Using ethernet cable for footswitch, problems ?

[Gabriel Simoes]

Hello folks!
Today I caught myself thinking about doing a rackmount setup with 2 different preamps, drive, compressor, this stuff, and I thought about using one or 2 ethernet cables to connect the rack to a footswitch I would build to control the stuff, and maybe to use a single power suply for both of them.
But then I realized, the cables are crossed, so I got the doubt : is that a problem since everybody ask people not to let in and out cables cross ?! would the be any other way of doing this or other types of cables that we could use for this purpose ? and conectors ?
Thanks,
Gabriel Simoes

ps: sorry for the bad english, I´m in a hurry, and now I gotta go back to class!

[TheBigMan]

Simple solution is to use relays for the switching.  Then it doesn't matter what sort of cable you use.  Cat 5 is good cos it's cheap and can handle 7 switches plus a common ground.  I wouldn't recommend having the audio running into and back out of the footswitch, you're asking for trouble with such long cable runs. 

[Paul Perry (Frostwave)]

I'm not sure how reliable cat5 would be, isn't it a number of single strands? if it gets kinked regularly it's going to break.

[DavidS]

Actually, you can get Cat5 stranded- or solid-core. Solid-core is usually used for more permanent installations, and the stranded is for patch cords, etc.

Also, Neutrik makes some really cool ruggedized RJ-45 plugs and sockets, which mouser carries, though I think there are cheaper sources for them.

[Gabriel Simoes]

What I don't know is if relays would pop when turned on and off ....
About the cable, some famous brands use them, including line 6 and stuff.
Now I'm looking for projects that include their own power supply, but it's kind of hard to find transformers here in Brazil, so I think that will bve a problem ...
An other problem will be finding rack enclosures ....
I'm thinking of using just bass effects, preamps and doing line out, effects loop, this stuff, a project that would be a hobby for months ...
let's see if we can keep talking about it and get the best ideias of how to connect rack and footswitches ...
Thanks
Gabriel

[Paul Perry (Frostwave)]

Actually, you can get Cat5 stranded- or solid-core.

Thanks, David! I'm not a computer guy.... all the stuff I find in skips is single strand. Loooking at the back of the computer here, there are some bits that I suspect are multi
To get back to the original poster, I think that if all the audio in & outs from the FX are run thru some kind of snake to the switchbox, there might be trouble from capacitance. A bunch of shielded high impedance cables will be exactly the same as a bunch of guitar cables, and that gets bulky pretty fast. Hence the relay approach, as suggested above.

[Andi]

I do a relay switcher that runs the control voltages over cat5 cables. I've not had reports of popping or clicking other than with an old pedal which turned out to have knackered decoupling caps.

If anyone is interested I could dig out the schematic and a board layout.

[R.G.]

...I thought about using one or 2 ethernet cables to connect the rack to a footswitch
...would the be any other way of doing this or other types of cables that we could use for this purpose ? and conectors ?

...you can get Cat5 stranded- or solid-core. Solid-core is usually used for more permanent installations, and the stranded is for patch cords, etc.

...let's see if we can keep talking about it and get the best ideias of how to connect rack and footswitches ...

...What I don't know is if relays would pop when turned on and off ....

...I've not had reports of popping or clicking other than with an old pedal which turned out to have knackered decoupling caps.

All good comments on pieces of the puzzle.

It's a bad idea to run high impedance signals any further than you absolutely have to, especially high impedance unbalanced cable. It's quite difficult to avoid treble loss and pickup of hum and noise. This is the fundamental reason that audio other than guitar audio uses 600ohm balanced lines. The low impedance keeps you from losing treble and the balanced configuration helps tremendously in rejecting noise.

Cat5 is four unshielded twisted pairs in a jacket with tightly controlled impedance. It's good stuff for low impedance lines. Its not good for high impedance signals like guitar. But it is available moderately easily everywhere because it piggybacks on the computer networking industry. And it's GREAT for carrying digital signals. The normal net wiring, as noted, is solid single strand, but the patch cables are multistrand. The patch cables are what you want. They come in lengths up to 100ft.

Relays can pop by capacitive coupling of the voltage transient on the coil into high impedance signal lines unless you either (a) use shielded relays, which do exist but are uncommon, (b) slow down the voltage transients across the coil somehow, or (c) get lucky with your choice of relays.

The bottom line:
(1) Use as few and as short runs of  high-impedance signal carrying cable as you possibly can. Best is an on-guitar buffer. Second best is a short guitar cord. Third best is one long guitar cord. Worse is more feet of cable, more cables and more connectors. Convert to low impedance signal as soon as you can. Multi-cord snakes carrying high impedance signals back and forth are the worst.

