Links and resources - Updated 11/2/2017

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Various "K" model circuits

Postby Ken Baker » Sat Apr 19, 2014 4:06 pm

Courtesy of Paul Gagon.

There's some fun stuff in there, folks.

Enjoy!

Just updated with 3 dozen drawing sets. Got most of the basses covered.

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Strings for your G&L bass

Postby Ken Baker » Mon Sep 15, 2014 4:18 pm

This is one of those posts that I've known should have been done, but was never done. Probably due to momentum. Or static friction. Or laziness. Pick one. Anyway, TDR1138 gave me one of his patented Nudges and here we are. Thanks, T!

Current G&L fretted 4 string basses ship with D'Addario EXL170 strings. Nickel. Regular Lights. 45-65-80-100. Long scale. Includes Tribute.
Current G&L fretted 5 string basses ship with D'Addario EXL170-5 strings. Nickel. Regular Lights. 45-65-80-100-130. Long scale. Includes Tribute.

Current G&L fretless 4 string basses ship with D'Addario ENR71 half-round strings. Nickel. Regular Lights. 45-65-80-100. Long scale.
Current G&L fretless 5 string basses ship with D'Addario ENR71-5 half-round strings. Nickel. Regular Lights. 45-65-80-100-130. Long scale.

All this is as of 9/2014. G&L being the guys that they are, this could all change on a moment's notice.

There are questions about different strings. Like, "Will I have to open up the nut slots if I move to a larger gauge?" or "Will I have to adjust the trussrod?" The answers are maybe and probably. Nice & precise, huh?

You have a certain amount of leeway with string gauge. G&Ls will typically handle a slightly larger string without having to file the nut. How much larger kinda depends. For most, it'll be unlikely that the nut needs filing.

Trussrod adjustment for a given action is all about string tension. Some string manufacturers (D'Addario, Thomastik, Circle) are listing their strings tension, so you can get an idea of what you're getting from what you've got. If you're changing strings to a different brand or type, plan on tweaking the trussrod a little. It probably won't take much of an adjustment.

Speaking of trussrods: US G&Ls have had three styles over the years. The original that is in Bi-Cut necks that compresses the neck, the first non-compression single action trussrod (Tribute too), and the current non-compression double action trussrod. Both non-compression rods are excellent. The double action adjustment will be smaller than the single action adjustment for a given deflection.

Oh! You might give this a read too, seeing as how you're probably changing strings.

That's about it. As always, this will end up being a work in progress. If something changes, I'll update as needed.

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Tap Test

Postby Ken Baker » Sat Oct 11, 2014 2:41 pm

Doing a tap test on an L Series pickup is one method of locating a potentially bad coil or a wonky switch. Here's how to do it:

Set your amp's volume bedroom-style low.

Set your bass to parallel mode, both pickups. Active or passive doesn't matter. Treble & bass about 75%, volume about 50%

Using a small screwdriver, tap a pole piece of each coil. You should hear a clear and sharp metallic sound. If you hear a sort of distant sound that is not clear or sharp, then that coil is open at some point (not working) or otherwise not connected. Further investigation is needed.

An open coil is caused by a broken connection somewhere in its circuit. It could be the coil itself or one of the coil's leads. It could be a problem at the series/parallel switch. You get to dig in to find the fault.

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What's the difference between normal and "K" L Series pickup

Postby Ken Baker » Tue Oct 21, 2014 7:04 pm

So many people refer to modding their L Series basses to provide single coil as the "K" mod that I don't even pause to consider how they're doing it. The "K" circuit from G&L is available for the L-2000/2500/ASAT basses and provides single coil mode using the outer coils of the pickups. There is also a third party single coil modification (originally from DavePlaysBass) that does the same thing. The differences are the leads from the pickups and how they connect to the pickups, and the wiring of the coil select switch. Because of this, the two circuits should not be confused. Indeed, if they do get confused the bass probably isn't going to work very well.

The original L series pickups have a white lead, a black lead; a green lead, and a yellow lead. The white, black, and yellow leads run from their coil connections directly to the control cavity. The green lead has a short little jumper that runs from its coil connection to one corner of the back plate. Connected to the opposite corner of the back plate is a longer green lead that runs to the control cavity.

The "K" model pickups have a white lead, a black lead; a green lead, a yellow lead; and a blue lead. The white, black, green and yellow leads run from their coil connections directly to the control cavity. There is NO short little green jumper that runs from its coil connection to one corner of the back plate; green goes directly to the cavity. Connected to one corner of the back plate is a blue lead that runs to the control cavity.

Why the difference? In the original pickups, the back plate in circuit with the green/yellow coil causes a tiny little weensie impedance imbalance. This impedance imbalance can cause the pickup pair to be a tiny, little, weensie bit less than humbucking, and it might be noticeable in series or parallel modes. The back plate needs to be grounded to help keep things quiet. So Paul, being smarter than the average bear, brought the green lead out directly from its coil and added the blue lead to ground the back plate. In practical application, this means that a true "K" model may be a tiny, little, weensie bit quieter in a humbucking mode than a non-"K" pickup.

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M Series Preamp Info

Postby Ken Baker » Thu Nov 06, 2014 12:42 pm

The preamp section in the M series basses, like the L series before it, is designed to present a low impedance to your amplifier. This reduces noise and eliminates the "tone suck" caused by long cable runs with passive instruments. While the L series preamp did a tiny bit of tone shaping in the form of a little treble bump, the M series provides no tone shaping.

The EQ section, on the other hand, can do extensive tone shaping. All three EQ controls can provide up to about 14db of boost or cut to their respective frequency ranges. The centers of the controls are 100Hz, 600Hz, and 3500Hz.

