Passive Volume Pad

[Robes]

Hi there, I'm new here and completely new to any DIY work so apologies for the very basic questions and project that this post comprises of!

I've just exchanged my 2 channel amp for a single channel JCM 800 and I intend to use plenty of gain on the amp.  I still need a clean sound however and I thought that building a pedal to pad my guitars signal may be a nice way to get into DIY.

Now I've had a look around the internet and these forums but I've yet to find a simple diagram for a similar pedal to the one I'm looking for.  There have been posts regarding this on this very forum but the schematics seem to be long gone.

So here is what I figure I need:

A couple of mono guitar jacks:
A foot switch
A potentiometer (1M?)
A case

Now as I said before I am a complete novice but this is what I have gathered so far in my research.

The input jack tip connects to one of the outside lugs of the potentiometer, the middle lug connects to the output jack tip and the final outside lug connects to the output jack sleeve.  That should make a simple non-bypassable volume control.  I'm not sure where the input jack sleeve should connect or can it just be left unconnected?

Now I have no idea how to connect the switch.  I would assume that the switch allows one input to be output to a choice of output connects.  Do I simply connect this before the potentiometer with one output attached to the first outside lug on the potentiometer and the other switch output connected to the output jack tip?  

I've also seen talk of a capacitor being soldered across the input and output lugs of the potentiometer to reduce "tone sucking" however values seem to have alluded me.

Basically if anyone can help me out that would be amazing!  I'm hoping to pick up the components tomorrow and finish the pedal for monday when I get to use my new amp!  Has anyone taken on a similar project with success?

(edited to remove a few links which may not have been appreciated  )

[Robes]

Clearly this is both a very unexciting pedal and has been done many times before! 

Anyhow, I plan to get the components tomorrow.  I think I've worked out how to fit the switch into the circuit and I've made the following diagram (sorry I can't draw proper circuits).  I would hugely appreciate if someone could let me know if it will work

[MikeH]

Hello and welcome!  I think what you're looking for is this:

http://www.aronnelson.com/gallery/main.php/v/DRAGONFLY-LAYOUTS_0/album19/album145/CLEAN_MACHINE_PASSIVE_001.jpg.html


Very similar to what you have drawn already, but has the cap in place to prevent tone suck.  FYI- you don't need to ground the pot casing, unless you're using a plastic enclosure; and even then it wont make much difference.

[Robes]

Amazing!  Thank you very much!

[joegagan]

i agree, a treble bleed may be useful in your application. but why lock yourself into a preset? i would recommend putting the treble bleed on its own control.
in the following drawing, the pot labeled 'guitar pot' would be your vol pot on your box. the 500k pot on the bottom of drawing could be externally mounted.

[Robes]

That's great, I was thinking about doing something along those lines with a variable resistor (is that what a potentiometer is?). I guess the cool thing is I can add that little extra circuit afterwards if I need to, thanks!

I have just a couple of questions, in the diagram which side is the input and which side is the output?  Also why is a stereo jack needed on one side of the circuit?  It only seems to use the mono connections.

[Robes]

Hmm, it looks like the stereo jack is simply a left over from the battery circuit so I think I can safely cut it out.  I'm guessing that the left jack is the input and the right is the output due to the position of the stereo jack.  It would make sense if the whole circuit is on it's back.

[joegagan]

yes. i would build it with two mono jacks.

[Robes]

Well my soldering is very shoddy and I need to work on the positioning of everything in the box but it works!  Should be good for tomorrow although I haven't tried it through high gain yet, hopefully it doesn't introduce noise.

[Robes]

Pretty annoying, when trying to screw the DPDT switch into the box the thread was too tight and I managed to snap the switch off the top.  Ah well, better get back to the shop tomorrow