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Mcpanse
08-11-2009, 04:21 PM
My DS15 SE arrived today and initial setup was a breeze.

I used the following settings on the back of the sub and ran Audyssey MultEQ through the first mic position to see how high or low it was setting the sub.

1. Low pass: EXT/12db (not 80hz / 24)
2. PEQ off at first. With it off, none of the knobs in that white box will have any affect.
3. Delay / phase at 0.
4. Crossover at the maximum to start
5. Level, start at 12 o'clock to begin
6. Extension 14hz to start.
7. Damping on HIGH to start.
8. Rumble filter on OFF to start.

Audyssey set the sub channel at +9 dB. I turned the D15 SE's level knob to the 2 o'clock position, re-ran Audyssey and ended up with a sub channel setting of + 0.5 dB -- almost spot on.

I tried the sub in the front right corner of my 23' x 16' room but felt like I was getting too much room gain. Besides, I'm in the market for room treatments and all the vendors I've talked to have recommended a bass trap in that corner.

For now, I've got the D15 between my television and left front speaker. I'll spend at least an evening with it in that location before moving it.

I'm curious about the PEQ controls but don't want to start messing without further guidance. Any recommendations out there?

So far, only two issues with this sub and current setup.

Movie explosions sound great but I'm not getting that deep in the chest impact I was expecting at higher volumes. Can PEQ help?

Standing behind my sofa -- my main seating position -- I noticed a definite lack of bass output.

All the room treatment folks I've talked to recommend bass traps back there. But that seems counterintuitive to me given that there's not much bass happening back there. Maybe this is what folks mean by a null.

Same question as above -- is there anything the D15 SE's PEQ features can do to help?

curtis
08-11-2009, 04:32 PM
I'm curious about the PEQ controls but don't want to start messing without further guidance. Any recommendations out there?

So far, only two issues with this sub and current setup.

Movie explosions sound great but I'm not getting that deep in the chest impact I was expecting at higher volumes. Can PEQ help?

Chest impact does not come from deep bass, it is in the 40-60hz range. Deep bass is more a sensation of wave movement than an impact or jolt.

The PEQ (Parametric Equalizer) on the amp is only for a single band/peak. Most rooms have at least one bad peak, and with some measurements, this function can help address it. With Audessey, there really is not need to use the PEQ.

It would be interesting to seen measurements with and without Audessey.

monomer
08-11-2009, 05:16 PM
Its important to realize that peaks can be attenuated using either Audyssey or the PEQ but you can NOT boost a null. A strong room reflection can compete with the direct signal source and if they meet up at your ear as crest-to-crest or trough-to-trough they will be additive (creating a peak) and attenuation will work to lower the overall sound level at that frequency... however if they meet crest-to-tough they will tend to cancel each other creating a null at that freq (similar to how noise canceling headphones work) and simply boosting the signal will cause equal increases to both crest and trough (meaning both the direct source and its reflected wave are boosted by a similar amount) with the result being the null remains unaffected. Keeping this in mind...

In general this is what you should be looking to do...

Pick a location for the sub that seems to eliminate or at least minimize any serious nulls from all the listening positions. Then run Audyssey to attenuate any peaks and you will have the best in-room response possible. Its a relatively simple thing to do. I don't know what testing or monitoring equipment you have at your disposal or what you might be running for mains so to keep it really simple just download a sweep that covers the range from 10Hz-150Hz or there 'bouts and play it at approx. 75-80dBs over and over again as you sit in each of the various listening positions. You are listening for nulls, either full or partials... ignore any peaks you hear as they can be EQed out later. At a full null the sound will completely vanish, you cannot tolerate even a single full null... find another place for the sub. A partial null will cause the sound level to dip, if its not too bad don't worry about it as every position will have some dips, just find the sub position with the least and shallowest dip(s) and call it good. Hopefully you won't have to try more than 2 or 3 positions... most people with wives will find they only have 2 or 3 choices for sub position given to them anyway ;) If you wanted you could use PEQ to remove any obvious offending peak and then let Audyssey take care of the rest.

