# BOSS MT2 Metal Zone Mods



## Chas Grant (Oct 20, 2020)

So the very first pedal I ever bought was a BOSS MT2 Metal Zone, that was 25 years ago. Well it finally died. This pedal is near and dear to me, not only was it the first pedal I bought, it was the pedal responsible for leading me down the pedal building rabbit hole I'm in now. A few years back the volume pot died and while researching a new pot I stumbled upon the the pedal building community. Fixed the pot and started building pedals for myself, then my daughter and have even built a few and sold them, so Good Times! Any way the MT2 Mid pot recently died. This is a three gang pot, 2 X C50K and W100K 9mm pot. Good luck finding this Frankenstein! BOSS must have these special ordered because the do not exist, except in the catalogs and data sheets. Since I have always had a MT2, I picked up a used one this past weekend at the local guitar center for $35. But part of me can't let the original die. Tayda has the W100K pots and dual C50Ks in stock, but they are 16mm and not 3 gang. So I have 6 pots and a momentary foot switch on order, and each control will get its own pot,  and everything is going into a 125B.

 I also started modding the circuit. 
So far this is what's been done:
Replaced C008 and C020. Was 220nF electrolytic, now 220nF box film
C009 Was 47nf ceramic now 100nF box film
C019 and C040 changed from 100uF/16V to 47uF/25V better +4.5V filtering
C041 changed from 100uF/16V to 100uF/25V again better filtering
C022 and C028 changed from ceramic to MLCC to extend life, kept 47pF
C026 changed from ceramic to MLCC to extend life, kept 100pF
Diezel Mod
   Removed C025 and C035, Changed C034 from 27n to 47n.  This does remove a lot of the harshness.
Replaced C011, C017, C037, C039 and C042 All were 1uF electrolytic now 1uF box film caps,  Lowered the noise in the signal path
Changed C026 Was 220nF, now 1uF. Expands the EQ section of the pedal.
Removed D003 and D004, Connected 1N4002's to D004 and 3 1N4148's(arranged asymmetrically)  to D003 gnds. Ran a wire from D003 signal side. Will install SPDT On/Off/On switch in enclosure.

I disconnected the W100K from the mids and put in a A100K to test the circuit out.
HOLY SMOKES BATMAN!!!! This thing sounds Great!
With these mods you can dial the mids back in totally changing the dynamics of the sound. The harsh tinny sound I loved/hated is gone. In its place is is a full fat sound. It still has all the distortion and sustain of the original! And if you want to you can dial the mids back for that scooped sound. All 3 clipping options sound better than the original diodes. But what shocked me is how good it sounds with no clipping diodes. With out the diodes, the op amps still clip but in a real nice sound. You can get a nice overdrive to good amount of distortion with out the diodes. The overdrive is real nice like this, which is something this pedal always lacked.

I also ordered more MLCC's for some of the other caps and I'm thinking of changing the carbon film resistors out with metal films. At least in the signal path. I have to see what I have in the 3.5mm range.


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## Nostradoomus (Oct 20, 2020)

I had one forever I meant to mod but I gave it away to a friend. Now there’s one locally for 40 bucks I might have to snatch up. I intend to mod the EQ to be more like an HM-2, should be pretty straight forward!


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## Chas Grant (Oct 20, 2020)

Nostradoomus said:


> I had one forever I meant to mod but I gave it away to a friend. Now there’s one locally for 40 bucks I might have to snatch up. I intend to mod the EQ to be more like an HM-2, should be pretty straight forward!


Grab It! The one I got was in mint shape. That's why I'm bringing the old one back to life. Also modding these is easy as can be. The circuit board is single sided and half the time the solder comes out with the component, so there no solder to suck away!


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## Nostradoomus (Oct 20, 2020)

I think I will. I think I’ll do most of your mods then just change the middle/mid freq gyrator values around and should be good to go!


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## Chas Grant (Oct 20, 2020)

Let me know how the gyrator changes go, and what you did. I might be interested in them.


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