Telephone Interface

[pellmell]

Back in the eighties, we had a telephone interface that was 600 ohms in and out mounted in a 3-1/2" rack space, and it operated like a speakerphone. There was a button on the front to answer or release the call. Instead of being a hybrid, it was a one-person-talking-at-a-time setup. It was quite inexpensive, as I recall. The benefit is that it was designed to interface with line level broadcast equipment, and it was quite impervious to RFI.

The unit is probably not being made any more, but I would sure love to find one for a podcaster. Does anyone remember the manufacturer or the unit? It was really nothing more than a speakerphone with professional interface, but it worked quite well. Even though it was simplex, it gave the DJ the ability to override the caller, which was handy at times.

 

[frankberry]

Why not buy a simplex speakerphone (Radio Shack has them)?
You can interface the speaker to your console with a small transformer and/or RDL Stick-On line-level amplifier.
A small transformer and attenuator pad is all that's necessary to get the console audio into the phone.

 

[pellmell]

Been there done that more times than I can count. This unit performed a lot better than a cobbled up speakerphone.

 

[Abner Jenkins]

Get one of these:

http://broadcasttools.com/view_product.php?pid=113

It does what that monstrous 2RU box did for you back in the '80s. And this one costs $140.

 

[RealityCheckr]

What do you have against the podcaster? Half-duplex is pretty hard to work make sound natural. Get a used digital adaptive hybrid on ebay (Telos One or the old Telos 100 would be perfect, as would a Gentner/Comrex DH-x).

 

[Kmagrill]

A simple analog hybrid coupler won't provide satisfactory performance for most users. First class performace requires a digital hybrid. Simple analog hybrids are fine for occasional newsroom work where it isn't very important to sound like the talent is in the studio. I would think that something like one of the JK Audio hybrids would be a more useful solution at an affordable price. I'd stay away from eBay hybrids, especially anything made by Gentner. Gentner sold their broadcast hybrid line off about 8 or 9 years ago to Comrex. Many of the Gentner units on eBay are either non-functional or near the end of their life. The risk is too high to justtify the cost, unless you can get the hybrid for under $50.

I've seen several half-duplex systems. Most are cobbled around various speakerphone designs and range from plain awful to amazingly good. How well they work depends entirely on the speakerphone design. I have not seen any dedicated hardware for that purpose, though.

 

[pellmell]

I've seen several half-duplex systems. Most are cobbled around various speakerphone designs and range from plain awful to amazingly good. How well they work depends entirely on the speakerphone design. I have not seen any dedicated hardware for that purpose, though.

The one we had worked amazingly well. If the balance between the callers was set carefully, it was hard to tell that it was half-duplex. After all, it's hard to understand either person when two people are talking at the same time. Ours was always set such that the DJ was slightly hotter than the caller, in terms of balance. On their, of course, they were the same level.

I bought the unit because there was no money for a hybrid. They were much more expensive at the time. After we started using it, I was so satisfied with the performance that I never even thought about getting a hybrid. The unit was transformer balanced in and out, sounded fantastic, and had no RFI problems even though we were at the AM tower.

 

[bossbill]

One of the biggest issues we had our small market was interfacing to an existing digital phone system, without the budget for a separate on-air system.

We finally settled on the PBXport. This unit inserts between the handset and the studio phone. It works much better than the simple interfaces. We have one in each studio.