February 2017 - Kansas City Home Theater Crawl - Page 42 - AVS Forum | Home Theater Discussions And Reviews
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post #1231 of 1408 Old 02-28-2017, 12:19 PM
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Quote:
Originally Posted by carp View Post
Here is the difference with the measurments using the vibsensor app.

Thanks to Paulo for showing me how to use this, it's pretty cool!

Here is a omnimic sweep of the 2 subs, I posted this earlier:

So here's a side by side of the 4000 vs the 8 sealed. The horizontal axis is lined up so that you can directly compare.




Generally speaking, the shape to the TR is fairly similar with two exceptions:

  • As highlighted in the red circles, the 8 sealed have significantly more TR between 18hz and 12hz or so.
  • The 4000's overall TR curve is choppy compared to the 8 sealed. It was also facing the wall and not the LP.

Your sealed is putting out some nice TR compared to the ported 4000. I wonder if the bass array effect is increasing the overall TR/PR you are getting.

My guess is that the choppiness of the 4000 is because there was only 1 sub location as opposed to the two locations for the sealed.

@carp , I know you said you could tell a slight increase in TR with the sealed. Did you compare any other clips other than JW? I'm guessing JW isn't the best scene to judge 20hz and below.


Carp ran his tests with the 4000 facing the wall...so I thought that might be the reason why it had less TR. He ran some additional tests with the 4000 facing the LP. I compared them below:




As you can see, the 4000 facing the MLP had LESS TR than the 4000 facing the wall. I'm scratching my head on this one as everything we've seen thus far predict that there would be more TR when the drivers and ports are facing you. There's obviously other things influencing TR/PR in the room.

Also note that the TR is smoother with the 4000 facing the LP.

Calibration was done with sweeps, but it would have been interesting to see what the white noise looked like on the SPL/Spectrum graph; perhaps that might explain some of the differences. Carp did look at the white noise in the FR chart of Omnimic, but I know you're supposed to use specific OM tracks for that screen.

I think these tests interesting and provided some good insight! However, it should also be noted that because they weren't in the exact same positions (impossible with this test!), I'd be careful to jump to any conclusions.
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post #1232 of 1408 Old 02-28-2017, 12:28 PM
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I should add that all of these comparisons were with the nearfield and Crowson off.
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post #1233 of 1408 Old 02-28-2017, 12:31 PM
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As far as content goes John Wick was pretty much it. It seemed like my wife was upstairs everytime I had to time to do some testing and she started getting tired of the house going crazy.
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post #1234 of 1408 Old 02-28-2017, 01:56 PM
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Quote:
Originally Posted by dominguez1 View Post
My guess is that the choppiness of the 4000 is because there was only 1 sub location as opposed to the two locations for the sealed.
what sort of signal was used for the measurement?

the spikiness looks like high(er) frequency noise aliased into VS's bandwidth
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post #1235 of 1408 Old 02-28-2017, 02:07 PM - Thread Starter
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The 4000 was not corner loaded like the 8 SI HT 18s.


Unless carp changed things up for this recent test -
The 4000 was actually firing into the cones of the SI HT 18's, which may have allowed the 18" SI drivers to dampen the output of the 4000ulf. (assuming the SI amp was powered down).


Was the JTR 4000 amp powered on when the SI were playing?


So I'd expect the 4000, if corner loaded, and not firing cone to cone into 4 18" drivers stacked in the corner - would have a wee bit more output than shown.


I agree that I don't think you can talk much scientifically away from the comparison between the 4000 and the 8 SI --- it's just for fun. You can subjectively take away that the 4000 ulf is a ridiculously potent subwoofer.

