Converting stereo to mono sounds like a no-brainer, right? Well, not so fast. There are some things to consider.
Mixing stereo L and R channels:
Converting stereo to mono sounds like a no-brainer, right? Well, not so fast. There are some things to consider.
Mixing stereo L and R channels:
Be sure to properly mix the two channels. Don't just short them together. There are audio adapter cables available that do this. They have L and R plugs on one end and a single mono jack on the other end and look like a "Y". The problem with just shorting the two channels together is that the driver circuits will load each other down causing reduced output and often, noticeable distortion. Virtually all the audio driver circuits, including headphone, consumer line level and even professional line level, are low impedance (8 - 100 ohms). They are intended to drive dedicated loads or daisy-chained higher impedance loads. With the exception of a headphone source, they are intended to drive higher impedance loads, typically 5k - 10k ohms. If your transmitter has L and R inputs, use separate L and R audio cables. If your transmitter has only one mono input, be sure the L and R signals are combined with a proper mixer circuit somewhere in the audio chain before connecting to the transmitter.
Problems with "enhanced" stereo modes:
Many modern consumer audio devices and some computer sound outputs have processing to enhance stereo separation or produce simulated surround sound. Turn these modes off! They can wreak havoc on the combined mono signal even when you use a proper mixer circuit. If you use a computer for the audio source, open the audio control window and look for a check box that enables any sort of enhanced stereo effect and make sure it is not checked.
PhilB
Yes, PhilB, and I've run into a rock wall trying to explain what you've said to a thick headed client when I provided pro audio service in the past. They thought I was creating fake work so I could charge more. But what you say is 100% true.
In my setup I have Winamp checked for mono so both the L and R outputs from the computer are each mono.
For the SStran transmitter I use the L line and one of those splitters you mentioned so I can feed both inputs for full level (since the transmitter has a built in L+R mixer);
For the transmitter with one input I use the R line from the computer straight in.
It's yet another way of managing mono.