The thing is when I look at the excursion numbers....I end up with LESS excursion from the midbass with the 3 way.....being a PPSL is likely misleading...due to the high efficiency of the AH18+ in the midrange....so you really should look at it like a 3 way that happens to be able to play into the sub range...in the 3way, I have the mid, high passed at 47hz 12db/oct, analyzing at my max spl target 115db excursion is PEAKING at 3.5mm likely due of the low pass 2nd order filter on the bottom woofer. This configuration is the most efficient in the bass region as well.
Looking at the 15m in the mtm section with no hp pass at 40hz excursion is at 3.7mm and CLIMBING as we go down the range....so as music ask for signal below 40hz excursion exceeds that of the midrange section of the...
It looks like the 3 way is actually more efficient.... in the midrange....Look at it like this;
In the 3 way the 15m couples with 2 - 18h+...VS in the MTMW theres only 1 18h+ coupling with the 15m....it obviously makes the difference.
Its just the strange FR from the slot....but apparently....its not wacky enough to be detrimental where it matters...
AS for multisubs....being that the bottom woofers can play sub as well.... There is multi sub....I use my sub co-located with the mains. If and when I get more subs they will be symmetrically in the back.
The Horn is helping out by 300hz....in either situation...I had to move the XO in a way that was removed from the more optimal programming to get it, just for comparison (in the MTMW)...I gained 1db over the 3way in the crossband...thats not worth it....not when excursion is lowest in all drivers with the 3way.....
I feel a lot better lol.
Looking at the 15m in the mtm section with no hp pass at 40hz excursion is at 3.7mm and CLIMBING as we go down the range....so as music ask for signal below 40hz excursion exceeds that of the midrange section of the...
It looks like the 3 way is actually more efficient.... in the midrange....Look at it like this;
In the 3 way the 15m couples with 2 - 18h+...VS in the MTMW theres only 1 18h+ coupling with the 15m....it obviously makes the difference.
Its just the strange FR from the slot....but apparently....its not wacky enough to be detrimental where it matters...
AS for multisubs....being that the bottom woofers can play sub as well.... There is multi sub....I use my sub co-located with the mains. If and when I get more subs they will be symmetrically in the back.
The Horn is helping out by 300hz....in either situation...I had to move the XO in a way that was removed from the more optimal programming to get it, just for comparison (in the MTMW)...I gained 1db over the 3way in the crossband...thats not worth it....not when excursion is lowest in all drivers with the 3way.....
I feel a lot better lol.
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You are talking about placing subs where they are going to play best in the room Randomly...thats not exactly what I do...I do symmetrical....Ideal for me is to have the mains be where I want them (tightly located with the "sub") and have them be corner loaded.... fortunately the corner is the best place in the room....only surpassed by soffit mounting......
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2 corner loaded subs (mains)... =)
If I am not mistaken, unless you have woofers on different heights....floor to ceiling cancellations still remain or no?
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Not for even response. To excite room modes most strongly? Sure. It's a shame this is even in question given you have the likes of Dr Geddes participating in this discussion. Look up the Harmon paper on multi sub placement for additional readings. Someone, like your Katz reference, saying "they don't prefer the multi sub technique" simply means they did it wrong. IMO of course.
Better yet:
https://www.google.com/url?sa=t&sou...FjAAegQIBBAC&usg=AOvVaw3B2YCKY-xIXgnx4ZS9jiaJ
Well, i'd say the multiple subs thingy is the first truly debatable topic this thread has seen in a while.
There are plenty of folks who don't prefer it (and have tried it properly). I'm one.
Imo, there are two ways to go about fitting subs to a room.
One is to maximize and distribute as many modes as possible, ala multiple subs, and varying room placements.
The other is to minimize modes, using as few subs as possible in corners.
A few additional random thoughts...
Both techniques can benefit from mode suppression EQs.
Corner technique offers 1/8 space gains, often helpful with looser construction.
Multiple small sealed subs benefit greatly for from very tight construction, as room gain is often needed to accommodate limited low output extension.
When main speakers can be located near corner subs, within 1/4WL at xover, it makes for the best sound i've heard indoors.
Multiple anything in audio, even subs, raises the odds for making mud. Every sub reflection becomes a virtual sub adding to the mud pie.
If you want to cry, go outdoors and listen to how much better your subs sound.
There are plenty of folks who don't prefer it (and have tried it properly). I'm one.
Imo, there are two ways to go about fitting subs to a room.
One is to maximize and distribute as many modes as possible, ala multiple subs, and varying room placements.
The other is to minimize modes, using as few subs as possible in corners.
A few additional random thoughts...
Both techniques can benefit from mode suppression EQs.
Corner technique offers 1/8 space gains, often helpful with looser construction.
Multiple small sealed subs benefit greatly for from very tight construction, as room gain is often needed to accommodate limited low output extension.
When main speakers can be located near corner subs, within 1/4WL at xover, it makes for the best sound i've heard indoors.
Multiple anything in audio, even subs, raises the odds for making mud. Every sub reflection becomes a virtual sub adding to the mud pie.
If you want to cry, go outdoors and listen to how much better your subs sound.
Can mains count as subs?
The three 36x18x12 boxes (NS-15) are his two mains plus the center channel, LCR. Then he has two separate dedicated subs 18x18x18.
If your main/LCRs don't play low like the NS-15s you add a sub to take on that duty.
