Hi guys, I'm working on a 6 strings CBG, and I'd like to install both a piezo and magnetic pickup; I don't know if it's possible, the idea is to use a 3 way switch to blend the magnetic and piezo, using them separately when I need: basically, position 1 is the magnetic pickup by itself, position 2 could be both magnetic and piezo, position 3 the piezo by itself.
I'd like to send the piezo through an EQ preamp system I've got on eBay (you can see it in the picture below), but I'm not sure about how the wiring works.
Thank you for your fast answers, you gave me few ideas that for sure will be useful for my CBGs.
Anyway, to answer to David: the 3-way switch I have is a Les Paul style (you can see it from eBay in this link: http://www.ebay.it/itm/271594846083?ssPageName=STRK:MEWNX:IT&_t...).
The links you provided me have been useful to get new ideas, expecially Ted Crocker's diagrams: there I've found some schematic plans about how my CBG has to work.
I did a new image, to better explain my original idea, just to know if that could work; I need the preamp just for the piezo.
As drawn here, it will work fine. The pre-amp appears to have a power on-off button, and if true, the comment from David L. regarding a switch, etc. is not needed.
One thing to note: when the 3 way toggle is in the middle position, the volume and tone controls for the humbucker will be bridged to the pre-amp. This likely will not result in the h-bucker volume affecting the pre-amp controls. But the h-bucker tone with its tone bleed capacitor can modify the overall sound. Not that this is a bad thing. Just go for it.
Ok, guys, some news... Today I tested the preamp. First, David is right, the preamp turns on when I plug the jack, that's confirmed by the led you can see right under the grey buttons, it blinks when I do that. Secondly, the two greys button work just for the tuner: the "Power" button it's to turn on the tuner, while the "Note" button works to choose the note you want to tune (it's very useful for open tuning).
Anyway, considering it's a cheap EQ, it works pretty fine, and yes, it's a copy of Prener LC-5 preamp.
So, it looks I need an on/off switch, as David said, to connect the negative wire from the battery to the common ground from the whole circuit. I guess it's the best solution for the circuit to work, instead of using the onboard power button: as David said, the display it drains the battery, also it's annoying to see blinking leds when you play, unless you're installing the preamp on a Christmas Tree. :)
So David, if you could post a wiring diagram when you're on desktop PC, it would be helpful; besides could you post a link of the type of switch I need? I'd be thankful!
Thank you guys for all your answers, I'm glad to know that my question could be helpful for other users here.
P.S. This site and its users are awesome!
If your amp is wired the same as this one it has a fault with the wiring such that the preamp is always on. If this is the case it will be much easier to add a switch.
Here you can see the four wires linking the EQ unit and the battery/jack module
From top to bottom
yellow B+ (positive battery connection)
whiteB- (negative battery which should be connected to one of the two jack socket sleeve lugs)
red OUT (live signal from the preamp going to the jack socket live lug which connects with the jack plug tip)
black GND (common ground which should connect to the other jack plug sleeve lugs)
So you can see better the 4 wire clip is removed and you can see a black wire from the battery (that I can trace going to the left of the white 4 point block to the lower right solder point for the jack socket) and a red + battery wire going to the yellow + of the 4 wire block via the circuit board (checked with multimeter).
The part we are interested in is the left hand side with the 1/4 inch jack connected ie the three left hand big blobs of solder.. Checking with my multi meter continuity function the signal live goes to the top blob. Theoretically the battery black wire connects to the right of the lower blobs and then the lower left blob should connect to the white battery - of the 4 wire block so then the jack plug acts as a switch between these two connections.
On this unit the two ground points are permanently connected (both of the lower two solder points, the black battery wire, the white B- wire and the black GND wire are all permanently connected with or without a jack. If I plug in a piezo rod to the EQ unit I can use test wires to an amp lead and without the plug inserted to the battery unit I can get a preamp signal using the top solder blob connected to the tip of the amp lead and either of the two lower blobs connected to the shaft of the amp lead jack plug. This means for this unit the EQ is always on even when not plugged into an amp (and also explains why I was getting a short battery life).
If yours is the same it will make adding a switch so much easier. (if you have two test leads you can quickly check by the above method ie plug in the piezo rod into the eq and connect to an amp using the two wires to connect the tip of the jack plug lead to the top blob of solder and the shaft of the jack plug to either of the two lower blobs. then tap and rub the piezo rod and listen for the sound transmitted through the amplifier).
This is (I think) how it should work
The black battery wire needs to be cut in half and add an extension wire to each to connect to the on/off switch and the power on/off is sorted.
To connect into the 3 way switch you solder a wire from the top blob of solder to the piezo connection on the 3 way and the ground is soldered to the common ground all the other grounding points are going to (back of the volume pot commonly).
You asked about switches any can be used such as a mini toggle switch (single pole single throw sp/st or single pole double throw sp/dt or a rocker type switch avoid any switch that is "momentary" as they don't latch and stay on)
some links but check on ebay for lowest prices
If when you check your module works correctly (ie no continuity between the two negative blobs of solder on the jack/battery module let me know and I will draw up the wiring you need for that to work.
Anything that is unclear please ask.
Thank you David, my module is wired the same way as yours; the only difference is that I don't have any capacitor in the top right corner (as it shown in the photo).
I don't know if this could be an issue, I hope it's not, because the way you explained it looks pretty easy to do.
If it's not a problem, I'll try to check in these following days.
Regarding switches, I've found on eBay these two types. Are they good for my purpose? Which of them it's better?
Here are the links:
P.S. By the way, here's a picture I just took, to show you how my module looks.
Ok, everything's clear about switches :)
Regarding the battery module, I'm almost sure the connection to 3-way switch and ground are the same; I should have a multimeter to check the circuit continuity, but I'm not sure about how to do that, I'd be thankful if you could explain what I need to do.
Unfortunately, I'm a wiring noob, I'm not able to check if the module it's switched on by the jackplug, but I'd like to learn this kind of stuff; if it helps, I can surely say when I plug the jack, the red led placed right under the grey buttons it blinks for a fraction of a second, the same whe I pull it out.