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Discussion Starter #1
Does anyone else agree with me on this subject? I am not talking about recorded surround channels here btw, simply the number of subwoofer outputs that can be independently adjusted.

If you put 4 passive subwoofers and place them on single subwoofer output (such as a Y-splitter), aren't you assuming that all the subs are equidistant from the measurement position?

Take an extreme example: One sub is 8 feet from you and another is 30 feet from you... Does it make sense to EQ both of these as a single sub without the ability to setup delay for each of them separately? Or does it matter?

Subwoofer math and experiments show that quad subs is optimal (this is the subject of multiple white papers and threads from the folks at Harmon and others). There are several optimal placement options but none of those options put the listener at equidistance from all the subs.

The Marantz 8801 that I have has 2 subwoofer outputs which allows independent delay settings on each of these. I put my front two subs (which are equidistant from the MLP) on one output. I put my rear 2 subs (also equidistant from the MLP) on the other output. In my case, this seems to workout ok due to the particular location of my subs.

Each of these outputs goes to a pair of stereo amplifier channels. The PEQ can be adjusted for the front pair of subs and the rear pair of subs independently.

It's time for manufacturers to build to accommodate for the available science. The consumer will think... hmm I wonder why there are 4 subwoofer outputs on this thing... and there will be an "education screen" during the subwoofer setup that demonstrates common "best" placement options for subwoofers. It surprises me how manufacturers don't actually include more product literature and "self help" within the actual AVR. At the very least they could have a browser with a link to their own website that they keep constantly updated with help info. This way, they don't have to re-invent the wheel with every AVR that they put out.

The only reason that they don't place 4 subwoofer outputs is due to most customers not using them. Most customers conversely don't understand the benefits of 4 subs even if they could afford them. The cost difference in mass production is tiny yet these manufacturers skip these details while daring to call their pre-pro a "flagship"...
 

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I completely agree. I currently have 5 subs in my setup and only the front two are equidistant to my listening position. The other three are in different position that varies to the MLP.

I have the front two hooked up to sub output 1 and the other three hooked up to sub output 2. I wish I was able to adjust the distant in the AVR for all 4/5. It would make using the built in PEQ much easier.

For example one of the back three subs has a peek at 60 hz at its position. I need to decrease that one sub by at least 7db, but then that takes a hit on the other three that don't have that peak. If I decided to lower the volume on that specific sub I lose output at 55 down to 40 hz as the right side of the couch has null in that frequency range, roughly -10db. And If I was to use the PEQ to raise 50hz then the other two subs would create a boost at 40 - 55 hz on the left side of the couch, which would cause an imbalance from left to right of the MLP.

Nonetheless I have a pretty impressive frequency response across multiple seats, 21 - 90 hz +/- 1db. My AVR is not capable of manual calibration below 31hz, so its tough for me to adjust the bottom end, but I can live with that the drop off at 20hz is about 4db. I've contemplated on getting one of those subs equalizer but I don't think I want to spend the money for a decent one.

I told my self I will not be upgrading my AVR until one is available with 4 sub outputs. However, when I purchase a 4K project it the next 2 plus years and one is not available I will need to suck it up and purchase a sub equalizer.
 

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I have 4 subs all at different locations and none are equal distance. A little DSP and things should be good. Two of the subs are vented and two are sealed. Great results can be obtained with a little DSP/PEQ. My avr is a .1.
 

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Discussion Starter #7
In my particular situation, I have found a solution as I mentioned.

My point is that pre-pro manufacturers should be responsible enough to release the most scientifically proven methodology available.

They certainly hike their prices by a wide margin on their "top flagships". At least deliver an actual "audiophile" component. audyssey can probably do a perfectly good job Eq'ing quad subs but it is being hamstrung by lack of discreet outputs.

As was mentioned, there is no doubt that harmon/jbl, datasat, and trinnov see the merits of this methodology. It is just annoying to me that most consumers (including myself) needed to "discover" the science long after we bought multiple pre-pro's.

Who am i kidding anyway... "Audiophiles" are the same crowd that are often still monkeying around with 2ch without separate subs. The home audio marketplace is such a circus.
 

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In my particular situation, I have found a solution as I mentioned.

My point is that pre-pro manufacturers should be responsible enough to release the most scientifically proven methodology available.

They certainly hike their prices by a wide margin on their "top flagships". At least deliver an actual "audiophile" component. audyssey can probably do a perfectly good job Eq'ing quad subs but it is being hamstrung by lack of discreet outputs.

As was mentioned, there is no doubt that harmon/jbl, datasat, and trinnov see the merits of this methodology. It is just annoying to me that most consumers (including myself) needed to "discover" the science long after we bought multiple pre-pro's.

