Klon with expression to control volume

[Harry Maes]

i have a question about controlling the volume of one of my Klon builds.
It's easy to use an stereo Jack to switch between the volume pot and expression pedal to control the volume.

What would be interesting is to know how to set the volume (Max) with the volume knob and control the volume in that range with the expression pedal. How would that be wired?

There are 2 pedals available AFAIKT that offer this option:
- Moog MF Boost and Vertex Boost.

Would anyone have an idea how these are working?

Cheers,

Harry Maes

[Harry Maes]

I was just thinking that wiring the tip/ring and sleeve of the expression pedal parallel with the volume control could be a way to go?

[Travis]

That would work but not how you want. In that case the exp pedal would just replace the Klon volume pot.

To set the max output on the Klon, then use an exp pedal to sweep the output within that range, I think you should wire the exp pedal to be following the output of the Klon volume pot. This should change the output impedance when the exp pedal is plugged in, and the sound may be slightly different, but I can't really think of another way to do it right now

Either way you do it, you're going to want to use a switched jack

[Harry Maes]

Thanks for your reply Travis.

So you mean that the 3 wires coming from the stereo Jack with switch go to the volume pot?
That's what I meant with my previous message connecting the wires from the stereo Jack parallel with the volume pot.

My current volume pot is a 50kB so with the 10KA of the exp pedal this would reduce to about 30k.

[Harry Maes]

It might also be better to change the current volume pot to a 10kA to not have too much of an impedance change when plugging in the Exp pedal?

[Travis]

No, I mean the output from lug 2 of the Klon volume pot would go (via the switching jack) to lug 3 of the expression pot. Expression lug 1 would be grounded and expression lug 2 would be the new output

But now after work my brain is kinda tired, and I'm having trouble thinking of how to route the Klon output lug 2 to either exp3 or output jack with the switched jack alone. I'm thinking you may need an SPDT for that

[Harry Maes]

How would this compare to this?

https://www.dropbox.com/s/qd68gyn9cm2bf7d/foto%2010-03-15%2017%2040%2054.png?dl=0

[Harry Maes]

Also if this controls minimum volume:

Then the reverse (have the 50k on lug 1) should control max volume?

[Harry Maes]

Anyone can help or confirm the schematic/wiring for the Klon volume?
- Set the max volume via the volume pot (or a trimpot like with the Jan Ray Landau or an additonal pot)
- Replace the volume pot with the expression pedal

Thanks!

[Travis]

The easiest way to do this would be to buy a volume pedal and place it after the Klon.. That will accomplish exactly what you're asking for without modification

Anyways, I drew this up for you. Sorry, I don't have time to make a nicer picture


The part labelled (output to bypass switch) may be a little confusing. It's just the final output of the circuit

[Harry Maes]

Thanks for your reply and schematic!

A volume pedal after the Klon would need to be a L (low impedance) type to work correctly.
A volume pedal in the loop of an amp or modeller would work well too. I've used expression knobs (25kA pot) before for volume. I do like to have a boost pedal where I can control the volume of the boost with an expression pedal (as an always on pedal).

The issue I have with your drawing is that I need to use a DPDT switch to select the expression pedal.
I'm sure that this could be done with a switch on the expression pedal input of the pedal since there are examples of pedals that work that way:

- Vertex Boost
- Moog MF Boost

Can you please check the link I send before showing the schematic of a possible copy of the Vertex Boost?
I don't exactly understand how I could apply that schematic to a Klon?

[Harry Maes]

Also again:

If you check the drawing of the EV-5 which has the 50k for setting minimum volume and a 10k for expression volume:

If you would reverse that:

The 50k (as is the volume of the Klon in my case) wired on the high side of the 10k pot from the expression pedal instead of on the low side? Shouldn't this work like a MAX volume then instead of a min volume?

So the 3 connectors from the expression input wired to the volume pot like in the EV-5 drawing?

[Travis]

Normally you could use a switched jack but since you want the Klons volume knob still in the circuit you'll need to use a switch

The EV-5 schem isn't going to do what you're asking because the exp pot would always be in the circuit

[Harry Maes]

Still not sure how this works in the Vertex boost then?
I've ordered a MF Boost today since this seems a great boost with expression support.
I'll leave my Klon as is.

[Travis]

The boost pot in the vertex is controlling the gain of an op amp stage while the volume control in the Klon is a voltage divider at the output. Since the output is coming from this voltage divider in the Klon it needs to be rerouted to either the bypass switch or lug 3 of the exp pedal pot which is why I had to add the switch