All the versions of the Fulltone OCD may be recognized by their serial number or, in case of the version 2, by the look of the pedal.
EDIT 2017: Fulltone stated that there was always one version of the OCD because the changes made to the pedal over the time were always so small that it was not possible to speak of a version 2, 3, 4, etc. On date 06.15.2017, however, they released the Official Version 2!
VERSION 1.1 - # 000 --> #4563
- Features: a lot of low and high end.
VERSION 1.2 - #4564 --> #9473
- Changes made: replaced the volume pot (from 100K to 500K).
- Features: less low end, more mids, softer high end.
I have written a review in italian about the OCD V1.2 that is actually my favorite version.
VERSION 1.3 - #9474 --> #16060
- Changes made: replaced the drive pot (from 500K to 1Mega) since the number 9127; replaced the tone capacitor (from 0.1u to 0.047u); replaced the tone pot (from 25K to 10K).
- Features: more powerful midrange, more sustain, more control of the tone.
Some units under the number 16060 are marked as V1.4 but still present the V1..3's circuit. Consequently, they have a different sound from the V1.4.
VERSION 1.4 - from #16061
- Changes made: added a germanium diode in the clipping section; replaced the volume pot with a logarithmic one; decreased the values of the opamp and tone capacitors to have a lower bass response. The color of the led now is red instead of blue. It's one of the most widespread versions, along the V1.7.
- Features: less low end, more harmonics, more control over the volume.
VERSION 1.5 and 1.6 - the number of the verson is written inside the pedal, with the sign V 1.6.
- There is only a little quantity of version 1.5, it seems that the Fulltone has gone almost directly to the V1.6, maybe after some tests.
- Features: coming soon.
VERSION 1.7 - the number of the verson is written inside the pedal, with the sign V 1.7.
- Changes made: coming soon. It's one of the most widespread versions, along the V1.4.
VERSION 2.0 - Version 2.0 can be quickly detected through the new aesthetic choices applied to the pedal: under the word Fulltone has been added "Built in the USA"; the jack input and output have been moved exactly half way the length of the pedal (they were located more towards the bottom.); The OCD logo is slightly smaller. Additionally, on the box you may read the additional phrase "With internally selectable" True-Bypass " or " Enhanced Bypass ".
- Changes made: input impedance changed from 330K to 1 mega ohms, internal switch to choose True Bypass or Enhanced Bypass (a sort of buffer 2.0), Fulltone switched to Surface-mount technology (SMT).
- Features: a complete different sound, more bottom end. I have written a review in italian about the Fulltone OCD V2.
The differences between the version 1.1 and 1.2 are really minimal, the control over the volume is more sensitive and the sound is pretty similar. The high end is softer and the low end weaker. This V1.2 is actually my favorite one.
In the version 1.3 the differences are more pronounced, the level of the volume and the distorsion have been increased, the midrange is boosted and there is lesser high end.
Version 1.4 further modifies the sound of the previous one. Asymmetric clipping creates more harmonics and the sound is more round and clear. Compared to version 1.3, the V1.4 has less distortion and a more fluid and natural sound. As soon as i can test versions 1.6, 1.7 and V2.0 i will include the details of the latter.
The version V2 has a complete different sound compared to the previous ones, with more bottom end.
However, regardless of the chosen version, the OCD is a devastating pedal and its distortion has entered my personal ranking of the best guitar distortions!