Bass Response on Dunlavy SC-IVa

I purchases a pair of DAL SC-IVa about a month ago and have been trying find the best placement in a less than optimal room. My room is 21ft x 12Ft with cathedral ceiling starting at 8ft in the back to 12 ft in the front where the speakers are set up against the short wall. I know they should be set up against the long wall but the existing HT won't allow this. The speaker are 49" from the rear and 20" from the center of the cone to the side wall. I have carpeting on the floor and ther is a 5ft openning 11 ft from the front wall.

I have experiemented with many placements but just can't seem to get the bass to sound right.

Any suggestions ?

You make no mention of what affects you are hearing. I would assume it's an overly boomy bass with many peaks.

Regardless, you might consider bringing them out even further into the room, say another 2 feet from the back wall and perhaps another 6 or 8 inches in from the side walls.

Are you adjusting your listening position as well as the speakers? I've found it best to work with each. Also, although many may not agree, you could actually space the speakers closer to the wall and compensate by doing some substantial toe in to reduce first reflections. You should also have a (Radio Shack) sould level meter and a (Rives) test disc to track your progress.
What type of floor do you have these on? What are the problems with low frequency reproduction that you are encountering? Any type of footer or support components between the cabinet and the floor? Sean
The problem is the variation in the reaction of the woofers to the floor and the ceiling. You have a large differential in boundary effects. The woofer on top is much further from the ceiling than the woofer on the bottom is from the floor. So you probably have a bass suckout of about 6db at 60 to 70 hz at ear height at your listening position. This is where much of the hit bass is on most recordings. Some geometric panels {and not soft} to act as a lens to refocus lost energy back at your chair would greatly enhance phase and frequency. Tom
I never got the bass right either. On the IVA or the V's. They are one huge speaker which makes it a lot more difficult to get right and live with
I have a possible solution, which is worth trying.
Try listening to the room.
Play one speaker, using a low frequency test tone, with the speaker in a 'probable' final,location.
Walk around the room, and find where the 'hot spots' of good bass are. This will give you an idea as to where the potential locations of the listeners chair might be. The key is to extrapolate that in to the 3 diminsional puzzle that setting up an audio system presents.
When setting up a system in a problematic room, I always try to get a 'fix' on the room's sound.
While i can dig up the facts / figures on this speaker, does anybody happen to have the crossover points handy?

I agree with what Tom / Audiotweak is saying in that the woofers are non-symmetrically loading into the room. Since all rooms have various ceiling heights, the results with this type of speaker will vary from installation to installation. Then again, this is true ( to varying extents ) with any design that raises the woofer(s) up above floor level / very bottom of the cabinet. That's because boundary effects are somewhat "set in stone" with a design of this type.

One will also encounter this with woofers that are stacked vertically but somewhat spaced apart from the other. This is especially true if the bottom woofer is already measurably up off of the floor. The larger Vienna Acoustics speakers suffer from this quite noticeably and even the reviewer in Stereophile commented on this. If i remember correctly, he went so far as to say that they were the hardest speakers that he's ever had to deal with in terms of placement.

Having said that, the staggered woofer array can be put to great use, but one would have to fine tune the spacing between the drivers and the crossover points for the individual listening area that the speakers would be used in. By "tuning" the output range of one woofer where the nulls of the other woofer(s) are occuring, the response sums to something that is much flatter overall. This is probably what Dunlavy was trying to accomplish, but without knowing the ceiling height and the distance from the side walls and how far they are pulled out into the room, there is no way to optimize the design.

