Boss - Metal Zone MT2 mods

A forum devoted to mod, tips and suggestions for upgrading and rehousing your VERY CHEAP commercial stompbox to near boutique excellence.
Post Reply
Seagurt
Information
Posts: 1
Joined: 07 Jan 2015, 19:39

Post by Seagurt »

Hello all, I am wondering if there is a definitive resource as to the quality of these mods? I notice too many demos with improper micing techniques. I will be making a comparison video, and will most likely build all the mods, but I wonder what the favourites are, and why.

I modded my old MT-2 (1998)

R41 - 22K
C34 - .047uf
D3 & 4 - 2 Red LED's
C25 - Removed
C35 - Removed
C36 - 1uf

I have tried the pedal on solid state devices, in the power and pre sections of both my amp (Fender 5150 III) and 8 track, and even on hacked radios turned into amplifiers to see how it translates.

I find in general, while the pedal is very usable in this state, it has a few fundamental issues (these mods do anyway)

I found the distortion was much more present with the bass all the way up

I found the mids to have dead spaces within the sweep ( things get pretty unusable with the mids, and on particular guitar/pickup combos, you get a massive boost of about 6 DB when you hit the mode.) There is also some modulation that oscillates on the release of certain notes when you get to a certain note/frequency.

The highs are ok, there seems to be a lack of usable hi end sparkle though, but considering what it was before... worlds of improvement. As a matter of fact, while testing the pedal with a buddy, he would forget that he was playing through my modded MT-2, because he comes over and loves to play my 5150 (loves that tube sound!) In short, it sounds like a Diezel, when the bass, Level and Distortion is at 100%, and it has more of a boosted JCM tone, when you start playing with the mids, but far less gain than it had to begin with.

With the distortion at 0, you still get a gritty sound, with distortion at 100%, you have about half the gain of what was originally on the MT-2. Volume all the way up provides a Tubescreamer like boost, it imparts some of the pedals tone, but it is a pleasant sound.

I also found that the sweep for the volume is not as strong (not as loud any more) and I will be looking into rectifying these issues with future project builds.

Feel free to suggest ideas, and I will do my best to accommodate.

For music, for science! :)

chumbox
Information
Posts: 11
Joined: 09 Feb 2012, 22:49
Has thanked: 10 times
Been thanked: 6 times

Post by chumbox »

Finally got round to doing the Diezel mod. If the metalzone just came like this as standard people would have actually loved it from the get go. Heaps better.

04325613
Information
Posts: 1
Joined: 30 Jun 2015, 10:14

Post by 04325613 »

I just tested out my Griffin MT-2 Death Metal Mod last night. The components cost about 4euro, Took about 3 hours to carefully complete. It's excellent!! It's now my favourite pedal instead of an absolute confusing nightmare of gain. The EQ really works well with the Mod instead of being a temperamental thorn in the side. I was worried at first that I didn't chose Keely or Deizel mods but this sound works great for the early black/death metal tone.

http://www.freestompboxes.org/viewtopic.php?f=1&t=14506
-Replace the limiting Diodes with 3mm LED's (D3 and D4)
-Remove C25 and C35, do not add jumpers
-Replace R14 with a 46k resistor
-Replace R41 with a 680r resistor
**the kit came with 1% metal film 1/4w resistors, not sure if that makes a difference or not.
-Replace C17 with a 1uf Panasonic Multilayer Film Cap (105)
-Replace C36 with a .068uF Panasonic Multilayer Film Cap (683)
-Replace C42 with a .1uF Panasonic Multilayer Film Cap (104)
**the rest of the caps are basic ceramic non polarized caps
-C10 and C18 with 101's
-C26 and C32 with 221's
-C22 and C28 with 121's
And that is the entire mod. 9 caps and 2 resistors.

More recently he included his "noise reduction mod" which I assume helps with the removal of the limiting diodes.
- 2 1n60p diodes facing opposite directions twisted to each other and then bridged between 2 lifted leads from the negative leg of C27 and the leg of R33 that is closest to IC4.

Pruttelherrie
Solder Soldier
Information
Posts: 244
Joined: 18 Feb 2011, 19:35
Location: The low lands
Has thanked: 45 times
Been thanked: 95 times

Post by Pruttelherrie »

04325613 wrote:I was worried at first that I didn't chose Keely or Deizel mods but this sound works great for the early black/death metal tone.
Could you make a soundclip?

