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2-wire comms nulling question

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brian maddox:
Okay, Peter, this one is for you.  :)

I'm encountering an issue quite a lot on show sites recently so i'm hoping you can shed some light on best practices in this situation.

I've got a Model 45A 4-wire to 2-wire interface between a Clearcom Matrix system and a wired TW Clearcom analog system.  Both channels of the Model 45A are being used to the TW analog system.  I've also got an HME DX210 system interfaced into the same TW Clearcom analog system using a TW701 interface to breakout the TW channels to two Single Clearcom channels.  I've got a two channel Clearcom power supply hanging off the whole rig to supply power for all the local TW belt packs.

Because the Clearcom Eclipse Matrix is being used over the inter webs, it is imperative that i get the maximum amount of nulling in the local 2-wire analog system to prevent very annoying echo to the matrix users.

Once everything is hooked up and operational, what should my nulling procedure be?  Both the HME and the Model 45A have excellent auto-nulling capability, but i'm not sure which to do first or why.  Also, would it be better to use the 4-wire capability of the HME to remove that issue from the equation?

Any guidance would be much appreciated.

FWIW, i also often do this exact same setup, but with a Tempest system in place of the HME.

Thanks in advance.

brian

Chris Johnson [UK]:
I'm going to jump in here, because why not!

First off, wrong forum! But I'm sure someone can move it.

I would definitely remove the 2W HME interface. Go 4W. By using the 2wire, you are unnecessarily adding another hybrid to the equation, and another point for less-than-perfect nulling.

Once you've done this, you simply null the 2W system on the 45A once all the 2W elements are connected.

Pete Erskine:

--- Quote from: Chris Johnson [UK] on January 29, 2016, 03:26:59 AM ---I'm going to jump in here, because why not!

First off, wrong forum! But I'm sure someone can move it.

I would definitely remove the 2W HME interface. Go 4W. By using the 2wire, you are unnecessarily adding another hybrid to the equation, and another point for less-than-perfect nulling.

Once you've done this, you simply null the 2W system on the 45A once all the 2W elements are connected.

--- End quote ---

Ditto

Pete Erskine:

--- Quote from: brian maddox on January 28, 2016, 12:44:28 PM ---I've got a Model 45A 4-wire to 2-wire interface between a Clearcom Matrix system and a wired TW Clearcom analog system.  Both channels of the Model 45A are being used to the TW analog system.

--- End quote ---

How many TW Beltpacks are you using and what channels do you have interfaced?

You also are using a TW701 to make your TW channel, right?

brian maddox:

--- Quote from: Pete Erskine on January 29, 2016, 01:49:27 PM ---How many TW Beltpacks are you using and what channels do you have interfaced?

You also are using a TW701 to make your TW channel, right?

--- End quote ---

Number of TW belt packs varies but usually less than a 12.  There's also a Model233 announcer console in the system [my personal comm station].

The scenario i listed above basically is the same two channels on everything.  So it's channel A and B on the Model45, connected to A and B on the TW system, and A and B on the HME.  There are times it gets more convoluted, but this is the most frequent configuration.

And yes i'm using a TW701 to make the TW channel for both the belt packs and the Model45.

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