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ken kaz

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Here is my issue. I have a large basement room 30x15. I am using half of it about 15x15 for my HT.

I have Chorurs IIs, academy, and 4 heresy IIs for surround. All driven by rotel amps.

The room has a cement floor.

I want bass you can feel.

I have a SVS PB ultra 2 in the front right corner and a SVS CS ultra (driven by a carver 1.5) in the back corner.

I just bought a Integra 9.8 in hopes that the audssey would help on the lack of bass ( It did, a bit)

Last night I had people over and the kids were watching the Bee movie while the adults were upstairs having drinks. There were a couple of times that (upstairs) i thought the house was going to come off the foundation. I went downstairs and noted the passages in the movie.

Later on, I replayed the passages while I was down stairs. Decent bass, but quite frankly there is quite a bit more upstairs.

I am considering another sub, but I think I have plenty since the house is literally moving. HELP!

My friend thinks i should put 2x4s on the concrete, then tounge-in-groove plywood covered with carpet. He says that this will allow the room to move. He blames the whole mess on the concrete.

Has anyone else been in my boat?


Ken Kaz

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Can you draw a picture of your HT setup, i.e., where the speakers are and where the listening positions are? Also, how high is your ceiling? Is your 15x15 HT walled off from the rest of the 30 x 15 room?


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I will draw it up and scan it. The long wall is actually 30 and the short wall is actually 20 with a 7 ft ceiling.

The HT is 17x20 and the related room is 13X20 but they are actually one big room. there is a support beam in the middle of the room at the 13/17 point, effectively dividing the room.

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So you have two SVS Ultra subs,and the house shakes but output at listening position not satisfactory.

Looking at the drawing I can see why.You have subs to your right and then a BIG space where you probably have most of the subs's work so to speak.

I would first take the lighter SVS Utra subs and move the sub along side the front(to your sitting position) wall. Find a spot where bass is plenty and not irritating(colored). Once you have this spot,search for another good spot or two whre again response is good at listening position(the HT viewing ...seats used).

Place the subs in the optimal spots. I would move the larger SVS in the optimal spot and work with the lighter weight sonotuve SVS to find the idal location.

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Sorry, im confused and your recomendations are going to be difficut as the PB12Utra 2 weighs 200lbs.

You are recommending that I move the PB12ultra 2 (currently in the front right corner) along the front wall twards the middle of the room? Possibly to the left side of the tv?

I can also move the CS ultra (currently in the back right corner) to the middle of the back wall, to the left of the book case.

Is your idea that I need to get the subs closer to the center of the room?

Will there be any benefit to moving a sub to the center of the SIDE wall?





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My God, I think if you post this same thread in 10 more places (you haven't hit the Russian section and Craigslist yet, have you?) you might get responses!

(Note, every one of your dimensions is a multiple of the other!)

I'll just repost what I have already posted...this is crazy.

A 30x15 room and
using 15x15 of it for HT...The only thing lacking in contributing to
the problem is a 9, 12, or 15 foot ceiling!

This is a room mode breeding facility!

The easy money is
that you are sitting in a null determined by the room dimensions. And
SW placement in the corners will drive and reinforce this null to the
greatest degree.

Adding more bass or magic processors will not remove a null.

You might want to move your seating position or change the dimensions of the room. I suspect the former is easier.

In this scenario, the only thing that will increase the sense of bass where you are seated is to place a sub closer to you where the direct signal is >= 10 dB greater in intensity then the ambient bass signal in that spot.

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What I said is very simple.

Use the lightweight cylinder SVS Ultra and find the optimal spot (probably along side the front(to you) wall and near the left speaker or around there. As this would be a practical and effective spot.Is this the best spot,no...but way more effective than what you have now (lets say one of the worst spots on relation to uour sitting position in this room.

SO like CAS said...adding more subs would be a waste. As you have placement issues and there is the listening position. Lets work on the sub ideal spots in relation to your current listening position.

Start expetimenting. After when the great spot is found with the CS Ultra...move the dual driver Ultra there. 200lbs sub that is far from huge or impossible to move.

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Well MAS look on the bright side. At least there has not been an outpouring of suggestions that a bigger amp or a different kind of amp will solve all the bass problems. Oh wait maybe I have jinxed things.

Seriously, take the above suggestion seriously. An afternoon of re-arranging furniture and speakers will make some noticeable differences, although it may not eliminate all the problems (it may simply shift where they occur in the spectrum).

Good Luck,


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Floor shock, you're missing floor shock.