I've modded an MT-2 in the past by just disabling the post-clipping high-frequency gyrator and I find that's already a huuuuge change.

User avatar
davizerrat
Information
Posts: 9
Joined: 21 Apr 2014, 21:39
my favorite amplifier: Deluxe 40w

Post by davizerrat »

Hello friends,

I think that without clipping section of the MT-2 will be sounding more like a boost with EQ . Removing the clipping you increase in body sound but lose a lot of gain character . Mr. K uses different types of clipping.

Thanks ;)

User avatar
skylark44
Solder Soldier
Information
Posts: 234
Joined: 09 Sep 2010, 01:41
Has thanked: 8 times
Been thanked: 5 times

Post by skylark44 »

Any new, or different/interesting mods for the Metal Planet?

cmr
Information
Posts: 4
Joined: 13 Jan 2016, 07:53

Post by cmr »

Hello everybody,

I use the Metal Zone for about 15 years and like it very much, but some things turned out to be a little problematic. When I play in a band it’s hard to hear what I play, because the sound is missing some mids. Turning up the mids is not a solution, because then it sounds like a saw. A bit more complicated chords easily turn into just noise. And there’s lot of buzzy noise in the sound.

I tried to preserve the character of the Metal Zone but improve the problematic aspects. Finally this worked very well. Since I found out some different solutions with slightly different sounds and I’m not sure yet, which of the sounds are the best, I made a circuit board with dip switches and placed it in the battery compartment. I removed the battery clip and used the hole for the six wires connecting the main circuit board and my dip switch board. The drawback is of course that I have to open the pedal and use a little screw driver to switch sounds, so maybe I will move some controls to the control panel once I find a concept for this.

The cause for the buzziness is the clipping of the two first opamps, 3a and 3b. To prevent the clipping I put antiparallel LEDs in the feedback of each opamp. For opamp 3a I connected several individually switchable LEDs parallel to C28. Different LEDs make slightly different sounds, especially red LEDs sound softer than yellow or green LEDs. Mixing of two different LEDs makes also good sounds. You should only make sure to always switch on exactly one LED for each of the two polarities. Any other diodes in this place did not work, they all reduced the gain and sounded very weak. While opamp 3a makes the actual distortion, opamp 3b only clips at signal peaks, for example if you pluck a chord a bit stronger. Here I connected two green LEDs antiparallel to C32. Now the attack does not sound buzzy anymore but more like crunchy. I used green LEDs, because they have the highest forward voltage and thus don’t clip the signal more than necessary.

To get better mids I replaced the clipping diodes D3 and D4. On the hot side I connected a row of dip switches, to which I connected individually the two original Silicium diodes, two 1N34A Germanium diodes, two BAT43 Schottky diodes and finally a 1k resistor. I don’t use LEDs here, because they have no additional effect after I use them already in the feedback. Between the end of the 1k resistor and the connected ends of all the diodes I placed a 2k5 trim pot with the slider connected to the ground side of where the original diodes were. This trim pot makes it possible to add some resistor to the clipping diodes to make the distortion softer while at the same time the volume is kept about equal. When using some middle position of the pot both the 1k resistor and two clipping diodes should be switched on, only on each of the ends the other side may be switched off to avoid any additional volume reduction or distortion. If one wants to have only the LED distortion, the clipping diodes should be all switched off, the 1k resistor switched on and the pot turned all the way to the resistor. Otherwise the LED distortion will be much louder than the distortion with the clipping diodes and maybe overdrive the following stages.

Since LEDs have a 3 to 4 times higher forward voltage than Silicium diodes, we now have 3 to 4 times less gain when we use only the LED distortion. I compensated this by rising the gain two times by factor 2. First I replaced R41 by a 440 resistor. I used 440 just because I had such a resistor, you can also use 470 or similar. But the resistor should not get much smaller because the current will rise. It could damage the LEDs, overload the opamp and drain the battery. Second I removed R42. Because this also removes treble, I replaced C31 by switchable 22n and 15n. With 22n I get about the same sound as before, what suits me best. With no condenser I get much more treble, it sounds more british dirty. It might be also possible to place a pot there to regulate between a british dirty and a modern tidy sound, but I have not tried this yet.

