Comments on a simple "Solo" switch for an overdrive pedal

[stm]

I was thinking about adding a "Solo" switch  to a generic overdrive pedal.  The idea is to keep things within reach of an SPDT or DPDT switch.

I identify three main aspects that you could change:

a) More gain (for additional sustain)
b) More volume (to be heard over the band)
c) Mid to high frequency boost (to cut through the mix)

Personally, I'm inclined to the "more gain" approach, combined with a 2.5 to 3.5 kHz 3dB boost.  What about you?

[Nasse]

I was thinking about makin those things voltage controlled, so you can make a preset or two. Perhaps diodes could be used for simple and cheap level cntrl

[Darkness, Darkness]

That's the question I was asking myself for my submini buildings

I agree with you the solo switch should increase the gain. As this might have consequences on the volume and help to compress the sounds thats perfect. For the boost I think I prefer darker sound...I prefer a boost starting around 800Hz and a bit higher around  1,6KHz (In fact I am doing this with a boss GE7 pedal). With 3DPT switch it seems possible to modify gain stage bias, coupling caps reduce voltage divider, include more clipping diodes, ... lots of possibilities indeed

(One other approach I am considering is to build a double A/B Box : first switch would engage the distorsion chain or bypass it while the second one would allow to use one distorsion sub-chain (rythm) or a second one (solo). That gives the opportunity to include efects such as compressor, equalizer, ... on the lead chain and have different flavor of distorsion for Rythm/Solo.... but it requires two distorsion unit too... )

[Ripthorn]

Could you maybe just use and SPDT switch to route the output through an extra gain stage and boost?

[CynicalMan]

A fetzer valve at the end of the circuit would probably work. They distort nicely, so if the od circuit is loud enough, you'd get the extra gain and the presence boost could be changed into a treble boost.

[petemoore]

  Circuit bend...
  Add a resistor here.
  Put a switchable capacitence value across an emitter resistor of gain stage, choose value, larger values increasingly boost bass gain, smaller values can be used as HF gain boost.
  Volume pot, vary resistance, try two volume pots...
  DPDT...[DPST?] vary two parameters simultaneously, say one side of switch for volume or gain control, the other side for voicing, increased or decreased treble as needed.

[DSV]

For me a solo switch is used to cut better through the mix, which means I'd go mainly with the 3rd option. More gain and sustain is also desirable. You don't need a volume increase, since the perceived level of a sound with more treble content is already higher.

[DougH]

I like option c). I did something like that on a recent design and based on how I did it, it added a little gain boost too.

[Ice-9]

I have to agree with DSV here, Boosting the high end will actually cut through more in a band situation.  If you distort the signal more you will lose percieved volume, it will just get lost in the rest of the band. You could set up the pedal with 2 output volume controls and those switched  so one is set for chords and the other for solo's

[stm]

Thanks for the input.  All good ideas.
On the subject of increasing gain or not, I think it depends on the type of pedal.  For a high-gainer I agree with Ice-9 that more gain might not be of benefit.  On the other hand, a low to medium gain pedal might benefit of some more gain if long sustain soloing is desired.
The emitter or source bypass trick mentioned by petemoore is something I've tried with success.  I've set the cap value so the boost effect drops around and below 150 Hz.  Of course this is a matter of personal taste.

[DougH]

On the other hand, a low to medium gain pedal might benefit of some more gain if long sustain soloing is desired.

Yes, that was the case with my pedal. Low-med gain which is nice for rhythm, then hit the solo switch and you get more upper mids and a little gain boost- nice for soloing. Or just use it to get two different types of sounds for whatever you wish.