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Switching, switch board.

12/10/1999 12:49 PM
Jsh	Switching, switch board. First of all thanks to Yang for giving me this link. I hate to tapdance on stage to switch my stompboxes, so this leads me to making my own switching board I am working on that switching board. I want to make 6 loops for 6 groups/Units of FX's. I don't know how the Boss FET-switching works , but it leaks the wet sound in your dry signal. My SD1 for example gives slight distorted FX when it is not activated; in other words it leaks sound. I first thought the FET-switching was a cheaper way to build a multiple switch board, but 1) I can't find a description (schematic) of it and 2) It leaks. So to the point. I made a schematic using relays. But I have some questions: 1) What are the bad sides of Relays for switching (besides the costs, of course) 2) Is there a better way to make it possible to switch 6 FX-stompboxes using one board of switches? Any schematics around? 3) How do those (Midi-)Patchers do the switching? 4) Can it be done with simple IC's? 5) Do I have to switch the (-) earth too when switching a FX or is the (+) enough? [this is respect to the possible 'POP' in the switching and possible the earth-loop] I will draw my schematic and post it here later today. As you will see, I 've tried to make it flexible and "programmable".

12/10/1999 12:49 PM

Jsh

Switching, switch board.

First of all thanks to Yang for giving me this link.

I hate to tapdance on stage to switch my stompboxes, so this leads me to making my own switching board

I am working on that switching board. I want to make 6 loops
for 6 groups/Units of FX's. I don't know how the Boss FET-switching works , but it leaks the wet sound in your dry signal. My SD1 for example gives slight distorted FX when it is not activated; in other words it leaks sound.
I first thought the FET-switching was a cheaper way to build a multiple switch board, but 1) I can't find a description (schematic) of it and 2) It leaks.

So to the point. I made a schematic using relays. But I have some questions:

1) What are the bad sides of Relays for switching (besides the costs, of course)

2) Is there a better way to make it possible to switch 6 FX-stompboxes using one board of switches? Any schematics around?

3) How do those (Midi-)Patchers do the switching?

4) Can it be done with simple IC's?

5) Do I have to switch the (-) earth too when switching a FX or is the (+) enough? [this is respect to the possible 'POP' in the switching and possible the earth-loop]

I will draw my schematic and post it here later today. As you will see, I 've tried to make it flexible and "programmable".

12/10/1999 1:58 PM

R.G.

quote:
"I don't know how the Boss FET-switching works , but it leaks the wet sound in your dry signal."

They do that if the JFETs are not set up right. They can be sound-tight if done correctly.

quote:
"1) What are the bad sides of Relays for switching (besides the costs, of course)"

High power to hold them in compared to solid state techniques, meaning a six-relay setup will need an AC-adapter source. Contact noise from the dissimilar metals.
Leakage of the on/off voltage from the coil into the audio path as a click.

quote:
"2) Is there a better way to make it possible to switch 6 FX-stompboxes using one board of switches? Any schematics around?"

First I get to do my standard question - can you define "better"? That word carries a lot of implications, just a few of which can be - cheaper, better value per money, easier, faster to implement, smaller, larger, older, newer, and so on.

If what you're looking for is a smaller, cheaper, easier to implement lower power switch, yes, and yes.

quote:
"3) How do those (Midi-)Patchers do the switching?"

Probably CMOS switch chips, but I don't know for sure.

quote:
"4) Can it be done with simple IC's?"

Yes. The simplest way is the CD4053 analog multiplexer. I have a design that I've been working on, might post that one.

quote:
"5) Do I have to switch the (-) earth too when switching a FX or is the (+) enough? [this is respect to the possible 'POP' in the switching and possible the earth-loop]"

You're not likely to have much problem with a pedalboard on a single AC adapter if you're careful about the physical setup. You may have to break the shield at one end of the connecting cords for lowest hum. You *will* have problems if you switch between two individually-AC-powered devices like two amps with this setup. Then you need either differential amplifier or transformer isolation, both of which have been covered here.

For an effects board, you only have to switch the signal line.

Keep the signal lines all short between the effects and the switch sections, and if you run the footswitches remotely, carry only the logic signals remote, don't run the audio in long cables; this invites hum and interference.

