switching question

[Vuki_Cro]

Hi guys,

I'm new to the forum and before You even read this, please excuse me for my bad English (I'm a Croatian).

So, I've got a tiny problem. I'm trying to make a switching system for guitar amp and effect pedals. Is there any way to wire switchers which could enable me to engage one switch on and immediately disengage the rest of 'em without using midi control?

So if You have an advice, please let me know.

Thanks!

 

[alec_t]

Welcome to the forum.
I would suggest using latching relays, because they have volts-free contacts for versatile handling of the audio and because they consume power only briefly when being switched on or off.

 

[Vuki_Cro]

Thank you very much

 

[crutschow]

Sounds like you want a variation on the old radio push button device, where pushing any button releases the one previously pressed, such as this circuit.

 

[Vuki_Cro]

Yes, something like that.

Let's say I've got 3 rack preamps (clean, crunch, lead), 2 chorus units, 1 delay unit and 2 reverb units. So my selector should have three "presets". For "preset 1" I've switched on clean, high output chorus, delay and high output reverb, then "preset 2"-crunch, low output chorus, low output reverb and "preset 3"-lead, delay, low output reverb. I'm in the middle of the gig and I'd like to switch these presets without doing the "tap dance". So, if I engage "preset 1", other two are off. Suddenly, I've got to play guitar solo, I'm turning on "preset 3" and immediately "preset 1" turns off without pressing it.

 

[crutschow]

So you could use the circuit I referenced to control the various presets. Will you use relays to switch the various units? They could be controlled by the referenced circuit outputs.

 

[Vuki_Cro]

My first thought was to engage/disengage loops (one loop, one unit) by 3PDT for true bypass and then control selected ones with the circuit you referenced. Is it possible to make it that way or there is a better solution?

Thank you for the circuit schematic.

 

[crutschow]

My first thought was to engage/disengage loops (one loop, one unit) by 3PDT for true bypass and then control selected ones with the circuit you referenced. Is it possible to make it that way or there is a better solution?

Thank you for the circuit schematic.

I need to see a wiring diagram. I can't visualize what you are suggesting to give you an answer.

 

[Vuki_Cro]

OK, I'll need a few days to make a sketch...By the way, which is the correct voltage for the posted circuit?

 

[crutschow]

If you use CD4000 series CMOS logic circuits the voltage can be anywhere from 5V to 15V.

 

[Vuki_Cro]

It's just a sketch of the guitar signal path. This setup gives me the best sound. So, after that old switching circuit my guitar signal goes to preamps and then splits to dry and wet. Dry goes to the poweramp and wet goes to the effects switching. The effects have two outputs, so I it gives me cool rotating stereo sound (especially ping-pong delay).

View attachment 60331

 

[crutschow]

Not sure which ones you want to switch but you can do it with relays controlled by the PB circuit. If you indicate which switches or paths you want controlled by which PB mode, I can make further comments.

But generally, just get relays with sufficient poles to switch all the circuits you need for each mode, with the number of relays equaling the number of modes. Depending upon the type of relay you get, each may require a transistor driver to operate from the PB circuit output.

 

[alec_t]

just get relays with sufficient poles to switch all the circuits you need for each mode

From my limited searching it seems that 3PDT and 4PDT relays are made, but are not as widely available (i.e. stocked by retailers) as DPDT types. So you may need two relays per mode (preset).

 

[Vuki_Cro]

Let me explain this. For example, selecting preset 1 enables preamp 1. Then I'd have to choose the type of sound->wet/dry or wet + dry. If wet signal is turned off, all the effects are off. But if the wet signal is engaged, I can choose which effect I'd like to use without plugging out cables and effects, and then replugging them. Something like this... https://www.youtube.com/watch?v=CdHwhMzJbeo

PB mode 1: preamp 1, wet signal only-> high output chorus, delay, high output reverb
PB mode 2: preamp 2, wet + dry signal-> low output chorus, low output reverb
PB mode 3: preamp 3, wet + dry signal-> low output chorus, delay, low output reverb

 

[crutschow]

I'm not familiar enough with sound circuits to understand the video or really know what you want. For example, I don't know what a wet or dry signal is.

But if you draw your circuit with the added relay contacts controlling the signals the way you want, I should be able to tell you if it will work or how to get it to work.

 

[Vuki_Cro]

Oh sorry, I forgot to mention what a wet or dry signal is. Dry signal has no effects in its mix, it's straight to poweramp. Wet signal has effects in it's mix.
Which of these relays (https://en.wikipedia.org/wiki/Relay#Latching_relay) should I use for PB switching?

 

[alec_t]

As an alternative to relays a much cheaper and far less power-hungry option would be to use the PB switching signals to control analogue multiplexer ICs. The MC14551 is one example, behaving as a 4PDT switch. You would need one IC per preset. Farnell have them listed at £1.43 each.

Edit: Correction, I think you would need 3 ICs (I'd forgotten the effects are stereo); 2 for the wet and 1 for the dry channels. But I may have misunderstood the required switching. When one preamp is enabled are the other two preamps muted?
Another IC is CD4053, which acts as a 3PDT switch. Farnell price £0.44.

 

[Vuki_Cro]

Then I'd have to program the MC14551, am I right? I do know how to program in C++ but only basic stuff :/

 

[alec_t]

You don't program an MC14551 (or a CD4053 or other analogue multiplexer). It has just one logic input pin (which you'd control from the PB unit) which switches either one of two sets of 4 inputs to 4 outputs, i.e. it's just a logic-controlled 4PDT switch. Check the datasheet.

Edit: A few questions:-
1) do the paths highlighted in yellow in your circuit indicate the preset #1 combination of signals?
2) are the outputs from switches numbered 1,2,3 hard-wired together (as appears to be shown) before going into the effects units (reverb etc)?
3) do you intend the relays/multiplexers to replace all the switches 1,2,3, or will those switches remain?
4) which part of your circuit is the 'high chorus', 'high reverb'?

 

[crutschow]

As an alternative to relays a much cheaper and far less power-hungry option would be to use the PB switching signals to control analogue multiplexer ICs. The MC14551 is one example, behaving as a 4PDT switch. You would need one IC per preset. Farnell have them listed at £1.43 each.

Edit: Correction, I think you would need 3 ICs (I'd forgotten the effects are stereo); 2 for the wet and 1 for the dry channels. But I may have misunderstood the required switching. When one preamp is enabled are the other two preamps muted?
Another IC is CD4053, which acts as a 3PDT switch. Farnell price £0.44.

A multiplexer requires a plus and minus supply to handle bipolar audio signals. And they are sensitive to voltage spikes and provide no isolation from the control signal grounds. For the tough world of commercial sound systems I would stay with mechanical relays.