Subwoofers essential???

I spent a very good Friday night listening to the following system

Naim CDX 2
Bryston Sp1.7 Preamp/Processor
Bryston 7B SST x 2
Bryston 6B SST (3 channel)

PMC MB2 Loudspeakers
PMC TB2 Surrounds and centre
PMC TLE 1 Sub

I was enlisted to help setting the subwoofer up properly (Unwise choice as I have a very basic knowledge!!) and was astounded at how much warmth and extra bass it added to the sound. Bearing in mind the MB2s offer bass down to 20 Htz frankly I was surprised.

The system was used in direct stereo mode for an hour or so whilst I pissed about with the subs position and then we spent another few hours dialling the sub in.

Sub is set on very low level, cut off at min (40HTZ) and running off its low level input.

Now this system, to my mind, is very accurate indeed so I was baffled as to why a sub made so much difference and not in a blooming, booming way. The bass remained very tight, very, very fast and frankly intergrated wonderfully with the mains. Turning the sub off made the sound unacceptable in comparison it seemed very, very bright without.

I now have no doubt that a decent sub will be my next purchase and wondered what you guys think of this experience is it normal?

 

PMC's specifications are apparently on the generous side (eg FB1 to 22Hz when IIRC one of the magazines measured it at -3dB @ 45Hz or so) and you'll notice they don't give any level tolerances. With the transmission line the bottom end rolls off slowly meaning they can quote a lower "usable" bass limit even if the level is way down from reference, resulting in a rather lightweight (albeit deep) sound. No idea whether or not this applies to the MB2 though.

 

its very surprising what a good sub will do. mine (no, not the one on my Altec Lansing set; the Ruark Logrhythm) really helped out separating the midrange and bass and the soundstaging was much more secure. they really are incredibly fiddly to set up though, as you found- very tricky to find the correct volume position where a) it doesn't overpower the main speakers and b) where the main speakers don't over power it.

 

Jools, didn't you much about with a sub before? with disappointing results?

 

I played about with a cheap one and it was pants. But the PMC one he's got seems pretty good.

I was shocked though, to the point hat today I phoned PMC to get their take on events, the chap I spoke with feels that we may have had the
Processor/ Preamp set to "small" front speakers, I will check but I reckon not as the stereo bypass option we were using is supposed to remove all digital processing from the signal.

It really was quite shocking at how little warmth and low bass was coming out of the MB2's so if that's how they sound I can't say I'm impressed. It really seemed the bass dropped about 2 octaves with the sub.
I am beginning to suspect that there may be a set up issue.

 

I wouldn't say a sub was essential allthough I think adding one can get you a long way to the kind of sound and impact you only really get with big phuk off speakers. I used one for a while, then took it out, but then put it back in again

Michael.

 

2 octaves = 80Hz to 20Hz. Sounds like they may have been set to "small" on the processor then.

 

yea, results can be astonishing.

but very good sub is a must.
and also very carefull setup. which can take even a month...............

 

:rds2: Hmmm... an AV processor, AV amps, more then 2 loudspeakers in one room and good lord even a sub could actually make a........... good sound.

Could this be yet another one of the stereo fanatic discovering the lure of the evil religion of AV surround?