Subwoofer connection query

[Willferox]

I recently purchased a Wharfedale SW-150 for my little room. I usually connect a sub to my CA540A via a SINGLE phono-phono lead, using the pre-out LEFT (white, mono) input on my amp. Just now however, I connected it to my amp using a standard phono cable, ie to the left AND right input of on the pre-out. When I connected to L and R, the subwoofer seemed to be louder/more powerful, which I like. Am I doing anything wrong using standard phono instead of the usual mono-single-phono sub cable plugged into the L channel of the amp (ie the mono channel)?

 

[Overdose]

http://www.whathifi.com/forum/home-cinema/subwoofer-connections-0

This may help, but the Sub manual and manufacturer would be the best place to ask for advice. Drop them an email.

 

[Deliriumbassist]

You would tend to use a mono signal for film from an A/V amplifier. For most music media, you don't have a 2.1 track- you have 2 channels. So by going mono out, you're only getting the bass from the left channel, by how you used to wire it. By adding the second phono lead, you're now getting left AND right channels through the subwoofer, so you're probably getting bass that you weren't hearing before.

 

[Willferox]

Why then are subwoofer outputs on amplifiers usually mono ie one phono input?

 

[Anonymous]

In the end, the signal has to be mixed to mono because there's only one speaker cone in the sub. So you can either have a ready-mixed mono output from the amp (I haven't seen your manual but I'll bet it tells you to connect to one channel and crank up the volume a bit), or feed a stereo signal in and let the sub convert to mono. Other than volume, you don't lose much with the single wire because bass isn't very directional and tends to be present on both channels. You'll obviously get a lower volume if the sub has two inputs and you only connect one of them.

 

[Deliriumbassist]

I was talking in the sense of your own amplifier specifically, after looking at the back of it, and it having L+R preout rather than a "dedicated" mono subwoofer output. As the above poster rightly points out, the signal will get mixed down to mono anyway in your sub. This will occur in amplifiers with a dedicated mono subwoofer output using some form of crossover. Specifically with your amplifier (and any other amplifier outputting purely out of a stereo preout) you weren't giving your subwoofer the chance to mix down to mono, because you were only sending it half the information from the track. When there's more signal, there's more bass. That's my simplified understanding of it anyways.