Now I didn’t go as far as measuring and matching gain and leakage (as much as possible), but here’s a comparison of a few Q3 transistors for a Tone Bender MKIII – all the same setting, just swapping Q3 on the breadboard.
Why? I saw someone on Facebook poking fun at an eBay seller in Thailand over what they thought were fake OC71. I bought some as the seller looked legit to me, as did the transistors – so I tested them yesterday, and it turns out they are real, so I promptly ordered more.
Lines on a screen don’t replace ears, but as you can see, they are quite similar. There are definite differences in harmonic content, with the 2nd and 4th being the most obvious. On the scope, the waveforms are very similar, with hard-to-pick differences.
I could talk about the sound, but it’s very subjective…
Unbranded OC71
Valvo OC75
Mullard OC81
