Timmy drive to mimic Boss Metal Core ?

[Hemmel]

Hi guys,

My nephew came by this weekend so I could add a tone pot to his Champion 600. While I was working he was checking out the projects I'm working on and he asked me if I could make him a Boss Metal Core copy.

I explained that since there's a lot of digital components in the ML-2 it's going to be quasi-impossible to copy (for me). But looking at the pots from the ML-2, they're basically the same as a Timmy Drive (volume - gain - bass - treble). The main difference I see is that the ML-2 is a distortion whereas Timmy is an overdrive. ( <--- I may be wrong here) Would there be a way to change a Timmy so it becomes a distortion pedal ?

[Mark Hammer]

1) You do know that the Champion 600 already has a Fender tonestack built in?  What would normally be treble/bass/middle pots are replaced with fixed resistors for a "preset" sound, but these can be replaced with pots.

Here's the schem:  http://support.fender.com/schematics/guitar_amplifiers/Champion_600_schematic.pdf   Download and install the Duncan Tonstack calculatior ( http://www.duncanamps.com/tsc/ ), and play around with the various values.  You can even consider installing a bright switch with a small (e.g., 47-120pf) bypass cap across the volume pot.

2) What a company calls the controls can be different than what they do, so I wouldn't turn to the legending on the box to provide guidance about what can be turned into what else, or what can be easily emulated in another way.  The Timmy is essentially a Tube Screamer redesigned to offer more restrained clipping.  Modding it to deliver heavier clipping would involve transforming it in several ways that run counter to its better nature.  Probably a smarter idea to simply make a harder distortion properly, rather than ruin something that already works well.

[Hemmel]

1) You do know that the Champion 600 already has a Fender tonestack built in?  What would normally be treble/bass/middle pots are replaced with fixed resistors for a "preset" sound, but these can be replaced with pots.

Here's the schem:  http://support.fender.com/schematics/guitar_amplifiers/Champion_600_schematic.pdf   Download and install the Duncan Tonstack calculatior ( http://www.duncanamps.com/tsc/ ), and play around with the various values.  You can even consider installing a bright switch with a small (e.g., 47-120pf) bypass cap across the volume pot.

2) What a company calls the controls can be different than what they do, so I wouldn't turn to the legending on the box to provide guidance about what can be turned into what else, or what can be easily emulated in another way.  The Timmy is essentially a Tube Screamer redesigned to offer more restrained clipping.  Modding it to deliver heavier clipping would involve transforming it in several ways that run counter to its better nature.  Probably a smarter idea to simply make a harder distortion properly, rather than ruin something that already works well.

Thanks Mark.

1) Yes I knew about the fixed tonestack. I looked at the schematic and saw that changing R19 for a pot (I put a 10k linear) would "unfix" the tonestack.

2) I was afraid of that. What if I take the MXR Dist+ and try to add the Bass and Treble cuts ? .... Just writing this makes me realize I'm getting ahead of myself. 

[Mark Hammer]

1) Yes I knew about the fixed tonestack. I looked at the schematic and saw that changing R19 for a pot (I put a 10k linear) would "unfix" the tonestack.

2) I was afraid of that. What if I take the MXR Dist+ and try to add the Bass and Treble cuts ? .... Just writing this makes me realize I'm getting ahead of myself. 

R19 subs for the midrange control on a standard tonestack.  Traditionally, in Fender amps that only have a treble and bass control, its value is selected to bleed off a certain amount of midrange and provide a midscoop.  That midscoop allows the bass and treble controls to act as if they provide boost (which they don't).  I would recommend subbing a 3k3 fixed resistor and 25k pot (wired as variable resistor) for it.  That is, make it possible to produce resistances to ground that are less than, and greater than, the original 15k value.  This will give you greater range of control over the midrange".

A trick I learned in an old Polyphony article is to make R15 (or its equivalent) "high", by simply lifting the ground connection.  This effectively removes the passive-bleed result of the tonestack, and increases the overall signal amplitude passing through the volume pot.  I installed it on an old BF Tremolux I had, and it works like a charm as an instant solo boost.  The treble control will still work to a limited extent, but with the ground path open or very high resistance, the bass and mid controls will essentially have no influence.  As you can imagine, the higher signal amplitude will result in a little bit of overdriving the next stage.

This is, incidentally, also a workable mod for any pedal that uses such a tonestack....and many do.  Take, for example, Jack Orman's Overdrive Pro.  It uses a form of Fender tonestack, albeit with different values.  If a person put a 18-22k resistor between the midrange pot and ground, they could use a SPST stompswitch to shunt/unshunt that resistor, producing a big midrange boost for solos.

[Hemmel]

Mark, you know I drink your info like coffee
I've copied your last post and I'll suggest the modifications to my nephew (the R19 replaced by a B10K pot is already done and he's back home playing like crazy).

However, we've strayed from the main topic.

About the Metal Core clone, I'm wondering if there's any DIY distortion that could be an approximate equivalent ?

[Mark Hammer]

Don't look at me.  I've never heard the darn thing. 

[Hemmel]

Don't look at me.  I've never heard the darn thing. 

