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Squier Vintage Modified Jazzmaster Rhythm Circuit Revisited

I've been playing my Squier Vintage Modified Jazzmaster a fair amount lately.  You may recall that I did a high-pass tone control mod to it.  The idea was to get a thinner sounding rhythm tone on the rhythm circuit.  I call it the Ching Rhythm Circuit mod.  Aka the Crawfish Rhythm Mod.

The way I had it wired wasn't sounding the way I wanted it to.  So I got to thinking.  (That is always dangerous.)

Both my Supro amp and the Fender Jaguar have a capacitor inline to cut bass.  On the Supro, it's the "Treble" input, and on a Jaguar, it's the "strangle" or "choke" (which is what Mr. Fender called it) switch.

Anyway I opened up my Jazzmaster and rewired it.

The drawing is on the right.  I didn't invent anything new here, really.  All I did was put an .002 cap in series with the rhythm circuit input to the volume control.  I also used an .01 cap for tone.  To be honest, a tone control is probably overkill and relatively useless here - but I had a pot there and I figured I should use it!  

Update 29 April: see more on the tone control below.

You'll also see that I have the tone control connected to the hot side of the volume.  This way you don't lose treble as you turn down the volume.  Yes, this is the Gibson 1950s style (aka Fezz Parka) mod.  I prefer this to a treble bleed.

Here's how I wired it.  I have an Orange Drop as the input cap, and a poly somethingorother for the tone cap.  In practice, I tied the ground end of the tone cap to the ground side of the volume control - just easier and better wiring practice than the way I drew it above.  The drawing was done that way for clarity and a minimum of crossed wires.

One thing I hate about Strats and Jazzmasters is you have to loosen the strings to get under the hood.  This time I loosened the strings, and stuck a block of wood under the pickguard to hold it up.  I was able to work on it that way.

How's it sound?  There is a volume cut and it's really thin with the .002 cap in it.  I suspect I may go to an .003 at some point.  I did some calculations though and found the corner frequency with an .002 should be 79 Hz, which is almost exactly the frequency of the low E string (80 Hz).  With an .003 the corner frequency is 59 Hz. 

But I'm a lot closer with this circuit.  If you try it, let me know what you think.  I'm really aiming for that 'ching' sounding rhythm guitar tone John Lennon had on the early Beatles records.  That's the word I use to describe that clean strumming tone.  The best example I hear in my head (!) right now is "All I've Got To Do" from "With the Beatles."  It's just a definitive tone in my view.  And of course, the polar opposite of a stock Jazzmaster's rhythm circuit tone.

Update 29 April:  I love the tone control!  I put an .01 cap on it thinking "thin."  And I didn't know what to expect.  Since there's a fair amount of bass cutoff to start with, the tone control actually lets you fatten up the tone a bit.  It's not boosting it, since it's a passive control, but the mids get more emphasized as you roll it back.

Full up it's the thin 'ching' tone.  But as you gradually roll it off, it rolls off a touch of treble and it starts to sound thicker (relatively speaking...).  Rolled all the way back it sounds a lot like the neck pickup on a Strat.  I really like this mod, especially with the tone rolled about half way back.  Not just good for rhythm, but it emulates that thin trebly tone Dave Davies had on "Till the End of the Day."

All Posts on the Squier Vintage Modified Jazzmaster Modification Project:

Part One: Starting Disassembly
Part Two: Removing Factory Wiring
Part Three: Shielding
Part Four: Wiring Modifications and Curtis Novak Pickups
Part Five: Neck Inserts and Installing Mastery Bridge
Part Six: Buffalo Bone Nut and Final Setup
Part Seven: Modified VM Jazzmaster Visits the Garden
"Ching" Rhythm Circuit Revisited: 28 April 2014 (This page)


Post a Comment 4 comments:

  • Anonymous said...
    July 16, 2014 at 12:11 PM
    Awesome blog on a JM. I pickicked up a sunburst for cheap on CL. I would love to hear your Ching circuit maybe sound cloud or youtube. Nice nut work btw.
  • Unknown said...
    May 5, 2016 at 10:12 PM
    You should consider making the Treble Roll-off fixed using a resistor, and using that Pot to bypass the Bass-Cut capacitor. The 50k might be too little, and 1M is probably too much.

    As far as the R-C calculation; remember that the Load is not just the 1M Pot, but the 1M Pot in Parallel with Input Impedance of the following stage. I think R(load) = 500k is a safe guesstimate.
  • Pete Hughes said...
    September 24, 2016 at 2:27 PM
    This is great, getting a squire jazz master soon, any sound clips/video?
  • Yr Fthfl Blggr said...
    September 25, 2016 at 11:45 AM
    Not yet, but I will have some eventually.

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