Ibanez JS Wiring, specifically, the HPF circuit.

[TonyFlyingSquirrel]

Does anyone have any experience using this scheme?

http://www.dimarzio.com/sites/default/files/diagrams/JS1200pp_mod1.pdf

I'm curious if I can combine two .180 pF caps in parallel to come up with a value of .360 pf, to accomplish similar results.

 

[mayfly]

I don't know much about that circuit, but you can wire two 180 pf caps in parallel to get 360 pf

 

[TonyFlyingSquirrel]

I don't know much about that circuit, but you can wire two 180 pf caps in parallel to get 360 pf

Thanks Mayfly.

 

[TonyFlyingSquirrel]

I have an email into Dimarzio.

Hoping to accomplish the benefits of the HPF to only the neck pickup, using only a push/pull volume pot/switch and a 3 way LP style toggle.

I have a .47 mf cap wired in series with the neck pickup (Dimarzio Chopper) which has resulted in a tad more stratty character with the low end roll off, but I'd like it to be switchable, and only on the neck pickup.

I use a volume and a toggle, so I don't want more holes.

We'll see what Blucher sends back, he's always been very helpful in the past.

 

[line6man]

That circuit simply places a capacitor parallel to the circuit, to cut lows. If you want it on only the neck pickup, that will work for soloing the neck pickup, but you run into a problem when you use both pickups together. Since the capacitor is parallel to the neck pickup, and the neck pickup is parallel to the bridge pickup, the capacitor is also parallel to the bridge pickup. Short of an active scheme, the only practical way to provide isolation is to place a resistance in series with each pickup, so that the bridge pickup will encounter too much resistance to have its low end cut by the capacitor. This comes at the expense of output, however, and it will change the way that the pickups sound, when played together, because the series resistances will increase the output impedance of each pickup, thereby decreasing the pickups' loads on each other.

The TL;DR version: You can easily put the HPF switch on just the neck pickup, but its going to be a master HPF when the pickup selector is in the middle.

 

[Cagey]

Just for fun, here's a site that explains what happens when you connect capacitors in series or parallel.

The general rule of thumb if you don't want to do much math is: caps in parallel add, and caps in series divide. The adding part is easy and straightforward - just add up all the values any you're there. The dividing part is a little more complex, but just keep in mind the total capacitance is going to be lower than the smallest value.

I've found over the years that with most pickups a .022µF is ideal for just about any guitar. Anything more than that tends to roll off so much high end that it gets into the mids and starts to make the tone control behave like a defective volume control. Anything lower, and it has too little effect. Either way, you seem to be reaching for unusable areas, which I suspect is why many folks don't use their tone controls. Throw a .01µF cap in, and it does nearly nothing while with a .047µF cap in there you can hardly touch the control without losing a ton of signal.

There are those that like a radical range, and for them I'd say put a .01µF and .022µF in parallel to get a .033µF. Roughly. But, that's as far as I'd go. Caps and resistors are usually pretty sloppy, tolerance-wise, so figure within 20% of those values. Which is, incidentally, why some folks think some caps sound different. They don't. They don't have a sound, they have a reactance, which is based on capacitance. So, an expensive .022µF oil-over-paper may sound different than a cheap .022µF ceramic, but that's only because neither one of them is actually a .022µF cap. They'll both be marked that way, but one may be a .019µF part while the other is a .024µF part.

 

[TonyFlyingSquirrel]

Thanks for that Cagey.

I'm just rolling off lows (High Pass Filter) on the neck pickup only.

 

[Cagey]

You may want to consider using one of Willie's "Q-Filter" parts. They're designed to play with low frequency filtering, while caps are generally used for high-frequency stuff. It's difficult to filter lows without an inductor involved.

 

[TonyFlyingSquirrel]

You may want to consider using one of Willie's "Q-Filter" parts. They're designed to play with low frequency filtering, while caps are generally used for high-frequency stuff. It's difficult to filter lows without an inductor involved.

Thanks Cagey, so I presume wiring a switch as such would accomplish the same results.

 

[Cagey]

I don't know if it'll accomplish the same results, but I've learned not to argue with Willy's ideas. Although, to be honest, I still haven't used one of these things yet. I've just heard happy reports from those who have. Man knew what he was doing.

Anyway, what's the worst thing that could happen? That you have an unusual tone control. What could possibly be wrong with that? If you don't like it for some reason, there are certainly 80 bajillion other wiring diagrams out there to experiment with.