It's that visceral sensation when the floor joists bounce under you and the room feels 'energized'. It's actually detrimental to the sound but feels really cool.

Placement or more detailed, musical subs would be the correct answer. I like the solution pointed out by esteemed colleague EAR. Leave the larger sub in the corner which reinforces it, move the smaller to a more balanced position.

Fill the bookshelves with stacks of varying depths, creating a giant diffuser behind you.

In the 'recommending another sub department' I recommend the THX sub setup. Remember that although you think you're 'using' a 15x15 space, your sub must move all the air in the entire room, which is quite substantial.

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Thank you.

I will play with the subs tonight and see what happens.

Changing the size is imposible, as im in a basement!

I have considered putting the tv on the 17 foot wall but the support beam in the middle of the room would kill me. As it would be against the back of the HT seating. Is there any reason to believe that this issue would be less if i roted the theater 90 degrees?

Finally, as I will move the sub along the front wall, is there any magic number as to where? The Integra manual says that 1/3 the distance of that wall is a good spot, but is that 1/3 of 15 or 1/3 of 30?

Thanks again.


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No no and NO.

I repeat again.The problem is not you need better subs,you have two great subs. Three Ultra drivers ,plenty of displacement and quality. Musicality lacking...PLEASE.

You need to find the ideal spot using the smaller cylinder SVS,when found ...place the big sub there. After you look for a secondary spot (second best if you will) and place the lighter cylinder there.


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When we started last night, running the sub test tone from my integra, i had 77db, 75db, 74dB, 73dB in the seats, going from right (closest to subs) to left (furthest from subs). Moving the cylinder sub from the back right corner to the front left of the tv gave me 2dB more. Moving the cylinder to the middle of the room did nothing, moving the cylinder to the back left corner helped, but not as much as it was in the front left. We then move the box sub (PB12 Ultra 2) into the front left spot next to the TV and began moving the cylinder around the room to find the best spot.

The best spot was the cylinder in the same spot it was originally (back right) with the box sub to the left of the TV. We were getting aunifom 79 dB in every seat.

Just for fun, I brought my sub from the garage (NHT) and put it in the front right corner. With that on, we got 82dB in the middle seat. When listening to music at loud volumes, however, it sounded better with that sub off. (Maybe this is because that sub is nothing in commparison?)

We still have not tried the NHT in the back left corner.

The adjacent 13X20 area is actually open to the kids play room (17X15) and the laundry room (10x10) and between those two rooms is the stairwell going up. We played a A-B spot of 20sec looping from a very heavy bass section in the Bee Movie. The bass response in the stair well was sick. I guess all the air that is pressurized in the basement is forced up the stairwell

ShouId I get another CS ultra and put it in the front right corner or the back left corner, or just stop here?


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This may or may not help, but can you not build a fake wall to enclose your listening area? I mean by either truly building a wall with sheet rock or using very heavy drapes. I would think that this would prevent some of the sound from leaving the area and increasing your bass.

Someone please correct me if I am wrong.

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To repeat what Ear has stated, he has plenty of bass.

The problem is its distribution due to the phenomena of room modes - standing waves established based upon the geometry of the room. And with standing waves you have peaks and valleys (nulls) where the gain at particular frequencies is either summed and made greater (the peaks), or it is minimized (the nulls). And this is a classic example in that the room dimensions cause the 3 major modes to sum at the same frequencies, thereby exacerbating the problem.

And his room has LWH mesurements that are all multiples of each other, further reinforcing the modes.

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Exactly, adding subs is trying to fix a leak with more water flow in the pipes. Not a logical solution.

There must be a spot in the room or several spots with more bass gain at listening position. I would use the lighter SVS to find the spot(s).

As a last resort...and solution...the sitting position has to change.I would rearrange the sitting, as it will change the result in a big way. For this pace the lighter SVS when you would like,walk around the room and note the good bass sports(playing music or a move with alot of bass).

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Great. the places I have the subs now helped quite a bit, it is even across my seating area, which is most important.

SO my room is 15X30 and there is nothing I can do about that. My wife, however is telling me that we need an addition to the house. If we do this, the system will go in it. When I do this, where do I go to get recommendations on wall sizes and cieling heights for HTs? Is there a guide of some sort? Or just call the EAR?

Thanks again, guys.


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Properly tuning multiple subs can be tricky..........even a pain in the butt. Be patient, keep experimenting, listen to the pros here (I'm not one of them) and when you get it right you'll absolutely love it.[Y]..............location.........location.........location.

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