• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Why is slope never discussed wrt subwoofer integration

tomlinmgt said:
Actually, I wasn't looking for advice or information for a particular problem I have...I was asking a general question that addresses a broad range of scenarios, but all dealing with the integration of a LF support system with main speakers and how slope, in particular, influences the quality of that integration.



I made no such implication about their quality. I did suggest that regardless of their performance capabilities, room acoustic issues will compromise their ability to fully reach those capabilities, particularly in the low frequency regions.



So long as that loudspeaker is suffering from the acoustic issues that can and do exist in practically every domestic living space...with the exception of unusually large rooms...that statement is pretty accurate, except I maintain that one subwoofer is typically not sufficient to overcome said acoustic issues.



If the suggestion is that one sub will improve the situation and louder is better then yes, that does sound like a sales pitch from a big box store. If it were someone who actually understood the science they would be suggesting several subwoofers....which Rob did when he specified "distributed bass"....and not with the intention of achieving "louder" but instead "better".



Large room/outdoor acoustics and small room/domestic living space acoustics are two entirely different animals and can not be dealt with the same way.



You're missing the point and if you understood the physics behind what is occurring in the small room acoustics scenario you'd better understand what is happening and what has been suggested as an effective and productive way to deal with it. Did you read the link on "distributed bass" I provided you? It has absolutely nothing to do with "rattling windows and pissing off neighbors". It has everything to do with achieving a balanced low frequency response at the listening position by using a supplemental low frequency reproduction system that strategically locates several subwoofers in the room so the inherent room acoustic issues that prevent the balanced reproduction of the low frequencies from the main speakers are overcome. In addition, because several drivers are sharing the workload of just a few distortion can be reduced significantly if not eliminated entirely. And this is not with regard to distortion at high SPL only, but at all volume levels (beneath the level where any one of the LF drivers begins to demonstrate break up).



No, at this point it doesn't and I didn't call you a jack ass (though I can see where my wording could've been better oriented to avoid any confusion) as the post you're referencing wasn't directed at you specifically but rather anyone who maintains that all one needs for balanced low frequency reproduction is a set of full range speakers and an EQ after having been presented with the science that clearly demonstrates that belief system to be tragically flawed.

I'm going to give you the benefit of the doubt and assume you haven't looked into the science behind small room acoustic physics. I have nothing to sell, no self-serving agenda to advance, or desire to make you or anyone else look like a jack ass. I'm only trying to help and here's some info that illustrates the theories from which I base my comments.

- Michael

https://www.youtube.com/watch?v=g3aHwTkMfBc

http://www.gikacoustics.com/video_bass-traps/

https://www.youtube.com/watch?v=xECtAruK0fM
Click to expand...
Michael, I did read the "distributed bass" link....and I think that might be the main reason for your questions (or possible confusion) about subwoofer slope.

If you can detect the physical location of a subwoofer with your ears, by true definition, it is not a subwoofer in that it is reproducing some sound frequencies that are not omnidirectional.

A true subwoofer should have at least an 18dB crossover at 50Hz. 24dB would be even better. A 20-50Hz band pass 24dB slope crossover would be best, especially if your system includes a turntable. THEN, if you want more rumble in the jungle, use more than one sub and/or a sub with a larger driver.
 
Bob, you seem to be missing a great deal of information about this topic like you've joined the discussion in the ninth inning.

You've made some outlandish comments in this thread which are simply untrue. I am not a salesman but rather someone trying to help inform those wishing to better their system.

It has been stated many, many times in numerous threads that if you can detect the location of the sub woofers you're implementing the distributed bass incorrectly. The proponents of distributed bass have not implied it should be loud as that is not the objective.

In your last post you say "THEN, if you want more rumble in the jungle, use more than one sub and/or a sub with a larger driver." That is completely contrary to a properly implemented DB system. You still don't understand DB. It's not about increasing the SPL of bass in any way whatsoever Bob. DB is not about increasing impact at all, but rather it's about eliminating room modes as much as possible by distributing the bass throughout the listening space.

In my distributed bass set-up, I have a sub located very close to each end of my love seat listening position as they are very effective in those locations vs being located near the front or side walls. I am constantly trying to determine if they are even on. I literally have to kneel down and put my ear within about ten inches, directly in front of the driver, before I can tell they are working. Their levels are properly adjusted and I only perceive music emanating from the sound stage. If they were disguised as end tables nobody would ever be able to guess they were there.

