# Tone Bender Mk2 Transistors?....



## PaulPauliePabloPaolo (Jul 30, 2022)

Hey Gang, 

Just a quick one about what kind of Ge. transistors are you guys using for the Tone Vendor? I want one and some friends have asked me to build one for them also. 
Ive looked through the forums and many of the places recommended such as Small Bear have sold out of the OC81D, or indeed any 'match sets' that they supply. 
From my research I have found that many say that you could use many different types for this pedal and they really only have to satisfy some conditions such as Q1 & Q2 being ~ 60-70hfe, and Q3 ~120hfe.... and that Q3 should be 'leaky'. 

So the question is... Where are you guys getting yours?... is there any up to date recommendations of where to get suitable transistors for this project?. 
Are there any recommendations of other types of transistors to use for this?
Obviously I'll be socketing them, and I have an M Tester to measure. 

And just for S&G's here are the pedals Ive made from PedalPCB... Who doesn't like pics right!?!?!

Thanks in advance
P.


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## Big Monk (Jul 30, 2022)

PaulPauliePabloPaolo said:


> Hey Gang,
> 
> Just a quick one about what kind of Ge. transistors are you guys using for the Tone Vendor? I want one and some friends have asked me to build one for them also.
> Ive looked through the forums and many of the places recommended such as Small Bear have sold out of the OC81D, or indeed any 'match sets' that they supply.
> ...



In truth, as long as Q1 has at least 15 microamps leakage, nearly any transistors with hFE around 70 for Q1 and 100 for Q2,3 will sound good. 

As a parallel, the MK II with silicon transistors is also phenomenal. As long as you put either a 470k-1M from base to power or base to collector, Q1 will conduct. 

Some of the best I’ve made had local feedback resistors from emitter to ground and medium gain silicon transistors.


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## PaulPauliePabloPaolo (Jul 31, 2022)

Big Monk said:


> In truth, as long as Q1 has at least 15 microamps leakage, nearly any transistors with hFE around 70 for Q1 and 100 for Q2,3 will sound good.
> 
> As a parallel, the MK II with silicon transistors is also phenomenal. As long as you put either a 470k-1M from base to power or base to collector, Q1 will conduct.
> 
> Some of the best I’ve made had local feedback resistors from emitter to ground and medium gain silicon transistors.


Thanks so much for the info. 
Is there a place you would recommend buying them from?.


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## andare (Jul 31, 2022)

Big Monk said:


> In truth, as long as Q1 has at least 15 microamps leakage, nearly any transistors with hFE around 70 for Q1 and 100 for Q2,3 will sound good.
> 
> As a parallel, the MK II with silicon transistors is also phenomenal. As long as you put either a 470k-1M from base to power or base to collector, Q1 will conduct.
> 
> Some of the best I’ve made had local feedback resistors from emitter to ground and medium gain silicon transistors.


Does Q3 have to be leaky?


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## fig (Jul 31, 2022)

PaulPauliePabloPaolo said:


> Hey Gang,
> 
> Just a quick one about what kind of Ge. transistors are you guys using for the Tone Vendor? I want one and some friends have asked me to build one for them also.
> Ive looked through the forums and many of the places recommended such as Small Bear have sold out of the OC81D, or indeed any 'match sets' that they supply.
> ...


Hi Paul,

You’ll also want to make certain you get PNP-type transistors for the TBMKII.


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## ICTRock (Jul 31, 2022)

I believe smallbear announced transistor kits were available again


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## Big Monk (Jul 31, 2022)

andare said:


> Does Q3 have to be leaky?



Nope. It helps if you are keeping the original stock circuit because you want the collector voltage up over 7.5 vDC, but you can just tweak the Q2 or Q3 collector resistor.

Leakage is not a benefit unless for some reason you want to keep the stock vintage circuit unmodified. 

In all other cases it’s a hinderance.


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## Big Monk (Jul 31, 2022)

fig said:


> Hi Paul,
> 
> You’ll also want to make certain you get PNP-type transistors for the TBMKII.



NPN works just as well and you can ditch the voltage inverter.


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## fig (Jul 31, 2022)

Big Monk said:


> NPN works just as well and you can ditch the voltage inverter.


Yes sir.  They’ll just want to make sure the transistors match the schematic.


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## Big Monk (Jul 31, 2022)

fig said:


> Yes sir.  They’ll just want to make sure the transistors match the schematic.



Yes.

Word of note: Whatever transistors are used, make sure all polarized components match that polarity.

Just did graphics for the Monk Bender MK II last night so this was on my mind!


