Interfacing 600 ohm Paging Speakers (Valcom V-1030B) with the Snom PA1 SIP Paging Adapter
Interfacing two Valcom V-1030B paging speakers with the Snom PA1 SIP paging adapter.
The Valcom V-1030B paging speakers have a built in 5 watt amplifier that is driven by a 24V transformer. These speakers can be daisy chained, and 4 conductor telecom wire is what's used to connect them together. Two wires carry the signal and two wires carry power for the amplifier. These speakers are older, being replaced by the V-1030C, which is still in production. A unique challenge that comes with these speakers is the input impedance of the amplifier being 600 ohms.
The SNOM PA-1 paging adapter worked out great for converting this specific site from an old analog telephony system to cloud based Intermedia PBX, but the expected speaker impedance for this device was 8 ohms, not 600. I didn't try to connect the speakers directly to the output, but if I did, I expect the audio from the speakers would have been very low if anything was heard at all.
To remedy this issue, I did some research and found the Hammond 119DA audio transformer. This transformer is usually used with vintage radios in order to use a modern 4 or 8 ohm speaker, but is also able to be used in reverse, which is what I did here, and it worked great!
You may notice that the sound is "muddy" in the video, even though it's working as intended. To resolve this issue, I set the amp gain in the Snom PA1 to "0" to disable the internal amplifier and turned the sound down within the same settings menu of the Snom interface. The way this setup is wired, very little power is needed on the "signal" line, which is amplified at the speaker itself via the built in speaker amplifier.
This project was made necessary to integrate the older speakers with a newer system, but understanding it now, I wouldn't hesitate to deploy a similar solution in a new installation. You'd have to run much larger wires to utilize the built in amplifier of the Snom unit and it still wouldn't be as loud. It's easy and convenient to utilize the 4 conductor telecom wire to daisy chain these speakers in a warehouse environment.
For those who may inquire about my sloppy wiring work, this was temporary for now. All wires will be properly soldered for the finalized installation.