I personally don't think bass traps will help with smoothing freqs much below 80Hz... plus they can be very large while only resulting in a modest improvement. I use them myself but can't and don't rely on them to deal with room modes.

Bottomline... sub positioning and listening locations are what you should try using to eliminate any nulls.

Mcpanse
08-12-2009, 09:46 AM
Here's a picture of the D15 in it's current location. I intend to move it to the right of the television, which will give it a near-corner position.

A large majority of subwoofer setup articles I've read make strong arguments for corner placement. GIK Acoustics argues against it while Real Traps' Ethan Winer has his big ol' SVS sub in the corner along with one of his bass traps.

Any real world experience and observations out there?

The corner the D15 will be near is the only unoccupied corner in my 24' x 16' room, only half of which is used for home theater (the attached picture will make this clearer).

I want to correct a statement I made in my original post about a possible null behind my primary seating. Must've been the material. There's plenty going on back there.

Running frequency sweeps with an SPL in hand, there doesn't appear to be too many wild peaks and valleys in my primary listening area.

davef
08-13-2009, 12:42 AM
Its important to realize that peaks can be attenuated using either Audyssey or the PEQ but you can NOT boost a null. A strong room reflection can compete with the direct signal source and if they meet up at your ear as crest-to-crest or trough-to-tough they will be additive and attenuation will work to lower the overall sound level at that frequency... however if they meet crest-to-tough they will tend to cancel (similar to how noise canceling headphones work) and boosting will cause equal increases to both crest and trough with the result being the same null. Keeping this in mind...

In general this is what you should be looking to do...

Pick a location for the sub that seems to eliminate or at least minimize any serious nulls from all the listening position(s). Then run Audyssey to attenuate any peaks and you will have the best in-room response possible. Its a relatively simple thing to do. I don't know what testing or monitoring equipment you have at your disposal or what you might be running for mains so to keep it really simple just download a sweep that covers the range from 10Hz-150Hz or there 'bouts and play it at approx. 75-80dBs over and over again as you sit in each of the various listening positions. You are listening for nulls, either full or partials... ignore any peaks you hear as they can be EQed out later. At a full null the sound will completely vanish, you cannot tolerate even a single full null... find another place for the sub. A partial null will cause the sound level to dip, if its not too bad don't worry about it as every position will have some dips, just find the sub position with the least and shallowest dip(s) and call it good. Hopefully you won't have to try more than 2 or 3 positions... most people with wives will find they only have 2 or 3 choices given to them anyway ;) If you wanted you could use PEQ to remove any obvious offending peak and then let Audyssey take care of the rest.

I personally don't think bass traps will help with smoothing freqs much below 80Hz... plus they can be very large while only resulting in a modest improvement. I use them myself but can't and don't rely on them to deal with room modes.

Bottomline... sub positioning and listening locations are what you should try using to eliminate any nulls.

Excellent post!

Thank you!

sbeveraggi
08-13-2009, 12:25 PM
Very helpful indeed!
I'm in the process of building my semi-dedicated home theater room, and am considering different sub placement options.
The room is basically 14x14, with a huge closet that takes a big chunk of space, but leaves a small free space at the back. It also has huge glass windows.
The big cabinet represents my R12 SE, the narrow cabinets are my front Sierras, and there's also a big futon type sofa (main listening position)
I will definitely try the "crawling technique", but from a pure theory approach, what do you guys think will be the best setup? A,B,C,D,E,F or G?
Thanks for your help!:)

Mcpanse
08-13-2009, 04:25 PM
I think a lot of folks will tell you that you don't want to put the futon against the rear wall.

You'll also hear that a perfectly square room is problematic. But it is what it is.

