Voodoo Lab Overdrive

[gaussmarkov]

The Voodoo Lab Overdrive belongs to the same family as the IC-Based Overdrive described in this project.  Here is my version of the schematic, with some notes to get you started on possible mods:



And here is the part list:

Part     Value          Library             

C1       10n            gm-caps-film-box   
C2       220p           gm-caps-film-box   
C3       100n           gm-caps-film-box   
C4       1n             gm-caps-film-box   
C5       220p           gm-caps-film-box   
C6       2.2u           gm-caps-electro-pol
C7       2.2u           gm-caps-electro-pol
C8       100u           gm-caps-electro-pol
C9       100n           gm-caps-film-box   
C10      100u           gm-caps-electro-pol
D1       1N4148         gm-diodes           
D2       1N4148         gm-diodes           
D3       1N4001         gm-diodes           
IC1      TL072P         gm-ics             
R1       2.2M           gm-resistors       
R2       10K            gm-resistors       
R3       470K           gm-resistors       
R4       470K           gm-resistors       
R5       47K            gm-resistors       
R6       10K            gm-resistors       
R7       10K            gm-resistors       
R8       150K           gm-resistors       
R9       47K            gm-resistors       
R10      150            gm-resistors       
R11      47K            gm-resistors       
R12      47K            gm-resistors       
R13      47             gm-resistors       
GAIN     500K-RA        gm-pots             
LEVEL    100K-A         gm-pots             


If you would like to try playing around with this circuit, here is another breadboard layout to get you started:



all the best, gm

[gaussmarkov]

another mod to consider is increasing C5 from 220p up to 680p, 1n, or even 10n.  this will lower the corner frequency of a low pass filter that will smooth out the sound of heavy clipping.  see Op Amps 4: Divided Negative Feedback for more info.

[biggy boy]

Thanks GM
I snagged the eagle layout from your site.

I'm thinking of building it but not sure if will be good for metal type distortion, Black Sabbath, Mega Death........ style.


Glen

[BAARON]

I'm thinking of building it but not sure if will be good for metal type distortion, Black Sabbath, Mega Death........ style.

Glen

Probably not.  The Fulltone OCD is based on this, and it's a far cry from being classic metal.  Check out some OCD demos to get an idea of what it might be like.  I personally have issues with the voicing of the OCD, but lots of other people seem to like it.

[biggy boy]

I'm thinking of building it but not sure if will be good for metal type distortion, Black Sabbath, Mega Death........ style.

Glen

Probably not.  The Fulltone OCD is based on this, and it's a far cry from being classic metal.  Check out some OCD demos to get an idea of what it might be like.  I personally have issues with the voicing of the OCD, but lots of other people seem to like it.

Ok thanks for the heads up!!

Glen

[knealebrown]

Hey guys just built this and i cant get it to work.

-Checked correct polarity of all components e.g diodes, electro caps
-Changed the opamp and pots
-re soldered everything
-checked for solder bridges
-changed the op amp for a 558, still nothing.
-checked all cap, resistor and diode values

did anybody else have any problems with this build?

im getting audio out but its clean and the gain pot doesnt give any effect but the volume works fine.

any suggestions?

Thanks

[biggy boy]

Do you have the Ic in the right way (direction)?
Is there any solder bridges maybe? shorting out between two traces.

[knealebrown]

yeah i have checked those simple things so many times 

measured across the pots just now and got good readings 0>500k on the gain and 0>100k on the volume so its not them. Thought i had solved it by identifying a wrong value resistor but when i put the correct one in it didnt make any difference. Will post the op amp voltages 2moro or sat when i get time. Until then any other suggestions?

Thanks for your time

[knealebrown]

yeah i have checked those simple things so many times 

measured across the pots just now and got good readings 0>500k on the gain and 0>100k on the volume so its not them. Thought i had solved it by identifying a wrong value resistor but when i put the correct one in it didnt make any difference. Will post the op amp voltages 2moro or sat when i get time. Until then any other suggestions?

Thanks for your time

my opamp is a tl072cp is that any different to the tl072p? is this my mistake? 

[kymar]

Hey guys just built this and i cant get it to work.

-Checked correct polarity of all components e.g diodes, electro caps
-Changed the opamp and pots
-re soldered everything
-checked for solder bridges
-changed the op amp for a 558, still nothing.
-checked all cap, resistor and diode values

did anybody else have any problems with this build?

im getting audio out but its clean and the gain pot doesnt give any effect but the volume works fine.

any suggestions?

Thanks

I have the same problem! It sound not bad but it has small amount of drive

[knealebrown]

dude im kinnda glad your in the same boat as me. Atleast your getting some overdrive all im getting is a clean boost. My gain pot does nothing. 

can anyone who has built this before give us some information? was it a straight forward build? or did you have problems?

thanks

[kymar]

my voltages are
pin            volts
1               4,54
2               4,55
3               4,22 at full drive; 4,3 at min drive
4               0 - Gr
5               4,53
6               4,54
7               4,54
8               9,05 power in

at some schematics there are no R5 47K res, maybe remove it?

[kymar]

I change drive pot to B500K and R5 to 2k2 it became much better. But not too much drive and sustain.