Q&A: Using the A/B Speaker Selector for Comparisons

Q: Hi, can I use the speaker A/B switch on my receiver/integrated amplifier to compare two different speaker cables with both sets of cable connected to my loudspeakers, or will it cause problems for the amplifier.

A: In addition to its normal function of facilitating multi-zone audio, the A/B speaker selector switch on an  amplifier can be quite useful for making comparisons between loudspeakers, and yes, even speaker cables.

Because the Speaker A and Speaker B binding posts represent the same amplifier connection, it is possible to connect two different sets of speaker wire to the same speaker using these outputs without damaging your equipment. The only caveat worth mentioning is that a small amount of capacitance would be added as a result of running the second cable in an additional open circuit. However, this isn’t cause for alarm under most circumstances.

Obviously, comparing speakers using the A/B switch of your amplifier avoids this issue; however, there are a couple hurdles to jump here as well. First and foremost is the matter of placement. Ideally, the speakers under comparison would be placed identically. One solution to this was thought up by the folks at Harman, who use a large turntable to shuffle speakers under comparison for their listening tests. If you don’t happen to have such a device in your home, one alternative is to stagger the speaker placement in the following pattern:

Speakers lined up for the 2010 Audioholics 1k loudspeaker faceoff. Note that each pair gets equal spacing thanks to the A B C D - A B C D arrangement.

While not a perfect solution, this system does give both speaker sets equal spacing between the pairs. If you’d like to go further, you can always do a second round of listening with the A & B positions swapped to help ensure that placement didn’t skew your results.

The second hurdle to mention is level matching. Since you’re using a simple A/B switch on an amplifier, you won’t be able to level match using the trim levels on your receiver or pre/pro. Instead, you’ll have to use your own test tones and an SPL meter to find the appropriate amount of compensation, and manually adjust the volume when switching accordingly.

With these problems out of the way, you’re ready to start making speaker comparisons, for which we have one final tip: invite a friend over. An extra set of hands can help with the switching / level adjustments so that you can focus on listening. A friend can also help you perform a blind test, which helps to remove bias as you won’t know which component is playing. 

Summary

If you’ve got an amplifier or A/V receiver with an A/B speaker switch, you’ve got an easy tool for making speaker and speaker cable comparisons. If you also happen to have a friend available to help you, it’s even possible to set up your own blind test at home. While there are a few bumps on the road to making useful comparisons, there’s no question that the A/B switch’s utility extends beyond multi-zone audio. Happy comparing!