Can these violins be used without their control box, i.e. just plug the violin directly into my amp/pre-amp pedalboard (just like the YEVs)?

  • As Alphonso's answer suggests, so long as you have proper impedance matching, any preamp is acceptable. Commented Jun 29, 2020 at 13:35

3 Answers 3


You surely can, however as the control box is acting a D.I. the sound will be better with the control box (and equalized, as a bonus)…


The control box for the Yamaha appears to be a pre-amp with EQ, DI, and headphone amp. To be honest, it looks like a pretty good addition to the instrument.

To answer your question, The instrument has two piezo pickups in it and the output signal should be the pickups sent through a blend circuit, which would let you plug it into any amp, pre-amp, or effects unit built to take instrument input.

There are other manufacturers of D.I. and EQ units designed for Piezo pickups, and you can build a completely different tone to the instrument using different combinations of pre-amp and effects.

I have a cheap electric violin that I found sounded much better when the built in pre-amp and EQ unit failed and I wired the pickup out direct.


The cable from SV-250 is actually supply voltage and mono signal together in a stereo cable, and I am not sure if any amp/preamp can handle this.

However it is pretty easy to get a signal out of it without modifying the violin itself, just by peeling and connecting some wires.

Pin out of SV-250

  • T(Tip)
    • Supply voltage for the piezo pickup, with the control box under battery I measured DC 9.8V when connected to the violin, or 10V when unplugged.
    • draws ~0.5 mA
    • Seems to be able to drive the piezo just with a 9V battery, so you may be able to avoid voltage regulators.
  • R(Ring)
    • Output signal
    • Around +/- 1V when driven by the default 9.8V supply voltage. This is about line level but a bit quiter than the control box cranked full.
  • S(sleeve)
    • Ground

Bypassing the control box

This can be cheaply done by buying a 3.5mm(1/8") stereo cable and a 9V battery box.

Cut and stripe the stereo cable and connect it as follows:

wire diagram

The sleeve is ground so they stay connected in addition to the battery negative terminal. Since the output is mono signal, R is also connected to ground. you can also just get a mono connector for the output.

The positive terminal is connected to T of the violin end to power the piezo pickups. You can also add a switch in between, or just unplugging the violin should also be enough when not in use.

Violin end R connects to T of the amp end for ouput signal.


  • I'm not sure if there's any risk of driving the violin with 9V instead of 9.8V. probably fine but use at your own risk.
  • The audio quality is worse, but good enough for me for practicing.
  • You should check the pins of the cable before connecting them. My ultra cheap cable had its T and R crossed.
  • You can sholve all the components into the violin chin rest, but the power switch probably require drilling some holes. I'd expect the battery to last quite some time so opening up the chin rest once in a while won't be too troublesome.
  • I'm able to make my violin wireless by hooking this into a wireless guitar dongle. The battery fits nicely between the violin and shoulder rest. If you want to go further you probably can draw power from the wireless dongle by hacking it too.

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