What NOS transistors for a Fuzz Face and a McCoy?

[VintageCharlie]

Dear forum members,

i'm about to order the nos parts i intend to use to mod a JH-F1 and a v847.
From what i've gathered, the right type for the si Fuzz Face is BC108 (without any letters after the number) and a BC109B for the McCoy - would these be the most authentic ones?
Also what HFE rating should each of these pairs be? Do they have to be matched (as in very close in value, or differ in a specific ratio or number?) for an authentic tone?
I found various NOS offers on eBay, but i just don't have a clue what to order.

So any help is needed very much and is even more appreciated!


Thanks!

Kind regards,

VintageCharlie

[brett]

Hi
the BC108 was a generic work horse BJT a few years ago.  The BC107 was a similar beast.  You'll find them (and their many equivalents) in transistor radios at the charity shop.  You might accidentally get a very early transistor radio with Ge transistors (2SB etc), which you can sell to your buddies.

The right hFE is quite subjective.  For less fizz and more bloom, low hFE is good.  And use the lowest device as Q1 in your FF.  The gain of Q2 is set by the fuzz control, so you can tame a device with a highish hFE.
I'd try to get keep the hFE of Q1 in a FuzzFace under 150.  With older devices like BC107/108 this shouldn't be difficult. 

Of course, many modern devices have similar properties.  The 2N2369A is about 70 (see the Axis Face).  IMO power transistors are ideal.  The BD139 is a medium power device perfect for Q2 in a FF at 150.  Power devices also have a curved relationship between Ic and hFE (a "knee").  Older devices had this too.  It might explain some of the preference for old devices and power devices. 
cheers

[Electric Warrior]

From what i've gathered, the right type for the si Fuzz Face is BC108 (without any letters after the number) and a BC109B for the McCoy - would these be the most authentic ones?

BC183L, BC183KA, BC108C or BC209C are what can be found in vintage silicon Fuzz Faces.

[VintageCharlie]

Thanks for the quick replies!
What about the Vox picture wah's - do the trannies in htese have to be matched closely? or is it the same as with the fuzzes? And which HFE would be good for a McCoy wah. I'm after a tone that's warm, full, not harsh, but detailed enough and with a broad sweep to the "wooooaaaah" (unlike some pedals that stop somewhere at "whoo" and never get to the "aaa" or "aaah" part

Thanks!

[VintageCharlie]

No suggestions guys? I'm pretty much depending on any advice from you - hope someone will jump in.

Regards,

VintageCharlie

[zombiwoof]

For the wah, BC108B or BC109B are good.  The main thing to keep in mind if you are going for the vintage sound is to get trannies in the 350-400 hfe range to work correctly in the vintage circuit.  BC109 is supposed to be a lower noise transistor.  The reason for getting ones with the "B" suffix is that they should be in the correct hfe range.   Actually, many NPN silicon transistors will work, as long as you get them in that range.  Dunlop (who made the older Vox 847 wahs, but not the newer Chinese 847A) uses high gain MPSA18 transistors in their wahs, which is one reason IMO they don't really sound like the old wahs.

This is a really good reference for modding a Vox 847 or similar wah to vintage specs:

http://fuzzcentral.ssguitar.com/mccoy.php

The only thing I would mention is that I tried putting the 100k resistor in parallel with the inductor that some vintage Clyde McCoy wahs had in place of the 33k that is in the Dunlop wahs, and it was too much.  I would advise keeping it between the stock 33k up to 68k.

Al

[VintageCharlie]

For the wah, BC108B or BC109B are good.  The main thing to keep in mind if you are going for the vintage sound is to get trannies in the 350-400 hfe range to work correctly in the vintage circuit.  BC109 is supposed to be a lower noise transistor.  The reason for getting ones with the "B" suffix is that they should be in the correct hfe range.   Actually, many NPN silicon transistors will work, as long as you get them in that range.  Dunlop (who made the older Vox 847 wahs, but not the newer Chinese 847A) uses high gain MPSA18 transistors in their wahs, which is one reason IMO they don't really sound like the old wahs.

This is a really good reference for modding a Vox 847 or similar wah to vintage specs:

http://fuzzcentral.ssguitar.com/mccoy.php

The only thing I would mention is that I tried putting the 100k resistor in parallel with the inductor that some vintage Clyde McCoy wahs had in place of the 33k that is in the Dunlop wahs, and it was too much.  I would advise keeping it between the stock 33k up to 68k.

Al

Thanks for the info Al!

do the hfe ratings have to be matched closely between the two transistors - say +/- 10, or doesn't this matter and all that counts is that they're about 350-400 hfe?

Thanks!

Regards,

VintageCharlie

[zombiwoof]

If you read that FuzzCentral info on the Clyde McCoy wah I linked to, I believe he says that if the two transistors are different values, to put the higher value one in Q1.  I would doublecheck that though, as I'm going from memory here.  There is also info there on making your own wah buffer, similar to the FoxRox type, if you're interested in that.

Al