Who am i kidding anyway... "Audiophiles" are the same crowd that are often still monkeying around with 2ch without separate subs. The home audio marketplace is such a circus.
If you think about it, it doesn't seem too long away when the AVR's only had 1 sub out and the norm was 5.1 or 7.1. At least they have 2 now. :) I bet if you did a poll, you would find less than .001% of the consumers has more than 2 subs, and most consumers probably has the HT in a box or just has one sub. You will be surprised how many people don't even have a sub. So yes it sucks for the people that has more than 2 subs trying to get the most out of there response. But I really don't see the manufacturers seeing this as a big selling point right now. It may progress to 4 channels someday. All it takes is a few manufacturers to take the leap, and if they reap the benefits of profit then others will soon follow.
 

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I think the issue is largely going to be that there isn't that much room on the back of an AVR to dedicate the space. Furthermore, how many people actually have need for that many sub outputs? I think the majority of people run either a single sub or at best dual subs. While I absolutely agree that there are people who run more and the flexibility is great, it's just not something I see companies worrying about. Beyond all that, if it really is an issue a DSP would get the job done just as well if not better.
 

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I say give it a few years or a decade and subwoofer outputs will be their own channel/object, or a least the ability to be their own.
 

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I say give it a few years or a decade and subwoofer outputs will be their own channel/object, or a least the ability to be their own.
I haven't read the Atmos spec, but I'm almost-sure that it already supports objects down to ~10hz.
The question is: Do you have 11 large speakers that are 10-50hz capable to take advantage of that (probably not). Are movie producers ever gonna use that ability? (doubt it...)
 

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Discussion Starter #13
Subs function as one unit and at some point they have to be EQ'd together.
yes but we are presuming that the individual delays need to be set before they are eq'd together, right?
 

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Discussion Starter #14
I say give it a few years or a decade and subwoofer outputs will be their own channel/object, or a least the ability to be their own.
it is not clear that they really need to be their own object... crossing over most of the channels at around 80hz or so seems to work perfectly fine since bass is not localizable.
 

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I have always had a problem locating subs equal distance due to room layout. When I only had two or three subs , I level matched the subs and let autocalibration EQ them as one since I have a .1 avr.

I switched to passive subs and now have individual DSP/PEQ for the four subs. I still EQ them as one since they all function as one. There are slight difference in the EQ since two are vented subs and two are sealed. In all honesty their is very little EQ needed running four subs. No major peaks or dips to correct in my 5300 cu ft. space. Even with this large space, the four sub can pressurize the room to an incredible level. As can be seen in my FR graph in the last post, no problems at the XO region or around sub tuning at 20 Hz. I have use this method in several different rooms.
 

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I would gladly replace a set of RCA inputs for another set of sub outs on the back of a receiver. Most receivers have 5+ RCA inputs. With HDMI in common use, who needs more than 2 rca inputs?

I have 4 subs and while I would probably prefer to have 4 discrete channels, I have doubts that setting the distances for all 4 subs would make much difference. For one thing, the distance only helps time the initial waves from the subs. it doesn't help with reflected waves at all. Also, the wavelengths from subs are extremely long. It seems getting the distances right for regular speakers is more important than for subs since the distance as a pct of wavelength is much smaller for subs than other speakers. If two subs are producing a 20 foot long wave and they're out of sink by a foot or two, would it make much difference in the combined wave?
 

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Never gonna happen, I doubt if it would be a feature used by more than 1 in 10,000 AVR's sold. As has been mentioned there are DSP units available that do a better job (in most cases) for the AV nuts out there. Kinda like asking why don't cars come with a backgammon set. I've been into serious AV for over twenty years and I've only met one person who had four subs in the same system and in that case it was a decision made by the guys who set up his theater not him. Very few people own more than four speakers total if you don't count those built into tv's and clock radios.
 

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Discussion Starter #18
You are both right... Way too many worthless rca inputs on the back wasting real estate.

Also a lack of assignable outputs is also a problem. Someone could use 4 outputs for subs or onlly 1 and then use the other three outputs for something else.
 

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yes but we are presuming that the individual delays need to be set before they are eq'd together, right?
No, befor I had separate DSP, autocalibration would come up with an average distance. This worked pretty well with MCACC in my Pioneer Elite avr.

I have moved subs around in my room without resetting the delay from one location to the next and the graphs are still pretty good. The key point is level match the subs, and check with an spl meter to see if the spl went up with the addition of a second and then a third sub. Adding a fourth sub many not result in an increase spl or very small increase. In rooms 20 X 20 ft. multiple subs will be mutually coupled at the lower frequencies.
 

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If you guys think it's not important set separate delays for subs, or groups of subs, you need to read this post by Mark Seaton to see how he used delays to optimize 6 Submerives WITHOUT EQ:
http://www.avsforum.com/forum/113-s...ptional-service-mark-seaton.html#post26403193
In that post and several subsequent posts, he walks the reader through the entire process of optimizing the subs using just delays, with measurements to demonstrate his points.

In my own system, I have 3 Submersives, 2 of which are equidistant to the LP, and are connected to the Sub1 output, and the other sub is closer and its connected to the Sub2 output. The different distances are compensated by different delay, (distance), settings. In addition, my subs are all gain-matched, which, for identical subs, is a better way of setting them up than level-matching.

Craig
 
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