If I am 12 feet back, then there will be very little falloff from the mains for several feet. Sideways there is both a rise and a fall so the average level stays about the same. I'd say that this level difference is not an issue in either of the two rows of seating that I have in my room. However, this effect is most obvious at the back wall, and again at the front wall, but not at all apparent near the middle of the room.
Employing a Bongiorno/SST Trinaural Processor has many huge advantages. Main spkr output is far more evenly dispersed throughout the room. Sweetspot is hugely increased in size. An active HP filter is included for the mains & a variable sub level output (pure analog throughout, 2.0 input/3.1 output; center & all ch's go through algebraic processing). The center is highest priority, L/R become effects chs. You can try the Trinaural w/ an audio buddy by employing one mismatched speaker for the center (the center speaker must equal or exceed the quality of the L/R). Another advantage is that only one channel of your favorite amp is required to power the center ch.
I can't recommend the Trinaural highly enough w/ Earl's sub setup philosophy. You'll never return to 2-ch.
(Apology for the digression; facilitator is welcome to delete this post if desired.)
I can't recommend the Trinaural highly enough w/ Earl's sub setup philosophy. You'll never return to 2-ch.
(Apology for the digression; facilitator is welcome to delete this post if desired.)
Hell yeah. Trinaural rules. I'm a big supporter for it, as it for sure doesn't get the deserved attentention. And it's so easy to do (with balanced gear you need some 13 resistors to come close to the real thing).ro9397 said:
For evaluation, you'd still need speakers with the same crossover topology (freqs and slopes), otherwise there is freq. dependent image blur or even L/R-reversal. In fact I had to phase-equalize the speakers I used for initial testing to get it right.
On the Bongiorno processor, I have to say the sub/mains xover is a bit strange, it doesn't sum flat (I measured the device extensivly, this is its only weak point, besides some cosmetic issues).
- Klaus
markus76 said:
And to compound matters, the actual spectrum balance that seems most "right" really depends on what one's typical listening level is -- just as the Fletcher-Munson equal loudness curves suggest. This has been bugging me for a while; I can't always (nor want to) listen to everything at concert level.
I would argue a benefit to some level/spectrum change: as mains are attenuated by increasing distance, you get a relative "loudness compensation" effect!
I can enjoy a "right" spectrum at lower listening levels when working at my desk at the back of my listening room, at >double the "regular" distance from my mains.
Anyone out there made a gain-dependant loudness compensation, including adjustment for system sensitivity? Unless everyone listens at one level all the time, this would be a very meaningful component . . .
Tubamark said:
It's called "Audyssey Dynamic EQ": http://www.audyssey.com/technology/dynamicEQ.html
Best, Markus
well really it was the loudness control, which originally varied the adjustment of bass and treble in relation to the position of the volume control. While I have no doubt the new dsp based versions are better, when it comes right down to it, we know about this 50 years ago. Dolby and THX also have a version of this, DTS as well maybe?
markus76 said:
Thanks! The Audessey is exactly what I was looking for . . . sounds pricey . . .
The Dolby feature linked above is nothing more than a limiter/compressor - Nothing to do with level-dependant frequency spectrum adjustment. Ack. Good for Low-Fi environments.
The term "loudness control" as the industry adopted it was a big mistake - No wonder nobody understood it. Many controls were nothing more than a fixed bass & treble boost - only valid, if ever, at one specific (and unknown) SPL. Even in the pre-digital era, a better approximation was possible - Using linked potentiometers with different tapers for making the spectrum change at a different rate than main volume, or vice-versa.
To be really valid, compensation would HAVE to include at least some sort of real-time SPL and frequency spectrum calibration event.
Tubamark said:
No, here's a list of AVRs:
http://www.audyssey.com/products/consumer_ready.html
Tubamark said:
No again:
http://www.dolby.com/professional/ce/home-theater/technologies/dolby-volume-specifications.html
Best, Markus
Audyssey uses absolute SPLs. Dolby can.
The new ISO standard shows indeed the biggest deviations in the region <500Hz:
http://www.nedo.go.jp/itd/grant-e/report/00pdf/is-01e.pdf
Best, Markus
The new ISO standard shows indeed the biggest deviations in the region <500Hz:
http://www.nedo.go.jp/itd/grant-e/report/00pdf/is-01e.pdf
Best, Markus
markus76 said:
Ah-ha! I stand corrected!
That initial Dolby link was all "consumer friendly" marketing-hype. They missed the opportunity to distinguish the technology from regular compression/limiting -- no mention of spectrum/tonal balance, etc. Shame on the Marketers. Bravo for the technology.
Thanks for (re)pointing me in the right direction!
