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DOD-308 YJM Guitar Overdrive

Posted: May 7, 2009

Introduction

So after swapping out the opamps in my Metal X I was wanting to follow what my friend Jeff Blevins did and mod a DOD YJM308 Yngwie Malmsteen (my favorite guitar player :) pedal. So I swapped the opamp out (another 4558 as I suspected) for two different OPA's. Luckily, unlike the Metal X, the OPA2604 worked in this circuit and actually I think this my fave of the three.

Related Projects @mikekohn.net

Guitar: MSP430F169 Guitar Processor, MSP430G2231 Guitar Processor, Metal X Mod, YJM Mod

Sample Sound Files
So here are some sample mp3's I made. I played the YJM directly through a Sovtek amp with no reverb or anything so the pedal can be heard in its rawest form. I think the 4558 sounds really dry and kind of boring and doesn't have much gain at all. The OPA2134 sounds a bit nicer, but the OPA2604 just sounds.. just the best of the three. More gain, bigger sound. For the pedal settings, I had the gain on full and level halfway up for all 3 tests. I was just playing some random crap (some power chords/some single note leads) with the pickups in both bridge and neck to show the different sounds this pedal can make. I think these recordings don't sound as good as they could since the volume level on the Sovtek is down really low.

yjm_4558.mp3
yjm_opa2134.mp3
yjm_opa2604.mp3

The next three recordings were made with the set up below: The Yngwie wanna-be guitar connected to the DOD YJM308 pedal modded with the OPA2604 set with the gain 3/4's up and the level a little over halfway up connected to a digital delay (for a little reverb) connected to a Mini Marshall amp cranked at full volume. Cranking the power amp makes a huge difference.

yjm_minimarshall1.mp3 (Some crunch chords from Hiroshima Mon Amour)
yjm_minimarshall2.mp3 (Some twangy lower notes from Now Is The Time)
yjm_minimarshall3.mp3 (Some random leads just because)

Pictures and Explanation (Click for a bigger image)

Here is the ultimate Yngwie Malmsteen wanna-be kit. Here's a Squier strat (not even a real strat) modified with Yngwie's old DiMarzio HS-3 pickups in all 3 positions and the fretboard scalloped, a Mini-Marshall amp, and the DOD YJM308 Yngwie wanna-be pedal.
Two things really bothered me about this picture. First the "Made In China". "Made In China" is slang for "This was carelessly put together, will probably break next week, and could be dangerous to your health". The second is the board looks like it was kind of just thrown in there pretty carelessly (hence, Made In China). Actually tho after opening the thing, the soldering job looked pretty nice and case feels like it's built like a tank.
This is the pedal ripped to pieces.
Here is a close-up of the PC board. The 4558 is still there in this picture. I removed this chip and replaced it with a socket so I can swap opamps in and out to try different ones.
Here are the opamps. The far left is the OPA2604, the next over is the 4558. The thing to the right of the opamps is a socket. I soldered this in so I could swap out opamps without resoldering them.
This is the setup I used to record the last 3 mp3's above. I think this guitar pedal sounds the best when the main amp is cranked to full volume. I couldn't do that with the first 3 recordings since my neighbors would probably kill me. The Mini Marshall however isn't so loud and actually sounds pretty decent.


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