Originally Posted by gpmbc
Sup Austin! Just curious since you owned the LMS ultras, did you hear a difference in sound quality going with the SI18s? I know the ultras are touted for their low distortion and am curious if multiple 18s using less excursion level the playing field. I have 8 SIs now with 2 FTW 21S coming soon. I'm not strained now just wondering from your point of reference.
Good question. I hate to sound like Mr. "Politically Correct," but I find it very hard to quantify a difference in sound quality.
One thing I can tell you right up front is that I found it much easier to get the LMS-U's to exhibit the "type" of sound that I wanted from them. As you (and I'm sure a lot of other people) know by now, I am extremely bias to the ULF end of the spectrum. I found that the LMS-U's provided much more low-end grunt without really having to manipulate the $hit out of the signal.
I was able to get the same result from my SI's, but in addition to boosting the bottom end, I literally had to cut the mid-bass drastically in order to get the same effect I was getting from my LMS-U's. To put it in layman's terms, the LMS-U's seemed as though I had two guys that could bench 600lbs helping me move furniture. The SI's seem more like having 16 guys that can bench 200lbs...lol
I'll be 100% honest...I if I tried to get very technical, I would probably end up mis-speaking or giving you bogus information. With that said and from what I have learned on the forums thus far, I want to say that (in addition to a few other design elements) the motor force (i.e. bl & bl Curve) plays some part what sets a driver like the Ultra apart from a driver like the SI.
I'm basing that off of a post I read from Scott awhile back... Can't seem to find the reference though? Maybe Scott, Bosso, LTD, Beast Ricci or some other technical guru can chime in to shed a bit more light on motor force and how it effects the SI and LMS-U drivers respectively?
As you already noted, with so many drivers on tap we have the ability to keep excursion low and still maintain gobs of headroom. I firmly believe that the SI's can (and do) sound just as good as my Ultra's did at moderate play back levels. Even on a one-to-one basis.
I think something like this would be an interesting experiment:
- Level match one LMS-U to one of the SI-18's
- Use the mini-DSP to manipulate the curve to match response as identical as possible.
- Keep xmax under some arbitrary number where THD doesn't become relevant (say 15mm).
- Compare blindly to see if anyone could tell a difference.
I would put my money where my mouth is and say that no one would be able to tell a difference in a blind comparison. One other thing I want to mention since I touched on the topic of THD. I notice when I have 8 or 16 of my subs rocking, I am picking up vibrations from literally EVERYTHING in and around my theater. Here is a list of what I have found contributing to the noise and (at some point in time) attributed to me thinking that my gear was making some nasty sounds.
Top 5 culprits of nasty sound in my room:
5. Light fixtures.
Seem to resonate around 32Hz and again somewhere around 7kHz.
4. Rear Box Vibration.
The boxes are unsecure, so in ULF scenes the box rocks back and forth and slams into my rear wall. Very annoying.
3. Mains stacked on top of front boxes.
My mains weigh 88lbs and they settle into the duratex finish. When a ULF scene hits, it will unsettle the boxes. Every time it does so, it makes a very loud cracking sound.
2. Bathroom door.
If I keep it closed, it is very very obnoxious.
1. Theater seats.
When I first engaged my near field subs, it sounded like I was having some serious distortion issues! I did some investigating during intense playback and it turns out that the leather was flapping against the seat frame at almost all frequencies. I'm pretty much at a loss for how to deal with this issue...lol If you ever come to my house for a demo and hear farting sounds on occasion, it's my seats man! In fact, I moved my seats to the middle of the room (about 6ft away from the rear boxes) and this no longer was an issue.
The LMS-U's always sounded smooth because there was much less room interaction. Sorry I can't give you a simple "yes" or "no" answer, but I hope this helps my friend.