-- Mark
I haven't spent much time here at DIYAudio recently, and just found this thread last night. Since my system was mentioned in the initial post, I thought I'd put in my $.02.
To briefly recap, I build a four-sub system that I call the Swarm, which is used in some of my complete systems and also sold separately. I got the idea for a scattered asymmetrical multisub system from Earl, and he gave me permission to use it in a commercial product. Of course they can also be set up in a symmetrical Welti or Welti/Toole configuration.
Speaking of Todd, it's great to see him posting in this thread. I must confess that he and Earl are the only ones whose posts I made a point to read (or try to read) every one of. Not that I understood them all!
One of my reasons for using four small subs (each about 1 cubic foot internal volume) is so they can be wired in series-parallel and driven by a single central amplifier, in this case a Parts Express 1000 watt shelf-mount amp that has some nice features (4th order lowpass and a single band of parametric EQ).
Up until I read Earl's posts in this thread I hadn't appreciated how important placing one of the subs in a corner is with an asymmetrical setup. I'll start making that a strong recommendation.
I don't use Earl's overlapping technique because I intend for the Swarm to be compatible with a fairly wide variety of main speakers not having the gentle low-Q sealed box rolloff that Earl's do. Also, I'm not using bandpass subs because I don't know how to design a compact bandpass sub that covers two octaves.
Regarding the ability of multisubs to smooth out the in-room sound, to the best of my knowledge none of my customers have found it necessary to use the parametric EQ feature in their amps. In a case like Earl describes where the lowest fundamental room mode cannot be tamed even by multisubbing, that feature might be useful.
But, I have a question about that: Earl, if I recall correctly, that lowest room mode you desribed is around 30 Hz, and isn't that below the passband of all except your one big ubersub?
Thanks,
Duke
To briefly recap, I build a four-sub system that I call the Swarm, which is used in some of my complete systems and also sold separately. I got the idea for a scattered asymmetrical multisub system from Earl, and he gave me permission to use it in a commercial product. Of course they can also be set up in a symmetrical Welti or Welti/Toole configuration.
Speaking of Todd, it's great to see him posting in this thread. I must confess that he and Earl are the only ones whose posts I made a point to read (or try to read) every one of. Not that I understood them all!
One of my reasons for using four small subs (each about 1 cubic foot internal volume) is so they can be wired in series-parallel and driven by a single central amplifier, in this case a Parts Express 1000 watt shelf-mount amp that has some nice features (4th order lowpass and a single band of parametric EQ).
Up until I read Earl's posts in this thread I hadn't appreciated how important placing one of the subs in a corner is with an asymmetrical setup. I'll start making that a strong recommendation.
I don't use Earl's overlapping technique because I intend for the Swarm to be compatible with a fairly wide variety of main speakers not having the gentle low-Q sealed box rolloff that Earl's do. Also, I'm not using bandpass subs because I don't know how to design a compact bandpass sub that covers two octaves.
Regarding the ability of multisubs to smooth out the in-room sound, to the best of my knowledge none of my customers have found it necessary to use the parametric EQ feature in their amps. In a case like Earl describes where the lowest fundamental room mode cannot be tamed even by multisubbing, that feature might be useful.
But, I have a question about that: Earl, if I recall correctly, that lowest room mode you desribed is around 30 Hz, and isn't that below the passband of all except your one big ubersub?
Thanks,
Duke
audiokinesis said:
The whole concept of "passband" is a free field one. When the subs are in my room they readily excite the 30 Hz mode even though it is theoretically below their "free-field" passband. But then my room measures a flat response down to 15 Hz with the subs that I have and supposedly none of them can do that. This is why I say that what a sub does on paper is kind of irrelavent. What is important is its response in-situ in the room, and that changes everything.
Very interesting - thank you, Earl! This raises even more questions than it answers for me, as I still haven't wrapped my head around thinking in modal geometry rather than Euclidean geometry when it comes to bass propagation in a room.
This flat in-room extension to 15 Hz... isn't that down well below the modal region? Is your room sufficiently sealed to exhibit "cabin gain"?
Can this seemingly free-lunch extension be reliably predicted and thus taken advantage of?
I presume you wouldn't get anything like this sort of extension if you had ported subs, as they'd be rolling off too fast below their tuning frequency... unless they were tuned down around 15 Hz!
This flat in-room extension to 15 Hz... isn't that down well below the modal region? Is your room sufficiently sealed to exhibit "cabin gain"?
Can this seemingly free-lunch extension be reliably predicted and thus taken advantage of?
I presume you wouldn't get anything like this sort of extension if you had ported subs, as they'd be rolling off too fast below their tuning frequency... unless they were tuned down around 15 Hz!