Here are passive circuits for G&L L-2000/2500/ASAT basses.  Descriptions are on the diagrams as well as below.  

Click the images for larger versions of the image.  PDF files suitable for high quality printing are available; see below.


The circuits shown below are passive onboard electronics packages.  There is no onboard preamp.  There is no boosting of signal taking place (see my piece on relative tone for details) and G&L-standard PTB controls are employed.  The EQ circuit is, with the exception of a resistor on the treble pot used in the early circuits, the same (basic) onboard circuit that has been in use by G&L since the Leo era.

This circuit also provides advanced coil switching beyond that provided by the factory. Each pickup has its own coil switch providing parallel mode, single coil mode using the "outer" coils, and series mode. Additionally, series mode adds a .1mfd filter cap to one of the coils, producing L-1000 style “bass boost” or “Oh My God” mode.

Special thanks to Daveplaysbass, on Talkbass and elsewhere, for his kindness in development of parts of this circuit, as well as sharing his work with the G&L bass community.  The coil switching used in these circuits are derived from his fine work.


Click the image fragment at left for the full version.  Click here for a PDF version suitable for high quality printing.

This is the "old" circuit.  What makes it old is the 6.8K fixed resistor connected in series with the .047mfd cap on the treble control.  This EQ circuit is lifted from the originial L-1000 circuit that can be found here on the G&L website.



Click the image fragment at left for a larger version.  Click here for a PDF version suitable for high quality printing.

This is the "modern" circuit, and uses the same EQ section that can be found in all modern G&L L-2000, L2500, and ASAT basses, including the BABP L-1000.  This EQ circuit is lifted from the circuit that can be found here on the G&L website.

Please note the following:


This is the circuit I used in my L-2500.  It's not designed to be fully passive unless you don't care about EQ, but close enough to passive that it fits here.  Besides, it saves me from having a page dedicated to the circuit.


Here's a little something for those who are after a circuit that can feed an onboard preamp, in this case an Aguilar OBP-3.  The coil switching provides series/single coil (outers)/parallel modes.  There are no OMG caps used in this circuit, though it could easily be done if noise isn't an issue.  Pickup selection is standard G&L.  The volume control is your basic 250K audio taper pot, after which the signal goes to either the preamp or the tip of the jack via the active/passive switch.  The active/passive  switch is NOT standard G&L because in passive mode the preamp input is isolated from the signal and shorted to ground.  As usual, click the image fragment for a full version.  A PDF suitable for high quality printing is here.  Note that the 4PDT coil switch used here can be used to replace the pair of DPDT coil switches in either of the top two circuits.


Copyright 2009 Ken Baker and bassesbyleo.com