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SV Subwoofers

 

 

Subsonic Filter and Port Tuning

Your new PC-Ultra subwoofer not only comes with our “Tri-Power” port flares, but custom port plugs and variable subsonic filter which allow your sub to be “tuned” to even lower frequencies than its stock configuration. For most people and most rooms, your SVS is already configured for

the best blend of extension (how deep/low your sub goes) and output (how loud it gets at a variety of bass frequencies). However, we know that bass is a very personal taste and no two rooms will react exactly the same with any subwoofer. So we include a custom “port plug” that, when inserted into a port, allows you the user to experiment with a substantially lower “tune”.

As with all such devices, there are compromises when tuning a sub lower. Installing a port block takes some capacity from upper reaches of bass, installing two port blocks naturally limits upper bass response even more. So while you will indeed get more bass down low (where DVD and music bass is more rare, but quite exciting!), you’ll sacrifice total output capacity above the stock tuning point of the sub (where bass is more common). You should decide if the effect is pleasing on the sorts of movies and music you enjoy.

How to do it? To insert a port plug, simply squeeze the foam on one end and press the plug into a port flare until it is about 1” lower than the edge of the surface of the sub. You can remove the plug by inserting your fingertips into the port flare and squeezing and pulling on the foam plug at the same time. Be sure to select the subsonic filter point on the back of your PC-Ultra amp which coincides correctly with your new “tuning point”. NOTE: We strongly recommend you do NOT run a lower subsonic filter point than your port plug configuration would dictate — especially if you are running the subwoofer at high sound pressure levels! Moderate levels are doubly important if you put the subsonic filter into “12hz” mode (essentially turning off this key limiter). This simple table indicates the settings you should use in setting up your sub blockers and the subsonic filter knob.

PC-Ultra Tuning Chart

Subsonic Filter Knob

Stock tune (no ports blocked)

20Hz

 

 

With one port-blocked

16Hz

 

 

With two ports-blocked

12Hz

 

 

Look to the next page for a computer simulated response chart showing the reduction of upper bass when adding one, and then two port-blockers to your SVS (along with addition woofer excursion needed to keep up with the lower frequencies). The bottom line? Many customers feel the slight loss in upper bass output to be insignificant compared to the deeper response the port block gives. We let you decide.