Mosfet Mu-Amp

[WGTP]

The Godz of Harmonic Enhancement have used me as a conduit to bestow upon the forum a Dual Mosfet Mu-Amp via late night component errors resulting from too much Skyy, darkness and poor vision.  I have a schematic drawn in Paint and would like to post it here so I get get some feedback about the biasing and whether it is still a Mu-Amp or not.  I used the P channel BS250's, which Joe Davidson has suggested for his Mosfet projects.  So far so good.   :twisted:

Now, if someone would be so kind as tell me how to post the revelation.  

[lenwood]

You could use a free photo image hosting service like this one I use:

http://www.imageshack.us/

It will stay on for (3) three months even if no hits.

On this forum on your post just click the Img button above paste in the URL then hit the Img button again. You're done. You can also hit the Preview button and see if it posting correctly.

Hope that helps.

[jimmy]

www.photobucket.com

cheers
Jim

[WGTP]

I'm having computer difficulties, could I e-mail it to someone?

[Jason Stout]

Send it to me, I'll have it up in no time.

[Jason Stout]

WGThickPresence's work can be seen at:

http://www.jstout.net/MosMu.gif

and

http://www.jstout.net/MosMadness3.gif

[Jason Stout]

Bump

[WGTP]

Thanks for the assistance with posting.  Guess I need to spend more time learning computer stuff and less time tweaking distortions.   :?

I had never seen a mosfet mu-amp, but read it could be done, so, hear it is.  I'm open to simpler/more correct ways  to bias, but these sit right between 4-5v and sound good with low battery voltage.

I assume these would work with BS170/2N7000's, but haven't tried them.

The Mos Madness is  :twisted:   I removed the .0047uf cap referenced.  It went from the drain of Q1 to V- ?  not ground.  Since this deal is reversed.  Anyway that was the best place to stop the squealing  that occured when I used all 3 by-pass caps.  Probably could use 470k resisitors between stages.  The middle stage with a 4.7uf by-pass cap and no by-pass on stage 1 and 3 has a nice sound, but stays under control.  Sounds good with the quitar volume turned down.  Stage 2 seems to benefit most from a by-pass cap.  I guess 1 and 3 both have help from the other mosfets in them.  The 3 stages can be arranged in whatever order fires your imagination and hormones the most.

I can't say they sound better than Jfet's, but they are pretty smooth and the Mos Madness has some squish to it.  Let me know what you think.  

[WGTP]

Jason was kind enough to add a page for these MOSTNERS.  I did a 3rd one las night with multiple diode insertions.  Somebody build one of these and tell me if they suck.  

http://www.jstout.net/WGThickPresence.html

[petemoore]

You've built three of these circuits or three stages?
 I want you to  try to sell me on the idea...What does it sound like and how did you orient the added diodes? Those are some rather large resistors...I don't know that I have all of them, do you notice noisiness? How critical do you think those large values are?

[WGTP]

Sorry for the confusion.  These are 3 different distortion circuits:

Mos Mu - 2 Mosfet Mu-amps, similiar to the original Booster 2.5, SweetThing, BSIAB, etc.

Mos Madness - Stage 1 mosfet Black Fire stage Stage 2 mosfet booster, both Joe Davidson designs, although biased differently and Stage 3 a mosfet Mu-Amp

Mutant Mos Mu - Is the Mos Mu with 3 diode locations added.  I used singles but pairs should also work.

All use the Vishay BS250 mosfets that "seem" to require different bias resistor values than whatever Joe used.  Accordingly the electro caps are reversed as is the battery connector.

Of the resistor values I had on hand, these were the ones that got me to approx. -4.5 volts.  The Mos Madness is noisey if you use all three by-pass caps, but the gain is rediculus then.  I think the plan Mos Mu may be quieter than my dual Jfet version.  

As indicated, these probably need some refinement, like a Drive control.

I thought the Mosfet Mu-amp (if that is what it is) would be of interest

All three have been bread boarded and have nice, rich, thick, high gain, sounds.  There are so many nice distortions around the forum, I can't say these are tops, but they compare favorably to the others I have built.

Sort of variations on a Theme.  

[Peter Snowberg]

                       

Now I just need some free time.