Hello Everyone,

I'm in the process of building a  ROG Omega and I'm curious how crucial the 3.3nF input cap is to the design. I don't currently have any 3.3nF caps on hand but I do have 1nF available. I would like to know if anyone could let me know if the smaller value would totally remove the bass response of if it would be close enough for rock and roll.

Cheers,

Neill

It is critical to the sound of the unit, but not critical to the functioning of the unit.  In other words it will still work but sound different.  The input cap along with the 22K resistor and 500K range pot control the variable high pass filter that is the actual treble boost (in reality bass cut) part of the Omega.  Changing that cap value changes the corner frequency of the filter.  A 3n3 to 1n change is going to raise the corner frequency about 1-1/2 octaves - that's somewhat dramatic.  However the control itself has a range of about 4-1/2 octaves, so it is possible that the smaller cap will still give you the setting you actually like best.  It is also possible that you might like this 1-1/2 octave increase better than the original.  If you've got room, you could always just use three 1n in parallel to get close to 3n3.

If by 'rock and roll' you mean even more of a treble booster then yes

Ok so I found a few 4n7 caps so could I just lower the 22k resistor to like 14k and still be in a similar ball park?

Yep, 4n7 and 14k should match up at the highest most trebley setting while adding making the low end setting slightly fuller.

10kiloohms would also work fine.