Hello & SD-1 Questions

[Bearded Fish]

Hi Chaps, I'm new to modding pedals and this forum and I'm going to be doing the RK 5-Star Ge mod on my SD-1 shortly but I have a few preliminary questions that I wondered if anyone can put straight...

Firstly, the Ge transistor. Robert says "take a germanium transistor and use the Base-Emitter junction (legs) of the device and use it in place of D6". So what do I do with the other leg? Leave it unconnected or cut it off maybe? How do I know which leg is which?

He goes on to say "add 47pF cap across diodes in clipping section to smooth out distortion". Can anyone explain that in more detail? What exact diodes is he refering to? How do I do it in practise?

Finally, I'll be getting my caps from www.maplin.co.uk (as I'm in the UK) and I had a quick look for the stack metal film ones required but wasn't quite sure what was what. Could someone just confirm the type I need from that site? What about the 47pF cap?

If anyone can help me out I'd appreciate it. Cheers.

[petemoore]

Hi Chaps, I'm new to modding pedals and this forum and I'm going to be doing the RK 5-Star Ge mod on my SD-1 shortly but I have a few preliminary questions that I wondered if anyone can put straight...

Firstly, the Ge transistor. Robert says "take a germanium transistor and use the Base-Emitter junction (legs) of the device and use it in place of D6". So what do I do with the other leg? Leave it unconnected or cut it off maybe? How do I know which leg is which?
 >>>Data Sheet, B/E junction of transistor is a diode.

He goes on to say "add 47pF cap across diodes in clipping section to smooth out distortion". Can anyone explain that in more detail? What exact diodes is he refering to? How do I do it in practise?
 You figure out what that diode was, remove it and put a bigger one in to taste...larger values across clipping diodes 'takes out harshness' causes the clipping diodes to clip less treble content.

Finally, I'll be getting my caps from www.maplin.co.uk (as I'm in the UK) and I had a quick look for the stack metal film ones required but wasn't quite sure what was what. Could someone just confirm the type I need from that site? What about the 47pF cap?
 I'd socket that cap slot if possible and try 47pf, 22pf, 68pf...or figure what you need comparitively by trying a larger or smaller value and noting the difference and deciding if that's enough rolloff or not.
If anyone can help me out I'd appreciate it. Cheers.

[cd]

Look here for answers (if you're new to this whole thing, read the entire site, as well as all the FAQ links above):

www.geofex.com

Specifically:

http://www.geofex.com/Article_Folders/TStech/tsxfram.htm
http://www.geofex.com/buildfx.htm
http://www.geofex.com/FX_images/to1dwg.gif

[petemoore]

Clipping diodes in SD-1 are from the - input to the output of...one of the opamps...check out the SD-1 schematicS at Fuzz Central.

[petemoore]

Gathering info is good...cd put some up, looking and linking is good.
 caps let high freqs through, bigger values mean more lows are let through.
 a cap in series, in signal path therefore can rolloff lows, depending on value...how much lows get cut, around 10uf or so all lows a guitar can make get through...check input cap values of various schematics to get an idea of what values are used, also other things vary what the cap does.
 A cap...from signal path to ground [therefore] allows a path for the high frequencies to get through to ground [called shunting to ground] any content shunted to ground is no longer in the signal path, so a cap from SP to ground cuts highs.
 Check out schematics that have a cap from SP to ground, they're usually very smaller values...
 The caps in the feedback loop with the clipping diodes works alot like a cap to ground does, rolling off highs....bigger values = less highs.