Modding a Behringer VT911
A few weeks ago I replaced my Line6 Podxt live multieffect pedal with a guitar amp, cabinet and 2 pedals. The amp is a Kustom Defender 5H head and I use a Kustom 1x12 cab with it.
To replace the multieffect pedal I bought a Behringer VT911 overdrive pedal and a Digitech Digital Reverb pedal. I chose for the VT911 because it contains a tube for the distortion and it only cost me € 14,90 at Thomann.
The pedal sounds fine. Not great but it's a great pedal for the price. I searched on the internet for easy mods to do on the pedal to improve the sound quality and found various suggestions on a few forums.
The first thing I did was adding a resistor and capacitor to the tube board to give the tube some extra headroom. One of the major problems I had was that it doesn't really have a setting to only distort a little. In the 0-1 range on the overdrive the pedal is usable but is very quiet even with the volume all the way to 10. On the 1-10 range the pedal distorts so much that I wouldn't call this a overdrive pedal anymore.
The mod on the tube board increases the headroom so the tube distorts later and has a lot less compression but the drive knob doesn't have a very large usable range. On the high distortion range the pedal also starts to sound very muddy. The second mod adds another resistor and capacitor parallel to the drive potmeter to change it's range and frequency response.
Here is a list of the exact values used in the mod:
Tube board: 4.7 nF capacitor between pin 1 and 7 on the tube (marked 472) 470 ohm resistor between pin 7 and ground (yellow purple black black brown) Main board: 1.0 nF capacitor connected to the outer pins of the drive pot (marked 102) 100 Kohm resistor parallel to the same pot (brown black black orange brown)
I've recorded a sample before the mod and after the mod. Judge for yourself: