My New C18 Focus Center Speaker!

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ttocs

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The C18 that replaces my 9 year old Motif arrived yesterday!
There's so little info about this speaker that I though I'd relate my experience with it from brand new to forward into the future (some time travel is expected).

It weighs 50lbs, which isn't super heavy, but being long and narrow it's awkward for one person to handle. It's only finished on the top and sides. The bottom is metal. Both the Flat and Angled speaker brackets allow for quite a bit of extra tilt if needed. The wall bracket is well designed and super strong.

I've had the Motif mounted on the wall above the tv for several years. With the C18 being 2-1/2 times the weight, and being awkward to handle, I'm not considering mounting it in the same location. So I first tried putting the C18 on the console table I've been using for my sources, but the speaker hides the bottom edge of the tv. Next I put it on a petrified tree stump I have as a "side table" for the sofa. Height wise it's great. So I used this all day yesterday.

I began the break-in process using music and listening to only the C18 setup as Large so it can run full range. Started at a moderate volume for the first few hours, then upping the volume to 85-90dB SPL measured 1 meter from the speaker, which is about 80-85dB at the MLP. The sound was better than I thought it would be, albeit a bit "squawky" with some instruments like clarinet and harmonica. It was bass-shy at first, but that settled in pretty nicely after some more hours. Played quite a lot of Jaco Pastorius because the bass was so good, and this is with a speaker that only goes down to 50Hz.

I watched drag racing today and the commentator's voices were so much easier to hear and understand. Everything in the center channel is better.

I'll show some measurements later, but I did an initial measurement at first turn on, then again a couple hours later and more a few hours after that. Measuring with the mic just a meter away from the speaker shows that the speaker itself is fine, no problems like my Motif. But with the mic at the MLP, it shows that there's mainly a problem with a null below the crossover that only seems to affect the cone woofers and not the stat panel, so it's gotta be SBIR. I moved the stump and speaker back and forth to see how the null is affected and the closer to the wall it got, the better things looked. So I decided that the C18 should be mounted on the wall, which I did today.

Next up is to play with absorption to find out what's going to work better to reduce the null. When I stack some absorbers on the floor between the MLP and C18 the null is reduced. I've tried using absorbers in various combinations and locations, but on the floor in a certain area seems to be the best so far. This makes me think that I should consider mounting panels on the cathedral ceiling, which might have the same effect (?). I want to try some ultra thick stuff just below the speaker, and maybe left and right of the speaker also, all right against the front wall.

If this null can't get much better with treatments, it's not so terrible. The rest of the response is already good enough that Dirac shouldn't have much problem with being able to improve things.

As much as I sort of expected that the C18 should sound great, I really didn't think that it would be this good!
 

JonFo

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Congratulations Scott, I hope you get many years of enjoyment out of this one.

Wall mounting does seem to be your best bet.

Floor-bounce nulls can indeed be mitigated with treatments overhead, I do that over the Monoliths and the SL3XC. Not sure about placement on a cathedral ceiling, but it should work.
 

ttocs

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Floor-bounce nulls can indeed be mitigated with treatments overhead, I do that over the Monoliths and the SL3XC. Not sure about placement on a cathedral ceiling, but it should work.
Thanks for confirming this. The roof slope is pretty shallow being just under a 4/12 pitch (3-1/2 to be exact), so it shouldn't be so bad with placement. I've got some 3-1/2" thick 30x48" panels laying about that I can experiment with. I've often thought about putting up clouds, so now is the time I guess.
 

ttocs

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Using REW's Generator and RTA, I set the Generator for Noise/Pink Periodic, then set the Custom control for 100Hz Low Cut, and 1200Hz High Cut, Brickwall. Then I got up on a ladder and held a 30x48" absorber in various areas of the ceiling while watching the RTA screen on the tv. I use the 85" tv for the Mac mini that REW runs on, so it ain't difficult to see.

Near the front wall directly over the C18 resulted in no change, but, once I got within 2' to 6' in front of the MLP where the mic is located, then the null fills-in as I move the panel around. This is opposite from what I expected, but who cares? I thought due to the slope of the ceiling that the panels would need to be closer to the front wall. Varying the distance between the ceiling and panel moves the frequency response around, as expected, but I thought I'd try it to see the effect "Live".

I'm shooting for the range from 200-600Hz, with 350Hz being the deepest point of the null. So now I'll get some ceiling grid wire and studs to quickly mock-up some panels up on the ceiling.

Thanks JonFo!

edit: Thought I'd mention something else here. I really don't need to go much above the crossover of the woofers to stat panel, because the stat panel is almost immune to this null as can be seen in the plots I've made which show the frequencies above the XO being fairly level, but just below the XO they dive to the bottom quickly, then rise as the frequency goes lower. So whatever makes things looks smoother is the general target.
 

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Then I got up on a ladder and held a 30x48" absorber in various areas of the ceiling while watching the RTA screen on the tv. I use the 85" tv for the Mac mini that REW runs on, so it ain't difficult to see.
Awesome, talk about a computer monitor, 85" should be readable from the home across the street ;)

Nice technique for finding the ideal location.
The bounce is going to indeed be largely from the dynamic woofers, so below the XO is about right.

Looking forward to seeing the permanent setup results.
 

ttocs

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Wow! There's a lot I don't know about acoustical treatment and workarounds!!

