Emerald Physics CS2 + JTR 12LF + 4 Hsu uls15

Remind me, what subs did you have before this? Also, have the CS2's replaced the 12LF's as Main's?

wow!

slowcar, what receiver do you use in that setup? Also, how do the quad ULS's compare to the single DTS-20?

Slowcar, we need some comparisons. The CS2 vs the triple 8's, and then the triple 12LF.
Of course the DTS-20 vs the quad ULF's would be great.

I wish I lived close to someone on the forum so we could compare and help each other out.

Might do that slowcar. I'll be interested in the quad ULS -vs- DTS-20 comparo!! Are they all 4 wireless or do you have to hardwire at least one?

This is an awesome picture of your set up, SlowcarIX. Emerald's and JTR's working together. I love it, even included your cat. Add a caption and you got yourself a sweet lolkitty pic.

Why put all four in the front as opposed to spreading them out in the room. For example, one in each corner, or one along each wall, or a combo of the two?

Slowcar, how did you set the individual sub levels?

I made the mistake of setting the gains equal thinking the output would be the same. I believe that was a tip I picked up from the how to set two subs thread a while back. I found out that was not true. Ultimately with HSU's help I set the subs (2 ULS) using test tones with the SPL meter 6" from the cones putting both subs in exactly the same spot in the room. You would think at 6" it wouldn't matter but it did the room has an effect.

I just did it last night but I think I have it right. I hope so I have had enough tweaking for a while. I think I'd just like to sit back and watch a movie without analyzing what is going on.

During testing I generally leave the lights on and it is interesting to see them dim on the big bass hits.

I don't feel there is anywhere to upgrade to either, I would have to reinforce the house if I was going to bring in any more bass.
Mental note stop reading forums.

Enjoy.

*Cough. . .what did I tell everyone. . .cough*. . .

Regards,

I championed the idea that setting each subwoofer to identical output levels would yield best coupling power between two or more subwoofers and I was right. This won't happen if the gain is set identically in most cases as the levels will vary due to location and overall placement.

Coupling requires level (phase and frequency) to be identical. I put forth my case in that thread and found little argument because I was, of course, correct.

Regards,

Different experts use different approaches. The sensible thing (and logical thing) to do would be to level match at the listening position.

Turn one subwoofer on and set to 70 dB's using a known gain level (x). Turn subwoofer off. Turn on the second subwoofer. Set to 70 dB's.

The gain levels shouldn't vary to achieve the same 70 dB level as all four subwoofers are closely spaced. Turn subwoofer off and repeat the process until you have finished with all four.

Turn on all four subwoofers and the maximum overall output should read slightly north of 80 dB for full coupling. Now you'll control all four subwoofers in unity by using the subwoofer level in your AVR.

I would shoot for a 72-73 dB reading (flat) but you'll have skyscraper levels of headroom with this configuration especially once you've achieve mutual coupling so you can increase the levels (using the subwoofer level) to taste.

You're done.

Regards,

I agree with what you are saying to a degree but having one sub 6 feet away from another may cause a problem. What if that sub has a null at that frequency in the seating position.

An easy way to explore this would be to run a test tone and swing the SPL meter in an arch around the seating position. With one sub I'll bet there would be wide variation in the SPL reading. If you hit a null or peak with the tone you could over or under drive the individual sub.

Hsu instructed me to place each sub in an identical position within the room and set the gain with the SPL meter 6" from the cone. This way the output of the sub is identical. I originally set the level with each sub (2) in their normal position which is 30” apart. When I checked the reading by putting the second sub in the first subs exact position there was around a 2 db difference.

I am far from an expert but I believe the goal is to have each sub carry an identical load thereby creating the magical headroom. I feel this is the best way to achieve that goal, the best way I have heard to date anyway.

Output might be identical when you are 6 inches from a cone but people don't sit next to a woofer cone which largely mitigates frequency response issues. At the listening position the results will be different due to sound wave reinforcement (and cancellation).

What HSU is recommending is that the gain levels be set identically but identical gain values does not mean that the output levels will be the same. Those are two different things handled in two different ways.


That is a noble goal and one worth pursuing. Since all four subwoofers are closely spaced within a 1/4 wavelength distance at most bass frequencies you should achieve full coupling provided the levels, phase and frequency are identical.


Fair enough.

Regards,

Goneten, you skipped the part about under or over drivng one or more of subs? What tone or tones would you use to set each subs gain? If one sub is in a null for that tone you could set it very high in which case it would bottom out when driven with a full range signal? A differnt sub could be at a peak for that tone in which case you would set it to a whisper, again not desirable.

Having all the subs put out identical output and using the AVR level control to assure the combined output is correct still makes sense to me. Isn't that the advantage of multiple subs? They overcome nulls and peaks by attacking them from multiple points?

Again no expert just trying to apply common sense to a problem.

Slowcar you have 4 subs I think it is time to drop the $44 on a SPL meter.

http://www.radioshack.com/product/in...ductId=2103668

Have fun