If I were you, I would plan on putting the futon well away from the back room and then try the subwoofer in the various locations you've identified.

I'd start with A, maybe move the futon even a little closer to the screen.

Mcpanse
08-13-2009, 04:32 PM
A quick update. After trying the sub in the front right corner, I moved it back to the left of the television, as shown in the picture a couple of posts above.

It didn't sound bad in the corner, but it didn't sound any better either and I prefer the way it looks to the left of the television. This placement also leaves the front right corner available for a bass trap when I finally make up my mind about all the options out there.

I've thought about putting my turntable on top of the D15 but I'm wondering if the vibrations would wreak havoc with playback. As it stands, I don't have a spot in my current setup for my turntable. I've only a modest collection of vinyl, so it's not a big deal. My other option is to move my old sub into my home office and listen to vinyl in there.

sbeveraggi
08-13-2009, 04:55 PM
I think a lot of folks will tell you that you don't want to put the futon against the rear wall.

You'll also hear that a perfectly square room is problematic. But it is what it is.

If I were you, I would plan on putting the futon well away from the back room and then try the subwoofer in the various locations you've identified.

I'd start with A, maybe move the futon even a little closer to the screen.

Thanks for your answer Mcpanse. :)
Although the room is technically 14x14x8, the floor to ceiling in-wall closet makes it about 12x14x8, with an odd free space in the back of the room.
Didn't know the futon against the back wall was problematic. Why is that?

Mcpanse
08-14-2009, 08:47 AM
Others could probably answer your question better than I.

monomer
08-14-2009, 11:06 AM
...Although the room is technically 14x14x8, the floor to ceiling in-wall closet makes it about 12x14x8, with an odd free space in the back of the room....
I don't like to be the bringer of bad news but...
I too agree that those two 14 foot room dimensions are going to prove to be a serious detriment to getting good, smooth bass response in that room and I'm not so sure that closet will make a huge difference as the low freq waves might easily pass through those glass doors... however another problem with having huge glass anythings in the room is what it will do to sound reflections at the higher frequencies.... additionally its asymmetrical to your direction of intended layout. Bottomline is your particular listening space I'm afraid appears its going to offer some serious sonic challenges to your efforts to obtain good imaging and a smooth freq response. You will have to rely on judicious speaker placements and lots of room-treatments to try to get the best from your proposed listening environment as it currently exists. This is just my opinion. If it were me, I would actually be considering ripping out the closet's glass doors and replacing it with an actual wall or hanging some very heavy doors in place of the glass at least.

...Didn't know the futon against the back wall was problematic. Why is that?
The short answer is because the length of travel for reflections will be multiples of the direct radiating wave which can often lead to complete room nulls (and boomy peaks) ...its because so many of the dimensions of travel across the room will be multiples of the straight line distance to your ear. This is also why a listening position in the center of the room is also inadvisable. Once you begin your search for a sub position that doesn't result in complete nulls you will come to the realization that one really doesn't exist for listening positions on a boundary or in the center of the room. That's why the suggestion is given to select listening positions that are at 1/3rds of a room's measured dimensions (really its 38% and 62% that are considered best). In your room that would be ~5'4" (38%) and ~8'8" (62%). The first dimension I would think would be a bit too close to be considered a reasonable viewing distance (unless your screen is really small) and so 8'8" would be the best place to locate the futon with the hopes of finding a reasonable place for the sub that's free of complete nulls (and boomy peaks too). Also if you plan to do any sort of rear surround speaker placement, then a listening position up against the back wall would destroy any directional sonic value those speakers might have provided. Bottomline... placing the futon against the back wall is not really a good idea.

sbeveraggi
08-14-2009, 05:38 PM
Thanks for you answer monomer.
Let me explain my room a little better. The in-wall closet has thick wooden doors, and it is the back wall of the room that has glass windows.
My screen is 47", so I will try the futon at 9'4" for better results. My receiver has Audyssey MultEQ XT, hope that also helps a bit.
I'll also try placing the sub in the 3 corners and behind the futon.

muzz
08-14-2009, 05:59 PM
Why not run REW and look at the FR at various locations?
I saw MASSIVE differences when I moved my sub around the room(and corner loading suckd).

