I seem to recall being called out to "fix" a problem that was a tape deck (auxiliary output) plugged into a mic input and the sound was horrific (till I "fixed" it by changing the phone plug to an RCA and plugging it into the aux input).
You guys say that quality was terrible but you need to define terrible. Was it distorted? Only thing it could be is distortion caused by overdriving the input. Many amplifiers have gain stages directly after the input and before the volume or level control. So applying too a high level to the input causes the input stage to clip and the volume control would have no effect except for turning the whole mess up and down. This would be the case here. All MIC inputs are low level inputs because microphones (except crystal) provide a very small signal that needs extra amplification to bring it up to line level. Your tape deck AUX output is already line level so connecting that to the MIC input caused all kinds of clipping- and if you were using an amp or mixer that had clip lights you would see that right away. You fixed it by changing to the AUX input which is a line level input. Line level into line level= good.
So you have to know what your inputs and outputs are. Generally anything that is not a MIC input is line level and most outputs are also line level.
Back in the day, I always used WMT-1 matching transformers to interface a telephone system (600 ohms) with an amplifier - either to a Balanced mic input of (approximately) 150 ohms or to an unbalanced auxiliary input of 15,000 ohms.
Depends. The transformer does two, actually three things: 1) it converts balanced to unbalanced and 2) changes the levels by virtue of the 600 to 15k ratio and 3)provides AC and DC isolation from one side to the other.
A good way to change from balanced to unbalanced and vice versa is with a transformer (balun) such as the WMT1 so if you have a balanced line and want to connect it to an unbalanced input it's one way to go.
It will also increase the level and note that the WMT1a has a changeable tap on the unbalanced (RCA) side that changes the output to 150 ohms from 15k (600:150) to go into a low level MIC input.
I connected telephone paging to an amp with out a WMT-1A in the office just to see, quality was terrible. I put the WMT-1A in and it was fine.
Generally a phone system page output is line level unbalanced and going directly into a line level unbalanced input works fine. But without knowing or seeing the system and how you connected it I can't tell. Again, define terrible. Distortion or hum? Might be that it was a balanced output and connecting it directly to the unbalanced input caused hum. Maybe you had a ground loop. Maybe the level was wrong.
Also Bogen amps have a switch on an input specifically for Telco paging, if it is no longer necessary why put it in?
Or they have a 600 ohm T&R input. It's a quasi-balanced (no transformer) input and the switch on those other amps I believe just puts a 600 ohm resistor across the input. There are some systems out there that probably do like to see a 600 ohm load, maybe some that use a station port for paging. Don't know. Just use whatever works best in those cases.
-Hal
