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Mono to Stereo Guitar Conversion

Ever wished you had a stereo guitar? If so, here's haw to get it.

Certain expensive and/or high quality electric guitars are available in a "stereo" version. This article describes how you can convert most American-style, two pick up guitars to TWO CHANNEL operation, (it is not really "stereo" in the eyes of an audio engineer), with little or no change to the outside appearance of the guitar and requiring only the ability to make neat soldered joints, and less than £5 worth of components including all special plugs and leads. (There are no photographs, diagrams are more appropriate.)

However before you read further, you may be uncertain of the advantages of stereo operation. Basically, the usual guitar arrangement switches, one pick up, or the other, or both, down one lead to one amp channel. Some players have made up special split leads which enable them to drive two amp channels (or two amps) — or more — with the same guitar, and a very few amps have this facility fitted internally in different ways.

The advantage of stereo guitars is that the pickups are connected SEPARATELY to their different amps or channels and the selector switch on the guitar can therefore also select which amp or which effect (such as reverb or fuzz) is needed at any time. Obviously, the choice is limited to A or B or both and you must decide in advance which pick up goes to which amp or effect, but the system is already much more versatile than before.

There is an equally important advantage, which is not often realised; once the outputs of the pickups are separated, you can devise footswitching arrangements which allow almost any combination of different pick ups and different effects units, to your own tastes, by simply interconnecting standard switches, fitted in a metal box.

If your guitar uses a standard American-type toggle switch, the stereo conversion is relatively simple. As you will see, you have the choice of replacing the existing jack socket with a three-pole type (with the limitation that you must always use stereo leads, or have only one pickup available on a standard lead) or you can fit an additional socket, and have full operation on mono as before, or stereo on a stereo lead, or stereo on two separate standard mono leads. The disadvantage here is that you must find space for, and fit, a second socket.

For reasons of space, I must restrict these suggestions to guitars with two pick ups, two tone and two volume controls and a selector switch which has two visible pairs of leaf-spring contacts operated by the lower end of the switch lever. Fender-type guitars may be converted but may need additional controls fitted, and their selector switches, while reliable in normal use, are easily damaged by removing and re-soldering wires. It is not important whether the switch is of the straight or right-angle type. If your guitar is Japanese and inspection shows that the selector switch is enclosed and has only three connections on a plate underneath, it should be replaced with the American type having four switch connections plus one to its chassis. Unless you understand clearly what you are doing, this job is better left to a qualified technician.

Assuming you have a suitable guitar and you have removed enough cover plates to see switches, controls and most of the wiring, first locate the screened wire connected to the jack socket, and trace it back the other way to the selector switch. You should find that the centre wire inside the screening goes to TWO switch tags, linked together. The screening braid may go to the chassis tag of the switch, probably in the centre, or may be dressed back out of the way. In this case you should find the screening connected to the screening of other wires elsewhere, or to the metal case of one or more controls.

Jack 1 3-Pole A-type 'stereo' to fit parallel-shank 3-pole plugs as on headphones and american "split" leads jack tip contact operates switch, normally closed when plug inserted.
Rendar R32720 * plastic fixing nut
Rendar R327 10 * metal fixing nut

Jack 2 Standard 2-pole 'mono' to fit standard guitar leads. Same switching as jack 1
Rendar 32629 or 32620 * plastic fixing nut
Rendar 32619 or32610 * metal fixing nut

* Note: these types have additional switch contacts which may be ignored.

You must disconnect this centre wire of the output lead from the two switch tags, and either cut the short wire joining them, or gently pry them apart, while keeping any solder joining them melted. It may be helpful to remove excess solder with De-solder Braid or a commercial suction tool, but I have generally found it sufficient to add a little fresh cored solder to the joint and then shake the soldering iron free of solder and place it UNDER the tags. Most of the solder will run onto the iron. Be careful where you shake the iron, molten solder can be-painful.

Now you must run two separate wires from these switch contacts to the jack socket(s) and remember to leave about six inches more than you think you will need. You can either use the existing wire for one channel, and add a second one, or if the old wire looks messy, fit two new wires.

The outer screening braid of any replacement wires should be connected at each end only to the same places as the original wire (except of course at the jack socket, which is going to be changed). Ignore any points where bundles of screened wires are soldered together; simply cut away any unwanted wire from the bundle without trying to unsolder it, but do ensure that you are not cutting the wrong wire. If your finished job hums, one of these bundles probably formed part of the screening interconnections. Don't worry, just take a plain insulated wire from any point on the outer braid of your new wires and solder it to the case of one of the volume or tone controls where you see other solder joints. Also if necessary a wire from point C on the socket(s), to the same control case. If the guitar still produces hum, you have probably made a mistake — take the instrument to a trained repairman.

Don't be tempted to use "twin and screen" cable for convenience — you will get "crosstalk" between the channels, and do not use un-screened wire.

When you have two screened wires leading to the position of the new jack socket(s), LEAVE THEM A LITTLE LONGER THAN YOU THINK YOU WILL NEED, separate the screening back for about 1 inch and expose the end of the inner wires. Join the two screens together and consider the inner wires to be A and B. Then follow one or other of the socket wiring diagrams shown. On the single socket version, the A wire is the one which will still connect to a mono lead.

The simplest way to fit a second socket to a Les Paul-type guitar is to remove the socket mounting plate from the outside, cover all the inside wiring with plastic sheet held down with masking tape then enlarge the hole in the guitar side, to take two sockets, with a carpenters brace and bit (not an electric drill). Stop just before the drill breaks through, and finish off with a sharp knife and a round file, taking care not to damage any wiring etc. with the end of the file. Then make a new mounting plate which can be bent to fit the curve of the guitar. This bending brings the rear ends of the sockets closer together and you must allow for this. Also remember that leads to the jack sockets should be long enough to go out through the hole and connect to the sockets outside, where you can see what you are doing.

Two points which may help are:-

When you remove the outer plastic sheath of a screened cable, the fine wire braiding surrounding the inner conductor is the "screening"; if it is plaited, it should be carefully unpicked and the strands SLIGHTLY twisted together before soldering.

Do not leave the soldering iron on a joint any longer than necessary for the solder to flow cleanly into place; excess heat may carry up to the screened wire and melt the insulation between the screening and the inner wire. This fault is often very difficult to locate, without replacing the wiring piece by piece.


* Pieces of Ivory may be obtained from Mr. Freidlein, who I believe is now in Old Ford Road in East London.

* Volume and tone control pots with long mounting bushes and splined shafts, may be obtained from Stephen Delft, or in larger quantities, from Radiohm, East Grinstead. The spindles are plastic and if gently pinched with wire-cutters to distort the splines, will fit most splined knobs.

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Carl Palmer

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International Musician & Recording World - Copyright: Cover Publications Ltd, Northern & Shell Ltd.


International Musician - Jul 1975

Donated & scanned by: Mike Gorman

Feature by Stephen Delft

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