GGG Tubescreamer and 2SC1815 - WRONG PIN LAYOUT ?

[axeman010]

Hi

I have just built the GGG Tubescreamer and it would appear that the board is designed for 2N3904 transistors rather than 2SC1815 transistors.

Can anybody else who has built it with 2SC1815's confirm this please.

As I have already soldered them and the layout is so differenet can anybody suggest who to re-wire then please ?

Many thanks

Axeman.

[ubersam]

I have not built the GGG TS but I do know that the 2SC1815 has a different pin-out than the more common 2N3904. To make the 2SC1815 work on layouts made for C-B-E pinouts, you'll have to twist the pins around to make them match. I do not know off-hand what the 2SC1815's pinouts are. I think it is B-C-E (see datasheet), if so, you'll have to twist B & C around so that it will be C-B.

[zjokka]

very right, from left to right legs down lettering facing front

2N3904 EBC
2SC1815 BCE

[markm]

Don't know if it is actually worth the trouble of building it with 2SC1815 trannies?

[mojotron]

Don't know if it is actually worth the trouble of building it with 2SC1815 trannies?

Right, the BJTs are just used as emitter followers for impedance isolation, not gain - they should not color the sound at all. Although there is some hype/mojo about which BJTs to use on this circuit, any low-noise transistor will do.

[ubersam]

Right, the BJTs are just used as emitter followers for impedance isolation, not gain - they should not color the sound at all. Although there is some hype/mojo about which BJTs to use on this circuit, any low-noise transistor will do.

It may just be mojo but I definitely prefer MPSA18 in this position over the 2N5089 and the 2N3904, both of which seem to be "too clean" for my taste. What I want to try, next time I build a TS, is to use JFETs in the buffer, maybe a J201 or a MPF102. I figure that all that would be required are a couple of resistor value changes.