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Passive Midrange control

8/20/2004 5:45 AM
Josh Pardes
Passive Midrange control
Does anyone out there have a schemo of a passive midrange cut/boost (like the Torres Super Midrange)? I find it hard to believe that the mids can actually be boosted in a passive circuit.  
A couple of years ago I had a US Master's LeGrande (basically their version of a strat). The tone control was amazing. As you turned it down it would focus the mids sort of like a wah pedal. When I was wiring up new pickups in it, I paid note to the design. It did not have an inductor coil. If memory serves correctly, it was a resistor and a cap only but I was dumb enough to sell that guitar (slapping head.. stupid stupid stupid!!!). If anything, I wish I had drawn out the the circuit before hand. Does anybody out there know how to do something along those lines? Common sense tells me that it was a cap and resistor running in series (maybe even parallel - brain not functioning at full capacity this late at night) but I have no idea of the values including the pot. It would totally make my day if someone knew how to do this as it was the most useful tone control I have ever used. Suggestions welcomed.  
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8/22/2004 7:19 PM
Steve A.

    Here is the circuit that I have used in a few guitars:  
    With the push-pull pot down it is a mid-cut control which is fairly neutral when set to 10. With the push-pull pot pulled out it is a mid-cut-boost control which is supposedly neutral when set to ~7. However, when I finally tried an A/B test you could definitely tell when the circuit was bypassed.  
I find it hard to believe that the mids can actually be boosted in a passive circuit.  
    You are correct... the mids are not boosted with the passive circuit, but just cut less than the highs and lows so the net effect is like a boost- only the overall signal level is cut. :(  
Steve Ahola  
P.S. I find both versions of the passive mid control to be useful- the mid cut cleans up the signal a lot while the mid boost will dirty it up a bit.
8/23/2004 1:37 AM
Josh Pardes

Steve, thank you so much, I have been trying to track down something like this for quite some time now. I had suspected that it used an inductor, but the circuit is a little more complex than I had anticipated. It makes sense though since it is cutting highs and lows to pronounce the midrange. Pretty cool! :) I play a G&L and as you probably know they have a master treble cut, and a master bass cut, however I have never liked the bass cut too much playing with single coils and all. I just made some beefy pups that have a pronounced midrange for blues and jazz but I want to be able to tame them a little for rockabilly and country. I've tracked down a source for push/push pots to make the switching even easier. I hate trying to pull out a switch with fender style knobs :) Probably going to throw in a series/parallel switch for even more tonal options while I have my baby opened up for "surgery". If you are interested I'll hook you up with a damn good deal on some handwound pickups for this little treasure of a mod. Thanks again.  

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