Question from a new guy

[tmack]

Hello, I am new here. I am wondering if the mike input for my xts2500 is "line level" or "Mike level". I am trying to mess around with some mike modifications and everything is sounding crappy. Thanks for any help. Tmack

[Tom in D.C.]

The short answer is it's mic level. The long answer is that the circuit is designed to work optimally for communications work with the mic element in the radio as well as an external mic, if used. You're also messing with a circuit that has an automatic switching circuit to go to the external mic when such is connected. The mic elements are nominally low impedance condenser types, usually.

[tmack]

Hm. I have tried it with mike level but it sounds terrible. Any suggestions on how I can get it to sound better. It sounds like I am talking into a tin can or from in a closet or something. The microphone sounds good when I use it elsewhere.

[Tom in D.C.]

The best short answer to your problem is that you should use a microphone that was designed for use with your radio. This is a communications system setup so you should have no concerns about fidelity of the sound. If the voice is clear the radio is doing its job and that's all there is to it. As I said before, external microphones for Motorola portable radios are designed as part of a system which involves circuitry in the microphone unit as well as in the radio. Plugging in an external microphone, however you do it, without the compensating/complementary circuitry is almost bound to lead to inferior results.

[Bill_G]

What kind of mods are you trying to make? Are you trying to tie the portable into an interoperability panel or something?

[marcosorourke]

This topic is of interest to me as I would like to tie our engineering/disaster prepardness radios into our intercom system at our broadcast station (so the operators don't have to have another piece of equipment to lose or break or deal with).

[ai4ui]

You may want to consider an off the shelf solution for this that will provide VOX based PTT and interfacing of the mic & speaker in a manner that accounts for different impedence levels. It would be a shame to damage a fairly expensive radio while figuring out a way to not damage a fairly expensive radio.

A Link Comm TCB-3 would probably work for this application. The TCB is not the best, but it isn't anywhere near as expensive as other solutions and won't damage your radio.

[MSS-Dave]

XTS2500. Analog or digital? Conventional or trunked? There are all sorts of audio controls for internal and external mic including AGC and treble cut. Adding all of this to impedance matching makes it tricky unless you get the off the shelf box as suggested. FWIW, I spent a lot of time goofing with levels to patch analog to digital through a JPS ACU. Don't know if this is the case but the quality of your source audio has to be considered as well as all of the other concerns.

Dave

[Bill_G]

Got it. If you're trying to do studio intercom with outside broadcast and talkback to talent and remotes, you're probably dealing with balanced audio, not single ended, to and from the board. I second ai4ui advise to get an interface panel of some kind so you can, at the very least, set levels. But, you can McGuiver something with a couple transformers and pots. Then you may have to play with the curves to get acceptable quality audio. Your final challenge will be getting VOX to operate reliably.

[Tom in D.C.]

If you're asking about a Production Intercom system, as it's known in the trade, such as those made by ClearCom, Telex, etc., most of these manufacturers make standard catalog interfaces for use with Motorola communications systems. Check with your sales rep or the particular website for more information.

[marcosorourke]

It's not a ClearCom, it's from a company called Axia. But do you recommend maybe the JPS unit?

Sorry to sort of hijack this thread...

[Tom in D.C.]

At this point the research and decision is your responsibility, that is if you think you might have found a unit that will interface with your radio system. You don't want a bunch of third-hand opinions and guesses from us when all you have to do is to evaluate the manufacturer's specifications and claims. I've personally never heard of an Axia intercom, but I've been away from the pro sound business for a few years now.

[Bill_G]

JPS makes an interoperability panel that ties one radio to many depending on user configuration. If you respond to a forest fire and want your UHF radios to talk on the VHF Forestry channels, you use a JPS panel. If you are responding to an oil spill in the bay and need the VHF Coast Guard to coordinate with the 800M trunking local police, the VHF county sheriff from across the bay, and the UHF refinery operators, you use a JPS panel. Might be kinda overkill for an intercom, but it should work. YMMV.