I've been beating my head against the rocks trying all sorts of ways to see if there's a methodical way to "find" the problem causing frequencies, whether it's what's causing a null or a peak. I cannot find any info on this that applies to my room with sloped ceilings and a glass right wall. So I'm flying by the seat of my pants on this, which I'm used to doing. So . . . . .

Mounting the C18 on the wall using the flat brackets and adjusting tilt, then using the angle brackets and tilting even more, allowed for really minor tuning but nothing more. I know I'm dealing with SBIR here, but sound panels only do so much with it.

I love using RTA for stuff like this, but I needed to bash my head for long enough to have that "a-ha" moment where I "consider everything" as the culprit. For days now I've been moving my love seat around when moving the MLP microphone, sometimes with the seat reclined and other times with it upright, but almost always with a blanket covering the leather - although you'd be surprised at how often leaving the leather exposed can help.

Ok. So I installed a couple cloud panels and that seems to be a really good idea and I'm making more of them to hang up in the next day or so. But, this null remains!!! and doesn't "move" left or right, so
"Something's missing" as Frank Costanza famously said at the dinner table with the Ross's (Susan's parents). Since having the cloud panels I hadn't tried the C18 on the stump, so I did. I placed the stump up to the edge of the rug and fired up RTA and Generator and started moving the mic around. After finding a good spot for the mic I moved the sofa, then moved the mic, then sofa, etc, until they both agreed that it seemed to be a good location for the MLP. It looked good on the RTA plot, and it also measured very well with the sweeps!! A Ha!! The null below the XO has been brought up to even with the frequencies above the XO of the C18, and the XO is 470Hz.

#1. The sofa affects the FR a lot.
#2. With only two cloud panels, I couldn't have gotten this result without them.

Nuthin's done, but I'm now happy that progress is being made. More fiddling with the C18 positioning with the hopes that the FR will remain after trying to move it farther from the front wall so I can move the sofa back to where I know I'm happy with the Left and Right speakers.

One thing that I am aware of is that after treatments are placed, some things will change and need more tweaks. It ain't done till . . . . well, for now, it just ain't done.
 
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BDH55

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One thing that I am aware of is that after treatments are placed, some things will change and need more tweaks. It ain't done till . . . . well, for now, it just ain't done.
At least in my case... it ain't never actually 'done'.... ;)
 

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Very glad your enjoying the C18 @ttocs!!! I always recommend the C18 to anyone looking to find a ML center channel, even if it means waiting a lot longer to save up for one. It was one of the best upgrades I ever did. IMO the C18 is leaps and bounds better than all the other centers I've heard or owned from ML. I'm sure the only thing better would be the C34 but thats a whole another animal.
 

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IMO the C18 is leaps and bounds better than all the other centers I've heard or owned from ML. I'm sure the only thing better would be the C34 but thats a whole another animal.
While the C34 is a great center, I'd take a three-stack of C18's behind an AT screen over the C34 any day.
 

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I love my C18 and have no desire to change it out. I use mine sans stand under Isoacoustics pucks. An Sbooster linear power supply helps further improve dialog and noise floor. Enjoy!
 

codesx100

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I love my C18 and have no desire to change it out. I use mine sans stand under Isoacoustics pucks. An Sbooster linear power supply helps further improve dialog and noise floor. Enjoy!

I've been curious about trying the Sbooster, I've heard Is it worth it, was it a noticeable difference at first?
 

tonyc

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Yes, I noticed a difference in being able to understand dialog, mostly when I use my Apple TV. I also noticed improvements in understanding lyrics on 5.1 music as well.
 

ttocs

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Tomorrow night is Movie Night! and the C18 will be the only speaker operating due to a Alfred Hitchcock double feature. I've been running the speaker setup as Large during break-in, but I'll run it with subs tomorrow even though the first movie has no audio below 70Hz. Rear Window has a better soundtrack and goes a little lower.

Both are Mono audio tracks:
The Lady Vanishes
Rear Window

I'm really happy with the purchase, it's a great speaker!

edit: Yes, the movies sounded great!
 
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ring909

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I just got a new C18 to go with my Montis and I am trying to decide if I should wall mount it or just have it sit on the fireplace wooden mantle on a set of Isoacoustic Gaias. Has anyone here tried both and can give a recommendation if wall mounting vs just sitting on the base is preferred for the C18?
 

ttocs

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I just got a new C18 to go with my Montis and I am trying to decide if I should wall mount it or just have it sit on the fireplace wooden mantle on a set of Isoacoustic Gaias. Has anyone here tried both and can give a recommendation if wall mounting vs just sitting on the base is preferred for the C18?
I wanted to wall mount mine below the tv panel - and did, but then found the best spot was on a stand.

The "stand" I'm using is a petrified tree stump. On top is a IsoAcoustics Aperta 300 Center speaker isolation stand, which is perfect for the C18. The Aperta has tilt adjustment.

The dimensions from front wall to front edge of C18 is 32", and from floor to bottom of C18 is 23". These dimensions along with the MLP being 11' from the front wall is what eliminated a very wide 300-400Hz null from about 200Hz up to 600Hz.

When wall mounted, to be able to get a flat response without this null, the MLP needed to be way too close to the front wall, or way too far from the front wall, neither of which will work for my room layout.

Speaker placement is a puzzle. The pieces need to move about within the confines of the immovable items like walls, floor, and ceiling. Measuring will show the repeating patterns of peaks/nulls. Armed with this information we can then decide what might work for our situation.
 
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