Madbean Swamprat with Nevrosa mods

[MAO]

Update 05/31/2016 - It appears to me the Nevrosa schematic I used for this layout had the 470p and 2n2 caps reversed.  I believe the 2n2* and 470p caps should be swapped. Otherwise, the Body control will not function properly.

By swapping those 2 caps, The Body control CCW will give the brighter setting and CW gives the bass-ier setting. Also, using a 2n2* will give the original toggle switch settings at both extremes of the Body control. Using 2n7 or 3n3 gives a little more bass fully CW.

Unfortunately my original layout (along with many others) has been corrupted, I won't be able to update the posted layout until I draw it up again.

Update 06/01/2016 -- 500k rev log seemed a bit aggressive , the gain comes on quickly and sounded full on with the control barely cracked open.  I didnt notice much of a difference throughout the control's rotation. I prefer a 500k log for the gain control...like the original
 
An 18v version of the Wampler Plexi Drive with an added blend pot courtesy of Rej at Grind Customs.

I left room to parallel the tone carrying caps as I purchased a bunch of monolithic caps that are a bit off expected tolerances. This will allow for easily doubling them up to get the proper values (big blue pads to the right of each cap).

Swamprat & Nevrosa mod details here

Note: Rej suggested biasing the J201s at 11.3v


05/31/2016 - The 2n2* and 470p caps need to be swapped

[Hozy31]

Verified! This is a really good overdrive with tons of gain to spare but also no background noise at all. Definitely for boxing. Cheers Mike.

[MAO]

Cool! And thank you.

What voltage did you use to bias the J201s?

[Hozy31]

I went with the 11.3v and it seems perfect.

[notnews]

How does this pedal sound? Do you guys really like it?

[Hozy31]

I can't really compare it with my other ODs and i haven't built the plexi drive. The closest it comes to is tube overdive (behringer, which i think is based on the tube screamer) but bassier and overall way nicer and to me more playable. However, this could just be my taste. Build it and find out, its a simple build IMO.

[MAO]

The Plexi Drive is one of my favorites,  the original toggle is a bit drastic between the two settings though.

This pedal uses a blend control rather than the toggle which gives the 2 extremes and everything in between.

It's also biased for, and runs off 18v for more headroom and gain.

Bottom line, if you like the Plexi Drive, you should love this one.

[notnews]

I'm actually unfamiliar with the Plexi-Drive. I just listened to a few demos but I'd love to hear more personal reviews... does anyone have the Plexi-Drive as a constant in their rig? In what situations does the pedal thrive?.. and in what circumstances does it leave you lacking?

I've read that the Plexi-Drive is supposed to be modeled off the old JMP Marshalls. Not the 2203/2204/etc series, or the newer stuff but the Marshalls that came after the Fender Bassman derivatives but before those Van Halen- era 2203's. Is that accurate?

Thanks for taking the time to respond. I'm looking for something to nail the classic Marshall sound.. if this does that then great, if it does something other than that but does that other thing really well, then great.

[MAO]

For me, this pedal, the Pinnacle, the Barber compact drive and the Marvel drive gets you just about every Marshall tone :0)

They are all super quiet too. (the Pinnacle needs J201s within a specific range and some shielding otherwise it will feedback like crazy. Be sure you have a bunch of J201s if you build that one)

My guess is this pedal ( or the Plexi Drive) would be used most often,  but once you play the others, you'll want them too.

[MAO]

Hozy31,

Is the Body control working properly?

I was considering some switching mods and while looking over the Nevrosa schematic it seems to me the 2n2 and 470p caps are reversed.

I'm thinking Body lugs 1&2 should probably be connected to the 470p and lug 3 to the 2n2 cap, otherwise the 2n2 is always in the signal path.

I'll be building mine next week, but let me know,

Mike

[MAO]

Update 05/31/2016 - It appears to me the Nevrosa schematic I used for this layout had the 470p and 2n2 caps reversed.  I believe the 2n2* and 470p caps should be swapped. Otherwise, the Body control will not function properly.

By swapping those 2 caps, The Body control CCW will give the brighter setting and CW gives the bass-ier setting. Also, using a 1n8 cap in place of the 2n2* will give the original toggle switch settings at both extremes of the Body control.

Using 2n2 gives a little more bass fully CW.

Unfortunately my original layout (along with many others) has been corrupted, I won't be able to update the posted layout until I draw it up again.

But swap those 2 capacitors and the Body control will function as it should. CCW, the brighter cap 470p is in the signal path, then as the Body control is turned CW, the darker 2n2 cap is paralleled in, allowing blending between the 2 extremes.

[rocket88]

dude. what happened to your layouts? that's really bad news that the file became corrupted.

[MAO]

I had been storing both my layouts and my Gimp face plate designs on a thumb drive so I could work on them anywhere...for the last year or so.

Somehow, the entire thumb drive was put into read-only mode and was no longer saving changes...but neither Gimp or DIY Layout was warning me.  Seemed like everything was working as usual. Unfortunately I didn't realize what was going on for a couple of days, in the meantime I had opened a bunch of files which all became corrupt.  

Once I finally realized the thumb drive was in read-only mode, I had to copy the contents to my laptop and "fix" the thumb drive with a software program. The thumb drive is now fine, but all the files I had opened the last few days were corrupted.

Maybe a virus, I don't know, but no virus was detected on either the thumb drive or laptop.  

Lost a lot of hours of work though, was sick to my stomach.

Not to slam the company, as I really don't know how it happened, but I was using a Transcend Jetdrive.

Luckily I had posted and/or printed most of the layouts. But the Gimp files are gone.

So, back to the drawing board...and making backups!  

[MAO]

Finished mine up tonight.

500k rev log seemed a bit aggressive for the Gain control. The gain came on quickly and sounded full on with the control barely cracked open.  I didnt notice much of a difference throughout the control's rotation. I prefer a 500k log for the gain control.like the original.