© 2011 Steve Feinstein and Atlantic Technology
Atlantic has a really nice, affordable in-wall sub, the IWTS-28 SUB (http://www.atlantictechnology.com/default.asp?NodeId=141 ). It can be used both actively and passively. When we say the IWTS-28 SUB can be used both actively and passively, does everyone really understand what we’re talking about?
The “passive” IWTS-28 SUB
A passive subwoofer has no dedicated amplifier of its own. It runs off the same amplifier that powers your main left and right speakers. You can think of a passive sub as adding the woofer section that’s missing in small speakers. With a passive IWTS-28 SUB, the little 4 ½” 2-way speakers that are powered by your receiver become 8” 3-way speakers, powered by your receiver.
This is a great solution for when you want to add some bass oomph, but you don’t want the expense or complication of a separate, stand-alone powered subwoofer.
Here’s how you connect it in passive mode. This illustration is lifted directly from the 28 SUB’s owner’s manual, but since no one ever reads owner’s manuals, here it is for the first time! (See figure 1.) Remember, your main left/right speakers should be at least 8 ohms impedance so when they’re paralleled with the 8-ohm individual woofers of the 28 SUB, the combined impedance doesn’t fall under 4 ohms per channel. Check your receiver’s owner’s manual for more details on impedance.
Used passively, the IWTS-28 SUB has pretty “normal” sensitivity, so it will blend pretty nicely with most speakers and fill them in at the low end. Just use your receiver’s bass control to touch it up to your liking.
The “active” IWTS-28 SUB
This one’s easy, because it operates exactly the same way that any powered box subwoofer works. You take an RCA cable from your receiver’s ‘sub’ or ‘LFE’ out jack, connect it to the input on the Atlantic SA-180 monoblock amplifier, and then run your speaker wires from the SA-180 to one set of terminals on the 28 SUB. Make sure the 28 SUB’s terminal straps are in place!. This is a full-fledged powered subwoofer, with its own amp, volume control, 3-position EQ, the whole enchilada. (See figure 2.)
The “sneaky” IWTS-28 SUB
OK, you’ve got the difference down cold between a passive and active IWTS-28 SUB. You like the idea of an active sub, because you like being able to control its volume independently of the rest of the system. But…you don’t want to actually pay for an SA-180 amplifier.
Are you cheap? No, you may be clever! (Well, ok, you’re probably cheap and clever.)
In your closet (or downstairs on the basement storage shelves or up in the attic in its 20 year-old box or wherever), you probably still have that old Pioneer or Kenwood stereo receiver you bought when you first got married. Still works perfectly, and you didn’t have the heart to toss it out when you got your fancy-schmancy new surround-sound system. Good move.
Here’s what you do: Run two RCA Y-cables from the front L R “Pre Out” jacks on your surround receiver (virtually every decent surround receiver has “Pre Out/main in” jacks) to the “Aux In” jacks on your old stereo receiver. (See figure 3.)
Make sure the jumper wires on the 28 SUB are removed (see figure 1 again), and its front-panel Low Pass switch is on. Connect one woofer on the 28 SUB to the Right channel on your old stereo receiver and connect the other woofer to the Left channel (it doesn’t matter which one is L or R). Turn the stereo receiver’s selector switch to “Aux.” Now your old receiver is powering your 28 SUB, and your surround receiver is controlling the system’s master volume (including the overall subwoofer level) but you can tweak the bass level and EQ with your old receiver’s volume and bass control. This is one sneaky, clever, and very effective powered IWTS-28 SUB system. (And you didn’t pay a dime extra for the “powered” portion. It was sitting in your basement all along.)