BAJA JVM overdrive pedal 040218  [documentation]

Original effect designs complete with schematics, layouts and instructions. Freely contributed by members or found in printed or online publications. Cannot be used for commercial purposes without consent of the respective owners of the copyright.
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bajaman
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Post by bajaman »

Hi folks
I have not built this one as yet, but see no reason why it will not work :D
This one is based on the Marshall JVM410 OD1 high gain channel (up to just before the passive tone stack as with all my recent high gain preamp models).
Hope some of you enjoy building it :wink: and as usual - vero, perf or pcb layouts are most welcome :thumbsup
cheers
bajaman
Baja JCM overdrive pedal 9v 040218.GIF
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bajaman
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Post by bajaman »

here is channel OD2 instead - slightly less bass response :wink: only two capacitor values changed around gain control :lol:
Baja JCM overdrive pedal OD2 9v 040218.GIF
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Post by bajaman »

But wait - there's more :D
Here is the crunch channel for a lighter overdrive and flatter frequency response - again only minor changes around the gain control but only three gain stages (two following the gain control).
All these three JVM410 models are based on the "red" gain structure.
enjoy :thumbsup
bajaman
Baja JCM overdrive pedal Crunch 9v 040218.GIF
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Cub
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Post by Cub »

Thank you so much, you're on a roll with the high gain pedals! :applause:
bajaman wrote:here is channel OD2 instead - slightly less bass response :wink: only two capacitor values changed around gain control :lol:
That would make for a very nice switch! Speaking of which, would it also be possible to have a red/orange mode switch? Or are there too many parts involved for that to be practical.
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Post by Ice-9 »

Congrats Bajaman on a nice series of amp sim circuits, and you have used my favourite 2SK117 Jfet for the input buffer on most which means I will have to have a few of these put on breadboard as soon as I get a moment.
Cheers for the schematics :applause:
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

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Post by bajaman »

would it also be possible to have a red/orange mode switch?
I will take a look - should be possible :wink:
cheers
bajaman
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Post by bajaman »

:oops: :oops: :oops:
I made a small mistake with the Crunch model
Here are the correct schematics for OD1, OD2 and CRUNCH channels with the red gain mode. By adding a small switch and additional resistor to the third gain stage it is easy to convert all of these to the Orange gain mode :wink: Just switch the 100 ohm resistor off, if you want the Red gain mode :!:
cheers
bajaman
Baja JVM overdrive pedal OD1 9v 040218.GIF
Baja JVM overdrive pedal OD2 9v 040218.GIF
Baja JVM overdrive pedal Crunch 9v 040218.GIF
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Post by Cub »

bajaman wrote:By adding a small switch and additional resistor to the third gain stage it is easy to convert all of these to the Orange gain mode :wink: Just switch the 100 ohm resistor off, if you want the Red gain mode :!:
This is awesome! OD1 orange is my favourite mode on this amp, very George Lynch! With a OD1/OD2 and an orange/red switch, one pedal will pack four great sounds. :applause:
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Post by rcustoms »

bajaman wrote::oops: :oops: :oops:
I made a small mistake with the Crunch model
Here are the correct schematics for OD1, OD2 and CRUNCH channels with the red gain mode. By adding a small switch and additional resistor to the third gain stage it is easy to convert all of these to the Orange gain mode :wink: Just switch the 100 ohm resistor off, if you want the Red gain mode :!:
cheers
bajaman
Baja JVM overdrive pedal OD1 9v 040218.GIF
Baja JVM overdrive pedal OD2 9v 040218.GIF
Baja JVM overdrive pedal Crunch 9v 040218.GIF
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Post by bajaman »

mr steve the images are low definition ,please add more pixels
Did you try clicking on each image to expand it :?:
Here are some 300dpi images :wink:
Baja JVM overdrive pedal OD1 9v 040218.GIF
Baja JVM overdrive pedal OD2 9v 040218.GIF
Baja JVM overdrive pedal Crunch 9v 040218.GIF
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bajaman
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Post by Willypp »

I'm thinking a version that can switch between all three might be a bit of fun...

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Post by FausterCraster »

Here all in one, thanks Baja for another great design !
Have fun.
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Baja JVM overdrive pedal 9v 060218.GIF

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Post by 287m »

FausterCraster, that great!
btw, can you describe with (redrawn) schemo maybe?
noob like me just can't understand at this moment, sorry

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Post by FausterCraster »

@287m here you go!
for mechanical switching an option would be a rotary switch 3pole 3 positions.

@Baja, why not to add green channel also, we need your advice here !?
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Baja JVM overdrive pedal 9v 070218.GIF

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Post by Willypp »

I've had a bit of a go at this, bit I have no idea if it's correct - especially in terms of labeling switches, but I don't see why it shouldn't work. If anyone can bang up a vero layout I'll be your best friend (as we used to say in primary school). The idea is that you can bypass the whole shebang, select crunch or OD, select OD1/2 within OD, and select the orange or red modes, with separate gains for each channel, and a volume each for crunch/OD.

So, 5 knobs, 4 footswitches, 3 channels with 2 modes each... Hopefully in something like a DD. Happy to have opinions and constructive criticism. Done in Photoshop.

Willy.
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BajaJVM3channel4switches.jpg

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albru80
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Post by albru80 »

If correct, this could fit in a 1590BB.

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Post by Willypp »

Is that based off my variation?

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Post by albru80 »

Not really but it should give the same results.
It always uses the same JFet buffer at the output (the way FausterCraster drawn it).
Adding an op-amp buffer instead shouldn't make any difference and just make the board larger.
The Crunch/ODs are still selectable.
I think it's correct but...

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Post by temol »

albru80 wrote:If correct, this could fit in a 1590BB.
Are you sure that 2SK117 pinout you have presented is correct?

T.

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Post by Willypp »

Not really but it should give the same results.
It always uses the same JFet buffer at the output (the way FausterCraster drawn it).
Adding an op-amp buffer instead shouldn't make any difference and just make the board larger.
The Crunch/ODs are still selectable.
I think it's correct but...
Awesome. I was just hoping for separate crunch/OD volumes but I reckon I can live without it. Looking at the layout, you'd need to add a pole to each switch for LED indication, yeah?

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