Ibanez Smash Box mods... anyone?

[edvard]

I have an Ibanez SM7 'Smash Box' that a friend loaned to me and said I could mod it if it was possible.
He hates the tone of it and isn't in a hurry to get it back, but if I could mod it I'm sure he'd enjoy it.
I found the [urlhttp://www.ibanez.com/parts/2004_PARTS/electronics/tonelok/circuit%20diagram/SM7-01.pdf]Smash Box schematic[/url] on Ibanez' website, but can't make heads or tails out of the built-in eq section that gives it the tone it has.
I'd like to disable or bypass that bit to open up the tone a bit.
Seems most pedal manufacturers 10 years ago all got the same idea to dump some gain and clipping sections into some choice gyrator buckets and ... Voilà! A new pedal!
Grrr...
Is it just a matter of removing a few choice capacitors like Lauriepedals' "Stormchaser" [urlhttp://members.shaw.ca/lauriepedals/info]Metal Zone mod[/url]?
Or do I need to dig deeper?

[Chrisq206]

The Brian Wampler How To Modify Effects Pedals book has some mods for that pedal (p. 259). If you don't have that book it's worth getting. It's not perfect, but it's the best thing I've seen by far.

Here's what's in there. I haven't done this, so I don't know what it sounds like. Consider this a plug for buying the book.

The mods are:
D3 1n4001, D6 1n4001, D4 & D5 1n4001 x 2 in series, C33 .01uf (adds distortion), C26 & R52 remove no jumper (adds body to EQ.

[edvard]

Thanks, I just saw that book when I was searching around for mods, and wasn't sure it was worth it for just one mod I'm not even charging for.
Though I think it'll be a must-have if this turns into doing more than a mod or two for a friend...
I'll report back when I get the mod done.

[Chrisq206]

Let me know. Screwing around w/ pedals is addicting. The descriptions on what the mods do are from the book. Like I've said Ihaven't done them so I would have no way of knowing.

[earthtonesaudio]

The fixed gyrator filters are what make or break these pedals in my opinion.  You'll want to mess with the gyrators based around TR6 through TR9.  TR9 you can already hear when you flip the EQ switch.  The others are at different frequencies with varying levels of boost/cut and Q.  Simplest is to eliminate them altogether by C22/C24/C26 etc. but you can also vary their relative boost/cut with the ratios of R51/57 and 52/56 and adding a resistor between R48 and U2A pin 3, for example.  Change the values of C22/C23 etc. to change the frequency in steps, or make R35 or R36 variable to change the frequency smoothly. 

These filters are the core of the pedal's EQ and their tones are highly subjective.

The good news is, if you do a re-house, you can make a lot of the resistors into panel-mount pots and end up with a distortion with a multiband parametric EQ built in.

Check out the AMZ gyrator filter calculator to save yourself the second order differential equation math.

[edvard]

Yes, that's it!! MOAR NOBBZ PLZ!!

If this wasn't such a complicated circuit to begin with, I might be tempted to try, but that's for another day...

The fixed gyrator filters are what make or break these pedals in my opinion.

And it's a quite valid one.
DOD/Boss/Ibanez/etc don't make their money off throwing arbitrary filters on a generic clipping circuit and hope for manna from heaven to fall (or maybe they do...).
No, they tune these circuits for a definite type of sound which they can then market effectively to a target audience (Grunge, Death Metal, Metal Core, Classic Fuzz, etc.) I fully understand that.
If my friend liked the Korn tone that the Smash Box gives him, he'd be happy.
As it is, he'd rather throw it out the window and enjoy the sound of it hitting the pavement rather than the sound of it through his amp.
I told him I'd open it up and see what could be done to make it sound different.
I didn't guarantee his amp would suddenly fart gold dust if I modded his pedal, but he's expressed great interest in hearing something different without coughing up the extra clams for a new pedal.

I'm doing the mod as described in the book right now.
If it doesn't open up as much as I'd like, I'll start pulling more.
Sound clips to follow...

[earthtonesaudio]

I do like the "noise gate" in that pedal though.  My buddy has one of those and that was always my favorite feature.  Might be worth copying and using as a standalone thing.

[edvard]

Yeah, it's surprisingly more useful than many of the noise gates I've tried.
I suspect it works so well because the triggering and muting is part and parcel of the signal path instead of 'tacked on', so I don't know if it would work as well as a standalone.

Either way, I did all the mods and found that doubling diodes at D4 and D5 didn't work so well.
It sounded like some clean signal was blending in, very weird.
Replacing C33 didn't make a difference I could hear, the original is a .015uf, so changing it to .01uf didn't make much sense anyways.
So in the end I ended up yanking C22, C23, C26, R51 and R52.

Here's the soundclip, please excuse my atrophied playing ability.
I haven't practiced or played regularly for ~10 years (having a family does that to you...) and just recently dove back into playing and stompboxing now that my son is old enough to learn soldering .
http://www.aronnelson.com/DIYFiles/up/sm7_before_n_after_mods.mp3
Just a simple riff (from a Seven System song I believe...) and some blues-ish noodling to test out the high notes, each part separated by a fade-out/in.
Gain at max (is there any other setting?) Bass and Treble at 12 o'clock, modded '82 Fender Bullet S-3, Wal-mart bass amp (don't laugh, it's a surprisingly good amp), cheap mike.
Part 1 is before any mods were done.
Part 2 is the first mod with just C26 and R52 removed.
Part 3 is with C22, C24 and R51 removed also.

Very subtle differences, but I did notice after pulling everything the pedal 'breathed' a bit, especially noticeable in the high notes.
I don't think I'd buy this pedal myself, even though I dig high-gain gear, but if I somehow acquired one accidentally through trade or hand-me-down, I'd definitely do this mod again.