Multi-selectable volume pedal

Hi, 

I posted about this idea a year or two back and people talked about using Arduino etc, and I contacted people and got nowhere....so now I'm considering this from an old school perspective.

Today I use a passive volume pedal in the loop of my Engl Ironball and it works great.  It's a Classic Audio Effects - Passive Volume Roller G2.  In rehearsals I can show ideas with all the gain that I need but at a much lower volume.  And live I leave the volume roughly halfway, and I can tweak the volume where needed.

However, I mostly leave it alone as I find it too difficult to reliably change the volume.

So, in this first example, the idea is to be able to somehow have the switching set up so that only the volume pot associated with the footswitch used is in circuit.  Perhaps some kind of relay system.  But as you can see, too many footswitches that would need to be spaced far enough across to be usable with my size 12s.




So here we've got a switch that rocks in either direction for up/down, the image stolen from a Boss FS-7.  Same concept, but far less crowded.



Does anybody have an idea how difficult this would be to make?  Are there schematics you could point me towards?  It's the relay that would switch to on of the 7 pots is where I have no idea.  Otherwise I can't see  how this would work.....

Thanks,
Andy

Easy to do with a basic programmable unit.



Set all the effects to off, save the resulting patch to as many memory slots as you need, then adjust the level for each one and re-save.

I’m sure that would work but I do want to build a small dedicated unit for this. 

Perhaps the first thing to decide is whether you want to step between each different vol setting sequentially (the left - right rocker) or do you want to be able pick whatever one you want at any time (individual buttons)?

Good.point - sequentially.

What about doing it with a rotary switch?

Then work out a way to turn it with your foot (ideally isolating the switch from physical shock).

Each switch position brings one pot into the circuit. It'll probably pop though. Relays will too. 

Hmm, I’ve built an xlr based volume control before with a pot operated by foot - and it would be too fiddly to operate for this purpose. 

I was thinking something like a 10cm diameter platform. Sitting on a  big thrust bearing. 

@ICBM's suggestion of using a multi-FX unit is good, specifically the Zoom 505, as it has a "pre-select" mode (to activate/de-activate it,press and hold the "Store" button for 2 seconds). In other words, in this mode, you use the up/down buttons to select the patch, but the unit won't actually switch to it until you press both together.

BobHillman said:

@ICBM's suggestion of using a multi-FX unit is good, specifically the Zoom 505, as it has a "pre-select" mode (to activate/de-activate it,press and hold the "Store" button for 2 seconds). In other words, in this mode, you use the up/down buttons to select the patch, but the unit won't actually switch to it until you press both together.

I have no doubt it would work, but real estate is very short on my pedalboard.  I also run 9v to the board using a pedalsnake, and adding a separately powered, comparatively large unit to my set up isn't something I'm looking to do.

I'm trying to achieve this in a unit that is 9v powered and perhaps the size of a zvex box of rock.

Also, it's not the end of the world, but I'd rather not introduce A/D, D/A conversion onto my board if I can manage it.

Looking online at relays it seems they don't tend to go beyond DPDT so it would need some quite clever circuitry to switch between 7 different pots independently.

The arduino / microcontroller type approach seems the most appropriate, but I haven't found anyone prepared to engage on designing that.

Sporky said:

I was thinking something like a 10cm diameter platform. Sitting on a  big thrust bearing. 

Have you seen anything like that available?

andyg_prs said:

Sporky said:

I was thinking something like a 10cm diameter platform. Sitting on a  big thrust bearing. 

Have you seen anything like that available?

Nope! I thought the plan was to DIY it.

I'd be looking on eBay for something. Or you could probably make the platform from ply with some anti-slip paint. Sit it atop an enclosure of a suitable size.

Doing it digitally is probably more sensible (if you're not going for ICBM's frankly excellent idea). There are basic chips that'll do the counting up and down, then you need a layer to give you a different output per "position", then some relays or soft switching to select which pot is in the signal chain.

You could take this as starting inspiration, though you'd need to think about how to clock and change between up and down with each footswitch - https://www.build-electronic-circuits.com/4000-series-integrated-circuits/ic-4510/

I don't think this can be done DIY without learning a fair bit.

andyg_prs said:

I have no doubt it would work, but real estate is very short on my pedalboard.  I also run 9v to the board using a pedalsnake, and adding a separately powered, comparatively large unit to my set up isn't something I'm looking to do.

