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Author Topic: Plexizer or is it Plexi-izer  (Read 4146 times)

spud

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Plexizer or is it Plexi-izer
« on: August 13, 2012, 12:08:39 PM »
I built this about a year ago and true to form, I stuck it in a box when it didn't work.  I say true to form because if something doesn't work and it's not obvious to me, I shelve it and come back later.   My thinking is that I'm too close to it to see the problem.  Like I said, this one has been on the shelf for about a year...  ::)     Anyway, I was cleaning up and found it so I figured I'd give it another go.  Long story short: after fixing a few boneheaded issues, it seems to be working but is a little noisy so that needs to be addressed - should put in an enclosure and use shielded wire.  I got the plan (schematic really) from DIYSTOMPBOXES from a poster there named Mojotron.  Here's the link to that thread where the original schematic is available.  If you can't get to it there, I can post it or I can email it to you.  Here's the link to the schematic (in the thread at DIYSTOMPBOXES):

http://www.diystompboxes.com/smfforum/index.php?topic=50207.0

Anyway, here's the layout as I built it and a really poor pic (sorry it was done with my phone).  I'll post a better one shortly (have to borrow my daughters new Cannon which just takes some awesome hi-res pics, btw). 

http://s252.photobucket.com/albums/hh7/spudjds/Public/Builds/PEDALS/Plexi-izer/?action=view&current=Plexi-izer_15hx24w_D_08-07-12.jpg

http://s252.photobucket.com/albums/hh7/spudjds/Public/Builds/PEDALS/Plexi-izer/?action=view&current=0805022022a.jpg

I think the sound is a pretty good Marshall emulation.  A cool thing about it is when you turn down the gain close to min and get the tone-stack adjusted right, you can get a pretty close approximation of the AC/DC grind - you know, that not so high gain but very mid rangy, punchy, break-up tone.  Anyway, I think it should make a great pedal or amp pre-amp - which I was intending it for anyway, attach chip amp, away you go.  Right now I'm testing it into a set of old powered computer speakers, so it's sort of not ideal.  I need to try it into a SS guitar amp and a tube one to see how it behaves in those situations as I know that using the computer speakers is pretty artificial as far as eq goes. 

It is kind of large as I did it in perf and it could probably be shrunk if you did it as a PCB but I'm an etching virgin. :-[  One of these days I'll start etching too.   

I'm thinking of ditching the presence but it's a trimpot not a reg pot so it's not that big.  From my testing it doesn't seem to have that big of an effect and the DIYSB thread confirms that, with the values I used.  I might try the others they recommended but I'm not convinced it's of any use at all - seems about the same wherever I set it.

I'll put together a clip of it to give you an idea of how it sounds.  Aside from my playing ability not approaching Mojotron's, his clips (later in the thread above) do represent the distortion character I'm hearing from the pedal.  I guess with this and the Dr Boogie, you could cover the whole gamut.  I have yet to build the Dr Boogie but will have to now to see what's up with that.   Seems like a variation of this sort of thing (JFET tube emulation), anyway. 

Jim
« Last Edit: August 13, 2012, 12:11:04 PM by spud »