Deqx powered systems from Salk, Selah, Lyngdorf and a few others are probably the current gen lineal descendants of the approach described by your Infinity Preludes. These are all actively crossed, multi-amped systems (the subwoofer amps are now BYO), and they now add digital room correction. Not precisely analogous to the Preludes, but these are probably the best for fit your "current technology" criterion that I know of.
Marty |
Drew,
Nulls can be fixed with EQ - with some limitations. I have Eq'd to +12db with a pair of Velodyne SPLR 8 subs (1000wpc internal amps IIRC) and achieved excellent results. To muster +12db, I doubled down on the SPLR's internal EQ and added extra maximum EQ in my SMS sub controller. This approach IS DEFINITELY NOT recommended by Velodyne, but I did it anyway. Make no mistake, it worked....in my application.
I suspect that the real reason this approach can work well in music only systems is because my max EQ occured below 35hz where the pair of 8" drivers in the subs conked out. In actual use (playing music) there's little sustained signal there. OTOH, the EQ'd subs performed like a champ running test sweeps! I won't disagree with you that this approach lacks "elegance" and, in fact, could prove risky if amplification demands exceed the power available.
The real point I was making Re: DEQX powered speakers, however, is that straight EQ (including bass nulls) is the theory behind the design. I agree that you have correctly pointed out one significant limitation of the "brute force" approach.
Marty |
Spatine,
In theory, one great advantage of subs is that they can be placed where they work best (against the walls) - which is almost always far from where main speakers work best (away from the walls). You lose this option when the subs and mains share a cabinet.
When bass is generated out away from the walls in a room, the omnidirectional, long wavelength signals (i.e. bass) will reflect back off the walls and cause cancellation (nulls, or dips in response) at some particular frequencies and reinforcement (peaks) at others. Near wall placement reduces this bass effect because the strongest reflected signal is virtually coincident with the original signal. There is nearly uniform reinforcement evenly across the sub's entire output, and you can adjust (lower, relative to free space placement) the output level of the sub accordingly. To (virtually) eliminate the remaining peaks and nulls, you can EQ, or try Duke's "distributed" system which provides flexibility in using one (or more) sub's peaks to offset the other subs' dips.
BTW, the other approach is to find mains that are designed to work up against (or inside) a wall. Shadorne's soffetted system is one approach, Roy Allison's designs have offered a variation on the theme for a long time.
The Deqx idea I mentioned in my previous post is simply a "brute force" EQ solution. It allows the peaks and nulls to develop and beats them into submission with EQ. Audyssey and Velodyne (among others) also make EQ products for this purpose.
BTW, I can't localize the (carefully integrated) subs in my EQ'd system, even though they're far from the main speakers. Of course, YMMV.
Good Luck
Marty |
Shadorne,
I can't recommend the approach (you state several good reasons not to), but I will say it worked really well for me. I filtered below 25hz, so the max boost was applied only to the narrow range between 25hz and 35hz. Test sweeps were run at app 95db and were quite loud - they exhibited no ill behavior that I could detect. Music reproduction was always pretty damn impressive to my ear, though I can't swear that there was ever much signal in the highly boosted frequency range under discussion here.
Marty |
Jax,
Killing the nodes bewteen 50hz and 150hz makes a HUGE difference IME. Getting flat in-room response in this range is really worth some effort and -IME- it will take some effort. I use bassbusters for the octave above 80hz - which works very well - and active PEQ below. In addition to much improved impact, weight, and "punch", the midrange sounds cleaner. Really flat response in this region also allows a more seamless integration of mains and subs - if you're crossing this high. My rule of thumb, cross where it's flat. The bass will seem to be a natural part of a seamless whole - it won't "stick out" at all. At least, not to me.
Below app 50hz, the whole excersize becomes a lot more subjective - IMHO. Again, weight is impacted as is, to my surprise, soundstaging. I'd heard people make this claim before, but I was doubtful - it wasn't intuitive. As it turns out, getting it right down low allows deep bass notes to "bloom" and expand in a way that feels natural and seems to define a larger space. To my ear, there's a decently broad band around truly "flat" response that achieves this result. I chose to extend flat in-room response to 25hz because it measured well and sounded great. Other folk's MMV.
Marty
BTW I currently use a pair of 12" Rythmik subs which require much less EQ than the 8" Velodynes. |
In re-reading this thread I may have given something of a wrong impression re: EQ vs distributed subs. I love the idea of distributed subs and wouldn't be at all surprised to eventually own a set. I might very well still utilize room analysis/EQ, but mainly to help optimize placement (room analysis) and fine tune for +/- 1db or so for the 1/2 octave above and below my chosen x-over frequency. I suppose that some additional PEq might prove beneficial if any little anomolies survive the placement excercise, but I suspect that it would be minimal.
Marty
PS Duke - is there pricing info on the Swarm and Planetarium systems? I didn't see any on your web site. Not that I'm thinking..... |
Spatine,
Didn't your Preludes utilize the RABOS system (IIRC a bass EQ scheme)?. Since you asked for current technological implementations, the answers naturally tended toward sat/sub variations and, eventually, EQ. The separate sub idea allows more placement flexibility. Additional placement flexibility isn't going to hurt things, though it's not 100% guaranteed to help, I suppose. Similarly, multiple subs offer even more placement flexibility. In the end, choose the approach which best suits your needs, but -in your place- I wouldn't be so quick to dismiss the potential advantages represented by some of the ideas here.
At the very least, there's some good food for thought.
Good Luck
Marty |
Spatine,
Fair enough.
I didn't mean to be critical of your response, just suggesting that you might want to kick these facts around in your head a little more before reaching any conclusions - hence, the "food for thought". IMHO, this thread probably contains more useful info for achieving good sound than 99% of the material on A'gon. Figuring out how to utilize that info is your gig.
In a nutshell: optimal placement of multiple bass sources is a useful tool if it's available to you. Maybe it's not available (WAF or cost). EQ, whether from Infinity, Audyssey/SVS, Velodyne or others is also a useful tool, but others have -quite correctly- pointed out certain limitations to the approach (careful with nulls). Room analysis will make placement easier. Any thoughtful, properly implemented combo of these techniques is likely to improve in-room performance.
Take that FWIW.
Marty |
