Replies to This Discussion

Permalink Reply by Skeesix on March 20, 2011 at 7:16am

I think it might work. The best way to tell without committing to solder is to get some of those alligator clip test leads, hook it up temporarily, and try it out. Radio Shack has them.

Permalink Reply by DrByte on March 20, 2011 at 3:35pm

Sometimes (rarely) you can get away with something like this but more often than not the one will interfere with the other and induce at the very least some distortion in both, especially since one is an 'active' pickup. A simple SPDT switch will alleviate this easily, wire switch center to jack, one side to mag PUP and other side of switch to piezo. It's a simple circuit and if you can add the piezo and vol it would be easy to add this switch also.

Permalink Reply by bucky on March 20, 2011 at 3:41pm

sounded too good to be true! I suppose I would have to keep the neg battery from the preamp wired to the switch on the jack in order to make it operational since it is a jack with a on/off built in?

Permalink Reply by Jim Felton on March 29, 2011 at 12:00pm

I think you would be happier with a stereo  jack or some kind of splitter. as difference in characteristics of mag and piezo pickups is vast.  Also, piezo will work best thru a preamp with at least 150K Mohm input impedance and a DI box.  Seems like a lot, but sound is all. BTW I'm coming at this from a washtub bass player's point of view, coupled with 15 years of experience with piezos (and installing telephone central office switchgear), and have put several radio shack 273-073s  in guitars.  I use 2 layers of heavy duty sticky tape to soften piezo at point of contact (makes removal easier without damaging piezo).  BTW  pickup may be cut but not bent.

Permalink Reply by bucky on March 29, 2011 at 4:39pm

jim, so even if i do use a three way toggle switch it won't sound right? when you say pick-up can be cut you mean I can cut or trim the under saddle piezo to fit a four string bridge? the piezo is encased in a metalic shell.

Permalink Reply by David L. on March 29, 2011 at 9:50pm

Hi Bucky,

Typical of me I am late to the party ;O)

I am not an electrician but as a hobby have wired up numerous guitars with magnetic/piezo discs/piezo rods/ with and without a preamp.

I have wired magnetic PUP and piezo discs via a 3way switch and in the middle position cannot see how it differs from wiring the two to the output as you suggested - the 3way is just a switch so all you would be doing is losing the ability to select just one - as you suggest turning the volume right down would do this job for you.  As Skeesix has said just wire it with clips or electrical tape before you solder to check you are happy with the sound options.

The sound you get with a preamp is different but good/bad depends upon what you want.  I did a video clip a while ago to try and show the difference http://www.cigarboxnation.com/video/comparing-cbg-pickups?xg_source... (sound is a bit low but you can get an idea)

At the moment I really like wiring a 3 way with a magnetic PUP with one of these "passive" tone and volumes discussed here for the piezo control http://www.cigarboxnation.com/group/cbgwiringelectronics/forum/topi... you can get these passive "preamps" (really a volume and tone control) off ebay cheaply from Honk Kong/China just search for passive preamp on ebay. you can attach piezo discs via a 2.5mm jackplug if you don't want to use the rod piezo.  I used this idea for part of the circuit for this 8 stringer http://www.cigarboxnation.com/video/8-string-cbg?xg_source=activity

David

Permalink Reply by Jim Felton on March 30, 2011 at 3:50am

You can trim the piezo element, but don't bend.  May not be necessary.  An article by some MIT dudes suggested only attaching about 1/2 of the disc to a guitar brace so as to leave the other half in free air.  I tried this but heard no benefit.  A 3-way switch works when A & B PUPS have same characteristics for blending.  Radio Shack 273-073 is in a plastic case, which must be removed with care. Red = +.

 

A TRS (stereo) jack would let u exit via a Y connection and use 2 channels to blend/compare signals.  Basically a mag PUP is a LOT stronger than a piezo. 

Permalink Reply by bucky on March 30, 2011 at 5:37pm

The piezo element that I want to use is a rod type that rest directly between the saddle and the bridge. If I could clip or cut it to fit a shorter saddle that would be more ideal for the 4 string I want to build. Dave, I have read a few post that say that the mag pu would drown out the piezo when both are selected, but I like the sound when both are selected in your video. I am going to try to wire then both directly to the jack and see if it works this way I like the idea of using the vol controls as a way to select pick ups and also to control the output of each while both are selected. I have included a crappy little diagram to show what I'm thinking.