DigiSnake over Fiber

[dlev13]

I know we can now send the digital snake over fiber using an RME MADI converter, but in the spec it says that the connection between the Stage Rack and the RME box must be made using very short coax cables. I have a situation where my two stage racks are rather far from one another (one onstage, the other in the orchestra pit), but they both have to follow the same cable path to FOH.

I am hoping to run a standard spec coax snake from one to the other. There they will both hit the MADI Converter and go FOH over their respective fiberoptic cables. I'm trying simplify the cable runs as this is a tour, and must be setup and struck a couple times a week.

Thanks.

[Kenmillerjr]

What spec documentation recommends that? I am by far no expert, but I would say that a 25' to 30' run of BNC's shouldn't be a problem...but if you were to tap a 250' BNC snake on there on the other hand, that might be what they were recommending against.

If that is the case, would it be much of a problem to get an analog snake that runs from the orchestra pit to the stage rack, keeping the two stage racks right next to each other? I've got some Radial stage slugs (I believe is what they are called) that has a mass connection into the snake which makes my setups easier...I typically leave the 5' tail patched into the stage rack and then connect the extensions from there to the break out boxes. Works very well in a touring scenario.

[dlev13]

There was something posted in one of these threads by one of the Avid guys. I was wondering if even a 250' cable of the right spec would have any impact (we routinely run 250' of the spec coax between FOH and the stage).

I thought about running mult from the pit, but I'm trying to cut down on the mass of cable they need to deal with on the road. Having to run two of the coax snakes versus two or three 19-pair mults is much much easier. Especially when there's also power, intercom, and video involved.

[eshop]

I am not speaking for AVID or RME on this......here are some things to consider:

The MADI coax output circuit on the RME device is a standard 600mVp-p (terminated 75ohm) driver, and the MADI coax input circuit has a sensitivity threshold of approx 180mVp-p. This results in a coax cable spec that allows for approx 10db of attenuation. The max coax cable length into the receiver is approx 100m (328')..dependent on cable specs - given that the receiver is driven from a 600mVp-p source. Since we do not know the launch (output) amplitude of the Venue transmitter circuit we can safely assume that is greater than 600mVp-p considering the 500' RG-6 spec. The Venue output circuit is not likely the problem here. However, the coax output (transmitter) from the RME device is likely going to be the weak link in your scenario considering that the input (receive) circuit on the Venue Stage Rack(or FOH Rack) has unpublished input sensitivity thresholds. Since the Stage Rack is being driven from a 600mVp-p MADI compatible source (not the FOH Rack) some experimentation is in order to determine the actual working distance for your coax runs. Unfortunately there is no hard right or wrong answer to this.

Why did you choose Fiber runs to FOH? How long is your run to FOH? Are you running dual RME devices @ FOH and Stage to preserve snake redundancy?