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. ;D
Look here>>>>>>>>>>http://aronnelson.com/gallery/album76/Modified_MosFET_Booster_LAYOUT (http://aronnelson.com/gallery/album76/Modified_MosFET_Booster_LAYOUT)
4 pages of layouts in just a few months... Mark, you're a Prolific Prodigy. :)
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
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
Quote from: 8bitRockOut on February 20, 2007, 02:40:50 PM
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!" :icon_razz:
Quote from: m_charles on February 20, 2007, 02:15:57 PM
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 :icon_exclaim:
Quote from: $uperpuma on February 20, 2007, 01:50:25 PM
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! :icon_lol:
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
Welcome ADR, thanks for looking, lurking and posting! :icon_wink:
I have a perf layout in the gallery if it help you at all.
Please let me know what you think!
Quote from: markm on February 20, 2007, 01:18:29 PM
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. ;D
Look here>>>>>
This method of using the AMZ Mosfet Boost (http://www.muzique.com/schem/mosfet.htm) 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
can it be built on the pcb from ggg? is it merely a parts change out?
Quote from: Barcode80 on February 20, 2007, 10:53:41 PM
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. ;)
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.
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!
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...)
Quote from: ponq on February 22, 2007, 03:29:05 AM
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
Quote from: ponq on February 22, 2007, 03:29:05 AM
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.
thanks! So it's just for protection of the mosfet?
Quote from: ponq on February 22, 2007, 03:57:30 AM
thanks! So it's just for protection of the mosfet?
Yes sir :D
Quote from: 8bitRockOut on February 22, 2007, 03:40:43 AM
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
Well, since Jack suggests the Zener, it'd probably would be wise to stick with the Zener however, the Peppermill uses an LED.
Quote from: markm on February 21, 2007, 06:28:05 PM
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!
That's interesting Jack, I've seen several builds using Mosfets and recommending
the use of an LED ......
Time to order some more zeners !!
MM.
You can also use a pair of 1N914 diodes... one from the V+ to the gate (anode to gate) and the other from the gate to ground (cathode to gate). This type of protection is used in cmos chips and was originally used in the SHO.
regards, Jack
Quote from: amz-fx on February 23, 2007, 07:28:57 AM
You can also use a pair of 1N914 diodes... one from the V+ to the gate (anode to gate) and the other from the gate to ground (cathode to gate). This type of protection is used in cmos chips and was originally used in the SHO.
regards, Jack
This would replace the Zener diode and work just as well as the Zener?
Quote from: markm on February 21, 2007, 07:10:46 AM
Quote from: Barcode80 on February 20, 2007, 10:53:41 PM
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. ;)
i'm a tad confused. part of that might be because i meant to say the tonepad layout, not the ggg one. also, i'm not sure what you mean by the "gain" pad.
Okay.
From the TP Layout, hook a jumper from the pad that Lug 3 of the gain pot is wired to ground.
Take your output from the .1uF cap and hook that up to lug 3 of an A100K pot.
Lugs 2 and 3 to ground.
That'll do it. :icon_wink:
I'm working on another right now with both Gain and Volume controls.
Next.....an OD circuit I think.
Does changing the voltage may take a good result ? ie. increase headroom ?
Quote from: fikri on February 24, 2007, 11:04:19 AM
Does changing the voltage may take a good result ? ie. increase headroom ?
Do you mean upping the voltage to say 18V?
I don't think it's neccesary.
I'm going to be experimenting with this on the mosfet boost, to be engaged with a DPDT switch and a mix knob.
http://www.muzique.com/lab/tclip.htm
I've always wanted to make a multiband overdrive. One that keeps the lower range nice and tight and crisp and one that overdrives and compresses the upper range.
That way I keep some snap on the lower strings and some creamy overdrive for soloing.
I'm also going to try this approach with a rat clone I'm building.