Note that there are two major ways to do this. One is to use a short run of cable from the guitar to the first effect out on the stage near the guitar, presuming that the first effect has a low impedance output. Putting all of the effects out on the stage in a clot is not all that bad in that it minimizes the first long cable run. The other is to use one long cable from the guitar back to the entire audio processing plant with a remote footswitch. The remote footswitch should be connected to the audio processing plant with cables that carry no audio.
(2) The length and impedance of cables carrying only logical on/off signals at low speeds like we use for footswitch control doesn't matter a whole lot. Use what is easy and affordable. The computer industry has made Cat5 patch cables easy and affordable, so they're a good choice. If you have more than seven signals, you can use two Cat5's or one set of DB25 connectors with up to 24 signals. Another choice is using two microcontrollers speaking to each other over a serial cable. This only requires three or four conductors for as many footswitch signals as you like, and can also send remote analog information like from wah pedal controllers and such that are remoted from the actual wah circuitry.
(3) With all of the audio in one place, you can work on optimizing the switching and shortening the cable runs. One nice thing is that with it all in one place, hum pickup from ground loops is minimized without special wiring.
(4) wah and volume pedal wiring is the fly in the remote ointment. You have a few choices there. One is to run signal line out to the pedal and back. This is a bad idea. The other is to use the rocker pedal to generate a control siganal for the effect operation and take only the control signal back and forth to the player.

[R.G.]

Hit "reply" too soon...

Another idea for rack setups. Racks are not all that good a setup for effects. The effects aren't usually complicated enough for one RU panel of their own, so you waste a lot of rack space.

Instead, mount pre-drilled rack rail *across* the relay rack opening about 3-4RU apart, then use effects mounted to cut-up rack panels across the rack. You can get up to a half dozen or so effects in three RU of space that way.

[Gabriel Simoes]

Thanks for the detailed debate!
Rg:
The ideia is to put together 2 different preamps and some effects, and be able to turn them on and off, so using a cat5 and dedicating 2 of the 8 cords for power and ground, I could control up to 6 relays ...
I could for example always use one of the 2 preamps so with one relay I can handle this and then I get 5 for effects and no problems with high impedance signals, since the outputs of those preamps are low impedance.
The thing I've been thinking about now is that if the relay would take long to change state or if it would pop.
Since no signal would go thru the cat5, I would not have anymore those headaches of hum and stuff ....
Right ?
Thanks,
Gabriel Simões

[mat]

I do a relay switcher that runs the control voltages over cat5 cables. I've not had reports of popping or clicking other than with an old pedal which turned out to have knackered decoupling caps.

If anyone is interested I could dig out the schematic and a board layout.

That would be VERY cool 

mat

[TheBigMan]

I do a relay switcher that runs the control voltages over cat5 cables. I've not had reports of popping or clicking other than with an old pedal which turned out to have knackered decoupling caps.

If anyone is interested I could dig out the schematic and a board layout.

Of course I didn't think of the Otter Shocker when I posted my original reply. 

[xshredx]

I would be very interested in that too...

[Dave_B]

Instead, mount pre-drilled rack rail *across* the relay rack opening about 3-4RU apart, then use effects mounted to cut-up rack panels across the rack. You can get up to a half dozen or so effects in three RU of space that way.

I started down that road, buying a short piece of 2" U-channel to experiment with.  Set vertically, that would be be the front panel for a single effect.  The thing that's slowed me down is all the posts about RF interference.  The rackmount stuff (the way I'm thinking of it) wouldn't be shielded as well as a stompbox, so I backburnered the idea.   

Paia makes a lightweight version if anyone needs a visual. http://paia.com/fracrak.htm

[R.G.]

Inside a metal-lined container, it should not be a problem. Well, not any worse of a problem if you fill all the open spaces with blank panels.

What I had in mind was a floor unit about 24" by 8" by 3-4" high. The rails go across the edges of the top in the 24" dimension. They provide only mechanical support for the effects modules in the box. The box is metal foil lined.

By the way, would you please can that animated GIF in your posts? We had a long thread on those things before the move here.

[Andi]

Okey - I'll dig it out this evening if I remember. I seem to recall that the basic relay switching thingy on RG's site is very similar in terms of schematic, but the PCB layout might be useful to someone. I'll see if I can find the relays I use too.

[Dave_B]

By the way, would you please can that animated GIF in your posts? We had a long thread on those things before the move here.

Done.  I obviously missed that thread. 

[Andi]

Okey; here's the board layout:



Here's the schematic:



And these are the Eagle project files:

http://www.monkeyfx.co.uk/sharing/OtterShocker6.brd
http://www.monkeyfx.co.uk/sharing/OtterShocker6.sch

Note that I actually use 1N400-somethings, but that diode was a nicer size, and at the time I didn't understand how to edit library files. The board could do with some cutting of the ground plane, or, better, a new layout with a specific signal ground track. And one day I'll probably get around to doing it! It has worked well so far as-is though, but comments and suggestions are always welcome. For reference I use the Neutrik push-in Ethercon RJ45 sockets.

Here's a picture of the biggest one I've yet made - 2 6-way units (older RJ45 sockets on this)



And here's a gutshot of a 2-channel one:



While I'm at it, here's the EAGLE library file for a Blue 3PDT I bodged together.

http://www.monkeyfx.co.uk/sharing/3pdt.lbr

You'll need to invoke the last pole - seemed like a good idea at the time.

[Andi]

No use to anyone?

You can get the freeware EAGLE client and print the layout off for PnP or similar...

[stompbox steve]

Does anyone have the schematic and board design for Andi's remote switcher?
Thanks, Steve