Prescription Electronics - COB ( Clean Octave Blend ) [traced]
- rousejeremy
- Breadboard Brother
Information
Okay, the one thing I missed (which probably is REALLY obvious to others) , is that according to the diagram, Blend 2 should be connected to Volume 3. This helped somewhat, but all I get now is a very very VERY slight sound out of the box. It IS making an upper octave/octavio effect, but my amp has to be crancked in order for me to hear anything...
- Brink
- Degoop Doctor
I just made one, with the extra vero cut, and it's extremely quiet with no octave. Looking at the vero it strikes me that the vero transistors are oriented backwards from the way the standard 3904 TO-92 pinout says they should be.
Can anyone else comment on that?
Can anyone else comment on that?
I thought they were backwards as well. After double checking, the emitters are in fact connected to the ground rail as should (via R4, R7, R12 and R17). To test out different possibilities, I installed transistor sockets, and ended up aligning the trannies as shown in the vero layout. Everything works fine. I can post soundclips and pics later, if needed for comparison.
-Jonah
-Jonah
- Brink
- Degoop Doctor
Please do post sound clips, I'll see if I can too.Jonah-S wrote:I thought they were backwards as well. After double checking, the emitters are in fact connected to the ground rail as should (via R4, R7, R12 and R17). To test out different possibilities, I installed transistor sockets, and ended up aligning the trannies as shown in the vero layout. Everything works fine. I can post soundclips and pics later, if needed for comparison.
-Jonah
I switched all 4 trannies around (the opposite of what is shown in the vero) and the circuit works now.
It's not a totally clean sound, kind of a splat thing going on and some compression as well as chords get very muddy, but it works and I kind of like the sound.
I don't think it's possible to get a whammy type digitally "clean sound" out of an analog device. As I'm sure you already know, a little fuzz is allways needed to produce an upper octave. I've found many usable settings, but mostly I turn the blend knob almost all the way. It seems that in order to get an approximate 50/50 ratio in the cleanest octave setting, the pot has to be turned about three quarters up. With the octave/fuzz knob turned up halfway, the blend knob can be proportionately turned down to get a satisfactory mix...
I used 2n3903 transistors and it wouldn't work until I flipped the first two. Once I did that it makes a great octavio/green ringer-ish upper octave. I think I'll add a boost behind it in the box and then it'll be great.
Not my work. Found it online.brejna wrote:Hey guys, do you have schematic for COB? I cannot find it..
Cheers
I'm having problems with mounting this schematic above, I can not seem to find the errors
Hey torchy and analogguru, do you guys mind posting the schematic and vero again? the links are old and dead
my apologies! my stupid ass didnt see there was a second page