I'm trying to achieve this in a unit that is 9v powered and perhaps the size of a zvex box of rock.

Also, it's not the end of the world, but I'd rather not introduce A/D, D/A conversion onto my board if I can manage it.

The 505 is not large - it’s only about the same width as a Box Of Rock, although admittedly deeper front to back - and runs on standard 9V power.

I’m not certain if the basic dry signal path goes through A/D/A conversion or not - it’s a very old unit now, it’s possible that it doesn’t.

Doing what you want to do in a custom-built analogue unit is not going to be easy, or cheap. It will need some sort of digital control even to operate purely relay-based switching sequentially like that. Unless something like it exists already as a production unit, I would guess it’s not practical.

Speaking of the Box Of Rock, you should maybe drop Zachary Vex a line - the Seek-Trem is actually close to what you want, but with the stepping automatic rather than footswitch-activated. I have no idea if it would be possible to reconfigure the control circuit to give forward and back functions instead... it might be possible, or even easy, I don't know.

Being lazy, I would probably just use a remote controlled motorized volume control .. then hack the remotes pcb so the up & down buttons are paralleled out to 2 non latching footswitchs 

These remote control volume PCB's tend to be stereo pots as they are designed for stereo hi fi but you can just use one gang of the pot 

Another possible way is a digipot chip like the MCP4231 ... this is an 7 bit resistor ladder pot that's easily controlled via an Arduino board .. there will already be code you can copy and past for this application 

Danny1969 said:

Being lazy, I would probably just use a remote controlled motorized volume control .. then hack the remotes pcb so the up & down buttons are paralleled out to 2 non latching footswitchs 

These remote control volume PCB's tend to be stereo pots as they are designed for stereo hi fi but you can just use one gang of the pot 

Another possible way is a digipot chip like the MCP4231 ... this is an 7 bit resistor ladder pot that's easily controlled via an Arduino board .. there will already be code you can copy and past for this application 

On a tangent, I've always wanted to try a Hook Wizard.  People have always talked about Arduino, but I have no programming experience, and so unless I had a pre-made schematic, or someone I could pay to put it together for me, I really wouldn't knkow where to start.

On the motorised pot thing....again, I'll google to find something of a suitable value (say 100k ohm) but then I'll need to see how I can control it via footswitches....  The idiot is right here, looking for the guide

For example, there's this

The older Boss pedals have a minimum volume knob on them. Could that be modified with a rotary to work as a max volume instead?

ICBM said:

Doing what you want to do in a custom-built analogue unit is not going to be easy, or cheap.

To paraphrase JFK, we choose to go build a multi-selectable volume pedal, and do the other things, not because they are easy, but because they are hard!

Is there potenial in this, with the push buttons flipping it up and down?

Can't you just build a massive pedal that's big enough for your foot? Pete Cornish type of thing. Sounds like a fun job - obvs just the relay bit that's tricky.

But ICBM is right...get a multi FX pedal and program it thus. Perhaps a Line6 M9 or 13?

Yeah the relays must be tricky, I asked Bright Onion pedals who have built me all kinds of things but he couldn't think of a way to send the signal to individual pots.  I actually really like the idea of a motorised pot...and they're not expensive.

But I need to know how I could wire up two momentary switches to move the pot up and down a defined amount.

andyg_prs said:

Yeah the relays must be tricky, I asked Bright Onion pedals who have built me all kinds of things but he couldn't think of a way to send the signal to individual pots.  I actually really like the idea of a motorised pot...and they're not expensive.

But I need to know how I could wire up two momentary switches to move the pot up and down a defined amount.

You take apart the remote control and remove the PCB  .. and wire small wires to the pads that get shorted when the volume up / volume down buttons get pressed ... 
That's the easiest way but it's a bit of a bodge 

But you will might find if you google the chip that  controls the motor then there's  V up and V down pins accessible on the pins that you can wire too .. a lot of BT PCB's have pads for local volume adjustment for example 

I can buy this for £20, I might just do it!  https://www.ebay.co.uk/itm/195207937619?

ICBM said:

The 505 is not large - it’s only about the same width as a Box Of Rock, although admittedly deeper front to back - and runs on standard 9V power.

The original 505 lasted about 30mins with a normal 9v battery, up to 4hrs with a lithium one.  I'm not sure why they even bothered putting that battery clip on it