Week 8, 2016: Adding inputs to an amplifier or receiver, L and R on headphones


Sound Advice

By Don Lindich

Week 8, 2016

Q. We have a classic Yamaha A1 stereo amplifier that still works well. It is great for vinyl because of the direct connection to the power stage, which sends the signal direct to the amplifier for very clean sound. Unfortunately, it has few inputs, all are being used and we want to add more devices to it. What amplifier would you recommend with at least four inputs, selling for up to $400?

-P.C. Warner, Minneapolis, MN

A. The Yamaha A1 is an outstanding amplifier, and you would have to spend a lot more than $400 to get something remotely comparable in quality.Fortunately, I have an extremely inexpensive solution that will allow you to keep using it.

You can buy a switch that will turn 1 RCA input into 4 RCA inputs.  They are readily available online and in stores for around $20 and usually include terminals for stereo audio and analog (non-HDMI) video.  The Monoprice #3027 is a great one and it learns remote commands as well.  See it at at this link.

Q.  Why are headphones marked for the left and right ears? Do the left and right ears hear differently, for example does being left or right handed affect an ear as being dominant? With digital and all the advancement in sound technology, is it still relevant to have headphones marked left and right?

-Gary Geist, Blaine, MN

A.  Your question about superior hearing in the specific ear being related to the dominant hand is better posed to a medical doctor or audiologist, though I admit you have piqued my interest and I will be doing some research on the subject.Regardless of the answer (and I suspect that both ears hear equally well in normal conditions) that is not the reason headphones, and for that matter amplifiers, have specifically marked left and right channels.

When a stereo recording is made, there is a left side and right side. That is the meaning of stereo. Putting the headphones on properly ensures the recording is heard in the way the producer intended.  If you put the headphones on backwards the stereo image will be reversed, so instruments meant to be on the right will be on the left, and vice-versa.

It is easy to understand this concept if you use photography as an analogy.  Imagine you are holding a color film transparency (such as a 35mm slide) up to the light and viewing it. In held one way, you are viewing the scene as it appeared in real life. If you flip it around, the scene would look much the same but things that were on the right would now be on the left. You could also make an analogy of holding a photograph and looking at its reflection in a mirror.  You would see a 100% accurate image with all the detail present, but the image would be reversed. That is what happens to the sonic image when you put headphones on backwards.

There may be practical reasons to make sure your headphones are on properly, as well.  Most people are right-handed, so the microphone and button are on the right to make it easier to control.  This is the only right/left dominant reason for headphone design I am aware of.