While perusing some forums I ran across several recommendations for the Behringer UV300 vibrato, especially when a new one can be had for about $30. Well worthwhile if you want to get a vibrato but not spend a lot of money. I also ran across a post to modify the rate to slow it down, sounded interesting so I bought one. The stock UV300 does sound quite good, very nice vibrato. I can see the desire to have a slower rate though. Using it on bass, I like to have the rate sloowwww with high depth. It adds a bit of dimension, the same for chorus for me. A few other things with the stock UV300 is that it is not true bypass, if that matters to some, and the housing is rather unattractive and plastic. Although it would probably hold up, as I have had an old Arion plastic pedal that shows no wear. Nevertheless, I decided to do a few modifications and rehousing. Thanks to Uma Floresta on the TGP for the info on which capacitors control the rate. Sure saved me time tracing through the schematic and investigating the layout.
The mods:
I added a foot switch to place in parallel with the rate modulation capacitor C15 so they would slow the rate down considerably in one position and stock rate in the other. I removed the pc mount pots in place of chassis mount pots. Values are Rise 250k (a) audio, Rate 250k (c) reverse log, Depth 50k (B) linear. You could use the existing pots, however with the rehouse and using a larger box it seemed best to space the controls out a bit. The stock jacks could be used also; I opted to replace with new chassis mount. I added a true bypass switch. The stock pedal has a mode switch to switch between latch (typical step on pedal once effect is on, step on pedal effect is off), bypass (no vibrato), unlatched (effect is only active when you press the pedal). I put the mode in unlatch, added the true bypass, and shorted across the stock effect pedal footswitch. If anyone looks to mod a UV300 a few things to consider: The rise really doesnt seem to have much effect, you could set and forget and only have the rate and depth as accessible controls. The input jack needs to be a stereo switch type jack with the tip switched. If the tip is not switched, when the unit is powered and you plug in, there will be oscillation that can only be rid of by power cycling. These are simple mods and rehouse to make the pedal attractive and more usable. In the pics you see several wires jumpered to C15 and C12. In the end I only placed a cap in parallel with c15, the black/red wires. I decided upon having footswitch place in parallel with c15 a 0.37 mf cap. This yields a very slow rate at the ccw position, to a moderate speed at cw position. The speed readily switches between the fast/slow speeds with the footswitch. I cut the pcb a bit to fit the new box. And thats the finished modded, rehoused UV300+*. The graphics were created on the computer, printed onto decal paper, applied and shot with several coats of gloss lacquer.
Here a few pics of the build: the modded caps, shortened pcb, completed, completed in use.
Enjoy Lapicide
The mods:
I added a foot switch to place in parallel with the rate modulation capacitor C15 so they would slow the rate down considerably in one position and stock rate in the other. I removed the pc mount pots in place of chassis mount pots. Values are Rise 250k (a) audio, Rate 250k (c) reverse log, Depth 50k (B) linear. You could use the existing pots, however with the rehouse and using a larger box it seemed best to space the controls out a bit. The stock jacks could be used also; I opted to replace with new chassis mount. I added a true bypass switch. The stock pedal has a mode switch to switch between latch (typical step on pedal once effect is on, step on pedal effect is off), bypass (no vibrato), unlatched (effect is only active when you press the pedal). I put the mode in unlatch, added the true bypass, and shorted across the stock effect pedal footswitch. If anyone looks to mod a UV300 a few things to consider: The rise really doesnt seem to have much effect, you could set and forget and only have the rate and depth as accessible controls. The input jack needs to be a stereo switch type jack with the tip switched. If the tip is not switched, when the unit is powered and you plug in, there will be oscillation that can only be rid of by power cycling. These are simple mods and rehouse to make the pedal attractive and more usable. In the pics you see several wires jumpered to C15 and C12. In the end I only placed a cap in parallel with c15, the black/red wires. I decided upon having footswitch place in parallel with c15 a 0.37 mf cap. This yields a very slow rate at the ccw position, to a moderate speed at cw position. The speed readily switches between the fast/slow speeds with the footswitch. I cut the pcb a bit to fit the new box. And thats the finished modded, rehoused UV300+*. The graphics were created on the computer, printed onto decal paper, applied and shot with several coats of gloss lacquer.
Here a few pics of the build: the modded caps, shortened pcb, completed, completed in use.
Enjoy Lapicide
, which is nowhere near the same as playing bass 
. I miss my basses...
, any chance someone knows where I can find the correct pots to use for this job... any help is greatly appreciated 