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## fig (Jul 31, 2022)

Here’s the SB link;









						Transistor Set - TB Pro MK II PNP - Generic
					

Small Bear Electronics DIY Parts




					smallbear-electronics.mybigcommerce.com


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## PaulPauliePabloPaolo (Jul 31, 2022)

Thanks Gents, 



fig said:


> Here’s the SB link;
> 
> 
> 
> ...


Thanks for that!... I was just going to post that link to ask if they were OK.... You beat me to it!... 

And maybe a shockingly silly or just plain remedial question regarding the included 'biasing resistors'.
How do I utilise these?... 

Thanks again for the enlightening answers guys!. 
P.


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## ICTRock (Jul 31, 2022)

you follow the included schematic regarding placement within the circuit ... now I was so OCD that I merely used the same values of resistors but in the same metal film 1% I was using in the rest of the circuit so everything looked the same. if any of them are where a bias trimmer would be you can A) set the bias trimmer to that resistance value or B) put that value resistor in there instead of a trimmer.


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## fig (Jul 31, 2022)

ICTRock said:


> you follow the included schematic regarding placement within the circuit ... now I was so OCD that I merely used the same values of resistors but in the same metal film 1% I was using in the rest of the circuit so everything looked the same


I was typing that…LOL

Edit: You put it more succinctly


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## andare (Jul 31, 2022)

Since I'm on a breadboarding binge and you got me interested in Germanium again.
Say I have a silicon fuzz face and i want to use PNP Ge transistors in it. I flip the electrolytic caps and swap the + and - jumpers. Is that all? Isolated power supply of course.


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## fig (Jul 31, 2022)

andare said:


> Since I'm on a breadboarding binge and you got me interested in Germanium again.
> Say I have a silicon fuzz face and i want to use PNP Ge transistors in it. I flip the electrolytic caps and swap the + and - jumpers. Is that all? Isolated power supply of course.


…and mind the pinout of the transistor.


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## andare (Jul 31, 2022)

fig said:


> …and mind the pinout of the transistor.


I will. I promise!


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## andare (Jul 31, 2022)

So I just breadboarded a TB Mk2 with the stock values and it sounds great through a Protoboard Micro w/power supply and reverse polarity cable. Here's what I got for transistors, more or less:

Q1 (AC125) hFE 55, Iceo 150mA, Q1c 7.7
Q2 (ASY34S) hFE 100, Iceo 44mA, Q2c 0.37
Q3 (ASY34S) hFE 100, Iceo 34mA, Q3c 6.7

It sounds like a good Ge Fuzz Face but it doesn't clean up as well. Just dime both knobs and go to town.
No RF either. I guess the 10n input cap to ground killed the radio star.


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## Big Monk (Jul 31, 2022)

andare said:


> So I just breadboarded a TB Mk2 with the stock values and it sounds great through a Protoboard Micro w/power supply and reverse polarity cable. Here's what I got for transistors, more or less:
> 
> Q1 (AC125) hFE 55, Iceo 150mA, Q1c 7.7
> Q2 (ASY34S) hFE 100, Iceo 44mA, Q2c 0.37
> ...



Voltages?


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## andare (Jul 31, 2022)

Big Monk said:


> Voltages?


Q1-2-3c are the voltages.


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## Big Monk (Jul 31, 2022)

andare said:


> Q1-2-3c are the voltages.



I missed that!


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## PaulPauliePabloPaolo (Jul 31, 2022)

ICTRock said:


> you follow the included schematic regarding placement within the circuit ... now I was so OCD that I merely used the same values of resistors but in the same metal film 1% I was using in the rest of the circuit so everything looked the same. if any of them are where a bias trimmer would be you can A) set the bias trimmer to that resistance value or B) put that value resistor in there instead of a trimmer.


Thanks for the answer, and yea.... I too also suffer that kind of ocd when it comes to things like this...I'll be doing the same I'm sure!. 
I don't see any trimmers on the PCB for the Mk.2 from here, but maybe a picture of the inside of your build might help me understand where the biasing resistors go?. Im now presuming that specific resistors in the circuit will deal with biasing the transistors. SB are providing the resistor values that they recommend for those positions.
Hopefully all will become clear when things start turning up. 

Thanks gang!... Stellar as always.


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## Big Monk (Jul 31, 2022)

PaulPauliePabloPaolo said:


> SB are providing the resistor values that they recommend for those positions.



I wouldn't use those. 

I had an email exchange with Steve when he was still running SBE and he admitted his bias points for the MK II follow the Fuzz Central voltages which are wrong. 

