Metalzone - Wire Eq before gain stage

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Metalzone - Wire Eq before gain stage

Postby Olivier V.Girard » 03 Jun 2018, 16:46

Hi!

I got a Metalzone to experiment with some mods.

Long story short, I will try the mod suggested by Brian Wampler on he's youtube channel and turn it into a Tubescreamer with parametric Eq.

https://youtu.be/KySRbaubEDs

The first preEq stage will become a buffer, the hard clipping section will become a soft clipping one and the next fixed Eq stage will be rewired to become a tone control.

Now, I would like to invert the order of the "Tubescreamer" circuit and the parametric Eq. I want to have it this way:

Guitar -> Parametric Eq -> "Tubecreamer" -> Amp

Here's the schematics:

Image

So far, my best guess (and that's really a guess since I've almost no knowledge in circuit design) is to:

1. Lift the leg of C039 that connect to Q011
2. Lift the leg of R014 that connect to pin 3 of "1A" 1/2M5218AL (what I believe to be the Eq input...)
3. Cut trace between Q002 and C002

Then

4. Connect the empty hole of C039 to the empty hole of R014
5. Connect the leg of Q002 (that went to C002) to the loose leg of C039
6. Connect the loose leg of R014 to the leg of C002 (that went to Q002)

My main concern is can the parametric Eq deal with a buffered guitar signal or it need something that have been decently amplified to work properly and of course, does my mod can work at all the way I have it planned...

Any thoughts/corrections/suggestions would be very welcome!

Thanks!
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Re: Metalzone - Wire Eq before gain stage

Postby sixthfloor » 04 Jun 2018, 08:51

As far as I can tell, your approach should work. Don't take my word on it though, and wait for more knowledgeable people's answers ...

The EQ stage shouldn't have any problems dealing with a buffered signal.

Mind the position of the volume (level) pot, as it will be placed before the distortion stage with the modification you suggest. Hence impacting the amount of signal going into the distortion stage, thereby changing the amount of dirt getting out of the circuit.
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Re: Metalzone - Wire Eq before gain stage

Postby Olivier V.Girard » 04 Jun 2018, 13:47

Oh you're right! Haven't seen that...

Not sure that's helpful though, I think I will simply change the "splitting point" and keep the volume as the master level out, I'll correct the main post.

Thanks!
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Re: Metalzone - Wire Eq before gain stage

Postby Olivier V.Girard » 04 Jun 2018, 13:58

Looks like I can't edit my first post... here's what I suggest to have the Volume control at the end before hitting the amp:

1. Lift the leg of C039 that connect to Q011
2. Lift the leg of R014 that connect to pin 3 of "1A" 1/2M5218AL (what I believe to be the Eq input...)
3. Desolder the cable that go to hole no.4 on the pots pcb

Then

4. Connect the empty hole of C039 to the empty hole of R014
5. Connect the hole no.4 on the main pcb to the loose leg of C039
6. Connect the leg of R014 to the hole no.4 on the pots pcb
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Re: Metalzone - Wire Eq before gain stage

Postby sixthfloor » 05 Jun 2018, 11:48

What you propose should place the volume pot at the end.

I'm unsure about DC filtering there, it might be necessary to put a cap (say 10uF) between R14 and hole n°4 since there is a cap (C005) between the output of the EQ and the volume pot.
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Re: Metalzone - Wire Eq before gain stage

Postby thetragichero » 09 Jun 2018, 11:49

https://electricdruid.net/boss-mt-2-metal-zone-pedal-analysis/
help me a lot while i was modding mine
breaks the circuit up into modules so it should fill in the missing gaps of what does what
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