Fitting an acoustic Pick-Up system

To hear yourself playing guitar face on from a speaker can be a revelation. If you want to enhance your tone, record into a computer (ok you could mic up), or add effects, or loop, or play in public – you probably want to “plug in”.

If you have something like a “Woody” pick-up that clips into the sound hole and you simply want a hole drilled into your treasured guitar and a Jack Socket. I can do that for you. I would recommend a tail-pin jack socket that also acts as a strap button. You can see one of these fitted in this next sequence.

BUT how about a volume control and an equalizer for tone control, AND a tuner. This requires a battery powered pre-amp and most commonly uses a piezo under saddle bridge pick up. Though some system also include a microphone that picks up the true resonance inside the guitar and has a blend control to choose internal mic or piezo or a blend of both.
This next sequence shows how I fit an under saddle piezo system and preamp …

123579111214Here is a ‘Tanglewood’ guitar – nothing wrong with it – it is a nice guitar – but no pick-up.

The system I fitted here was about £10 direct from Hong Kong and I have used a few of them. I have also fitted Fishman systems, as used on ‘Martins’ and at around £40. You get what you pay for – well – yes or no – This unbranded unit does works very well and has a wide range of equalizer settings allowing you just the sound you want and helping to cut feedback.

This one has bass, middle, treble and presence as well as volume, low battery indicator. it comes with a jacket socket but I prefer the more rugged Stereo tail pin socket that has less detriment to the look of the guitar. Another thing I like in this unit is the built in battery box. I like this because there is no need to locate and cut in another hole spoiling the look and lines of a nice guitar. It uses a 9v rectangular battery like most of them. This battery box is also nice because it has a carrier that pops out and the battery just slots in. As the carrier goes back in it connects to two springs. No fiddling with battery connections that inevitably break.

The piezo pick-up is that copper strip. The lead plugs into the main preamp unit with a  mini jack.

First job is, choose where to locate the main preamp/battery box. This one has a double curve which limits the choice. I use a piece of masking tape to mark the best position.

After carefully measuring the unit to work out the exact hole size I use more masking tape to draw on the position. Remembering that if I cut it too big there will be no material to hold the screws that hold the unit in place.

The tool I use is a ‘Fein Multimaster’ saw.

The ‘Fein Multimaster’ vibrates the blade like a dentists tool and is easy to control and it makes a very quick neat job. The actual blade only moves a few millimeters.

I fit with a 1″ fine wood blade. The blade is carefully offered up to the lines drawn on the masking tape and simply plunges straight in. Reposition plunge until the waste falls in.

If the side of the guitar is laminated the glue used can make this cut much harder than it may first appears.

The next job is the tail pin Jack Socket. This ‘Tangelewood’ had a tapered strap peg that wedged into a 3/8″ hole through the center line of the guitar.

I simply pulled this out and enlarged the hole to suite the diameter of the new Stereo tail pin Jack Socket.

The Stereo tail pin Jack Socket has a flange with three holes for screws. I like this in comparison to the round ones (that do look neat) but so easily get loose especially with tight jacks plugs that you may find at some “walk in” gigs. These sockets will in time pick up dirt (from dirty plugs that inevitably get dropped on dirty beer soaked carpet – ok I hang out in dodgy dirty dives but that’s where you find the best music). With this type of Stereo tail pin Jack Socket three screws and she is out and then just solder on a new one. They are about £4 and cant be cleaned easily.

The purchased main preamp unit has been screwed into place. A  fine drill, to suit the screw size, was used to ensure a good fit. Those guitar sides can be really tough to screw into without a proper pilot hole. Especially if laminated with a tough glue.

A piece of wire (I use a straightened coat hanger) is offered up through the hole and up through the sound hole. The jack socket “provided” was cut off. I tape the jack wire to the coat hanger wire and pull it through.

Stereo ? tail pin Jack Socket. Yes Stereo because the second of the two positive connections in the socket is used to turn the battery on. This is why if you leave the guitar plugged in for long periods of time the battery goes flat. If you unplug when not playing – the battery is disconnected and the battery last for ages (a good 6months).

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Copying the wiring connections used on the “provided” jack socket, I strip the wire and solder the connections.

I use a continuity meter to check that I have sound good connections. I keep a jack plug in my kit to plug in so I check the continuity through the unseen connections in the socket and soldered joints. (I also use this to trace the connections in “provided” sockets or those I am replacing.)

fishmanFinal job – After taking all the strings off, (which I hate doing as the neck loses tension – whenever I can I always replace one string at a time and tune to pitch to maintain tension). So with strings off I drill a suitable size hole to feed the piezo pick-up lead into the guitar body. I plug the pick-ups mini jack into the main pre-amp.

Before seating the piezo pickup I …

  1. Check that the saddle slot is deep enough for the final assembly
  2. That the bottom of the slot is very flat and debris free
  3. Check that the saddle is a tight fit (if not replace it)
  4. File the bottom of the saddle (nice and flat) to achieve the previous “action” height with the piezo pickup sandwiched underneath.
  5. Check that the string angle off the back of the saddle is close to 20 degrees (ramping the peg hole into a slot if need be).
  6. Ideally that there is 50% of the saddle below the bridge and 50% above

 

There is much more details to perfect this set up at …
http://www.fishman.com/files/advanced_undersaddle_pickup_installation.pdf

Looks tricky – OK so let me do it for you …