Subwoofer location/settings

Posted by SMR [WizOp] [IP: 194.128.83.228] on March 21, 1999 at 13:55:51
Using Mozilla/4.5 [en] (Win98; I):

In Reply to: Subwoofer location/settings posted by Tom on March 02, 1999 at 20:49:31:

Tom,

: My connections are: OUT of pre-amp L&R main - IN of sub - OUT of sub - IN of amplifier... speaker terminals to speakers (Advent's: freq resp down to 45 Hz). This is a low-level (line-level) connection... right? Is this "carefully integrated"?

This is a low-level connection method with a bit of high-level thrown in (just to confuse things). I take it the signals leaving the pre-amp are full-range, in which case to integrate ideally, the outputs from the sub-woofer to your amplifiers need to be high-pass filtered which from the sound of things is what is happening at 85Hz.

So, full-range signals go to your sub-woofer, the bass is stripped off at 85Hz and the sub-woofer reproduces this portion of the bass, the outputs to your amplifiers and then to your loudspeakers do not have any bass content. In this situation the low-pass filter of the sub-woofer should be set to a similar frequency, just about 80Hz (allowing for some overlap roll-off).

That's fine although some of the response of your Advents is being 'wasted'. Without a variable high-pass filter (at 60 or 40Hz for example) there's not much we can do to change that.

You should be using the filter in the sub-woofer, otherwise full-range signals will be sent on to your Advents in which case both they and the sub will be producing the low bass.

There is an alternative which you might like to try. Take the line-level outputs of your pre-amp and Y-Split them. One set going to the sub-woofer and the other set on to your amplifiers. In this case the Advents will produce full-range signals and you'll need to adjust the low-pass crossover of the sub-woofer to 40Hz or so, nestling it in under their response.

: I understand that the high pass crossover doesn't let frequencies below 85Hz go to your mains... what does the low pass crossover do???

The low-pass crossover controls the uppermost point at which the sub-woofer operates, allowing for the roll-off of that crossover (somewhere between 8dB and 36dB per octave). If you set the low-pass crossover to, for example, 60Hz, that will be the point where the sub-woofer starts to roll-off.

Stuart.

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