When the transistors come on, post here on the forum and we can help you determine the best values to get Q1 and Q3 up over 7 vDC.


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## PaulPauliePabloPaolo (Jul 31, 2022)

Big Monk said:


> I wouldn't use those.
> 
> I had an email exchange with Steve when he was still running SBE and he admitted his bias points for the MK II follow the Fuzz Central voltages which are wrong.
> 
> When the transistors come on, post here on the forum and we can help you determine the best values to get Q1 and Q3 up over 7 vDC.


Thanks very much!


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## PaulPauliePabloPaolo (Aug 1, 2022)

So.... This was interesting!...
I ordered (and paid) 3 sets of transistors yesterday for the builds for myself and my friends with an online stock of 10sets.
Today I get an email from SBE saying they can only ship two, and how would I like to proceed with the additional money they took from my account?...Store credit or wait for availability of next shipment (whenever that might be!)?.
Not a great first experience with SBE!???... and what happened to all the other sets?. you b'stards!. haha

Should I...
A. Cancel the whole order out of protest of the 'treatment'.
B. Wait for them to get more stock?.
Or...
C.  Just smash the place up, and then realise its only guitar pedals and have a beer.

Answers on a postcard! 

*I actually just read the email again in not so much of a fury and they said their head engineer is away until the 11th and will make more sets from then.

**And just a few hours after my response, I got another e-mail saying they have found another set. 
I guess they are good guys after all as they put in the extra effort to rectify the situation and get another set together. 
Bravo SBE. panic averted, the mission is still on!.


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## Feral Feline (Aug 2, 2022)




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## PaulPauliePabloPaolo (Aug 2, 2022)

Feral Feline said:


> View attachment 30196


Wow, I haven't seen that before!... A penny for postage to good ole Blighty!... If only... ..
That is most def. an A for effort and the cool Postcard!!!!
I will now have 3 beers!.... Cheers!


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## PaulPauliePabloPaolo (Aug 8, 2022)

Hey Gang, 

Thought Id show you what turned up today after its 3358m trip.... 3 sets (2 pics each as I turned the packets round so you could see the transistor).

Wondered if you guys could 'clue me in' to what I have, and what you think about the sets. Which set you'd prefer, and why?. 
Seems like a few different types going on here, but some of the usual suspects turned up OC71, OC75, OC77 (mil spec?).
Which set would you keep for yourself?. and why!?!?!?!
Seems like they're all obeying the ratios of gain that have been discussed here.... Q1&2 ~ 60 and Q3 ~ 120. 

Waiting for the PCBs to get here so I can start putting these beaut's together and make some sweet sweet solo's.

Let me know what you think.... and thankyou again for the wealth of knowledge and comedy that I have found here!. 
P.


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## PaulPauliePabloPaolo (Aug 11, 2022)

Hey Ya'll,

I just wanted to check the values for the biasing resistors and see if there was any advice on doing this?... before I get too excited and start soldering things in....
Im starting with the set below (set 3 from previous. post).
I did notice that the resistors use a slightly different designation from the schematic provided for the build docs and the one listed on the packet below. (prob. cause of the power inversion network).
A. R3 on the Transistor packet (47K) seems to correspond to R5 on the build docs (100K).
B. R4 on the Transistor packet (100K) seems to correspond to R4 on the build docs (100K).
C. R6 on the Transistor packet (8K2) seems to correspond to R7 on the build docs (8K2).

So my question would be what to follow on the first resistor?... And how to determine this. Obviously I think the general opinion would be to follow the Transistor packet and use a 47K for R5?.

Hope you can help.... my trigger finger is itchy.


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## andare (Aug 11, 2022)

While we wait for the experts to chime in I'll just suggest you breadboard the circuit and see for yourself. I did and the 3 transistors I chose from my stash, with somewhat standard gain, all bias in the ballpark and the circuit sounds great.

Breadboarding is a game changer. You can build any circuit quickly and non destructively. If it sounds bad you can reuse the components and never buy the PCB for a pedal you won't enjoy. The tutorials on this forum are what got me started.


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## PaulPauliePabloPaolo (Aug 11, 2022)

andare said:


> While we wait for the experts to chime in I'll just suggest you breadboard the circuit and see for yourself. I did and the 3 transistors I chose from my stash, with somewhat standard gain, all bias in the ballpark and the circuit sounds great.
> 
> Breadboarding is a game changer. You can build any circuit quickly and non destructively. If it sounds bad you can reuse the components and never buy the PCB for a pedal you won't enjoy. The tutorials on this forum are what got me started.


