Is this a trick question? : )
I prefer mag pickups because they don't need a preamp and don't pick up handling sounds.
Joe, I don't usually put a pickup on a straight acoustic build. That said, I have used disc piezos and rod piezos on acoustic builds, and I like the rod piezos better. Good direct contact under the bridge has yielded good results for me. Shane had a good video regarding this installation in this forum. I havn't yet installed my rod piezp with equalizer yet, but I've done several with a rod piezo installed direct to the jack, and several with a volume control in line over to the jack. The other side of my reply to your question is ...I've installed a lot of mag pup's in cbg builds, built to be electric gits, and they have been so good acoustically that I rarely plug them in to play solo. Since I never know how a git is going to sound while I'm building it (a surprise, like Christmas morning!), I go with what feels right when the box is in my hand. Hope this is somehow helpful. I guess you can go with what you think will work for you, and be surprised,
Certainly not a trick question. It's easy enough to insulate a piezo from extraneous sounds, but I'm new to electronics and just interested in how folks with more experience evaluate different types of pickups.
Magnetic pickups in a semi-hollow or hollow body guitar/cbg can often lead to feedback and RF noise. Shielding the inside of the body is often required, shielded wiring is prefered and sometimes foam around the bottom of the pickups is needed.
Also magnetic pickups work better with steel strings. Acoustic strings used with magnetic pickups often have problems with balanced output( solid strings are louder than the wound strings).
I have a acoustic cbg with acoustic strings and installed a Flatcat pickup(thin humbucker made for cbg's), it works fine with the acoustic strings. However that git is a 4 string and only 1 string is solid out of the 4, so that maybe the reason this git works well with a magnetic pickup and acoustic strings.
I add both types so you get 3 different sounds from the same guitar (piezo/magnetic/both).
Hey David L. Do you do anything special to use both types of pups? I tried it when I first started building and the balance between the two pickups was horrible. One of them (I think the rod piezo) was incredibly weak. I had a three-way switch mounted on a chrome plate that is commonly sold.
Hi Ricky D,
In the first builds I used to swap in piezo discs (2 or 3 wired in parallel) for one magnetic pickup into any standard diagram for a 3 way or 5 way switch. These were still weaker than a magnetic but for bedroom playing worked fine for my own use - I just dial up the amp when on piezo only. With the switch on both piezo and magnetic pickups you got a distinctive change in tone from magnetic or piezo alone and some acoustic playing properties comes through (for example the attack on the strings was much more noticeable with both than magnetic alone). This is a poor quality video from years back - you need the volume on full (used to be via a slider on the video window but not sure if still the case on all devices). If you can get sound this demonstrates what I mean. https://cigarboxnation.com/video/comparing-cbg-pickups
In later builds I have used rod piezos and they are much weaker. I went through a phase of trying blend pots but found them limited (because the way they work is as one pot increases the other decreases such that at the mid point it is the same as two volume pots on ‘5’) result is the magnetic wins. After this I used instead a volume pot for each pickup (all piezo counted as one pickup) and added a diode to the hot output lug of each volume pot (1N5819 type diode - note they are pole specific and only work one way round). These act as a one way point in the circuit stopping other bits of the circuit further on in the wiring from having an effect to the circuit before the diode. This turns each volume + diode into a mixer control. Result being you can then dial in as much of the piezo or magnetic pickups into the final output. If you wire pickup->volume pot/diode->switch selector->output jack then connecting other pickups with volume/diodes at the switch selector with the common hot wire to the jack you will be able to switch between preset amounts of each pickup type. This can be wired with the pot/diodes in the box and a final master volume added after the switch to let you control overall volume outside the box as per a normal guitar. (Or if a quick pickup selection is not needed you can do away with the 3 or 5 way switch altogether and control pickups via the volume/diode controls.
This is the first place I found the idea of the diode mod https://www.strat-talk.com/threads/the-stracciatella-3-volume-w-var... it was a few years back so not sure how many of the links still work.
I opted for the 1N5819 diode because it could tolerate a higher voltage which theoretically piezo discs could generate.
I hope this is of help.
PS In the sound demo video the preamp had a bypass switch and was connected between the final common output and jack so both piezo and/or magnetic signals went through the same input of the preamp.
Rod Piezo's need a preamp to match the output of a magnetic pickup. Gitty sells one for about 20 bucks.
Round disc type piezo's will have more output on a passive circuit, but they don't sound as good in my opinion. They can be placed in different areas of the box for different results.
I See, your talking both being used at the same time.
One way to do this would be one of those Gitty preamps for 20 bucks and comes with a rod piezo and install in your CBG if the box is thick enough and a magnetic pickup or 2 with volume and tone pots wired to a 3-way switch to the jack. That way you have pickups on one side of the switch, preamp piezo on the other side and both together in the middle without having to wire in diodes.