How to add a Subwoofer to 2 channel stereo setup?


I hope this doesn't sound stupid, but I am looking to add a subwoofer to my system, but am somewhat unsure about how to do so. I have both a stereo preamp(Classe CP-50) and amplifier(actually a couple of stereo/mono amps- Monarchy Audio SM-70 Pros) which I use to drive my front speakers. However, as they are small bookshelf speakers, they have rather limited frequency response only going down to about 70 Hz or so. I am looking to add a subwoofer to extend the bass response, but don't know how to connect my sub. To what output?

I have tried outputting the signal through a line-level sub/LFE interconnect directly from my DVD player's Digital Coaxial out, and the 5.1 channel analog audio output to my subwoofer's(Sony SW-M 500 or something like that) line-level input while of course outputting the front speakers from the Left and Right channel outputs to my preamp, but this doesn't seem to work as there is no sound coming from my sub although the front speakers apparently sound fine. My preamp being only stereo does not have an "extra" line-level input/output for a subwoofer, so I don't know what to do.

I don't know if it means anything, but I believe I have an "active" powered subwoofer, as I must plug in a separate AC cord into the wall. It also has a volume control, frequency response, phase control and everything.

I am hoping to upgrade my speakers to a more full-range model to match my recent amplifier upgrades(in both sound quality and frequency range), but until then is there anything I can do to add my sub?

Also, does anybody have any good speaker recommendations to go with my above mentioned equipment?

I am seriously considering Totem Arros, but they only reach about 40 Hz according to Totem's specs. I have given thought to some others, but given both aesthetic, space and budget constraints(maybe $ 1K for a pair of speakers used), it has been a difficult search.

Anyway guys, thanks for your help, and take it easy.

Thanks,
The Audio Novice in training ;-)
audio_obsessed_novic
Wrongo bongo...I use a single channel summing REL and there is no phase cancellation at all. None. Zero. Also, I listen to modern recordings all the time (especially acoustic jazz trios lately) and the bass is usually NOT dead center...often it's panned by the engineer more to the left or right of center although it varies (and the lowest notes are not directional but may seem so from aural cues from overtones). Brad Mehldau's stuff is a good example...bass middle to one side, drums middle to the other, piano across the middle.
I would first check your DVD manual to see if there is a configuration setting that downmixes audio tracks to 2.1, with .1 being for the subwoofer output.

If a music dvd or cd has no dedicated .1 track (as most normal cds do NOT), then there is no signal coming out of the subwoofer connection.

There may be a setting on your DVD player that does mix 2 channel audio discs to synthesize the .1 output.

If it doesn't then you would need to ensure that the DVD player is sending downmixed full range audio to the left & right outputs which are then connected to your Class Pre-amp.

From there, if it were me, I'd simply buy some rca splitters so that you can run a set of rca cables to both the sub L/R line level inputs and L/R inputs to your power amp.

Your speakers would get full range audio - so no 'bass management' - but it seems you run them this way now anyway.

I don't think there is any phase cancellation - if there were then your main speakers would see the same effect.

This is how I have my sub set up - get plenty of bass.
I've just started using a sub with full range speakers. Although my ML Summits go down to 24 Hz, I have a deep (-10dB) null at ~60Hz, and couldn't really change their position in my family/listening room to address it. I just got the new ML BalancedForce 210 sub, and, at first blush, looks like it will really smooth out that null, while further "energizing" the low bass region.

However, I believe the need for adding sub(s) to a full range speaker is very room/system dependent. I have two audiophile friends running ML Summits in smaller rooms, and both sound exquisite as-is, so sometimes it could be overkill.
Actually, modern recording have "stereo" bass, and is not summed to the middle. Older recordings are ther ones that have the bass summed, and this is done on purpose because with record Lp's, if you have out of phase bass, it could actually cause the needle to vibrate so much and pop out of the groove.
AON-

REL subwoofer is the easiest to integrate into any system.
Otherwise, check the Sony site for correctly setting up your sub.

Keep me posted & Happy Listening !