Adding a Subwoofer to a 2-Channel Music Listening System (Polk PSW108 Review)

I review a lot of audio gear, including many turntables. And I’m a big fan of vinyl. So in my office, I have a listening setup that includes a 1981 vintage Pioneer SX-6 receiver, a reference turntable, and a pair of PSB Alpha P5 bookshelf speakers. I quite recommend those PSBs, by the way, if you looking for a great pair of compact bookshelf speakers below $500. Before I acquiring these I went through options from JBL and Polk, and the PSB Alpha P5s have been a real upgrade. However, while their 5.25-inch woofers provide solid bass, I’ve been having a hankering for something with a little more low-end punch—more than any bookshelf speakers can deliver.

So I decided to add a powered subwoofer into the mix. Specifically the PSW108 from Polk Audio. This post is a bit of how-to, a bit of review, and a bit of problem-solving.

Picking a Subwoofer

I chose this particular subwoofer for several reasons. First, I’ve had a number of Polk Audio products and reviewed many others. Even though PSB has taken over my bookshelves, I still think Polk makes some good gear for the price. At $199, the PSW108 is affordable, and with a 10-inch front-vented woofer, it had the specs I was looking for.

Second, the subwoofer needed to fit under my desk. The wall in my office where the speakers are located is all bookshelf, with my desk in between. So I was looking for a solution that would fit within the 28-inch gap between the pedestals of my desk, while still leaving some room for my feet. The PSW108 is 14-inches wide so that works. Its front port also means it can be placed close to the wall without distorting.

Third, the subwoofer needed to have speaker-level inputs and outputs because this system’s receiver doesn’t have a separate subwoofer output.

Making the Connections

Hooking everything up was relatively straightforward. The bookshelf speakers were disconnected from the receiver and instead connected to the L and R speaker outputs on the subwoofer. Then, new speaker wire was used to connect the L and R speaker outputs from the receiver to the corresponding speaker inputs on the subwoofer.

Plug in the subwoofer to power, and it’s good to go. Almost…

Adjusting the Audio

The back of the PS108 subwoofer has two controls that come into play as part of the setup: Low Pass and Volume. Low Pass is used to determine the crossover point—when the subwoofer takes over the audio versus passing it through to the bookshelf speakers. With smaller speakers like these, the typical low pass setting is 100Hz. Volume is what it sounds like: the level of sound coming out of the subwoofer.

Adjusting these two settings takes some time. It’s a matter of tweaking them while sitting back and listening to music until the bass gets the desired punch without being distorted or too loud for the mix. When it’s perfect, the bass blends in perfectly—you can’t even tell that it’s coming from a different source than the rest of the audio—but the low end is suddenly much more muscular than a pair of bookshelf speakers should be able to produce.

The Hiccup

I had everything adjusted perfectly, but then I ran into a problem. When I turned up the volume, items on my desk and shelves vibrated. The subwoofer had small feet, but sitting on a hardwood floor they were clearly not up to the task of preventing vibration from traveling.

I thought about adding some foam to the mix, then remembered that I still had a sample ZaZen noise isolation platform from ISOAcoustics. You can read that review here, but the ZaZen is a thick slab of solid material with four sound isolation feet mounted in the corners. It was rated for 25 pounds and the subwoofer was 26 pounds, but it fit perfectly on the platform and I figured (hoped) there was probably a little room for error on the weight rating. And the ZaZen effectively killed that vibration generated by the subwoofer. Problem solved. The company sells individual “Pucks” that are specifically made for speaker and subwoofer sound isolation, but the platform turned out to be an easy and elegant solution.

To celebrate the final setup, the first album I put on the turntable was Ghost in the Machine by The Police, and it was glorious.

Recommendation(s)

I have a few recommendations out of all this.

First, if you have a 2-channel audio setup that you use for listening to music and wish it had a little more bass kick, consider adding a subwoofer to the mix. It can make a huge difference.

Second, the Polk PSW108 has been a welcome addition to my audio system. It strikes a nice balance between cost and performance, and the five-year warranty doesn’t hurt. There really isn’t much I would change about it. I have no idea how it would perform in a home theater setup where it’s handling movie sound effects, but for music, I’ve been quite happy with it. It was money well spent.

Finally, if vibration is raining on your music parade, check out the solutions from ISOAcoustics—they work.

Disclosure: As an Amazon Associate, I earn affiliate fees from qualifying purchases.