madbeanpedals::forum

Projects => General Questions => Topic started by: Boba7 on May 21, 2017, 12:47:57 PM

Title: Quick impedance question (demo tape fuzz)
Post by: Boba7 on May 21, 2017, 12:47:57 PM
Hi!

So I'm probably gonna build a Demo Tape Fuzz and try various mods (hard and soft clipping diodes, maybe a boost in front) and I'm wondering about its input impedance. According to the schematics it should be fairly low right? If I raise R2 and R3 to something like 1M, or even 2.2M, the impedance will rise right? Or am I missing something?

(http://www.madbeanpedals.com/EP/schematics/424.gif)
Title: Re: Quick impedance question (demo tape fuzz)
Post by: drolo on May 22, 2017, 10:22:10 AM
You're right, now the question is whether you actually need or want higher impedance. High impedance can sometimes make circuits pickup high frequency noise and oscillate, especially in high gain situations. 100k is still quite ok for usual applications
Title: Re: Quick impedance question (demo tape fuzz)
Post by: Boba7 on May 22, 2017, 11:16:32 AM
Quote from: drolo on May 22, 2017, 10:22:10 AM
You're right, now the question is whether you actually need or want higher impedance. High impedance can sometimes make circuits pickup high frequency noise and oscillate, especially in high gain situations. 100k is still quite ok for usual applications

Thanks for the answer!

I built it before, it was one of my first builds, and I remember if I placed it first in the chain, playing with my strat, it lacked treble, even with the treble pot maxed. After a buffer it was perfect. Salvaged it to build something else, but I wanna build one again.
I might just try to raise the impedance and put a 1nf to ground to avoid noise.

Thanks!