminated by simply not closing the loop fully. Just makes sure that the foil or shielding tape or whatever you're using doesn't overlap or wrap all the way around. Leave a small gap. This, of course, reduces the shielding effectiveness. Tradeoffs are...

Theoretically a dummy coil would be most effective as close as possible to the actual pickup. I'd be inclined to try attaching it the bottom of the pickup, much like the pickups 4real is speaking of. Course, dummy coils affect tone also, being inductors. Put it in series with the pickup and you lose treble. Put it in parralel and you lose bass or gain treble, depending on your perspective. One could probably buffer both the pickup and the dummy before mixing them to avoid this.

[4real]

Do you know if there's a string ground? Does the noise get better when you touch the strings? If not, then adding a string ground might be just enough, at least while you're playing.

Ahh, forgot about that! I just did this to my acoustic when I installed a pickup in the sound hole too...I simply put a bit of adhesive shielding foil around the string end holes with a wire stuck to it, then pushed that through from the inside with a peg so that the string ball ends made contact. Worked perfectly.

I still think though one might as well do the whole job with shielded wire if not already used. A single coil can be reasonably quiet with all that, but for absolute quiet hum-cancelling pickup is best in my book. Especially if gigging where there are fluro lights and such about.

[jaylow]

Wow thanks everyone! I guess I'll try all of them to see what works best.

There's no string ground. It doesn't get quieter when I play, so I'm not worried about that.

With regards to shielded wire, the wire running from the preamp to the jack is shielded. The other major length of wire runs from the pickup to the preamp. I twisted the two wires together for as long as I could, untwisting just enough length to attach it to the preamp. (I read somewhere that twisting was the next best thing to shielded wire.) Is twisting good enough or should I replace that wire with a shielded piece?

I also have a small metal box (took a part a dead 9V battery for the terminals to make a battery snap). I can insulate the inside and then close it up as a box for my preamp.

And I also have an old el cheapo pickup that I can unwind to match the resistance of my pickup to make a dummy coil.

[4real]

Well, you can try those things, don't let the battery acid get you.

I'd suspect the twisted wires, can help, but not enough...creates a big Arial for noise...you wouldn't use twisted wires as a guitar lead, it is just an extension after all of that and the pickups coil.

I would not try unwinding that old pickup to match, have a go and see what you think of the sound as is, chances are you'll never get those hair thin insulated wires back anyway.

It's not going to be as good or simple as a decent noiseless pickup though I suspect, but it sounds like a cheap guitar and one can not expect too much...good luck with it all...

[jaylow]

I tried everything short of the dummy coil and managed to quiet it down a bit but I can still hear it a little when I turn up the volume. I'll have to try it in a live setting to see if it's noisy everywhere or just noisy at home.

If I do end up going with a dummy coil, would it be better to hook it up in series or parallel? What are the effects of each? I've read that going in series will reduce my high end but I'm not sure about parallel.

Cheap guitar... Yes. As in I spent the equivalent of $50 on it. But cheap in sound... goodness no. As an acoustic, it is very bright and boomy and much better than some of the cheaper acoustics I've played around with at the local guitar shop which are still much more expensive than what I payed for this one.

[andy]

Well, it may not be very guitarnutz-y, but there is always the option of a noise suppressor pedal of some sort.

The Electro Harmonix Hum-Debugger seems to be the current buzz in suppressors (yeah, I'll leave that accidental pun in there!). A pedal stays outboard, and would be available for other instruments if you needed it any time.

Not as much fun as fabricating something though, I know.



pɐƎᴚ⊥ǝᴚ, at least you can now mail a piece of that guitar to Ray for him to sign!

[newey]

would it be better to hook it up in series or parallel? What are the effects of each? I've read that going in series will reduce my high end but I'm not sure about parallel.

In Gunther's dummy coil thread, he said that he found wiring the coil in series to be better.

That seems counter-intuitive to me, but "Empirical is" . . .

This is one of those obvious things, so I don't mean to insult anyone's intelligence by mentioning it, but since no one said it before- when running the shielded cable, did you connect the shield to the ground lead of the output jack, or to some other grounded point?

