amz mosfet question

[jimbob]

I know this is a simple circuit but it has me stumped. I used all the correct values but used a 2n7000 (i originally used a bs170 but due to this issue I assumed that was the problem and used a 2n7000) but this sounds more like an overdrive pedal than a clean boost. It definetly does boost so no issue there. Anyways, I added a 100kb pot as in markm layout for bias but it only went from crackle to clear smooth overdrive. I actually lie the sound and may consider just leaving as is, but this is my second mosfet boost so i know it can get clean.

Anyone else with this issue?

Any thoughts. Would I need a bigger pot value to bias?

[squidsquad]

Look at data sheets for both types to make sure the drain, source & gate legs are the same.
I believe mosfets can vary...like jfets....so you may want to try a few of the same batch.

[cpm]

first, beware 2n7000 must be rotated to replace a BS170

by removing the gain pot at the source of the transistor i think it delivers the highest gain, you are just attenuating at the output with a 100k volume pot.
At that maximum level is likely to appear clipping, also more noise is being amplified (and mosfets tend to be noisy).

try placing a resistor (500ohm-1k) where the gain pot should be, to clean up the output.

[demonstar]

You know the gain pot is in series with the cap across the source resistor? Try putting a resistor in series with the cap to reduce gain. I can't see why that shouldn't reduce the gain so that the boost will remain clean. What do you think?

[Renegadrian]

I know this is a simple circuit but it has me stumped. I used all the correct values but used a 2n7000 (i originally used a bs170 but due to this issue I assumed that was the problem and used a 2n7000) but this sounds more like an overdrive pedal than a clean boost. It definetly does boost so no issue there. Anyways, I added a 100kb pot as in markm layout for bias but it only went from crackle to clear smooth overdrive. I actually lie the sound and may consider just leaving as is, but this is my second mosfet boost so i know it can get clean.

Anyone else with this issue?

Any thoughts. Would I need a bigger pot value to bias?

I built it too - If I remember well, this circuit seems a lot like the SHO - they both give me a cleanish boost but aren't clean at all at full gain!!! I used a BS170.

[cpm]

i would say that 2n7000 is cleaner than bs170

at least, they are less fizzy when overdriven