After the gain modification we have the the same gain with the LED distortion that we had before with the Silicium diodes. If we now switch to the Silicium diodes we have to turn the gain pot from maximum to about 2 o’clock to get the same gain. With the Germanium or Schottky diodes we have to turn it down even a bit more and turn up the volume a bit or to avoid this we could use for each diode two of them in series.

Suggestions and questions are welcome.
Attachments
IMG_20160120_210448_.jpg
IMG_20160120_210448_.jpg (37.24 KiB) Viewed 1247 times

Pruttelherrie
Solder Soldier
Information
Posts: 244
Joined: 18 Feb 2011, 19:35
Location: The low lands
Has thanked: 45 times
Been thanked: 95 times

Post by Pruttelherrie »

The buzziness is also emphasised by the gyrator *after* the clippers. Hi frequencies are boosted far too much. Remove C 24 and hear the difference!

That said, I like your switches :D

cmr
Information
Posts: 4
Joined: 13 Jan 2016, 07:53

Post by cmr »

I tried out disabling the high frequency gyrator now. And that seems to be a good idea, thank you!

It reduced treble very much. I have to turn the HIGH pot from 1 o'clock to 4 o'clock to get about the same amount of treble as before. But then the treble sounds better, more even. Indeed the gyrator emphasizes the buzziness. I also tried out to rise the treble with a Boss PQ-4 Parametric Equalizer with a band set to about 5kHz and also that sounds better than the original gyrator. However this is only my first impression, I will have to check again with higher volume.

So I wonder if the gyrator could be improved instead of just disabled. Could it be that it sounds better with a lower Q? I could also add a trim pot in series to C24 to control the intensity of the gyrator. Or I could replace the gyrator by just a condenser and a resistor in series to ground to rise treble evenly.

Pruttelherrie
Solder Soldier
Information
Posts: 244
Joined: 18 Feb 2011, 19:35
Location: The low lands
Has thanked: 45 times
Been thanked: 95 times

Post by Pruttelherrie »

cmr wrote:So I wonder if the gyrator could be improved instead of just disabled. Could it be that it sounds better with a lower Q? I could also add a trim pot in series to C24 to control the intensity of the gyrator. Or I could replace the gyrator by just a condenser and a resistor in series to ground to rise treble evenly.
Sure!

Compare the original: http://milas.spb.ru/~kmg/files/schemati ... _shema.jpg
and play with the calculator here: http://www.muzique.com/lab/gyrator.htm

Good luck!

cmr
Information
Posts: 4
Joined: 13 Jan 2016, 07:53

Post by cmr »

The best solution I found is the original C24 15nF capacitor in series with a 1k resistor to ground. This sounds even better than just disabling the gyrator and turning up the HIGH pot. It still has less treble than with the gyrator, but I have to turn up the HIGH pot only a little bit for compensation.

I used two of my DIP switches to connect the resistor or the rest of the original gyrator to C24, so I can switch between all three options.

guiltyspark
Solder Soldier
Information
Posts: 202
Joined: 18 Aug 2007, 05:24
Has thanked: 3 times
Been thanked: 39 times

Post by guiltyspark »

Here's a link to a pretty nice looking MT2 mod:

https://www.google.com/url?sa=t&rct=j&q ... hFI4C2_g-g

I found it while googling and thought I would share. The link will automatically bring up a PDF. It's safe to download or view, not a virus or anything. :D

ststitov
Information
Posts: 1
Joined: 23 Feb 2016, 16:02

Post by ststitov »

Has anyone tried this Sustainiac mod?

Vivianfr
Information
Posts: 1
Joined: 08 Mar 2016, 15:45

Post by Vivianfr »

Hi,

When it's written "remove the caps'', do i have to let a "jump" or do i have to wire ? A kind of replacing a capacitor by a wire ?

Thanks for help :)

cmr
Information
Posts: 4
Joined: 13 Jan 2016, 07:53

Post by cmr »

I can't imagine many circuits where replacing a capacitor by a wire would make any sense. So remove a capacitor should usually mean just remove, not replace or short connect.

indyguitarist
Resistor Ronker
Information
Posts: 380
Joined: 11 Jul 2007, 02:25
Been thanked: 142 times

Post by indyguitarist »

Vivianfr wrote:Hi,

When it's written "remove the caps'', do i have to let a "jump" or do i have to wire ? A kind of replacing a capacitor by a wire ?

