freestompboxes.org

trrs exist in 1/4" size?

I've just purchased a TOM acoustic piezo bridge... what I'm thinking is that I can could use 4 conductors in a single cable for the following
- earth
- electric signal
- piezo signal
- +9v (from board PSU back up to drive the onboard preamp).

I already have my board all wired up to have a single i/o thru to my amp so I would just need to add a tap out to xlr to go to the desk to get the peizo signal going through PA.. but it all depends on a TRRS 6.5/6.3mm (or 1/4" if that's your system)... anyone ever see one of these? I've only been able to find 3.5 (1/8") size so far..

I remember at work we had aircraft headsets that had TRRS jacks on them, probably 1/4". Big numb Bakelite things with brass contacts, probably dating back to the 40s or 50s.

I think I have a plug somewhere in my spares but definitely don't have a socket.

The socket would obviously be necessary. Seems that this is prolly either not in prod or fricking rare so maybe I should just stuck a battery in the back of the guitar. Seems a shame since it'll always be plugged in. Surely I'm not the first to consider this? Seems pretty obvious to me

Pretty rare I guess plus It wasn't the sort of thing that I would have put on a guitar, it all looked a bit "army surplus".

too much equipment was probably hooked up wrong. you'll have to do xlr or din, i guess

yeah, I'm considering xlr.. but I dunno... I guess it makes sense, will just have to get a new plate for my guitar...

It's a shame that CAT5 cables aren't shielded.

Whatever you use it is probably best to stick with something that is "standard" so you can pick up any cable of that type. XLR is the obvious choice, bummer that you have to get a whole new scratch plate though.

I did notice that they do 3.5mm TRRS jacks but I really don't think that they are robust enough for a guitar lead.

agreed re the 3.5mm (and 2.5 also has them). .. I think I'll just stick a battery in the cavity and use a trs... reason being that if I stuck an XLR in, I'd want to do as you say delafred.. keep it consistent so I can use any other cable but that'd mean a mic cable and then I'd only have 2X signal and a ground.. back to fail....
so I may as well just make up a couple of TRS 6.5mm ones... >.<

You could use a FET buffer for the Piezo and superimpose the 9v on the signal line as shown here http://www.till.com/articles/PreampCable/index.html
Using a 2 core screened cable and stereo jacks would work.

very cool idea.. will look into this further...

rocklander wrote:yeah, I'm considering xlr.. but I dunno... I guess it makes sense, will just have to get a new plate for my guitar...

A mini XLR might fit in your jack plate, like this: http://www.aliexpress.com/item/Free-Shi ... 12584.html
But that would make the gitter unusable with any other cable around.

Personally I would go with tonyharker's idea. <mictester mode>I've used the phantom power trick in the past for some experiments with EMG's, works like a charm too.</mictester mode>
You can then wire the piezo to the ring, keeps the normal pickup available when the stereo cable breaks down and you have to borrow a normal cable.

Values are starting values for experimentation:

that's some great news and kinda what I was hoping .. will play about with this.
I see you've not put the FET in there the way that tonyharker's link suggested... any reason why nor, or have I missed something?

agree re minixlr (it did cross my mind), and also, I've got a device or two with them and they just don't feel robust enough for gigs... the angle of them coming out of the LP shape would just be a disaster waiting to happen I reckon. if I was gonna go XLR, I'd just replace the plate but I didn't want to paint myself into a corner re cable replacement as you mentioned... thanks heaps.

That schematic was for the EMG situation. It should work with your piezo preamp too, but it all depends on the power (current) requirements of the preamp. EMG's are low-power (they draw micro-amps) and supposed to run like 3000hrs+ on a 9V battery. I don't know about your preamp.

ah right... it just arrived this morning.. seems there may be no preamp in the kit.. eep! will investigate later today.