 

[drewfx]

It's difficult to filter lows without an inductor involved.

No it's not, and I know you know this. A cap in series filters out lows with the cutoff frequency determined by the cap value. If you put a pot in parallel with it you can allow some lows back in.

 

[drewfx]

It's semantics, but I would call that a treble bleed rather than an HPF, as it only really does anything when the volume is turned down. IMO, calling it an HPF (though technically accurate) perhaps only confuses the non-technical folks by implying it's something different or special compared to the treble bleed circuits they are already familiar with. It's just a switchable treble bleed.

If you want a high pass that works at full volume, you don't want that circuit.

What are you trying to achieve?

 

[TonyFlyingSquirrel]

My hopeful accomplishment is to cut off some of the lows at full or any volume just by switching the circuit in/out, and have it affect only the neck pickup.

Basically, going from a full on creamy neck sound to a more paf'ish neck sound.

I've played these JS models with this circuit through a Marshall JVM410H and can attest that this circuit does indeed accomplish what it boasts, but the JS setup is such that it's all or none, meaning, both pickups affected, or none affected.  It also uses a Volume + Tone + Toggle setup, with one of the pots switching a split coil function.

I only have a Volume + Toggle, don't want the split, don't want the HPF affecting the bridge pickup.  I want it affecting the neck pickup only.

 

[drewfx]

OK. It's pretty simple - you just put a cap in series with the neck PU between the PU and the PU selector and switch it in and out.

A cap blocks lows, with the frequency at which it starts allowing lows to pass determined by the cap value. Bigger and bigger cap values allow lower and lower frequencies to pass, smaller and smaller cap values start blocking lows at increasingly higher frequency.

You can also put a resistor/pot/trim in parallel with the cap to allow some lows to pass.


[EDIT: Ric bridge PU's often traditionally had a bass cut cap in series. It's popular nowadays for people to use push/pulls to switch it in and out. I'm sure we can find a diagram pretty easily...]

 

[TonyFlyingSquirrel]

OK. It's pretty simple - you just put a cap in series with the neck PU between the PU and the PU selector and switch it in and out.

A cap blocks lows, with the frequency at which it starts allowing lows to pass determined by the cap value. Bigger and bigger cap values allow lower and lower frequencies to pass, smaller and smaller cap values start blocking lows at increasingly higher frequency.

You can also put a resistor/pot/trim in parallel with the cap to allow some lows to pass.


[EDIT: Ric bridge PU's often traditionally had a bass cut cap in series. It's popular nowadays for people to use push/pulls to switch it in and out. I'm sure we can find a diagram pretty easily...]

 

It's the switch part that I'm messing my head with.

Which of the 6 terminals to do what with.  If memory serves, looking at the switch, up would be the 2 terminals going away from the pot with the shaft on the shaft side, down would be the middle (bypassed).

 

[TonyFlyingSquirrel]

Mr. Blucher comes through as usual.

 

[drewfx]

Mr. Blucher comes through as usual.

That works, but you could also wire it so that you only use half of the switch - which only really matters if you wanted to switch something else at the same time.

Also note that the caps used in the JS may be way too small for use as an HPF rather than a bleed. Rics used .0047uF caps for their HPF's.

 

[TonyFlyingSquirrel]

Mr. Blucher comes through as usual.

That works, but you could also wire it so that you only use half of the switch - which only really matters if you wanted to switch something else at the same time.

Also note that the caps used in the JS may be way too small for use as an HPF rather than a bleed. Rics used .0047uF caps for their HPF's.

I have an idea about wiring those terminals up to some alligator clips so that I can audition various caps in real time with the guitar plugged in. 

Blucher said the same thing as you regarding the HPF/Bleed function.

 

[TonyFlyingSquirrel]

Found a couple of more options.

I'm thinking just the bass cut will apply most appropriately for my intended purpose.

 

[Jesse]

Ibanez has used that 330pF cap for a long time.  It used to be something that you only got on a Jem as a treble bleed thing.  But now they put it on pretty much all their Prestige guitars.  Typically it's wired between the side and center lug on the volume pot.

But you're right, on the JS when you pull up the volume know you cut out all the lows, even at full volume.  Since every guitar I have has a bridge humbucker, I use the JS with the high pass to approximate a Strat tone.

If you're really interested in one of those 330pF caps, you can get them from ibanezrules.com, part 3CP1J331