Thursday, January 13, 2011

Stereo Guitar Pickups


Stereo pickups can be used to split the signal from bass and treble strings of a guitar to different amplifiers. This means that different effects and EQ can be applied to the different string fields.

The simplest way to achieve this is to remove pole pieces from regular guitar pickups. The pickups are then wired to separate jacks.


Pole pieces can also be removed from a 4 conductor humbucker, which can then easily be made to retrofit a LP style guitar.



Guitars with single coil pickups may have limited pickup combinations with this setup.

    for example, A stratocaster:


    Low Strings: Middle

    High Strings: Bridge / Bridge + Neck / Neck







Humbucking pickups can be split, and used as two single coils. This could then lead to several stereo pickup combinations:

    for example, a les paul style guitar:


    Low Strings: Bridge / Bridge + Neck / Neck

    High Strings: Bridge / Bridge + Neck / Neck







This style of modification is used by Jesse Hall of 'Experimental Dental School' to great effect. Jess uses a variety of string gauges, and breaks the pickups into thirds, so allowing him to play bass, rhythm and lead all at once on the same instrument through three amplifiers.
Here is my example of a guitar with removed pole pieces.


I have also designed and made a stereo guitar with rotated pickups, similar to the designs of Yuri Landman.


I should note that removal of pole pieces is much simpler to retrofit, as with the rotation method it is very hard to align the pole pieces beneath the strings.

Wednesday, January 12, 2011

Valve Amp Volume Control


Valve amplifiers must have correct output impedance to work, they can be damaged if they do not. An L-Pad is used to control output level, while maintaining load resistance.
A 100W L-Pad can be bought on ebay for about $30 including shipping.

The L-pad ensures correct impedance to the amplifier, while varying the current to the speaker. The result is reduced volume at the same impedance.





Heavy gauge wiring MUST be used, as this box goes between the amp and speaker. It's also very important that the cables to amp and speaker are in the right sockets. Be sure to buy an L-pad to match your amp and speakers. Mine is 16ohms.