And why? Because mono is one of the very best, and certainly one of the cheapest and easiest ways possible for you to finally get your System "dialed-in" and sounding better than it ever has before!
Before we go any further, let's take a look at the two most important reasons why that is:
The first is simply that, no matter what your system is; how old it is; how fancy it may be; how much or little it may have cost; whether it's tubes or solid state; or even what kind of speakers you're using, if you're not listening to it through headphones, you're not listening only to your system but also to the room that it's playing in, and that's the one element of your listening chain that has, until now, almost certainly gotten the least of your audiophile attention.
The second is that a mono recording (or even a perfect simulation of one, like I'm going to show you how to make) has, unlike signal generators, test discs, or any of the other tools available to you, all of the elements of music (broad and varying frequency range, multiple complex tones playing all at the same time, attack, decay, full ranges of both harmonics and dynamics, etc.), all arrayed for your easy use, and all coming to you identically and simultaneously from two separate points (your speakers) in your listening room.
What that will give you is a near-perfect test for both your system and your room and also the most effective tool available for making sure that your speakers are perfectly placed to produce the very best possible image and soundstage. I'll tell you how to use them in coming parts of this series. First, though, let's talk about how to get your system set up for mono:
If you've got a mono LP and the ability to play it, you're already good. One of the playback programs on your computer that supports mono playback (Audacity is a good example) can also be a source to consider. Because whatever you use is already mono, it will always give a true mono source signal, and nothing further needs to be done. You can, if you wish, and if your preamp or receiver has a "mono" setting, also switch over to mono, but, because your source is already mono, it shouldn't do anything at all. If it does do something, and things sound noticeably different in the mono position, you will already have gained valuable information about something strange in your electronics.
If you don't have a mono LP or other mono source, but do have a mono setting on your preamp or receiver, use it. It will sum the right and left channels of your stereo source into a single mono signal and then split that signal into two identical mono outputs to be sent (finally) to your speakers. Because summing a stereo source will result in cancellation of material that is out of phase in the two stereo channels, sonic differences between mono and stereo playback (other than just the loss of stereo ambience and directionality) are, in this case, not an indication of anything wrong in your preamp or receiver, so don't worry about them.
If you don't have a mono setting, you can still create a mono signal to send to your speakers: One way is simply to use a "Y" adapter to split the output of one of the channels (either one--it doesn't matter) from your stereo source and plug it into both the right and left inputs on your preamp or receiver. Because this is only one channel of musical information, it will sound different from playing your stereo source in stereo, so, once again, don't worry about it.Once you've done whichever of those options is best for you, you'll be set up for mono. In the next part of this four-part series, we'll talk about how you can use mono playback to improve the sound of your system.