Setting up an audio system is a lot trickier today than it was many years ago. In the past, speakers were designed to reproduce bass frequencies, so the need for seperate subwoofers were non-existant. When the size of speakers began shrinking, the need for subwoofers to handle bass increased.

In learning The 'Bassics' of Bass Management, you'll discover that receivers figure out what speakers should get bass digitally, and send the appropriate bass information to a powered subwoofer using a line-level connection. But before receivers were digital, bass management had to be handled by the subwoofer using a age-old technology.

Subwoofers have undergone some serious change in the past decade. Intitially, most subwoofers were passive. A passive subwoofer does not have its own amplifier built in, and is therefore connected with speaker wire between the front or all speakers. What makes it more confusing is that even newer powered subwoofers can be connected passively, which means that it is still connected in the same manner as a passive sub. This method of subwoofer hook-up is very common for those that use Bose speaker systems, or anyone with a passive subwoofer.

In the Receiver

The receiver's "yes" or "no" setting for the subwoofer only applies if you own a powered subwoofer connected to the receiver using a line level RCA style cord. When set to "yes" all redirected bass is output through a line level "sub-out" connection on the back of the receiver, thus removing the bass information from the amplified speaker line. Passive subwoofers rely on bass information to be present in

the speaker level signal, both to provide sound information and power to the passive sub driver.

The trouble with this system is that size based logic means nothing in this situation. In many Bose speaker systems, the bass module is connected to all of the speaker wire outputs on the back of the receiver, and all the Bose satellite speakers are connected to the bass module. Most people using size logic set all the speakers in the receiver to "small", and subwoofer to "yes". While logically this is correct, it is not correct settings in this setup.

What happens is that all bass information is removed from every speaker, and redirected to the line-level sub out jack on the back of your receiver. Since this cannot be connected to the bass module or passive sub, there will be no bass at all.

Configuring your receiver for this type of system will vary on how the passive sub is connected to the receiver.

Passive or powered subs that connect to the front left and right speaker lines should have the fronts set to "large", center and surrounds to "small", and the sub set to "no". The front left and right speakers will plug into the sub, not the receiver.

Passive or powered subs (Bose bass modules) that connect to all speaker terminals should have all speakers set to "large", and the sub set to "no". All speakers will plug into the sub, not the receiver.

Subwoofers with speaker level connection may have additional bass management controls at your disposal, most commonly a crossover control. For more information on bass management and crossovers, read the article The 'Bassics' of Bass Management

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