# Tone Vendor MKI HFE



## Travis (Nov 4, 2019)

Where can I buy the 2SC381 ??

Wich HFE I must use in Q1, Q2 and Q3??

Could I use three OC75 instead 2SC381 ?

Thank you all, is my first fuzz


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## Mir9 (Nov 5, 2019)

I hope you get some help here as the MK1's  can be tough to get right, especially for a first fuzz.  Leakage will matter here.  You may want to buy a set already auditioned for you and even then, use sockets to keep experimenting.


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## Travis (Nov 5, 2019)

Thanks, I wanna learn more about fuzz


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## Chuck D. Bones (Nov 5, 2019)

You picked a good one to learn on.  Q1 & Q3 are leakage-biased.  Q1-E and Q3-C should be somewhere between -3V and -6V.  The collector voltage on Q2 varies with the ATTACK setting.  With ATTACK at zero, Q2-C should be near -9V.  With ATTACK at 10, Q2-C should be somewhere in the middle, depending on what sounds good to you.  Part number is unimportant, leakage and hFE are what matters.  I agree with Mir9, buy a transistor set that was selected for a Tone Bender MK1.  Otherwise, you will need to buy a bunch of them and select them yourself.  Definitely install sockets.


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## Travis (Nov 6, 2019)

Chuck D. Bones said:


> You picked a good one to learn on.  ?  Q1 & Q3 are leakage-biased.  Q1-E and Q3-C should be somewhere between -3V and -6V.  The collector voltage on Q2 varies with the ATTACK setting.  With ATTACK at zero, Q2-C should be near -9V.  With ATTACK at 10, Q2-C should be somewhere in the middle, depending on what sounds good to you.  Part number is unimportant, leakage and hFE are what matters.  I agree with Mir9, buy a transistor set that was selected for a Tone Bender MK1.  Otherwise, you will need to buy a bunch of them and select them yourself.  Definitely install sockets.


Where can I Buy one set?


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## Chuck D. Bones (Nov 6, 2019)

Small Bear

http://smallbear-electronics.mybigcommerce.com/transistor-set-tb-mk-i-pnp-generic/

This is the lowest cost option.  Otherwise, you're buying 10 transistors at something like $3 each to get 3 that will work in the TB MK 1.


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## Travis (Nov 6, 2019)

I know one shop in Spain who can sell me three OC75 with the hfe I need. Someone know what hfe it's okey?


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## Chuck D. Bones (Nov 6, 2019)

You need two transistor parameters to be matched to the circuit: HFE & Icbo (leakage).  Better buy 10 and hope you get three with the right properties.  Or maybe build a different circuit.  Consider the Scythe (Earthquaker Tone Reaper).  I has only one Ge transistor and can produce similar tones to the Tone Bender MK 3.


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## Travis (Nov 6, 2019)

Ok THX, i Will think about it


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## Nostradoomus (Nov 6, 2019)

I would definitely build something else to start with, this build may very well put you off diy pedals for a long time due to sheer frustration ?


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## zgrav (Nov 6, 2019)

Note -  "wanting to learn more about fuzz" can refer to building a pedal or to playing a fuzz pedal.   A good fuzz to build _if you want to learn about how to make it work_, is not the same thing as a "good fuzz" to build if you want an easy project to build that will sound good.   Learning how to make something work can be a project that will require more time and learning on your part.  It can be more rewarding if you understand that is what you are choosing to do.  

For a first fuzz project I would take CDB's suggestion to look at the Scythe.


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## Chuck D. Bones (Nov 7, 2019)

Or build a *Big Muff*.  Everybody ends up owning some of those.  They're iconic and not hard to build and make work.  Listen to some demos first, because the various versions are tuned differently.


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## jjourard (Jan 5, 2021)

Travis said:


> Where can I buy the 2SC381 ??
> 
> Wich HFE I must use in Q1, Q2 and Q3??
> 
> ...


Note that the original Texas Instruments transistor was a 2C381 not a 2SC381.  I made the same mistake and now I have 20 silicon NPN 2SC381 transistors that are of no use in a Tonebender MK I.


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