Maybe I missed something?:confused:

sbeveraggi
08-14-2009, 06:32 PM
Why not run REW and look at the FR at various locations?
I saw MASSIVE differences when I moved my sub around the room(and corner loading suckd).

Maybe I missed something?:confused:

I already bought a RS Digital Meter to get basic measurements, but I think I would also need a very good soundcard and a something like a BFD (Behringer Feedback Destroyer) to use REW properly... :(

monomer
08-14-2009, 09:00 PM
Thanks for you answer monomer.
Let me explain my room a little better. The in-wall closet has thick wooden doors, and it is the back wall of the room that has glass windows.
My screen is 47", so I will try the futon at 9'4" for better results. My receiver has Audyssey MultEQ XT, hope that also helps a bit.
I'll also try placing the sub in the 3 corners and behind the futon.
Ah, I see now.... I read that description your wrote a little differently... I thought the glass was somehow integrated into the closet (possibly big door mirrors or such). Now I get it... the glass you were referring to was the windows. I might suggest you consider heavy thermal drapes to cut the 'liveliness' of the room, however its fortunate its located at the back wall away from the mains. Yes, try the sub in each of the corners but in addition you might also try it at several positions along that wall to the side of the couch and pick the spot with the least 'dips' for the bass. Then use Audyssey to flatten the peaks. Good luck buddy.

TooManyHobbies
08-15-2009, 06:32 PM
As has already been suggested, a square or almost square room can be an acoustic nightmare, and a cube or near cube even worse, although I'm aware of many people that are happy with their audio systems in such rooms. I believe the ceiling height being discussed here is 8 feet which will add to the problems since 14 is almost a multiple. There are a few additional problems this room, and particularly the speaker and furniture placement may create. Large window areas, in addition to being reflective to higher frequencies, can rattle with heavy bass. Placing the sub next to a large window area will aggravate window rattles. Large closet doors may also rattle, especially sliding doors or any that are not tight and secure in the door frame when closed. Asymmetrical speaker placement where one of a pair is placed in or near a corner and the other is mid-wall, or where they are different distances from a back wall will cause output differences that will steer the sound image toward the one in the corner or closer to the wall. This can be further aggravated by differences in diffraction or absorption of the surfaces close to each speaker. Corner placements can also create reflection issues that color the sound. Moving the seating area into the middle of the room is likely an improvement in most rooms if it can be tolerated, but the difference between being flush against a wall and a couple feet away is not likely to make much difference. I'd actually expect the sound to be better with the seating area flush against the wall than a couple feet away - reflections will not be as noticeable - and pillows placed along the back of the futon or sofa propped against the wall make cheap, effective sound absorbers for further reducing the effect of the back wall reflection. Of course the more near-field (closer to the speakers) the seating position is the less noticeable other room effects will likely be, so that's not a bad thing to achieve, but many times its just not practical in a multi-purpose room to have furniture in the middle of the floor.

Harmon-Kardon has several excellent white papers on speaker placement and room acoustics in the technical support area of their web site. While these are written by H-K audio engineers, I did not find them too technical to be very worthwhile reading, although I must admit that I am an engineer myself, though not in audio. The articles provided some practical ideas for improving the audio experience that I have used to experiment with my setup. I believe I have improved my system without any significant added expense and, most importantly, without serious objections from my wife.

One of the Harmon-Kardon articles suggested a diagonal room arrangement as an improvement in square rooms, and you might want to try that arrangement, although 12 x 14 may prove too small to work for that arrangement (insufficient free space to move around in the room or use for other purposes). I believe the example in the H-K article was about 18 x 18.

Bill