Modified AMZ MosFET Booster

[markm]

It seems like forever we've been reading the posts about the Gain Control of the MosFET Booster having all the power "bunched-up" at the end of the throw so, in doing some more circuit research with the aid of the AMZ cd-Rom I put together this little modified version of the AMZ MosFET boost and the results are quite favorable!
If I'm correct here, the Mosfet is running at just about full-gain and the 100K act as a Master Volume control for the overall output.
This circuit when biased properly and using a 100K log pot, has great volume control, is still very clean yet has a bit of sheen and some twang to it as well.
If you feel like playing around with it, give it a try! The mod kind of adds a nice twist of color to an already Great circuit.
**DISCLAIMER**
I am not claiming this as my own idea, just never saw it implemented before. 
Look here>>>>>>>>>>http://aronnelson.com/gallery/album76/Modified_MosFET_Booster_LAYOUT

[$uperpuma]

4 pages of layouts in just a few months... Mark, you're a Prolific Prodigy.

[m_charles]

Awesome Mark!

I'll be building soon.  Sorry, but can you explain what you mean by more "twangy" than the original mos boost?
Less bassy?


chuck

[calculating_infinity]

Hey Mark thanks for sharing!  I haven't even gotten around building your Mosfet boost layout with bias control.  I am wondering if I should go that route and add a volume control at the output for a master volume as I would like to control the gain still.  Rather than running at full gain and having a master volume.  Who knows maybe I'll build both!  Thanks again.

-Jonathan

[markm]

Hey Mark thanks for sharing!  I haven't even gotten around building your Mosfet boost layout with bias control.  I am wondering if I should go that route and add a volume control at the output for a master volume as I would like to control the gain still.  Rather than running at full gain and having a master volume.  Who knows maybe I'll build both!  Thanks again.

-Jonathan

Thanks Jonathan.
All I can say is, "Stay Tuned, there's more to come!" 

Awesome Mark!

I'll be building soon.  Sorry, but can you explain what you mean by more "twangy" than the original mos boost?
Less bassy?


chuck

Well, it's brighter but not "ice-pick" bright....a bit of extra "color" to the tone, it's not a pure transparent boost.
To me it sounds more "twangy".....
Help me out here guys 

4 pages of layouts in just a few months... Mark, you're a Prolific Prodigy.

I used to do crossword puzzles or wordfinds......now I do layouts! 

[ADR]

I'm new here, lurked here for a while, and have consumed much info from the geofex/amz/tonepad/ggg sites.

I'm going to build this guy either tonight or tommorow. I have the parts on hand and will let you know.

I've built a brian may boost and a fat boostered in the last few months, and I really like the fat boostered. I've also built the Tillman preamp cable... HOLY smokes does that thing work well.

The BM boost sounds great into my podxt driving a set for low gain SLO-100 and the like, but not so hot on my voxAC30.

Hopefully, the mosfet boost will do the trick that I'm looking for. I might incorporate a low end rolloff tone pot/or trim as well in case it gets too wooly sounding.

I'll build your setup here first and see how it sounds. I'll probably just perfboard it for now.

Cheers

/A

[markm]

Welcome ADR, thanks for looking, lurking and posting! 
I have a perf layout in the gallery if it help you at all.
Please let me know what you think!

[amz-fx]

It seems like forever we've been reading the posts about the Gain Control of the MosFET Booster having all the power "bunched-up" at the end of the throw so, in doing some more circuit research with the aid of the AMZ cd-Rom I put together this little modified version of the AMZ MosFET boost and the results are quite favorable!
If I'm correct here, the Mosfet is running at just about full-gain and the 100K act as a Master Volume control for the overall output.
This circuit when biased properly and using a 100K log pot, has great volume control, is still very clean yet has a bit of sheen and some twang to it as well.
If you feel like playing around with it, give it a try! The mod kind of adds a nice twist of color to an already Great circuit.
**DISCLAIMER**
I am not claiming this as my own idea, just never saw it implemented before. 
Look here>>>>>

This method of using the AMZ Mosfet Boost is demostrated on the page of extra circuits that is emailed to everyone that buys a pcb from me...  it's the first schematic in the mosfet booster section, if you have the link...

regards, Jack

[Barcode80]

can it be built on the pcb from ggg? is it merely a parts change out?

[markm]

can it be built on the pcb from ggg? is it merely a parts change out?

It's simple actually,
Ground the "Gain" pad on the layout and hook up a 100K pot to the output and that's about it. 

[ADR]

I built it last night. Success! A very good and simple circuit.

Markm, like you said, it's not perfectly transparent, but it sounds very good. I left space on my perfboard layout (which was loosely based off the one you provided) to incorporate a tonestack if need be. I think I will add that on sometime soon.

I also put a 5k trim pot in for the gain and a regular pot for volume. The idea that I'll take this proto, and seal it all up in a 1590B  and have it after my a/b box for one of my channels in front of my voxac30. I might turn the 100k pot to just a trimmer that is accesible from the top of the enclosure. I don't like how I have to be careful with my feet for accidentally tiddling knobs when going for the stomp switch.

Again, it just needs a slight roll off on the bass to be a permanent fixture on my pedalboard. I don't think it has what it takes to bump the fatboostered off, but it can hang beside it.

P.S. Mark, I love your etching work too. It inspired me to make etchings for my enclosures. I'll post pics in the future.

[markm]

I'm glad you like it Sir and many thanks for the kind words. 
Right now I'm working on a version with a bit more Gain and a pot to control it....stay tuned!

[Auke Haarsma]

Does the Diode have to be a Zener? Or could it be something like 1N4148 (1V forward voltage) or be omitted? In otherwords, what's the function of the diode (other than protection of the mosfet) and could that function be fulfilled by something else? (I don't have a zener lying around...)

[calculating_infinity]

Does the Diode have to be a Zener? Or could it be something like 1N4148 (1V forward voltage) or be omitted? In otherwords, what's the function of the diode (other than protection of the mosfet) and could that function be fulfilled by something else? (I don't have a zener lying around...)

I'm almost positve it must be a Zener.  Correct me if I am wrong anyone. 

-Jonathan

[MartyMart]

Does the Diode have to be a Zener? Or could it be something like 1N4148 (1V forward voltage) or be omitted? In otherwords, what's the function of the diode (other than protection of the mosfet) and could that function be fulfilled by something else? (I don't have a zener lying around...)

No, you can simply use an LED , ordinary red 3mm will do fine .

MM.

[Auke Haarsma]

thanks! So it's just for protection of the mosfet?

[MartyMart]

thanks! So it's just for protection of the mosfet?

Yes sir 

[amz-fx]

I'm almost positve it must be a Zener.  Correct me if I am wrong anyone. 

You are correct.   There are probably 10 or more chemistries of LED composition with different characteristics... LEDs usually have a reverse breakdown rating of 5 V minimum and 15 to 25 V typical,  which is way too high for proper protection of the mosfet.

Put what you like in the circuit, it's probably okay with no protection, but I'll stick with the zener.

regards, Jack

[markm]

Well, since Jack suggests the Zener, it'd probably would be wise to stick with the Zener however, the Peppermill uses an LED.

[markm]

I'm glad you like it Sir and many thanks for the kind words. 
Right now I'm working on a version with a bit more Gain and a pot to control it....stay tuned!

There's now another version in the gallery too!