Wednesday, February 23, 2011

Weak Bass

Listening to DSOM, Supertramp COTC, and Dire Straits Brothers in Arms, they don't sound bad, but just a bit weaker in the bass than I'd like, and not as "sweet" as I like.

I then listened to Brothers in Arms on Bedroom System.  That system really rocks when you are sitting at the headboard, which is at a wall boundary.  It's very sweet and surprisingly transparent ($2199 Revel M20 monitors which IME far surpass LS3/5A and other classics, though comparable to modern delights such as Harbeth M30 which are even more expensive), though lacks the ultimate spaciousness of the dipolar living room system, not as much difference as between being in a movie theater and watching a 32 inch TV, but going in that direction.

It appeared I could make the bass in living room system more full if I move the listening spot backwards, even just 10 inches to where I was sitting last year.  But the problem with that is it reduces the stereo separation, which I have come to value more strongly this year.

I suppose best solution would be to move both speakers AND listening position further away from the front wall.  The cancellations at mid-room are most likely room modes and are associated with the listening position in the room, not the speaker position in the room.

That's just not very practical.  My multipurpose living room is already being taken over by stereo equipment, most people would consider it bordering on some kind of insanity.  The speakers are already the recommended 3' from the back wall, taking up a rather significant chunk of floorspace.  Further movement of the speakers runs smack into the entry path (would have to move speaker to get into the room) and the couch.

I think I will go back to trying Tact room correction again, but following the strategy of setting the "room curve" to pretty much match actual measured response, except with a slight tilt away from the highs and toward the midbass (deep bass already loud enough thanks to room and corner gain).

Maybe that would be reinventing the Quad preamp "tilt" control.

I wasn't happy with my collection of 3 and 4dB boosts in the midbass that I worked out last weekend.  They seemed to cause some sort of compression like near clipping.  And they didn't seem to help much either, bass sounded equally weak either way.

I suppose there is also the "move speakers out when listening" strategy.  That sort of thing always gets in the way for me, I wouldn't listen as much, etc.  I like systems that are ready to play at a moment's notice, and moving speakers is alway a job that takes me about 15 minutes because I'm fairly obsessive about positioning to nearest mm.

This isn't really dependent on subwoofer level, the midbass weakness is mainly in the panels which now play from 84 Hz up.  Measurements suggest weakness from 60Hz - 250Hz. (Detailed measurements show a series of 4 10dB cancellations, which I tried to doctor unsuccessfully with EQ.)

I do plan to do such things as measuring the sound at potential listening positions.

The in-wall metal fireplace is clearly having a bad effect also.  Actually I now believe I can convert the fireplace into a kind of damper by lining the walls with heavy magnetic vinyl (i've got several rolls) and then stuffing the inside with the same fiberglass as is used by bass trap makers, or something like that.  The real coup would be making a "membrane" damper by putting some lossy thick plastic diaphram over the front to convert pressure to motion. Membrane dampers can be quasi-tuned also.

(As an experiment, I'm sending this both as an email and a post to my blog.)

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