Cobbler preamp- component question

[Synchrony Pedalworks]

I got the new Cobbler board today and the build docs are pending. I wanted to double check a few components. There are several slots, like a diode, that read 3v3, 5V1 and 6V2. Are these components zener diodes at these voltages? Anything special with part selection for them?

 

[Robert]

That's correct, those are zener diodes. The original used Vishay BZX55C series zeners.

3.3V - BZX55C3V3
5.1V - BZX55C5V1
6.2V - BZX55C6V2

 

[mcr-pedals]

Hello... what do this zener's exactly do in this case?... in the BOM of bobby the valve and the type don't match... in BOM of cobbler,
john and cetos it matches... thanks... C.

 

[oldtone]

mcr, the zener's function as clippers. I'm wondering if Andrew Barta at Tech 21 came up with this originally, at least in guitar pedals. I'm not an expert in the use and history of zener diodes however. Just wondering.

 

[mcr-pedals]

this way of clipping, I never seen before (but I'm not a specialist)... but also the values in schem. don't match with values in BOM... only Bobby, the others seem to be correct.

 

[Laundryroom David]

this way of clipping, I never seen before (but I'm not a specialist)... but also the values in schem. don't match with values in BOM... only Bobby, the others seem to be correct.

I’d go according to the pcb itself.

 

[mcr-pedals]

I have a john kit, but want to built a bobby... ;-)