AMZ MOSFET Booster Pot.

[Pakaloabob]

After building and playing with the AMZ MOSFET Booster, I have noticed that the gain pot doesn't have much effect until the last few degrees of rotation. This leads me to think that it should be reverse-log taper. Searching through the forum, I have seen mention of this but I wanted someone to verify for me.
Also, is the gain pot meant to be used as volume, with output of the circuit going directly to the output jack?
The reason I ask is that I have a testing board set up with a barrier strip for power/ground/in/out to the circuit, input/output jacks, bypass stomp switch w/ led indicator and one 100k-A volume pot . I didn't feel that the gain pot on the booster circuit worked well in conjunction with the volume pot on my test setup. I was thinking of adding a switch to bypass the volume pot for those circuits that use values other than 100k. But I'm not sure if that is necessary. Would putting volume to full be the same as bypassing the volume pot altogether?

[fuzzo]

Yep you can change the gain pot for a kind master volume , just change the source resistors with the cap.

Otherwise, what I did, just put a 1KL instead of 5KL. Works perfectly (even it boosts with the pot. at min!)

[Mark Hammer]

1) You'll want a pull-down resistor on the output anyways, just to avoid switch popping.  May as well make that resistance a pot.

2) The MB lends itself very nicely to having a second stompswitch that selects between two different fixed gain settings; one of which can be max gain, and the other of which can be something less than max.

3) You'll likely want to avail yourself of the buffering capacity of the MB at the head of your pedal chain, so it's a useful thing to simply leave it on, rather than true-bypass it, and simply select between more boosted and less boosted levels.

4) It will probably be easier to dial in desired levels using a log volume pot on the output, than it is to dial it in with an oddball taper 5k pot on the ground connection.  Incidentally, you CAN use pot values higher than 5k, but they will make the need for reverse-audio taper that much more critical.

5) If you still prefer having adjustable gain, with no attenuation on the output (and that IS a reasonable choice) you can use a 10k linear taper pot, and monkey around with the taper using parallel resistors, as per the "Secret Life of Pots" article.

[Pakaloabob]

3) You'll likely want to avail yourself of the buffering capacity of the MB at the head of your pedal chain, so it's a useful thing to simply leave it on, rather than true-bypass it, and simply select between more boosted and less boosted levels.

That is kind of what I was starting to think I would do. Since I wasn't getting much control over the gain and there wasn't very much range (to my ears) I was thinking of using a switch for low/high gain settings.
I think that having 2 pots was redundant IMO for my uses, but using a switch for 2 different gain levels and then an output volume level would be more what  I want out of this pedal.
Thanks for the input 

[askwho69]

Bump!!! i tried amzbooster using 50k log pot.. stilllessvolume and cant boost alot to me.. i attached the booster direct to my guitar and use toggle switch... how ca i add volume on this wonderful booster?

[Barcode80]

This booster has more volume on tap than most. if you aren't getting a HUGE amount of boost with it cranked, there is an issue with your build. mosfets are easy to fry with static from your hands.

[askwho69]

yeah maybe i'll try other mosfets i used 2n7000 im waiting for my bs170

[Barcode80]

I've built a few of these with the 2n7000 with great results. Like I said, the mosfets are VERY easy to fry with the slightest static electricity in your hands (you won't notice it either). When you get your new mosfets, handle them with plastic tweezers or grip them in your fingers through a static free bag. ZVex used to include an extra bs170 with every SHO he sold for a long time because they would blow so easily from static.

[Jaicen_solo]

Actually, the 2N7000 is pretty difficuly to fry like that, because it incorporates an internal protection diode. It will give you plenty of boos though, and I agree about the reverse log gain pot, that would improve things substantially. Also, a BS170 sounds better in my opinion, the 2N7000 is a little dark sounding.

[askwho69]

ohhh... thanks for that it really help and understand the comparison of both mosfet . . . i'm waiting for the bs170 to be delivered. . . by the way i found my 2n7000 to a ruin old monitor heheheh thats why i tried the mosfet booster . . .

ps. im sure my gain pot is not reversed