Paul McGowan writes:
Now you’ve gotten your main speaker system in order and imaging properly, according to yesterday’s post, it’s time to think about adding our subwoofer. Let’s start with a fairly broad overview and then later we can dig down deep.
Your subwoofers are going to be placed behind and to the outside of your main speakers to start with, symmetrically placed and perhaps halfway between the rear of your loudspeaker and the back wall. This will be a good starting point for us. If you are using a single subwoofer, use the same setup technique I will describe but make sure the woofer is on the right side as opposed to the left and never in the center. We use the right side, as opposed to the left, because the bass instruments in an orchestra are on that side. We never use the center because that’s perhaps the worst area for a sub to perform well in your room.
Next we have connection to deal with. How your sub is connected to your system can be of critical importance to you. In my system the PerfectWave DAC, which serves as my preamp and main output, is perhaps 18 feet from the subwoofer as the cable lays. That’s a lot of cable and that kind of load can be very difficult on a preamp or DAC to drive, especially if you have dual feeds.
On the back of the PerfectWave DAC there are both single ended and balanced outputs, which is the case with most high end DACS and preamps used as the main feed to an amplifier. It is typical that we use one of these outputs to feed the power amplifier for the main speakers and the remaining output for the subwoofer. In my case it would make the most sense to use the XLR balanced outputs to feed my power amplifier, as this is the best sounding option in any system, and then use the remaining set of RCA connectors to feet an equally long length of cable to feed the two subs. Unfortunately that’s a bad idea and here’s why.
Two 18 foot lengths of cables hanging off the back of your preamp or DAC is going to degrade the performance of the preamp or DAC because of the cabling strain you are presenting. If you doubt what I am suggesting, make the experiment yourself; drive your power amp with a 20 foot pair of XLR cables then add a set of 20 foot RCA to the output and see what it sounds like. In the vast majority of cases you’ll hear a flattening of the soundstage that you’ve worked so hard to achieve and loss of image roundness and specificity that you had to begin with. Not a great situation.
I solve this problem with a Y connector. Yup, you can get these for balanced or single ended, but single ended is certainly the more common. If you have a long length like I do, just use one long excellent cable between the DAC/preamp and main amp directly into the amp through the Y connector. Then Y off of the connector with short cables feeding the subs.
If you’re closer than I am, then certainly feel free to run two shorter cables – I would suggest 3 meters as the maximum for a dual run of cables on a preamp that is well designed and solid state. If you have tube equipment, then nothing longer than 2 meters to be on the safe side.