Metal Zone: how to widen the pre-distortion filter?

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MF_Kitten
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Joined: 08 Jul 2019, 11:37

Post by MF_Kitten »

Hi! I am looking to mod my Metal Zone, but unlike alot of people I don't need to do very much to it. I am removing the post-distortion EQ, as that's where most of the bad tone actually comes from. this is easy, and I can do that already.

But I also kind of want to change the pre-distortion filter a little. I literally just need to widen the Q of that peak.

The exact part of the circuit is described here, under the section "Pre-distortion tone shaping": https://electricdruid.net/boss-mt-2-met ... -analysis/ ?

I need to move the upper and lower cutoff frequencies of the bandpass filter. I am a huge fan of the Klon curve myself, so it can get quite a bit wider than the narrow peak that it has stock. I would also be happy with something tubescreamer-esque here, as that's also less peaky and narrow. I don't need something crazy wide, just more natural sounding.

Does anyone know how this could be done? I am very green with electronic components, even if I know what they are capable of. I am guessing I need to change two components for something with different values?

Thanks for any help you can give me guys!

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spacecarrot
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Post by spacecarrot »

hi!

the easiest way to get exactly what you want would be to throw it at a circuit simulator such as ltspice or qucs. however if all you want is to make the curve flatter _somehow_, you might want to focus on r44 and c31.

r44 is sorta-kinda a gain control for the filter, by shorting it the section is just a buffer, and by replacing it with a 250k trimmer you get a good control range over the input peak. it's not a q control though.

c31 does an additional -6dB above 680Hz. it's not much, but opening it up may help a bit if r44 is already low. the corner frequency is 160kHz/(5k*c31[nF]), note that the effective output resistance of a voltage divider is the values of both resistors in parallel.

if you want to create a specific response in a simulator, it might be helpful to insert a resistor in series with c34 to get independent control of gain and q.

hope this helps :D

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