The combination of the M-2000/2500 & MJ pickups and 18v power means that this preamp has enough headroom to virtually eliminate clipping at the instrument, delivering a clean signal to your amp or effects chain.

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Switch pinouts and shunt mappings

Postby Ken Baker » Mon Nov 10, 2014 10:41 am

These are pinouts and shunt mappings for the specified switches. They're useful for "proofing" a circuit path when trouble shooting as well as for circuit design. While I do spec applications, the drawings themselves are NOT specific to any instrument. The idea here is to print these and then pencil in where leads would go. The views shown are looking directly at the bottom of the switch and the solder lugs. The images are large and will not scale well on the board, so only links are provided. The aspect ratios are 1-1 (square), so scale as needed when printing.

These are JPGs exported from proprietary source files I created in EastDraw 3.9.6 for Mac. PDF and other formats are available on request.

4 Pole Double Throw (4PDT) and 2PDT 2 Position ON-ON


4 Pole Double Throw (4PDT) and 2PDT 3 Position ON-ON-ON (Thanks Glazenn!)

    This 4PDT switch is used for early L-2000, modern L Series "K" model, and the "DavePlaysBass" circuit for coil select switching; ie, Series/Single Coil/Parallel. The 2PDT switch is used for standard L Series pickup select and Passive/Active/Active w Treble Boost. The 2PDT switch is effectively half of the 4PDT switch and be used to provide Series/Single Coil/Parallel switching of individual pickups.

    2PDT and 4PDT ON-ON-ON Position 1

    2PDT and 4PDT ON-ON-ON Position 2

    2PDT and 4PDT ON-ON-ON Position 3

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Battery Basics and Battery Testers

Postby Ken Baker » Sat Mar 14, 2015 1:56 pm

A battery uses a chemical process to produce electricity. How much electricity that gets produced is a function of the chemistry and size (an over-simplification) of the battery. A battery is drained by the application of a load across its terminals. The load could be a lightbulb, a motor, an electronic circuit, etc. When the battery is fully drained, meaning that it can no longer provide sufficient electricity to your load, you either replace it or recharge it depending on its chemistry.

The electricity produced by a battery can be measured as two things: voltage (volts) and current (amps), and rated by current produced over time (amp/hours). If you compare volts and amps of a fresh battery to a garden hose, volts would be analogous to the speed of water through the hose and amps would be analogous to the volume of water through the hose. In batteries, volts and amps generally walk along hand in hand in a pretty predictable manner until the battery is drained. At that point volts remain pretty much normal and amps drop off.

A voltmeter is NOT a battery tester. It can be, but typically is not.

If you measure voltage across the terminals of nearly any battery using a voltmeter, you should see its rated voltage. This is true whether it's new, partly used, or almost completely dead. Unless the thing is chemically flat, it will still produce enough voltage to register a rated voltage reading (or very nearly so) on a voltmeter. So why, if it's showing rated voltage, won't it light up my flashlight? This is because it cannot produce enough current to heat up the filament enough to make light.

To properly test a battery, you don't measure the voltage at the battery terminals. You place an appropriate load on the battery and measure the voltage across the load. This is called measuring the voltage drop of the load. From here it's a matter of measured voltage vs. the rated voltage of the battery under test. The closer the measured voltage is to the rated battery voltage, the better the battery condition.

So, TL;DR: Get a battery tester that actually tests the battery under an appropriate load.

One more thing: When you're playing your bass in active mode, the preamp and electronics are the load for the battery.

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Service contact information - 4/2018

Postby Ken Baker » Sat Apr 11, 2015 4:48 pm

If you need service for your G&L instrument, your first call is to the selling dealer. This is especially true of USA-built G&Ls, and is absolutely true for warranty work on USA-built G&Ls. If you're out of warranty you can still contact your dealer or any qualified service tech or luthier, or you can contact G&L directly. That contact info is:

Memo Romero:
repairs@glguitars.com
1-714-897-6766 x156

Calling on the telephone will normally lead you to Memo's voicemail, so leave a message. Email or phone, he should get back to you in a day or two.

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Bass Control Pots for G&L Basses

Postby Ken Baker » Mon Jan 11, 2016 12:50 pm

I asked Paul if he knew of a source for bass control pots for our instruments. His comments:

Paul Gagon wrote:The 1 meg reverse audio pot is in deed a tough pot to get. They are made by Alpha but only for G&L........unless you wanted to do a minimum buy from them which is 1,000 pieces. However, there are two pots that will work as a substitution. I am including a picture of both. (links below - Ken...)

These can be purchased from http://www.tubesandmore.com and aren't that expensive. If you go to the website and look through their potentiometers you will find the ones I'm talking about. There are two reverse audio values. 3megs and 500K. Both pots will sound like the standard G&L bass pot when fully on. The 3meg pot will take out a bit more lows and the 500k will take out a bit less lows. For my money, the 500K reverse audio is the one to get. I'm not sure if most people could tell the difference between the 500K and 1meg. The hard part will be needing to route into the body cavity because the pot bushing and shaft are kind of short.

Anyway, that's my two cents worth. There are 23 pages of pots on the TubesandMore website but this is a great place to buy stuff. They have almost everything your heart could desire.


And here are the links:

500Meg RA
3Meg RA

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Re: Links and resources - Updated 1/11/2016

Postby Ken Baker » Mon Oct 24, 2016 9:01 pm

Boy, did I get lucky! I was updating the preamp upgrade post and ended up poking around at BuildYourOwnClone. I thought their parts department was pretty cool until I checked the pots section. They have 1M reverse audio taper pots ("C" or anti-log)! They went from pretty cool to extraordinary!

http://buildyourownclone.com/collection ... ntiometers

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