Welti's system is different. He intentionally removed the low frequencies in Floyd Toole's Salon 2s because they interfered with Harman's Sound Field Management tool. In that case, the mains would not count as one of the subs in a multi-sub system.
The three 36x18x12 boxes (NS-15) are his two mains plus the center channel, LCR. Then he has two separate dedicated subs 18x18x18.
If your main/LCRs don't play low like the NS-15s you add a sub to take on that duty.
Welti's system is different. He intentionally removed the low frequencies in Floyd Toole's Salon 2s because they interfered with Harman's Sound Field Management tool. In that case, the mains would not count as one of the subs in a multi-sub system.
Perhaps. There definitely hasn't been much useful discussion. But I keep reading...Well, i'd say the multiple subs thingy is the first truly debatable topic this thread has seen in a while.
I can appreciate 1/4wl@c/o. I guess I've never set up in a room where small mains could be 1/4wl@c/o from the front corners.
My best setups have included either full range mains, or sub assisted mains following 1/4wl@c/o, along with a spattering of additional subs throughout the room. Never experienced mud this way myself. Thank you Geddes.
As far as "minimizing or maximizing" modes, the number of modes don't change with the number and placement of subwoofers. Room modes exist exclusively due to the dimensions of the room. What does change with number and placement of subs is how those modes get excited. I believe that is what you were talking about but it struck me as needing clarification.
As far as your "two ways" both needing EQ, in practicality yes. But I do love the idea from the Harmon paper of 5000 subs randomly located. No EQ required with that approach!
Subs I have taken outside did indeed make me cry. All the low bass went away...
My indoor subs have never been built for flat anechoic response down to ~20hz, usually not even 30hz. No room=no low bass for me.
Proper large outdoor subwoofer systems are one of my favorite things but I never hear them dig as deep as my relatively puny indoor subs. Quite disappointing sometimes.
But you know all that, and I know your mainly talking about the lack of modal resonances. On that I wholeheartedly agree! Bass, and indeed all sound, is so nice outside.
I was hoping to try a DBA system someday but the house I just bought will not allow for that. DBA seems to address some the indoor modal issues in a rather neat way. They have their own quirks but I still find them quite intriguing.
Rather than get bogged down in the logistics look at the aim of it. Multiple sources when combined properly can create an even bass response across a fairly large area reducing spatial variation and the most important locations can be prioritized for flat response rather than minimal variation.Well, i'd say the multiple subs thingy is the first truly debatable topic this thread has seen in a while.
There are plenty of folks who don't prefer it (and have tried it properly). I'm one.
If you get that then you did it right, if you didn't then you didn't get the best out of it.
If you can get less response variation and better frequency response from using other techniques great. More data than "I don't like it" would be helpful
There is nice free software that can work out the level delay and EQ settings for the target you set
Multiple Subwoofers: Optimize Them With Multi-Sub Optimizer Software
With these drivers all together, finding a spot in the room where it works out as planned is the tricky part camplo. Optimizing the bass, even with a lowly 2-way, isn't the easiest to do. If your room isn't used by others .. like family stuff .. that's a plus. Otherwise, be prepared to compromise bass response .. which suks. Get inside a room mode and parts of the response seem to just disappear. You'll do a sweep and bits will just be gone.
Even IF corner loading doesn't fix every issue... until I could go to the lengths that someone like Dr. Geddes has done to literally create a Mastering room...( which on some level is what hes done I think) there will be issues...Corner loading is the next best thing to soffit mounting is what Ive come to conclude from my studies...one comment that stuck with me was "you've never really heard your speakers until theyve been soffit mounted"...it is possible to create a false wall to create this affect, for the ambitious. I could see that happening once I am not a renter.
To the topic of multi space situated - multi mode stimulators (lol!)
What about floor to ceiling modes?! If all your subs are in different areas but still located on the same height plane.....doesn't that mode exist at every sub location? Or does the relation to listening location take care of that?
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There are many modes in the room, floor to ceiling and wall to wall are the simplest but there are many more. Corner placement is nice but it seems to leave strong "power alley" at least in my living room. Corner placement is maybe a bit better than not in the corner. Multisub setup seems the easiest way to help with the issue. If the speakers are in the corners, have at least one more sub somewhere else than in a corner.
I think multiple subs could be on any surface, floor is just the most practical. I haven't studied if there is any difference if the subs are on the front wall or on the floor, or in the ceiling. The point is you EQ and adjust delay and level on all of them separately. Symmetric positioning is probably not as effective than "random" positioning since the point is to produce as many room modes as possible and statistically even out the listening area response.
I think multiple subs could be on any surface, floor is just the most practical. I haven't studied if there is any difference if the subs are on the front wall or on the floor, or in the ceiling. The point is you EQ and adjust delay and level on all of them separately. Symmetric positioning is probably not as effective than "random" positioning since the point is to produce as many room modes as possible and statistically even out the listening area response.
Hi Kevmoso, thx for the thoughtful reply.
Yes, your clarification is spot on. It would be better if i said multiple subs magnify the number of 1/4 wave and 1/2 wave cancellations and reinforcements, both with room boundaries and with each other. (along with changing how the room modes get excited)
And yep re outdoors....sorry your experiment didn't let you hear clean down low sounds there. It does take a significant amount of displacement and efficiency to make 30 Hz outside. That's as low as I can go, but it's strong with 135dB+ @1m SPL.