basic question about subwoofers

[edlchiang62]

Sorry about this basic question about subwoofers since I've only had a 2-channel system all my life. Is there anyway to incorporate a powered subwoofer into a 2-channel system? I have a 2-channel tuner/preamp with 3 pairs of main outputs for multi-room capability. Can I hook up a subwoofer into a second pair of main outputs or must the preamp specifically have a subwoofer output? Again sorry for this dumb question.

[Geoffcin]

Sorry about this basic question about subwoofers since I've only had a 2-channel system all my life. Is there anyway to incorporate a powered subwoofer into a 2-channel system? I have a 2-channel tuner/preamp with 3 pairs of main outputs for multi-room capability. Can I hook up a subwoofer into a second pair of main outputs or must the preamp specifically have a subwoofer output? Again sorry for this dumb question.

The short answer is YES, absolutely! That's exactly what I do in my audio setup, and it's pretty easy, especially when your preamp has multiple output lines.

Most subwoofers accept both line level (RCA jacks) and high level (speaker wire) inputs. If you decide to go with the RCA inputs, you can usually adjust both the crossover frequency and volume level of the sub directly on the subwoofers amplifier. The preamp will send a full spectrum audio signal to the subwoofer, but the subwoofers high pass filter will allow only the lower frequencies to be amplified. With my subs I can adjust the hinge point of the filter, and phase. If done correctly this makes the subs completely invisible sonically.

[markw]

Maggies are polite enough to simply ignore what they cannot handle, bass wise, so they can be run full range and you can then blend in the Velo sub to fill in where the maggies dropped out. All in all, a vey clean marriage can be made.

You may need to experiement on what works best for you. I find my 1.6's blend with vy velo with the xover set around 50 hz or so. YMMV.

[iano]

I've been doing this with 2 channel for years. I use Dynaudio audience 42 bookshelf monitors with a 12" powered sub. The sub is fed a line level signal from the 2nd set of speaker terminals on my Rotel integrated. I borrowed a friends HT receiver which uses a dedicated subwoofer output terminal and compared results, in my opinion running line level definately sounds nicer.

I've never owned floorstanding speakers, and this is for 2 reasons. They are too big for my listening space and I believe stand mounters offer a much more sharply focused and balanced sound.

Tuning a setup like mine isnt at all difficult. If you set the roll off frequency absolutely dead on the sub vanishes. It can take a while to perfect this, you'll notice some tracks will sound fine and others may have some quite nasty holes in the frequency spectrum. Don't resort to simply adjusting the high pass frequency and the amplifer gains on the sub - move it to another spot in the room and see if it improves.

[edlchiang62]

I appreciate the responses to my question. However, please fogive my next question. In some pictures of the backs of some subwoofers I see only 1 RCA input yet on my preamp the RCA outputs come in pairs (L/R). How do you take a L/R outputs and plug it into only one RCA input? Again sorry for this question.

[markw]

In some pictures of the backs of some subwoofers I see only 1 RCA input yet on my preamp the RCA outputs come in pairs (L/R). How do you take a L/R outputs and plug it into only one RCA input?

Simply put, cross off any powerd subs with only one input off your short list. They are designed for the HT market where one LFE output is the norm. You would need to buy a signal combiner, which is usually combined with a crossover. This would be an unneeded expense since it can be avoided without sacrificing anything.

[Geoffcin]

I appreciate the responses to my question. However, please fogive my next question. In some pictures of the backs of some subwoofers I see only 1 RCA input yet on my preamp the RCA outputs come in pairs (L/R). How do you take a L/R outputs and plug it into only one RCA input? Again sorry for this question.

Most receivers have one RCA output for the (.1) LFE channel. If you get a sub with dual voice coils like my Velodynes, you MUST get an RCA splitter so you can send a signal to both sub inputs. If you don't, one of the voice coils will not be energized.

[markw]

If you get a sub with dual voice coils like my Velodynes, you MUST get an RCA splitter so you can send a signal to both sub inputs. If you don't, one of the voice coils will not be energized.

It probably has one amplifier and one voice coil. My velo states in the manual that even though it has a L/R input, feeding a (LFE, or mono) signal into one channel will result in he same output as feeding the signal into both inputs.

After all, the first steps that go on inside that powered sub is to combine the two stereo channels into one channel. that one channel is then amplified and fed to the speaker.

Now, I have an old passive sub that has two voice coils but that's a different animal.

In any case, a splitter costs a few bucks almost anywhere if it helps one sleep at night.