Fog machine remote controll, using a snake channel ?

A

Alan Sledzieski

Senior
Sep 11, 2011
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Hamburg, NY.
I bought a Chauvet hurricane 1800 with a 15 foot wired remote. Can I use a channel from the snake to plug the remote into, go 100 feet through the snake, then use a mic cable at the stage box to the fogger?

What I'm worried about is other channels picking up noise from remote, clicks and pops?
 
Re: Fog machine remote controll, using a snake channel ?

Milt Hathaway said:
If I read the product page correctly, that's DMX running through that cable. No, you don't want a DMX line in your mic snake. The mic inputs will pick up the noise.
Click to expand...

Wrong, they aren't strong enough to pass through. Sorry to correct you but DMX is more likely to pick up noise from the audio lines than vice versa. DMX is very low voltage, and very low amperage. Running the dmx through the snake however is a no-no DMX needs 120 ohm wire. I'd like to bark at the effect of 3-pin versus 5-pin but honestly no one seems to want to follow the standard.
 
Re: Fog machine remote controll, using a snake channel ?

Jordan Lahr said:
Wrong, they aren't strong enough to pass through. Sorry to correct you but DMX is more likely to pick up noise from the audio lines than vice versa. DMX is very low voltage, and very low amperage. Running the dmx through the snake however is a no-no DMX needs 120 ohm wire. I'd like to bark at the effect of 3-pin versus 5-pin but honestly no one seems to want to follow the standard.
Click to expand...

DMX is RS485, which typically runs at around 5V rail to ground (10Vpp). It's reasonably robust as far as control signals go. You typically run into timing and reflection issues long before you run out of signal strength.
 
Re: Fog machine remote controll, using a snake channel ?

Jordan Lahr said:
Wrong, they aren't strong enough to pass through. Sorry to correct you but DMX is more likely to pick up noise from the audio lines than vice versa. DMX is very low voltage, and very low amperage. Running the dmx through the snake however is a no-no DMX needs 120 ohm wire. I'd like to bark at the effect of 3-pin versus 5-pin but honestly no one seems to want to follow the standard.
Click to expand...

1. I've done it, it didn't work because mic voltage is even lower than DMX voltage, and I had DMX noise in my mic channels.

Data is transmitted in serial format asynchronously with the transmission speed of 250 Kbps. Voltage on both pins ("+" and "-") should be between +12 volts and -7 volts (measured to ground). EIA485 defines that the signal voltage between the two wires should be at least 200 millivolts. Higher voltage on the "+" pin and lower voltage on the "-" pin results in a digital "1". Higher voltage on the "-" pin and lower voltage on the "+" pin results in a digital "0". The ground wire is only a reference point and often used for shielding. About DMX-512 lighting protocol - Pangolin Laser Systems
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Mic level is typically around 14 millivolts.

2. Back when I had my 120K rig I ran DMX through a 300' snake made of multicore mic cable (the other lines were fogger control, intercom, backups, etc.) and never had a problem. I probably wouldn't run movers that way these days, but simple DMX systems. Yes, the standard calls for 120 Ohm cable, but the signal is rather durable and can handle worse.
 
Re: Fog machine remote controll, using a snake channel ?

Milt Hathaway said:
1. I've done it, it didn't work because mic voltage is even lower than DMX voltage, and I had DMX noise in my mic channels.



Mic level is typically around 14 millivolts.

2. Back when I had my 120K rig I ran DMX through a 300' snake made of multicore mic cable (the other lines were fogger control, intercom, backups, etc.) and never had a problem. I probably wouldn't run movers that way these days, but simple DMX systems. Yes, the standard calls for 120 Ohm cable, but the signal is rather durable and can handle worse.
Click to expand...


Yep I do the same up my 250' mulitcore CBI snake. When I get noise I switch to dmx dedicated lines, but that's not often. My only caviat is I use an opto splitter at the other end. Runs a dozen movers and a dozen led pars. Truth be told its mostly the conventional dimmer hash that makes the noise, not dmx.
 
Re: Fog machine remote controll, using a snake channel ?

Milt Hathaway said:
If I read the product page correctly, that's DMX running through that cable. No, you don't want a DMX line in your mic snake. The mic inputs will pick up the noise.
Click to expand...

What?? I use a snake channel to run DMX to control lighting almost every weekend with no problems.
 
Re: Fog machine remote controll, using a snake channel ?

i know next to nothing about the signal levels or DMX and how they relate to audio levels. i do know that i have been asked by the lampies many many times if they could 'borrow' a spare snake channel. and my standard response is always 'sure, but the second i get noise from it, it's got to go'. i don't recall ever having to pull it...
 
Re: Fog machine remote controll, using a snake channel ?

Milt Hathaway said:
If I read the product page correctly, that's DMX running through that cable. No, you don't want a DMX line in your mic snake. The mic inputs will pick up the noise.
Click to expand...

Back in the day------------------- I used to run my DMX signals through the snake (that also had the send and return audio lines) and never had a problem.

Part of it depends on the quality of the snake cable and teh quality of the mic pres and the common mode rejection ratio.
 
Re: Fog machine remote controll, using a snake channel ?

Milt Hathaway said:
If I read the product page correctly, that's DMX running through that cable. No, you don't want a DMX line in your mic snake. The mic inputs will pick up the noise.
Click to expand...

Hello.

I have done it many times with no ill effects, but have had issues on a few rare occations where a high-pitched whine was audible in just about every mic input. I have found that the likelyhood of having issues seems greatest with snakes where all pin1's are connected to each other.

Generally, dimmer noise is a much bigger issue.

I do have the following observation to contribute: One big issue with running an "unknown" DMX line through the audio snake is that we soundfolks usually take great care in making sure that FOH is on the same circuit or gounding scheme as what the other end of the snake is connected to . With an "unknown" DMX line we don't really know what and where our FOH shares ground with.
 
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