Thanks for help :)
Just remove them and leave the holes, don't jumper them.

Some more mods I put out recently as well whoever wants to check them out.
part 1 (overdrive mod)


part 2 (2nd version of overdrive mod and mod to change it into eq pedal)

User avatar
Ichabod_Crane
Solder Soldier
Information
Posts: 239
Joined: 26 Apr 2016, 15:11
Has thanked: 33 times
Been thanked: 14 times

Post by Ichabod_Crane »

Nice mod! :)
In this case the pedal change completely.

I want to make the Deizel Mod with my old stock MT-2.

nitraus
Information
Posts: 28
Joined: 26 Dec 2009, 02:10
my favorite amplifier: Ampeg V4
Fender Bassman
Location: Torino, Italy
Has thanked: 4 times
Contact:

Post by nitraus »

Dudes, I did the following:

C34 to .047 uF
D3 to 1n4007
D4 to red LED
C25 removed
C35 removed
R41 to 22k (I don't remember if I did this too or not, I don't have any guts of the modded pedal right now)

My MT2 sounds awesome (I run it through an Ampeg V4 with 6550s in the power section, super clean amp), really full and defined, not thin/trebly at all.
But, since being a gear nerd I can't be satisfied for good, does any of you know any way I could bring some dirt/fuzziness in the low end without sacrificing the definition in the hi mids?

teddeeh
Breadboard Brother
Information
Posts: 62
Joined: 13 Jun 2016, 21:54
Has thanked: 8 times
Been thanked: 12 times

Post by teddeeh »

Hi guys.
So on my quest to drive a great mod for the mt-2 i have come accross a problem and thats the bass/low end of the eq. I find that it sounds a bit flabby and im wanting to tighten it up. Would anyone know where abouts and what i can mess around with to alter the eq of the low end? I.e tighten it up.
Also where abouts are the eq components and what would be the affect of changing the values?
Many thanks guys keep this thread going its awesome and really the only place i can find that is keeping the mt-2 mods going. Its been alot of fun so far.
Heres what i have done so far..
I followed the deizel mod as a starting base and made a few adjustments as follows.
C25, c35 removed
R41 -5.1k ( still to much gain, im planning on upping to 10-12k)
D3,d4 changed to symmetrical red LED clipping which i am going to start experimenting with asymmetrical clipping and different diodes. I also changed i think c34 to a 47nf cap and changed
C42 and c36 to 100nf

Sounds pretty awesome apart from the low end.

Leito79
Information
Posts: 10
Joined: 23 Nov 2009, 15:38
Has thanked: 1 time

Post by Leito79 »

teddeeh wrote:Hi guys.
So on my quest to drive a great mod for the mt-2 i have come accross a problem and thats the bass/low end of the eq. I find that it sounds a bit flabby and im wanting to tighten it up. Would anyone know where abouts and what i can mess around with to alter the eq of the low end? I.e tighten it up.
Also where abouts are the eq components and what would be the affect of changing the values?
Many thanks guys keep this thread going its awesome and really the only place i can find that is keeping the mt-2 mods going. Its been alot of fun so far.
Heres what i have done so far..
I followed the deizel mod as a starting base and made a few adjustments as follows.
C25, c35 removed
R41 -5.1k ( still to much gain, im planning on upping to 10-12k)
D3,d4 changed to symmetrical red LED clipping which i am going to start experimenting with asymmetrical clipping and different diodes. I also changed i think c34 to a 47nf cap and changed
C42 and c36 to 100nf

Sounds pretty awesome apart from the low end.
To change the response of the bass control knob you can modify the values of the components associated with it (C8,C9,R12,R13). It is centered around 100Hz, you can use the AMZ gyrator calculator to modify the values and get different frecuencies and filter width to change the bass response controlled by the bass knob. If you want more overall bass you´ll have to mess with the coupling capacitors in the different stages. You could try to increase C42 (first input cap) to let more bass into the circuit, every guitar/amp rig is and sounds different, so experimenting is key

Post Reply