12/10/1999 2:29 PM
Jsh	Thanks for the info R.G.! I set up a small "schematic", just to explain the idea http://utopia.knoware.nl/users/jsh/fxloop.html R.G., are you saying that I should try to power my stompboxes with the same DC adaptor as the switching board? It is better that way? (less noise and hum, I mean). What I meant with "better": An easy, less expensive way to switch six fx-stompboxes in a single-press-on-the-footswitch way, so I can switch more than one stompbox from his on/off status? for example: I'd like to use the following: 1: chorus + Delay 2: Distortion 3: Volume pedal + Chorus + delay 4: Chorus 5: distortion + Delay Switching stompboxes like that.

12/10/1999 2:29 PM

Jsh

Thanks for the info R.G.!

I set up a small "schematic", just to explain the idea
http://utopia.knoware.nl/users/jsh/fxloop.html

R.G., are you saying that I should try to power my stompboxes with the same DC adaptor as the switching board?
It is better that way? (less noise and hum, I mean).

What I meant with "better": An easy, less expensive way to switch six fx-stompboxes in a single-press-on-the-footswitch way, so I can switch more than one stompbox from his on/off status? for example: I'd like to use the following:
1: chorus + Delay
2: Distortion
3: Volume pedal + Chorus + delay
4: Chorus
5: distortion + Delay
Switching stompboxes like that. :-)

12/10/1999 3:20 PM
MJ Harnish	I've got a schematic drawn up for the relay box used with the old Scholtz midi-octopus. As I recall it's basically just a 5v relay, a cap, and a resistor or two, along with the jacks.. Of course you need the midi-octopus to run the box. I could probably locate the schematic if you were interested. Just my $.02 but I own a DMC GCX and Ground Control and have been very happy with it; of course this is more expensive than building your own but it gives you a LOT more flexibility since I have 8 loops that I can turn on-off at will or can program them via midi to switch multiple loops with a single button push. The hidden cost here is patch cords (4 plugs, plus cable per loop, which cost me close to $100 when I was done making them. I used George L cable and soldered on some Mouser 1/4" plugs). I think I paid a total of $350 for both the pedal and the switcher new. MJ

12/10/1999 3:20 PM

MJ Harnish

I've got a schematic drawn up for the relay box used with the old Scholtz midi-octopus. As I recall it's basically just a 5v relay, a cap, and a resistor or two, along with the jacks.. Of course you need the midi-octopus to run the box. I could probably locate the schematic if you were interested.

Just my $.02 but I own a DMC GCX and Ground Control and have been very happy with it; of course this is more expensive than building your own but it gives you a LOT more flexibility since I have 8 loops that I can turn on-off at will or can program them via midi to switch multiple loops with a single button push. The hidden cost here is patch cords (4 plugs, plus cable per loop, which cost me close to $100 when I was done making them. I used George L cable and soldered on some Mouser 1/4" plugs). I think I paid a total of $350 for both the pedal and the switcher new.

MJ

12/10/1999 6:56 PM
Joe Fuzz	MJ: This is one project that strikes me as more cost effective to buy rather than build. (My philosophy on building is to build if a) the product is no longer made, b) if the cost of the product vs. building one is significantly lower, or c) if I expect to do a lot of tweaking with the box.) Do you have a manufacturer's link on this DMC GCX switcher? Can it/they be purchased on line? Any more details you can share?

12/10/1999 6:56 PM

Joe Fuzz

MJ: This is one project that strikes me as more cost effective to buy rather than build. (My philosophy on building is to build if a) the product is no longer made, b) if the cost of the product vs. building one is significantly lower, or c) if I expect to do a lot of tweaking with the box.)

Do you have a manufacturer's link on this DMC GCX switcher? Can it/they be purchased on line? Any more details you can share?

