Post by Mike Richardson on Apr 15, 2008 16:32:19 GMT -5
I have an old Mike Christian pickup on one of my guitars. If you've seen the Ghost pickup that Stewmac sells, it's exactly the same thing: Piezo elements in Graphtech saddles. I don't use a preamp with mine-sounds better without. I've been panning from the magnetics to the piezo so far. I never use them together, so I'd prefer a switch. Problem is that the switch pops like crazy when I use it. Might be the very high (5M Ohm) impedance of the piezo. Switch is good, for what that's worth. How can I get rid of this popping business? Thanks in advance.
Problem is that the switch pops like crazy when I use it.
Which is worse; when it goes from piezo to mag, or mag to piezo?
High impedance (since you stipulate 5M Ohm I might presume that this is really resistance) alone would serve to help damp such transient events.
I suspect that it's either that reactive component (which one does not measure with an Ohmmeter) of the crystal's capacitance, or the piezo signal being induced as an edge transient. Or both, or charge storage.
I might suggest a three-way switch with the middle position reserved for transient suppression.
When the switch is in the far magnetic position, the piezo's could be shunted to signal ground thru a 100K to 1 M Ohm resistor and the mag signal would be connected to the output. Only in this position are the mag pickups connected to the output.
In the middle position, the resistor would still be in-circuit, and the piezo would also be connected to the output. The mags are retired.
In the far piezo position, this resistor would be removed.
A variation of this would be to have the piezo shunted to signal common in the far mag position, connected to the output thru the resistor in the middle position, and then to short out said resistor in the far piezo position.
You'll have to experiment with this since the actual characteristics of the crystals are somewhat nebulous.
You're also looking at at least a DPDT ON-ON-ON switch.
Additionally, these suggestions are biased towards the piezo crystals. If the real culprits are the magnetic pickups, your solution lies over there.