An alternative to powered sub woes?


Yesterday, I took home a trial a REL R305 sub to go with my C220/MC252 and Sonus Faber Guarneri Homage. The room is 11x14x9. I am driving the REL from the MC252's speaker posts (as recommended). I read all the instructions about proper placement and setting of level and xover points, etc. I tried a bunch of different level/xover settings and room positions (in 1", 1/2" and even 1/4" inch increments) and angles.

Four hours into this and I still haven't found anything close to satisfactory - let alone an improvement in sound over my sub-less set-up. I am getting more bass, no doubt about it, but I don't like the it's quality and how it integrates with rest of the sound spectrum.

When it comes to subs, people are often concerned with lack of speed but what I keep hearing is almost the opposite - the sub seems to beat the Guarneris to the punch and the two just don't seem to "play well together". It's hard to describe it in words (perhaps coherence is the word I'm looking for), but easy to hear.

I will spend some more time on it tomorrow - after giving my ears and head a chance to recover, but I believe that what I am experiencing is a significant and hard to reconcile difference in sonic signature - which should not be too surprising given the REL's digital switching amp.

Another problem is that more bass = more room acoustic problems. I have very limited flexibility in terms of positioning speakers and listening chair and there are 25 and 50Hz peaks that are hard to defeat and are now accentuated.

As I was going through this, I remembered reading an article in some audio magazine about this very problem of smooth integration between subs and the rest of the system and room acoustics. The writer thought that, in many cases, a better solution would be to take the low-level signal off the pre-amp, pass it through a digital eq (to perform low-pass filtering and equalize away room problems), send it to the same model amp being used for the main speakers, and then go to a passive sub-woofer.

In other words:

pre --> power-amp --> main-speakers
|
|--> digital eq (low pass + room eq) --> power amp (same as above) --> passive sub

According to the writer, this would have several advantages:

1) Takes care of room eq problems and allows an low-pass xover curve to match the main speakers roll-off. Gives more flexibility in positioning.

2) Using the same amp for main and sub would keep similar "sound signature".

On the down side, cost (ideally another McIntosh MC252) and the fact that passive subs are not that easy to find anymore.

The other alternative is to forget this subwoofer thing altogether (this system is a pure 2-ch, music only system, not a home theater) since the pluses from that extra bottom octave punch come with a problems of their own.

Any thoughts? Has anyone else given up on subs for similar reasons or tried the eq +matched amp + passive sub route?

Before going all out (or forgetting subs altogether), I am planning to find a passive sub, use a spare, older, McIntosh amp and Behringer DEQ2496 and see what comes out.

Alberto
__________________
Main System:
McIntosh: MCD201, C220, MC252, MR80
Thorens TD125mkII, SME 3009II, Clearaudio Maestro
Sonus Faber Guarneri Homage, AKG K1000, Sennheiser HD580
as1963

Showing 1 response by swampwalker

If you have two very specific room node peaks and no significant valleys, you might try reading up on the Rives Parc bass equalizer. It will allow you to precisely attenuate those peaks; its eq is parametric and fully adjustable, IIRC. They even have a new one with an amp built in for a passive sub.