[ashcatlt]

Jun 14, 2012 19:32:40 GMT -5 jaylow said:

There's no string ground. It doesn't get quieter when I play, so I'm not worried about that.

With a proper string ground it probably would get quieter when you play, or really anytime you touch the strings. Isn't quieter what you're looking for?

[cynical1]

Jun 15, 2012 4:16:02 GMT -5 andy said:

Well, it may not be very guitarnutz-y, but there is always the option of a noise suppressor pedal of some sort.

This is how I'd go. It was a cheap guitar so a cheap and dirty solution seems in order. ReTreads is cheaper, but the results may not be as desirable.

HTC1

[jaylow]

Jun 15, 2012 9:26:36 GMT -5 ashcatlt said:

Jun 14, 2012 19:32:40 GMT -5 jaylow said:

There's no string ground. It doesn't get quieter when I play, so I'm not worried about that.

With a proper string ground it probably would get quieter when you play, or really anytime you touch the strings. Isn't quieter what you're looking for?

Oh I mean I don't have a string ground problem to worry about. Otherwise, the guitar would quieter when I play. But since the buzz is the same regardless of whether I touch the strings or not, then the buzz isn't from the strings right?

Also, shield goes to ground pin of jack.

[4real]

Jun 15, 2012 14:27:51 GMT -5 jaylow said:

Jun 15, 2012 9:26:36 GMT -5 ashcatlt said:

With a proper string ground it probably would get quieter when you play, or really anytime you touch the strings. Isn't quieter what you're looking for?

Oh I mean I don't have a string ground problem to worry about. Otherwise, the guitar would quieter when I play. But since the buzz is the same regardless of whether I touch the strings or not, then the buzz isn't from the strings right?

Also, shield goes to ground pin of jack.

No, definitely try grounding the strings first. Sounds like there is no connection. I had a small piece of adhesive ground tape, I suppose for a real dirty solution, aluminium file might work, run a wire from it, perhaps attach with double sided tape and put in inside where the string go through the top and push holes through it with a peg from the inside. This will ground all the strings when you wire it to the ground of the jack or shielding.

The shielded wire needs to go to the ground NOT the tip of the jack.

This alone may fix the problem enough!

With string grounding and shielded wire, this should be as quiet as a shielded strat for instance...cant vouch for that circuit which could be adding or increasing the noise...perhaps remove it while testing, put it in a box and use it separate from the guitar and you could use it as a preamp on anything as required.

While a dummy coil is something to try, I don;t think it would be as good as a $30 stack pickup designed to work that way and more trouble than it's worth I suspect.

So, yeah... definitely try the string grounding and shielding and it may well be tolerable...even electric guitars (which this really is) make a heap of noise without grounding the strings as a rule.

[reTrEaD]

Jun 15, 2012 14:27:51 GMT -5 jaylow said:

Oh I mean I don't have a string ground problem to worry about. Otherwise, the guitar would quieter when I play. But since the buzz is the same regardless of whether I touch the strings or not, then the buzz isn't from the strings right?

Hi jaylow!

The buzz isn't from the strings. It never is from the strings. It's from the Big Ole Bucket o' Noise. Seriously, read the article in the link.

There is a dead-easy way to determine how much of the problem will be cured by adding a string ground. Strap up the guitar in whatever (electrically) noisy environment you've been having problems with. Turn the volume on the amp up to whatever volume you would normally play there. Now take one hand and reach over to where the cable is plugged into your guitar. Touch your hand against the metal outer shield of the plug on the end of the guitar cable. Did the noise get quieter? Is it quiet enough to be a satisfactory solution?

If so, devise a plan to ground the strings. Yes it's a pita to do it properly with an acoustic, but you only have to do the work once. Then every time you touch the strings, you will ground the big ole bucket, just like you did by touching the metal cover of the cable.

[jaylow]

A small dummy coil has solved the problem. It's a lot quieter now and the sound hasn't changed too much (at least not that I can hear).

[andy]

Cool, glad it's worked out well.

a cheap and dirty solution seems in order

Cyn, you know that's my speciality!