Ruetz Mod

[soupbone]

Been doing some mods to me rat pedal.I wanted to do the "ruetz mod",Where you clip the 47ohm resistor.I wanted to put the 47ohm resistor on a switch.One side,The 47ohm "on" and the other side "off"(no resistor).Would i just need a spst on-off switch?

[Govmnt_Lacky]

You would probably want a DPDT switch.

This way, in one position, the circuit would be completed WITHOUT the resistor. In the other position, the circuit would be completed WITH the 47 ohm resistor.

[add4]

i'm quite sure a spst will be enough for this situation :

cap ---- resistor --- switch on/off --- circuit
the switch takes the resistor on and off the circuit it should work

[Mark Hammer]

Severing the 47R/2u2 path at any point will lead to audible popping when switching in and out, because the 2u2 cap will have nowhere to drain.

A more satisfactory solution is to simply replace the 47R resistor with a 1k resistor, and use a SPST toggle to switch in a 51R resistor in parallel.

  Why is this an improvement?  First, the 2u2 cap will always have a path to drain so it will not pop.  Second, the 1k resistance will be higher than the 560R resistance on the other leg, so it will have a negligible impact on gain.  The 560R path will be doing the talking when it comes to setting gain.  When you switch the 51R resistor in parallel with the 1k, it will provide an effective combined parallel resistance of 48.5R, which is close enough for rock and roll, given the likely use of 5% resistors all round and the tolerance of the various caps.

[soupbone]

Severing the 47R/2u2 path at any point will lead to audible popping when switching in and out, because the 2u2 cap will have nowhere to drain.

A more satisfactory solution is to simply replace the 47R resistor with a 1k resistor, and use a SPST toggle to switch in a 51R resistor in parallel.

  Why is this an improvement?  First, the 2u2 cap will always have a path to drain so it will not pop.  Second, the 1k resistance will be higher than the 560R resistance on the other leg, so it will have a negligible impact on gain.  The 560R path will be doing the talking when it comes to setting gain.  When you switch the 51R resistor in parallel with the 1k, it will provide an effective combined parallel resistance of 48.5R, which is close enough for rock and roll, given the likely use of 5% resistors all round and the tolerance of the various caps.

Interesting Mark!That's very cool info!When you said 51R are you meaning a 51ohm?

[Govmnt_Lacky]

I recommended a DPDT simply because there is no way to "close" the circuit with a SPST.

TOP LUG - -->Resistor --> Board

MID LUG - --> Board

BOTTOM LUG - --> OPEN?

One side of the switch connects the resistor to the circuit BUT, the other side leaves the circuit open 

With the DPDT you can do this:

                    0--Resistor--0

    Board------0                 0--------Board

                    0--Jumper---0



My 2 

[Mark Hammer]

Stock, the Rat has one gain-determining ground leg that sets default gain for the entire spectrum, and a second that sets the gain much higher for content above 1.6khz.
The SPST suggestion I made essentially renders the treble-boost ground leg moot.  Nothing is switched in or out, as with a DPDT, and nothing has to be switched out.  All it has to be is irrelevant, and making the 2nd ground leg a higher resistance than the 1st one accomplishes that.

[soupbone]

What about using a 50k Linear pot?

[Mark Hammer]

Well you could, I suppose, but everything above 560 ohms would be wasted.

[soupbone]

Well you could, I suppose, but everything above 560 ohms would be wasted.

I didn't think about that.Thanks Mark!

[rosscocean]

I just used a on off switch and it worked fine.

There's some info on the beavis audio site about doing this mod with a pot. I think it's the lube pot on the Four Knob Rat. They also have some very nice schematics and layout if I remember correctly.

Ross

[soupbone]

I just used a on off switch and it worked fine.

There's some info on the beavis audio site about doing this mod with a pot. I think it's the lube pot on the Four Knob Rat. They also have some very nice schematics and layout if I remember correctly.

Ross

Thanks Ross.Lube pot..I'll check it out.