Feeding a sub

I was ready to jump onto a different subject than setup today but a number of you have asked me to at least touch on how to connect a sub and make sure it integrates properly in the system – which is interesting and surprising to me because I have come to learn most people don’t have subwoofers. Go figure. To me that means most people don’t have or know what true bass is, or don’t listen to music that requires it, or think they already have it. I hope that if you have a really good high-end system that you do, indeed, have proper low bass available to you for that extraordinary recording that requires it – and if you can achieve that without a sub, my hat’s off to you and your loudspeaker designer. Most people don’t know what they’re missing.

The thrill of having a pipe organ rattling your pant leg, the added realism of the flamenco guitarist and dancer combo pounding on a wooden floor – the impact of which is shaking your own room as if they were in it, the annoying air conditioner rumbling on the Cowboy Junkies Mining for gold intro when Margo Timmins is singing quietly in the church, the almost never heard New York subway rumbling past in an old Mercury recording in Carnegie Hall – are all part and parcel of what makes a good system a great system IMHO. And for many of us, we don’t have the required equipment to appreciate the added realism and enjoy these hidden treasures buried deep within our music. For that, you probably need a subwoofer.

But be that as it may, I’ll get off my soapbox and first take a look at the history, then take a look at some of the options and their good and bad points.

If you look up the word Subwoofer in Wikipedia, it credits my friend and former partner in Genesis Arnie Nudell as the inventor. The article suggests that when he, John Ulrich and Cary Christie (the founders of Infinity Loudspeakers) first introduced the Infinity Servo Static in 1966 – which coincidently is the same year I graduated from high school – the included servo subwoofer was the first to be sold commercially. I haven’t any clue if that’s true but what I do know is that because the Electrostatic panels that were used to create the Servo Statics did not have the ability to produce much bass, there really wasn’t any choice but to augment them with a separate woofer – if a full range system was to be created.

Whatever the facts are the subwoofer era, as an add on device to home stereo systems, was off and running and has been an essential category ever since. It lost favor for two-channel systems somewhere in the late 1980′s, early 1990′s but was revived again by the home theater crowd who are still the largest consumers of the category.

At the beginning of the subwoofer era, around the late 1960′s, most powered subwoofers had only a high level input that was meant to be fed from the main power amplifier output. This arrangement was created out of convenience, rather than necessity, as the actual wattage from the main amp was never used to power the sub itself. No, the powered subs with high level inputs took the output of your power amplifier and necked it down with a few resistors so it would match the same level as the input to the main power amp. The designers of these subs did this because it made it “easy” and “convenient” to connect the subwoofer since it was next to the main loudspeakers anyway.

As subs became more popular and as the home theater folks started getting interested, the low level RCA input was added as well as fancier crossover options, servos, setup guides, wireless connections, etc. Before too long we found a situation where almost none of the modern powered subwoofers have high level inputs anymore and they are almost all outfitted with a low level input only. Some companies, like REL, still have high level inputs on their loudspeakers – but it’s pretty rare.

Tomorrow let’s take a look at the advantages and disadvantages of both input types, then we’ll look at connecting them up.

Paul McGowan – PS Audio, Intl.