Me neither !!!
I guess I'm up for a little trip on Youtube tonight...
Apparently it's the sh*t for distortion. I read a lot of very positive reviews.

[mremic01]

Well, Boss isn't really known for great distortion pedals. I used the Metal Core in stores, but it didn't stand out as anything special. I had a Metal Zone and thought it was cool for a few months, then hated it. It's the kind of pedal that sounds 'brutal' to someone who hasn't been playing long, but will leave you disappointed in the long run.

Some quick googling didn't turn up any Metal Core schematics for me, but the other forum (fr-ee-sto-mp-box-es-dot-org (remove the dashes)) might have some more info. There are plenty of alternatives. The Dr Boogey is great high gain distortion circuit that might do what you want. I like the Brown Sound In a Box II for nice smooth high gain lead tones. I'm also a fan of the Crunch Box and Rat, but the Rat does need a bit of a boost to get super metal. The Wampler Triple Wreck might work too, but it's a pretty big build.

[Hemmel]

Well, Boss isn't really known for great distortion pedals. I used the Metal Core in stores, but it didn't stand out as anything special. I had a Metal Zone and thought it was cool for a few months, then hated it. It's the kind of pedal that sounds 'brutal' to someone who hasn't been playing long, but will leave you disappointed in the long run.

Some quick googling didn't turn up any Metal Core schematics for me, but the other forum (fr-ee-sto-mp-box-es-dot-org (remove the dashes)) might have some more info. There are plenty of alternatives. The Dr Boogey is great high gain distortion circuit that might do what you want. I like the Brown Sound In a Box II for nice smooth high gain lead tones. I'm also a fan of the Crunch Box and Rat, but the Rat does need a bit of a boost to get super metal. The Wampler Triple Wreck might work too, but it's a pretty big build.

Thanks mremic !
Those are some very nice suggestions. It's for my nephew, he's in his early 20's and loves stuff like System of a Down, Metallica, Avenged Sevenfold, and probably many other bands of the same type (I know, purists will say those 3 bands are of 3 different types )
I have gaussmarkov's Dr Boo planned for a 1590BB. Once finished, I'll suggest it to my nephew. BSIAB II is also very tempting. Wampler triple Wreck looks cool too !

[Mark Hammer]

Of course, knowing what DSP chip/s are used in the ML-2 doesn't exactly give you the firmware, does it?  Which, to my mind, is one of the many reasons why the bigger companies are all migrating to digital pedals: to protect IP.

The AMZ Overdrive Pro has a lot to recommend it.  I made one, and while it is not my personal taste (a little too metal-ey for me), it provides a useful platform for those who want to go a step beyond something like a DOD250/Dist+, and tailor the tone to their liking.

The Q1 stage has some gain, and IC1 has a gain of 1000x, so when the Saturation and Drive controls are maxed, there is more than enough push to do whatever you want.  I can see why a tweaker would want to be able to play with both, but for all practical purposes, I think only one is really necessary.  T'wer I, I would make R6 470R, and replace R7 (Drive pot) with a 100k fixed resistor, controlling the distortion via the Saturation pot.  The change in R6 value will retain more bass.  If you want a little more oomph, you can make R7 120k or 150k, or just replace is with a 250k trimpot, set it and forget about it.  If using only the Saturation control, you'll want to follow the Big Muff's lead and stick a small resistor, like 100-220R, between ground and the ground end of the pot, so that you can turn down all the way without completely cutting the sound out.

Increasing C5 to 220pf will help to bring the hiss under control.  Finally, you can do the King of Tone trick, and use double clipping, by putting a 2+2 pair of diodes in the feedback loop of IC1.  That will clip once, and D1/D2 will clip again.  If that still isn't enough for yur nephew, you can add some crossover distortion by inserting a back-to-back pair of Schottky diodes between C7 and C8.  This will clip the sides of the waveform, and is part of what the HM-2 does. (remember? essential for Swedish metal)

[anchovie]

(remember? essential for Swedish metal)

...but not metalcore!

Wampler triple Wreck looks cool too !

Worth a shot if you're comfortable with the build complexity. The Okko Dominator is worth looking at too - see what your nephew thinks of this comparison:

I'm not sure if there's a schematic for the Morbid Drive available yet.

[Hemmel]

Thanks James, I'll need to have a look at that at home since Youtube is blocked at work 

Mark, how about these changes ?



I thought I'd put a 330k in parallel with a 150k instead of the drive pot, so with a switch I could go from around 103k to 150k. Like a "oomph" switch. Does this make sense ?

[Mark Hammer]

I can't see it at the moment, but from your verbal description I'm guessing that you are using a simple SPST to work parallel resistance to your advantage, and choose between two different values.  Remember that you can use series resistance and the same switch to your advantage as well.  So, a 100k resistor in series with a 47k resistor.  Shunt/bridge the 47k with a SPST switch, and your feedback resistance is 100k.  Open the switch and it's 147k. 

Both approaches accomplish the same thing, but the second approach is just a little easier to calculate and may be more compatible with what you have in your parts bin.