That's when you know you've set up DB correctly. Even though the sound coming from the DB is undetectable to the listener, when it's turned off you quickly realize why it was worth the extra effort.

Just to be clear, I'm not affiliated with any business that sells audio gear or literature of any kind, and have zero vested interest in anything related to DB aside from sharing my experience with anyone interested in DB. :thmbsp:
 
Last edited:
Bob Orme said:
Michael, I did read the "distributed bass" link....and I think that might be the main reason for your questions (or possible confusion) about subwoofer slope.
Click to expand...

If you think I'm curious about subwoofer slope because I'm trying to successfully implement distributed bass into my system then you're about two years too late to that party. I'm actually more interested in slope/integration because I have a DIY build in the works and wish to experiment with ripole, slot-loaded open baffle, slot-loaded open baffle push-pull, w-frame, h-frame, u-frame, and standard OB subwoofer configurations and would like to explore the ramifications of different slope orders wrt mating the LF driver to the mid bass driver.

Bob Orme said:
If you can detect the physical location of a subwoofer with your ears, by true definition, it is not a subwoofer in that it is reproducing some sound frequencies that are not omnidirectional.
Click to expand...

What you're talking about is "localization", and it generally begins to lose effect at around 80hz, sometimes a little higher. If a supplemental LF driver is operating from 20-125 Hz and its location is detectable it is still a subwoofer. The fact that it is reproducing content in the first octave is what makes it a subwoofer, not whether or not its position can be located in the room.

Bob Orme said:
A true subwoofer should have at least an 18dB crossover at 50Hz. 24dB would be even better. A 20-50Hz band pass 24dB slope crossover would be best, especially if your system includes a turntable. THEN, if you want more rumble in the jungle, use more than one sub and/or a sub with a larger driver.
Click to expand...

I'm not even going to touch your last comment, but the comment about what slope a "true" subwoofer should have is not consistent with what I've read. As a matter of fact, I don't think there is any standard that's been written in stone. And I've certainly not seen anything that dictates "at least 18db" as I've seen as low as first order slopes as the preference...I'm pretty sure it depends on the drivers at play.

Man, I really hate to seem like I'm picking your comments apart for pleasure, Bob, but some of them are so riddled with inaccuracy I simply can't allow them to go unchecked in my thread as I created it as a reference for others to use in their quest to extract better sonic performance from their implementation of sub drivers.
 
Slope to my way of thinking is the obvious decay of acoustic power. Some like a shard, defined drop off at a given frequency- others may not so much! If you cut a bass signal off at first order, 50 hz- you slowly realize the 6db drop 1 octave later at 100hz.

Seems to me tat gradual roll of of acoustic power may well be prefered by some. If you roll you satelites in at 6db//oct the transition would seem smoother as well. There is a time an place for 1st order networks so long the drivers can bear it- and that usually being mids and tweeters!

DC
 
^^^

So it sounds to me like driver voicing and sonic characteristics such as dynamics could be heavy influences in slope selection, as well. :scratch2: At which point we start to venture into the realm of the subjective. where's the "oh ****" emoticon?
 
Thanks for sharing the link Ken. I've read that whole site several times before and always manage to pick up something useful.
 
tomlinmgt said:
^^^

So it sounds to me like driver voicing and sonic characteristics such as dynamics could be heavy influences in slope selection, as well. :scratch2: At which point we start to venture into the realm of the subjective. where's the "oh ****" emoticon?
Click to expand...

Exactly so. There is a fantastic example of how moving the x/o point and the slope around changes the voicing in this thread; it doesn't matter the speakers are smaller monitors :
http://www.audiokarma.org/forums/showthread.php?t=642919

One needs to open the file the author attached, but not a big deal 'cause it's a pdf. The entire paper is worth reading, but the issue under discussion starts around p.43 or so.
 
GuyK said:
Exactly so. There is a fantastic example of how moving the x/o point and the slope around changes the voicing in this thread; it doesn't matter the speakers are smaller monitors :
http://www.audiokarma.org/forums/showthread.php?t=642919

One needs to open the file the author attached, but not a big deal 'cause it's a pdf. The entire paper is worth reading, but the issue under discussion starts around p.43 or so.
Click to expand...

Three pages into the write up. Very cool. Thank you, Guy.
 
You must log in or register to reply here.
Back
Top Bottom