Thats a really good point!.... I don't have a breadboard but I will get one. These smaller circuits seem like they wouldn't be too complicated to lay out, and as you say... I actually could have a listen prior to soldering.
Also just popped into my mind... You guys all socket the transistors?.


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## ICTRock (Aug 11, 2022)

PaulPauliePabloPaolo said:


> Thats a really good point!.... I don't have a breadboard but I will get one. These smaller circuits seem like they wouldn't be too complicated to lay out, and as you say... I actually could have a listen prior to soldering.
> Also just popped into my mind... You guys all socket the transistors?.


I don't but you certainly can. Some guys take the transistors with them when they find a good set.


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## Big Monk (Aug 11, 2022)

PaulPauliePabloPaolo said:


> Thats a really good point!.... I don't have a breadboard but I will get one. These smaller circuits seem like they wouldn't be too complicated to lay out, and as you say... I actually could have a listen prior to soldering.
> Also just popped into my mind... You guys all socket the transistors?.



I don;t socket transistors. I always breadboard.


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## andare (Aug 11, 2022)

I socket transistors but I'll probably stop soon unless they're really expensive or hard to find.


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## PaulPauliePabloPaolo (Aug 11, 2022)

Are we saying that the procedure for finding the correct values is to breadboard the circuit first?
As I currently don't have a breadboard (I will get one and learn how to use it), would another solution be to put sockets on the R5 resistor lugs and experiment between 47K and 100K  until I find what I like sonically?.... (or until the voltage is correct?... best values to get Q1 and Q3 up over 7 vDC.).


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## Coda (Aug 11, 2022)

PaulPauliePabloPaolo said:


> Are we saying that the procedure for finding the correct values is to breadboard the circuit first?
> As I currently don't have a breadboard (I will get one and learn how to use it), would another solution be to put sockets on the R5 resistor lugs and experiment between 47K and 100K  until I find what I like sonically?.... (or until the voltage is correct?... best values to get Q1 and Q3 up over 7 vDC.).



Yes. Make sure that you correctly identify the pcb component, though. Compare the schematics so you know which component is which; the ID’s for the PPCB board may not match the schematic used to bias your transistors…


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## PaulPauliePabloPaolo (Aug 11, 2022)

Ahhh ok.... As I said, I don't have one, and I don't know how to use one, but I will get one and go through the instructional material.

Good point about identifying the components, I did go through them with my limited knowledge and experience and I came up with....

A. R3 on the Transistor packet (47K) seems to correspond to R5 on the build docs (100K).
B. R4 on the Transistor packet (100K) seems to correspond to R4 on the build docs (100K).
C. R6 on the Transistor packet (8K2) seems to correspond to R7 on the build docs (8K2).

Could anyone confirm that?. 

Anyone got any thoughts on how to proceed without a Breadboard?  is Socketing R5 a viable 'workaround'?.
I do have a DMM and an M tester.


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## PaulPauliePabloPaolo (Aug 16, 2022)

Hey gang, 
Just wanted to make sure I get the orientation of the transistors correct. 
Very kindly SBE gives the red dot as the collector.... but on the silkscreen there is no CBE markings, but there is a 'tab' next to the socket like you would have on metal can transistors. As stated before I am not using OC81's, but OC75's and an OC71. 
They are not the metal can type but I do see on the web that the 'tab' is usually next to the emitter.

I just wanted to make sure before I install them.
Also I tested them quickly with an M Tester and they all test as resistors.... Is this something 'normal'... just seemed a little strange as Ive tested a few Si transistors and they tested fine and gave me the pin out correctly.

Thanks in advance, and I will await the wisdom of the forum!. 
P.


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## PaulPauliePabloPaolo (Aug 18, 2022)

Thanks guys!... Victory!.... I just can't believe how great it sounds!!!... Instant Page, Ronson & Townshend!.... 
PPCB are undoubtably my favourite source for all things like this, unbelievable quality at a price that makes it possible for 'normal folk' like me and my friends to enjoy these circuits without a 2nd mortgage!. 
I am in heaven tonight!.... and no stairway required!.


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## andare (Aug 18, 2022)

PaulPauliePabloPaolo said:


> Thanks guys!... Victory!.... I just can't believe how great it sounds!!!... Instant Page, Ronson & Townshend!....
> PPCB are undoubtably my favourite source for all things like this, unbelievable quality at a price that makes it possible for 'normal folk' like me and my friends to enjoy these circuits without a 2nd mortgage!.
> I am in heaven tonight!.... and no stairway required!.


So you managed. Enjoy!


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