Breaking down a Boss pedal

[Seven64]

So I am starting on trying to design my own modded Metal Zone, and am looking for a little help in discerning the schematic.

This pedal is advertised to have dual gain circuitry.  Am I correct in assuming that this is Q7/Q8?

If changing the transistors in this circuit, I assume I will have to re-bias anything I change, correct?

Would there be any difference in cascading the transistors in the gain stage?

What purpose does Q10 serve in the distortion circuit?

Are the hollow arrows to +9v and the filled arrows to +4.5v?

If I were to insert the Tone/Sustain circuit from the BMP, would I put it before or after the EQ circuit?

I have searched google for all of this, but can't find much info at all

[twabelljr]

Are the hollow arrows to +9v and the filled arrows to +4.5v?

Yes. Good luck sorting out the other questions.

[Seven64]

ok, just read that q10 is for input tone shaping and q7/8 are for output tone shaping.  does this mean that q10 is 1 stage and q7/8 is the other stage?

[ayayay!]

Q7, Q8, & Q10 are all part of gyrators. Google that.  That'll probably help you with most of the rest of the questions.

If changing the transistors in this circuit, I assume I will have to re-bias anything I change, correct?

Probably not. Which transistors?

If I were to insert the Tone/Sustain circuit from the BMP, would I put it before or after the EQ circuit?

Probably neither.  You'd put it in instead.   The EQ is a tonestack.  A BMP is a tonestack.  Putting those two in series, either way, can be done sure, but you'd probably only have one sweet spot.  The other 99% would most likely be scary god-awful. 

[Thomeeque]

ok, just read that q10 is for input tone shaping and q7/8 are for output tone shaping.  does this mean that q10 is 1 stage and q7/8 is the other stage?

Q007/008/010 subcircuits (e.g. Q010, R046, R053, R054 and C035) form simulated (virtual) inductors, which form LC branches with C020/C024/C034, which add some boost to given stages at certain frequencies (like in graphic equalizer, where is being this "trick" used a lot too as real inductors are problematic parts).

T.

Edit: I've seen Juno's answer when I was about to post mine, I've decided to post it anyway as it adds little more.

[anchovie]

This pedal is advertised to have dual gain circuitry.  Am I correct in assuming that this is Q7/Q8?

No, that's BS marketing spiel to try and make metallers go "woo! it's got twice as much gain!".

Wouldn't you be better off creating mods for a pedal that you understand the workings of? (no offence intended!)

[Seven64]

i dont understand any pedal 

[Seven64]

If I were to insert the Tone/Sustain circuit from the BMP, would I put it before or after the EQ circuit?

Probably neither.  You'd put it in instead.   The EQ is a tonestack.  A BMP is a tonestack.  Putting those two in series, either way, can be done sure, but you'd probably only have one sweet spot.  The other 99% would most likely be scary god-awful. 

ah.  that makes alot of sense.  i was getting all confused in my head about how having one before the other would affect the latter one.

we should get together for a beer soon!  maybe you can teach me a thing or 2.  still have my phone #?

[Mark Hammer]

i dont understand any pedal 

You understand what you understand...at this point in time.
Just because you fall over when running doesn't mean you don't know how to walk extremely well.  Don't try to run before you can walk, that's all.
"Designing" takes time and patience.  be patient and learn the little details.  You'll get there eventually. 

[ayayay!]

If I were to insert the Tone/Sustain circuit from the BMP, would I put it before or after the EQ circuit?

Probably neither.  You'd put it in instead.   The EQ is a tonestack.  A BMP is a tonestack.  Putting those two in series, either way, can be done sure, but you'd probably only have one sweet spot.  The other 99% would most likely be scary god-awful. 

ah.  that makes alot of sense.  i was getting all confused in my head about how having one before the other would affect the latter one.

we should get together for a beer soon!  maybe you can teach me a thing or 2.  still have my phone #?

PM it to me again, just in case.    We definitely do need to get together!    Oh, and Keppy lives in Olathe!!!  (I think...)

[Seven64]

i dont understand any pedal 

You understand what you understand...at this point in time.
Just because you fall over when running doesn't mean you don't know how to walk extremely well.  Don't try to run before you can walk, that's all.
"Designing" takes time and patience.  be patient and learn the little details.  You'll get there eventually. 

basically all i know is what each component does.  i have been working on this all morning:

pt1

http://www.seymourduncan.com/tonefiend/wp-content/uploads/4-v02.pdf

pt2

http://www.seymourduncan.com/tonefiend/wp-content/uploads/DIY-Club-Project-1-Part-2-of-4-v03.pdf

and it is helping me learn the basics of the distortion circuit.  i think next up is going to be either a 3 tranny circuit, or the tubescreamer (1ic/2tranny).

I really wish I had a resource that could do this kind of stuff, but add in the oscilloscope, as i have one on my desk, but can almost never find a use for it.

i know that would help me understand all this stuff BUNCHES quicker!

[Mark Hammer]

Well you DO have that sort of resource: THIS PLACE!! 

It's a lot faster to turn to Joe Gore's pieces (and nothing against him, sharp guy, and great player from what I understand), but there is a lot more reading to be done, before you could look at somethng like the schematic for the Metal Zone and identify functional stages (i.e., this cluster of parts does THIS and that cluster of parts, starting from here and going to there, does THAT).

There are escellent tutorials at RG Keen's geofex site and at Jack Orman's AMZ site.  Not that you won't find that same content here as well, but it's a lot easier to search through on those sites.

[Quackzed]

heres a layout i found, its a metal zone layout, without the boss style switching. so youd use a 3pdt for true bypass switching and led...
but a layout is a bit easier to follow than a schematic... figured it might help...
also i have to say that these pedals are easy to find rather cheap on ebay etc... for all the trouble and expence of building one i'd say buy a used one! less time and money spent in the end.
http://elkit.web.id/page/13/

[Quackzed]

see?
http://www.ebay.com/sch/i.html?_nkw=mt-2&_sacat=41410&_sop=1&_dmpt=Guitar_Accessories&_odkw=&_osacat=41410&_trksid=p3286.c0.m270.l1313

[Seven64]

Well you DO have that sort of resource: THIS PLACE!! 

It's a lot faster to turn to Joe Gore's pieces (and nothing against him, sharp guy, and great player from what I understand), but there is a lot more reading to be done, before you could look at somethng like the schematic for the Metal Zone and identify functional stages (i.e., this cluster of parts does THIS and that cluster of parts, starting from here and going to there, does THAT).

There are escellent tutorials at RG Keen's geofex site and at Jack Orman's AMZ site.  Not that you won't find that same content here as well, but it's a lot easier to search through on those sites.

yea, i have read a little of geofx's site, but i am a visual/tactle learner.  i am very aware that it will be a while until i can understand how to break this circuit down, hence the thread.  just looking for a little booster.  i have a TON of AMZ bookmarks that i have been sifting threw.  i love reading about this stuff!!!!!

[Mark Hammer]

Well, keep at it, and I'm sure in due time, you'll be able to move from the kids' table to the grown-up table.