Helmut Gragger
From:
Austria
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Posted 26 Jan 2013 2:35 am |
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Recently I bought a stringmaster clone guitar. It was a new guitar, a look-a-like, although partially assembled from original parts.
Two pots had not survived the rigors of transport and had to be replaced. While I had the guitar open I changed a few things that were long time to be changed.
Those guitars are post-war technology from a viewpoint of signal handling. Now this has grown historically. Back in times long bygone everything was pretty low gain, and, as the case may be, low electrical pollution too.
The engineering standards and methods for handling sensitive electric signals have meanwhile dramatically improved, but either production has been abandoned (as in the case of stringmasters), manufacturers are anxious to change well-selling models despite their technical obsolescence (as in the case of Stratocaster or Les Paul guitars), just pure penny-pinching for that extra sales margin, ignorance, customers adhere to vintage phantasies, or a malign combination thereof.
By today´s standards for treating sensitive electrical signals, a guitar should:
* have a well screened electronics compartment and a well screened pickup cavity
* employ star-wiring
* employ proper ground management
* employ proper impedance management
* optionally, for the sake of useability, have pots with useful tapers.
There is few contemporary guitar models that come equipped with those features and of course none of the vintage guitars. But those things can be remedied without great effort or the risk of degrading an alleged collector´s value.
Those were the steps I performed on my stringmaster:
* remove all metal covers from the top to have access to the wooden compartment below.
* Cover all cavities with copper foil and solder the joints on one point for a continuous reliable plane. Allow for a few millimeters of extra foil that is folded flat over the top for good contact with the top plate. All compartments per neck should have good electrical contact and make for a complete electric screen. Take care that no part of the copper touches any other electrical contact
* Solder a piece of flexible wire to each compartment. This will eventually have the same potential as the strings and all other metal parts except the ground lug on the plug (signal ground).
* Solder a 470 nF/600V cap to the copper planes. The other pin goes to the signal ground. By this procedure the strings and compartments have a potential equal to zero for noise signals, but isolate the player from hazardous DC potentials.
* Replace all stiff wire by flexible for increased reliability.
* Replace all ground connections on pots (like the ground pin soldered to the case) with a piece of wire. All those signals finally go to one single ground summing point right at the signal ground lug of the plug.
* Optionally, experiment with different law pots for tone for greater range and try a higher impedance pot for volume for less load on the pickups.
* Finally, use a buffer right after the guitar. This is crucial for great tone and proper impedance matching.
Does it change anything? You bet. Not only is the guitar noticeably less prone to catch external noise (single coils will never be immune), it is quieter, appears pristine, fatter and the tonal center is shifted downwards. The copper around the electro-magnetic pickup seems to shift its frequency response downwards. For humbuckers this may be too much.
The buffer on its own will make a dramatic improvement on any guitar, and it can be a home-brew cheap single transistor buffer.
The whole procedure does not consume more than a few hours and is most rewarding. It also costs little money. It does not degrade the value of any guitar, because it can be removed again (who would want this?).
The process used to be described on a website called „guitar nuts“. FYI, I have described the process in more detail on my web pages for a Stratocaster.
Have fun,
-helmut
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