Switchable Clipping Diode

[Tamir]

Aye mates!
I have a Boss SD-1 and I just modded it to a 808 tube screameish tone.
I want to get a swich that will add a cliping diode and remove it (D6), or that's what other suggested, If I understand right the mode.
anyway, I searched about wiring the switch and found some topic about making it work but for some reason I still don't understand it.



would someone please draw lines (with paint or close) of the wiring?
thank you very much.

[bancika]

ther ya go, just watch diode orientation. With DPDT you can wire it directly on switch rather than let it "float" around.

[Tamir]

cool, thanks a lot!
What I want from my pedal is a smooth warmer blues tone, with more bass and the swith so it will hae more gain.
the clipping diode should give me more gain when switched (correct me?) and I want more bass response (will keeley's mod - changing C2&3 to 0.1uF will give me that?), and a smoother sound, what should I tweak to to that?

sorry about annoying and the stupid questions but I wanna know that I understand.

[AL]

Tamir,

Your information is a bit cryptic. Are you wanting to add/remove a diode for asymetrical clipping? Meaning 2 diodes on one side and a single diode on the other.

Just showing a diode won't help much. What circuitry is connected to it? Which end is ground? etc.

so if I understand right, this switch should give me more crunch? or gain?

Not really. If you're just adding an asymetrical diode you won't notice too much of a change. Read the GEOFX "Technology of the Tube Screamer" article. This will help with adding gain - among other things.

http://www.geofex.com/Article_Folders/TStech/tsxtech.htm

AL

[Tamir]

Cool, this link is great! thank you very much.
The swich I wanted is the ts9 like sound, as I understood, less one and more one change between these sounds, am I correct? like a switch between a screamer clipping mode and a SD-1 mode. how would you describe the change in sound between these? what does it do the to sound itself?

I understood how to increase the bass response. If I would like a boost switch that will give me crunchier sound with more gain, how would I do it?
sorry about my bad bad english, it is not my native language.

[AL]

The GEO article has a few ways to increase gain.

I don't hear much of a difference between asymmetrical and symmetrical clipping. Oh it's a good buzz word for selling pedals but personally I think it should be called the Eric Johnson effect. It's so subtle that I don't think it's worth the extra space it takes up.

You may want to try adding in different sets of diodes. Such as 2 Ge diodes and 2 LED's. I do notice a difference between those. Use a switch to do this.

AL

[Tamir]

ok understood about the diodes, I'll give it a try... only thing I can loose is a dpdt/spdt.
your idead about diodes and leds is related to the boost switch? because I know now how to increase gain but I want a switch that will give me that boost. and what leds?

is there a mod that does this pedal's drive more smooth and "healthy"? something more nice and gentle 

[Tamir]

OK, I understood everything I need to mod except one thing, on keeley mods they say to add a 47pF cap across the diodes - where is it exactly? if someone can explain it better or show in a scheme/layout.
sorry about so many different questions but I think it is better than starting few different topics. thanks mates. 

[MetalGod]

OK, I understood everything I need to mod except one thing, on keeley mods they say to add a 47pF cap across the diodes - where is it exactly? if someone can explain it better or show in a scheme/layout.
sorry about so many different questions but I think it is better than starting few different topics. thanks mates. 

the SD-1 doesn't have a cap in parallel with the diodes - the TS-9 has a 51pF cap here but you can experiment with the value for more/less smoothing of the treble.  try anything from 25pF upto 250pF and see what you like.

also, if you're wanting to switch D6 in/out why not just use the switch to short it out?

[aron]

Tamir,

Check out the Wiki:

http://www.diystompboxes.com/wiki/index.php?title=Main_Page

And the simple mods page:

http://www.diystompboxes.com/wiki/index.php?title=Simplemods#Simple.2C_Easy_Mods.2FTips_.26_Techniques

[Tamir]

oh, I was reading this wiki at least 8 times from the time I registered and I forgot about what I read - and that's exactly what I needed. so me.
if I realy don't have holes for this cap on the board, is there an elegant way to place the cap?
on the wiki they said to connect a fet as diode this way:

Connect a FET Gate+Source to ground and the Drain to signal. Then connect another FET Drain to ground and Gate+Source to Signal.

and on keeley they say to connect a GE (but i am going to use mosfet) this way:

Here is the tricky part of our mod, take a germanium (Ge) transistor and use the Base-Emitter junction (legs) of the device and use it in place of D6. If you use a PNP transistor, the Base will be the negative or cathode side, the Emitter will be the anode

which one should I choose?
can you stand me?

[Tamir]

Is there anybody out there?

[Tamir]

Am I right? sorry for the 3 posts but it is a busy forum and it almost got to page 2.

BTW
for all what will search for these questions I asked in future, here are some posts links that helped me a lot to understand:
http://storm-software.co.yu/diy/index.php?project=flexi_clip
http://www.diystompboxes.com/smfforum/index.php?topic=38581.0

[aron]

You want to do it like bancika shows. You want it across D6 not across the capacitor. You are trying to replace D6 right?

[Tamir]

I want to give it a switch mode between:
I. Just two diodes, as tube screamer
II. + diode (maybe mosfet, maybe germanium, but plus one)

this is part of the keeley mode if I understood it right, correct me please if you can.
the cap should be across the diodes, if not like that, how can I wire it? problem is that I DON'T have where to solder the cap after the diode, that's why I asked you guys for elegant way to do that.

thanks you for the care.

[Rattlehead]

I am doing this mod as well and I would like to know the answer too.
I don't understand where to put the 47pf cap

[MetalGod]

[Tamir]

I already knew this. anyway, I've got my answer from someone. what he told me to do is that:


solder the cap to the diode that stand alone there (the bottom one), desolder one of the series diodes, solder it to the switch and then connect it to the board.
one thing I don't understand on my board - all the diodes are connected in one position - from cathode to anode, I can't decide what is the diode that stand alone.

[MetalGod]

one thing I don't understand on my board - all the diodes are connected in one position - from cathode to anode, I can't decide what is the diode that stand alone.

D4 is the diode you'd solder a 47pF cap across (as per TS-808 spec).

I still think you're overcomplicating things by removing D6 to switch it in/out of circuit - the mod I posted avove uses two wires and you don't need to remove D6.

I also like to clip out C6 (in the feedback loop of the 2nd opamp section).

[Tamir]

well, first thank you very much for the replay..
ok. I will solder the cap across D4 legs - so I guess this should be the "lonely" diode.
I am overcomplicating things because I am confuesd. I know what I want - swich between asymmetrical and symmetrical clipping diodes, I am not sure how I am doing this.
so, I guess I didn't understand your mod correctly - does it do what I want? add/remove the diode? and is it the right diode to add/remove for this mode? because it seems to have just one position. If it does, I'll kiss you.
and I think I would like to change the diode to mosfet anyway so I have to desolder it.

it's a bit late, but I took pictures of the circuit so everyone can understand me...



best wishes.