12/10/1999 7:44 PM
MJ Harnish	I would agree completely. I just don't think you can build a cost effective unit that is as full-featured. I've found a million uses for the GCX... Digital Music Corp is AKA Voodoo Labs; try www.voodoolabs.com. I bought my through J&S Music (www.jsmusic.com I think) and got the GCX for $209 brand new! That's about 50% off list. I got that price by submitting a competitive bid request for the units through Harmony Central's service. The last time I checked J&S has both a used GCX and GC listed for ~$300 total. However, that page hasn't changed in 4-months so I'd bet it's not still available. Now, be forewarned, J&S is very unreliable in my experience. I got my GCX from them three days after I ordered it; I ordered a Ground Link controller for the GCX at the same time, and two months later I was still waiting... I got the run around from both J&S and DMC (they just kept pointing the finger at the other). I finally gave up and bought a used GC (the midi pedal; a Ground Link just controls the loops rather than being a full-blown midi controller) used for $150. I will point out that J&S never charged my CC for the GL so it wasn't like they were ripping me off... About a month ago I decided to upgrade my GC's software to version 2 and figured I'd give J&S one more try (their price was $20 vs. $30 everywhere else I looked). I ordered it and got a reply saying it would get it in 7-10 days. 40 days later I'm still waiting.... My suggestion is that if they don't guarantee you that it's in stock to look elsewhere. MJ

12/10/1999 7:44 PM

MJ Harnish

I would agree completely. I just don't think you can build a cost effective unit that is as full-featured. I've found a million uses for the GCX...

Digital Music Corp is AKA Voodoo Labs; try www.voodoolabs.com.

I bought my through J&S Music (www.jsmusic.com I think) and got the GCX for $209 brand new! That's about 50% off list. I got that price by submitting a competitive bid request for the units through Harmony Central's service. The last time I checked J&S has both a used GCX and GC listed for ~$300 total. However, that page hasn't changed in 4-months so I'd bet it's not still available.

Now, be forewarned, J&S is very unreliable in my experience. I got my GCX from them three days after I ordered it; I ordered a Ground Link controller for the GCX at the same time, and two months later I was still waiting... I got the run around from both J&S and DMC (they just kept pointing the finger at the other). I finally gave up and bought a used GC (the midi pedal; a Ground Link just controls the loops rather than being a full-blown midi controller) used for $150. I will point out that J&S never charged my CC for the GL so it wasn't like they were ripping me off...

About a month ago I decided to upgrade my GC's software to version 2 and figured I'd give J&S one more try (their price was $20 vs. $30 everywhere else I looked). I ordered it and got a reply saying it would get it in 7-10 days. 40 days later I'm still waiting.... My suggestion is that if they don't guarantee you that it's in stock to look elsewhere.

MJ

12/10/1999 5:25 PM
R.G.	Ok, I understand. I have sketched up a switch-monster that I'll post to GEO tonight. It does the following: 1. Select one of six "programs" of effects with a single stomp. 2. Each program contains any group of one to six effects individually selectable. 3. Effects one to six are plugged in in a given order, no order switching is done. For instance, if you have Distortion 1, Distortion 2, Tone control, auto wah, chorus, echo effects in that order, Program 1 could be Distortion 1, tone control, chorus. Program 2 could be Distortion 2, auto wah, echo Program 3 could be distortion 1, distortion 2, chorus, echo. and so on. Foot stomps select the whole "program". The schematic is a conceptual level. Each actual section would have to be designed/selected. For instance, the six DPDT bypass switches may be relays or CMOS multiplexers; the one-of-six footswitch may be a mechanical one-of-six, a relay setup or a logic arrangement. There ARE ways to implement each one. For everyone - is there any interest in having this as an on line project, perhaps as part of the upcoming Fx of the month club?

12/10/1999 5:25 PM

R.G.

Ok, I understand. I have sketched up a switch-monster that I'll post to GEO tonight. It does the following:

1. Select one of six "programs" of effects with a single stomp.
2. Each program contains any group of one to six effects individually selectable.
3. Effects one to six are plugged in in a given order, no order switching is done.

For instance, if you have Distortion 1, Distortion 2,
Tone control, auto wah, chorus, echo effects in that order,
Program 1 could be Distortion 1, tone control, chorus.
Program 2 could be Distortion 2, auto wah, echo
Program 3 could be distortion 1, distortion 2, chorus, echo.
and so on. Foot stomps select the whole "program".

The schematic is a conceptual level. Each actual section would have to be designed/selected. For instance, the six DPDT bypass switches may be relays or CMOS multiplexers; the one-of-six footswitch may be a mechanical one-of-six, a relay setup or a logic arrangement. There ARE ways to implement each one.

For everyone - is there any interest in having this as an on line project, perhaps as part of the upcoming Fx of the month club?

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