atcomsystems.ca/forum Forums TDM Business Telephone Systems Nortel Telephones & Systems Low Volume Music on Hold

I've tried 2 different cables and have turned up my portable cd player all the way. I can hear music if my background music is turned all of the way up...but the music on hold is barely audible. Is my headphone output too low of an output for this? Thanks for the help!

Rich Basinger

If you are using a portable discman type I have run into those not providing enough volume. I would recommend going to a guetto blaster type. Just my 2c worth

Actually, the most common problem is using a mono plug in a stereo source which so shorts the output. If this might be your problem, try getting a stereo to mono adapter plug.

The problem is mismatched impedance. The headphone output of the Discman is 8 to 32 ohms: most of the sound energy is in current, with very low voltage. The MOH input of a phone system is line level - about 600 ohm, so the MOH is expecting a little more voltage. Radio Shack used to and may still sell an 8 ohm to 600 ohm audio transformer, or you could use a 70 volt P.A. transformer with the MOH connected to the 5 watt tap, which is about 600 ohm. (It shouldn't overload the MOH because the Discman output level is nowhere near that of a P.A. amplifier.) One other thing: with this setup, it also helps to put a 100 ohm resistor across the Discman output, in parallel with the transformer.

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Together We Prosper

[This message has been edited by Baron-B (edited August 02, 2005).]

Baron-B is right, however, the Norstar MOH functions just fine without a matching xformer.

I have never had problems with any music source on any Norstar (cross my fingers). Using a discman or a big ol' boom box.

I see a couple easy fix's for you. Double check that you are on the correct pair going into the KSU (yellow/orange). If so, you can change from a mini stereo cable to a mini mono cable or visa versa.

I dont see the need to do anything else here.

You might try reversing the input leads and repunching them. This has worked for me.

You guys are right in using a stereo/mono adapter and connecting directly to MOH. One problem I see with the stereo plug is that instead of hot and ground connected, the left and right hots get connected, so what MOH receives is left-right differential, which would sound weak.

HOWEVER, I still swear by using a transformer, if for nothing else but electrical isolation; I learned this the hard way. One time I hooked up a cheap radio to an ITT 801. The radio did not use a power transformer: they simply had a dropping resistor and a rectifier diode directly on the AC power line. I hooked it up, and of course one side of my input had a path to the house current. Next thing I hear a loud bang and there's paper and foil confetti from a blown capacitor all over the KSU. Fortunately the MOH was on its own replaceable card. That's just something for you all to consider.

The stereo/mono adapter simply "Y" connects the left and right from the source. You still only use one hot lead and the ground to connect to the KSU (the mono side of the adapter). A mono plug being used in a stereo headphone jack actually shorts out the right channel on the music source which is hard on the output transistors/ic.

The MOH is supposed to be an isolated input already on the KSU so no external transformer should be required. However, like "skwirl" stated earlier, I have also reversed the polarity on the input and found it to work better as well.

[This message has been edited by twisted pair (edited August 05, 2005).]