MKI FAQs

MKI FAQs

“I'm looking into an MKI fuzz and reading about your MKI mini ... What is the difference between the OC75/AC128 and the all OC75 configuration please? I don't know much about the Mk I, what are the tonal differences and which is more 'correct'?”

Both transistor sets are very close to the original OC75 + 2G381 sound. There are sonic differences, but they are subtle in the mkI mini's. They both share a Mullard OC75 as the first transistor. The first position is responsible for setting the general input tone characteristics, so they are fairly similar in terms of the input signal getting amplified. In a MKI circuit, the tonal subtleties of the Q2 and Q3 get lost more so than some other fuzz circuits, so the differences are minor. The all Mullard OC75 (3X) MKI is generally "gnarlier" sounding. It has a little less bottom and a bit more upper mids hump, grainier break up (in a good way), and the 3X OC75 generally have more sonic artifacts, most noticeably on the note decay. This is a hair closer, or more "correct" in terms of the original 1965 Mullard OC75 + Texas Instruments 2G381 MKI sound. The OC75 + AC128 set is better behaved. It has a bit more full freq. bottom end, a bit smoother break up, and typically doesn't have as many sonic artifacts as the all OC75 set. Some players actually prefer this transistor set because it retains the characteristic Mullard OC75 tone, but tames the MKI's unpredictability a bit and makes it more "controllable".