In yesterday’s post I mentioned I added a single sub to the setup in Music Room 2 and got great results. Several of you asked me why I didn’t add two, which is always my stand on subs, and where I got the sub. I wanted to also touch on how I connected the subwoofer as well.
Indeed, whenever possible, two subs are better than one – but not necessary. The advantage of a separate left and right sub is primarily in the setup of the room – one on each side makes placement of the sub actually easier as it takes over the room better at those lower frequencies. Further, if you need to run the sub at frequencies higher than 80Hz (perhaps you have a pair of bookshelf speakers) or would prefer to have a gentle rolloff on the subs low pass filter (determines how high the sub goes) then the sound of that subwoofer can start to become a bit directional.
So my rule of thumb regarding subwoofers is to keep the subwoofer from going too high, hopefully never higher than 80Hz, keep the slope of the low pass filter to no less than 12dB/octave and adjust the sub level so it never stands out by itself; instead it helps the main speakers sound as if they have deep bass.
If you’re using a single sub, never place it between the two main speakers, always place it either to the left or the right of the mains and NEVER rolloff the bottom of the main speakers. By this I mean many subwoofers have an in and an out set of connectors where the output connectors on the subwoofer are called a high pass filter. This filter is used to make sure the main speakers don’t have to work as hard going down in the bass area – and allows the subwoofer to do the work instead. This notion of rolling off the main speaker’s bass response was popular a few years ago in home theater circles, but trust me, it’s not a good sounding plan. Let your main speakers do what they were designed to do and use the subwoofer to fill in what they don’t – and almost no full range loudspeaker gets down to 18Hz with any authority so you pretty much need a sub.
With respect to connecting the sub, in many cases I prefer to use the subs high level inputs and tap off of the main power amplifier’s output. This method doesn’t use any of the main power amp’s wattage – just its output signal – the sub’s power amp doing all the work. What it does accomplish is two things: removes the extra cable load off of the preamp or DAC feeding the sub and helps maintain the sonic characteristics of the main amp giving you a more seamless blend.
The subwoofer I am auditioning is a new product from a Colorado based company that is extraordinary, but they did not include a high level input. I had to make my own and tomorrow I’ll tell you how.
Paul McGowan – PS Audio, Intl.