So full disclosure - I built the slurpee schematic but on a Veroboard layout. So I used the schematic from madbean and subbed part values and/or swapped in pots where appropriate on the tagboard layout.
http://tagboardeffects.blogspot.com/2013/06/ehx-bassballs.html
With this schematic:
http://www.madbeanpedals.com/EP/schematics/Slurpee.gif
Basically I get a filtered effect - the bass and treble pots work and the distortion switched in and out both work as well. However, I get no auto-wah type effect. The response control doesn't seem to do anything. Here are voltages:
IC1 (1458):
1 - 4.3v
2 - 4.3v
3 - 4.2v
4 - 0v
5 - 0v
6 - 1.9v
7 - 2.1v
8 - 8.6v
IC2 (4558):
1 - 4.4v
2 - 4.3v
3 - 4.3v
4 - 0v
5 - 4.3v
6 - 4.3v
7 - 4.4v
8 - 8.6v
The two transistors in the tone circuit (the bottom two in the layout) measure:
C - 0v
B - 0.65v
E - 0v
The transistor following IC1 and the attack and decay controls (the one off to the right of the board in the layout) measures:
C - 8.6v
B - 8.6v
E - 8v
Any ideas? I checked over and over again for solder bridges, cap and diode polarity, layout, etc.... I don't know the circuit well enough to understand why I would get the filter effect but no auto-wah.
So I decided to revisit this one tonight. I had placed a Mouser order, so I ordered some different varieties of 1458 chips and none of them seemed to make a difference in the performance of the pedal.
Has anyone built this? I get some change in tone when I mess with the bass and treble pots and the distortion switches in and out (doesn't sound that great). But the auto-wah part of the circuit seems to do nothing. No changes when I adjust the sensitivity, attack, or decay pots. No auto-wah effect at all. Any thoughts?
Is the polarity of the tantalum cap reversed in the spec in the slurpee doc? That seemed to get me a somewhat functional auto wah. Still doesn't blow me away or sound like some of the bassballs clips I hear online.
Quote from: taeagan on March 24, 2017, 07:46:38 PM
Is the polarity of the tantalum cap reversed in the spec in the slurpee doc? That seemed to get me a somewhat functional auto wah. Still doesn't blow me away or sound like some of the bassballs clips I hear online.
Hi, have u got any news on this project?