Having said that, Dunlavy gives pretty specific placement suggestions for these speakers that seems to work quite well, but if you can't follow them, there are other methods that may work for your given installation. Only problem is, this requires a LOT of moving & listening, which large speakers like this aren't exactly easy to work with. Sean
Try this: Move your listening chair,place a ladder where your chair use to be. Play a constant test tone at about 60hz. Climb the ladder up to ceiling height, make reference of the 60hz tone with either an spl meter or your audio memory. As you come down the ladder at each step make another measurement and record the output, do this until you reach about 2 feet from the floor. Now after you have done this move the ladder, re-install your chair at the original position and take the same measurement at ear level {38to40in.}..At ear level you will have a 6 to 8 db contrast to the floor and ceiling measurements.The frequency of the suckout maybe 50 to 80 hz so your reference tone may vary slightly.While doing any of these tests do not touch the volume control. ..You can mitigate some of the phase cancelation by moving your ceiling or by building an acoustic lens attached to the ceiling ..Tom
I agree with Theaudiotweak. But a potentially easier way to mitigate phase cancelation here might be to just lay the IVa's on their sides. But that solution is not without it's own problems. :)
John, Peter Snell had a speaker [Type 1} that had its drivers near the floor level on an angled baffle tilted back with a ramp in front to reduce the floor bounce effect..He also had a U.S.patent on baffle designs to reduce room boundary effects. Truly a designer who thought outside of the box. Had a in home demo of that Type 1 speaker and a sales meeting with Peter Snell...that was probably in 1980 or bad he is no longer with us.He was truly a innovator. Tom
It is a very interesting question, cathedral ceiling and Dunlavy 4.
I had never known it until I bought a Behringer deq2496. It also took me a week to spot root cause of the problem. However, I got a 20dB hump, instead of suckout, from 45 to 65Hz at listening position, 3.5' from floor. If I move vertically up to 7' from floor, the hump reduces significantly by more than 10 dB.
Yeah you're dealing with differnt issues with speakers designed like that.
The basic "layman's" answer to all of this is that the IV's will do better set up in large spaces, or where at the very least they're on the "Long wall"!(where you can get the speakers spaced further apart!
Yes these speakers have the potential(set up right) to have very smooth, fast, well balanced bass with the Dual woofer Dappolito design(not to mention 1st order cross, multiple driver array). One woofer might balance out the other on the speaker, placed on a "different plane" in space. Still, in small room settings, or where they're not more "optimally set up", you'll have comb filtering issues, boundary to woofer cancelation/reinforcement issues(compounded with multiple woofs on the same planes), and other compouned issues. Sitting at "tweeter level" with your ears is also more critical in regards to comb filtering here as well. That said, stick these speakers in a room where the woofers and walls/boundaries are spaced at distances which are multiples of each other, as well as the listening distance, and you can easily have holes and peaks that will pronounce the problems!
Basically, without getting to into it, the easy solution, besides tinkering with every possible "short wall set up possibility",is to put em in a larger space or set up on the Long wall. You'll likely have an easier time getting fuller more balanced bass if your seating possition is good.
I personally have yet to hear a set up for the IV's/V's where they sounded good too close together, or in smaller more confinded locations (such as along the "short wall".
If none of this is an option for you, your focus/target should be to do whatever you can to ensure all the woofers and boundaries are not at "multiples" of each other.
If I were you, I'd try the long wall set up as a comparison, and also seating location. At least then you can figure what the speakers can do in a potentially better set up scenario.
Don't dispare, the speakers have Bass. But also be aware that your set up is likely the problem..infact, I"m sure of it. I've heard those speakers have excellent bass in larger room layouts than yours. Infact, my buddy has the same problem in his "short wall/smaller room setting" as you with this SCIV's! His bas has sucked sinced day one with these. I told him it's his set up also...he's just too lazy to fix it.
Here are the measurements that I have using a SPL meter and a Stereophile test CD. The biggest problem seems to be in the 40-50 HZ range. Thanks for all the help so far. Further suggestions will be greatly appreciated.

1KHZ - 78 dB
200 - 70
160 - 72
125 - 82
100 - 82
80 - 84
63 - 74
50 - 68
40 - 67
31.5 - 79
25 - 77
20 - 74
1) What are you using for an SPL meter?

2) At what distance were these readings taken from the speakers?

3) Where in the room were the readings taken i.e. at your listening position, standing up near the speakers, etc ???

4) How close were you to spl meter when taking the readings? If holding the meter, how far away was it from your chest area?

5) At what height were the readings taken?

6) Have you tried measuring one speaker at a time and then taking readings with both speakers operating?

7) Have you verified that the speakers are properly wired i.e. using the same polarity?

8)Is it possible to do a wider sweep i.e. one that shows the lower midrange response readings also?

The more that we know, the more that we'll be able to make constructive suggestions. Sean
1) I am using a Radioshack digital SPL meter

2) The readings were from 14 feet from the speakers

3) The reading were taken from the listening position

4,5) I held the meter in the listening position about 42-44 inches above the ground and mabe a 12 inches from my chest

6) No, I did not do them individually - only together. But I will try that.

7) Yes I have verified proper connections

8) I do not know how the change the settings to do a wider sweep. If you know how to do this, please let me know.

Thanks in advance for the assistance.