Simple Circuit mods/questions

[Guitarfreak]

So I am learning the fundamentals of electrical properties and how to manipulate audio signal slowly, but I need some reinforcement especially on some of the finer details.  I've got some mods in mind and I am just hoping to clear up some things prior to.  The mod is to my trusty SD-1 pedal.  I want to increase the pedal's low end response, so I should increase the value of certain capacitors, but which ones?  Only the ceramic disc caps, or including the electrolytic as well?  Only ones placed in series?  Only ones placed in parallel?  All of them?

Could changing the value of a capacitor damage anything assuming that I solder it correctly and it is placed in the correct orientation if it is polar?  I am just wondering if there are certain ones that you don't want to touch.

[Top Top]

I don't know the sd-1 circuit well, but most circuits have caps for cleaning up the power supply and possibly others that don't directly affect the audio signal.

Others may already only filter very low sounds that you don't actually want to add back in.

It would be best to first find out what does what in the circuit. You will learn a lot more from the whole process that way anyway.

[GibsonGM]

Try searching "SD-1 mods" online, you will find there are a couple of good, explanatory sites someone has put up for just that purpose!  That was my 1st mod, too )

[Guitarfreak]

I am looking at the Erik Hansen site for reference and he says to change C2, C3, and C8, a few other sites seem to recommend the same thing, I was just wondering if there was a way to take this mod to a more extreme level, like if there were other components holding back the low end.  I want the tone to be fat city with a nice rolled off soft high end.  I know that experimentation is the best way, but that is expensive and time consuming.  A few mods have mentioned the coupling caps as setting the frequency response of the pedal.  To my knowledge, the coupling caps are the ones in the input section of the pedal directly after the input resistor, correct?  Also I have heard that stacking two IC chips improves circuit clarity, how do I do this since there is no designated space for another chip in the board?

[Guitarfreak]

It would be best to first find out what does what in the circuit. You will learn a lot more from the whole process that way anyway.

From what I can gather from connecting mods to schematics is that a capacitor placed directly before a transistor has a great effect on the frequency response of the circuit... yes/no?

[petemoore]

 Maken smaller value rolls off more bass is the easy expl.
  The getter one describes the capacitor as a device that imparts an increasing impedance as frequency gets lower, because of that we can make a capacitor do different things, such as:
  HP filter, >Cap>...cap being an increasing impedance as frequency drops, starts making it harder for bass to get through [impedance] the signal path.
  LP Filter is Signal>Cap>Gnd. so, all the frequencies that make it through the capacitor [the higher ones] get shunted to ground, dumped for all eternity, never to make it past that point.
  So if the cap is small enough and it is in the signal path, the increased impedance lower frequencies feel will make the sound less trebly.
  Worth a look at AMZ labs notebook, have a look at R/C networks there.