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post #1236 of 1408 Old 02-28-2017, 02:56 PM
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Quote:
Originally Posted by carp View Post
Ryan's room has a lot of feel!! I remember feeling my pants leg flap and getting a lot of tactile sensation and being in complete disbelief that he only had a single dual 12 SVS - the same one I used to own.
This has been mentioned a couple of times. I'm curious how that was accomplished.
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Did you really need to quote that entire post in your reply?
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post #1237 of 1408 Old 02-28-2017, 03:40 PM
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Quote:
Originally Posted by 3ll3d00d View Post
what sort of signal was used for the measurement?

the spikiness looks like high(er) frequency noise aliased into VS's bandwidth
REW White Noise 0-50hz
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post #1238 of 1408 Old 02-28-2017, 03:40 PM
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Quote:
Originally Posted by LastButNotLeast View Post
This has been mentioned a couple of times. I'm curious how that was accomplished.
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post #1239 of 1408 Old 02-28-2017, 04:21 PM
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Sitting in the back corner helps too.
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post #1240 of 1408 Old 02-28-2017, 05:07 PM
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Quote:
Originally Posted by Archaea View Post
The 4000 was not corner loaded like the 8 SI HT 18s.


Unless carp changed things up for this recent test -
The 4000 was actually firing into the cones of the SI HT 18's, which may have allowed the 18" SI drivers to dampen the output of the 4000ulf. (assuming the SI amp was powered down).


Was the JTR 4000 amp powered on when the SI were playing?


So I'd expect the 4000, if corner loaded, and not firing cone to cone into 4 18" drivers stacked in the corner - would have a wee bit more output than shown.


I agree that I don't think you can talk much scientifically away from the comparison between the 4000 and the 8 SI --- it's just for fun. You can subjectively take away that the 4000 ulf is a ridiculously potent subwoofer.

I did set it up so that the back of the 4000 was in the "corner" - meaning where the stack of subs and side wall meet - and facing the drivers right at my main LP. Subjectively I liked it better this way because I could feel the wind from the ports, but it measured lower on vibsensor.

I agree that there is really no way to do an exact comparison. Even if I moved a sub stack I couldn't get the 4000 in the same position as the sealed because it's so deep. I think it would be cool if there was a tall version of 4000. The way I have my 8 subs setup is very footprint size friendly.
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post #1241 of 1408 Old 02-28-2017, 11:40 PM
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Quote:
Originally Posted by dominguez1 View Post
REW White Noise 0-50hz
Well that scuppers that theory
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post #1242 of 1408 Old 03-01-2017, 01:19 AM
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In regards to the increase in tactile response firing into the wall vs firing into the MLP. I have measured in my own room I usually get an increase in SPL firing a sub into a wall or corner vs out into the room. So maybe that influenced it(increase SPL firing into the corner=increased tactile) if he wasn't close enough when firing it at the MLP.

How far away was the 4000 from your MLP @carp when firing into it? Edit I see where you mention it was in the corner by your subs so it was long ways your MLP so I wouldn't think you would get much tactile response on the phone measurement tool but you would feel air blowing towards you. At least from what I remember other people saying they were getting within inches of their MLP with their subs or ports.

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post #1243 of 1408 Old 03-01-2017, 06:49 AM
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Quote:
Originally Posted by LastButNotLeast View Post
A description of this curve would be appreciated.

Besides friggen' awesome, that is.
How does it sound with other material?

And, since it doesn't seem to be on a demo disc yet, the John Wick club scene:
https://www.dropbox.com/s/dstm3dbyvc2a4zx/jw.m2ts?dl=0

Michael
@MrGrey , could you graph (peak and avg) the above scene for us? It would be great to know where the sweet spot spl range this is!

Appreciate it!
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post #1244 of 1408 Old 03-01-2017, 06:54 AM
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Quote:
Originally Posted by dominguez1 View Post
@MrGrey , could you graph (peak and avg) the above scene for us? It would be great to know where the sweet spot spl range this is!

Appreciate it!
I have the disc so ill graph that club scene later on.
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post #1245 of 1408 Old 03-01-2017, 08:37 AM
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Originally Posted by dominguez1 View Post
@MrGrey , could you graph (peak and avg) the above scene for us? It would be great to know where the sweet spot spl range this is!

Appreciate it!
John WiCK (CLUB SCENE)
Time Stamp
00:47:29 - 00:54:42


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post #1246 of 1408 Old 03-01-2017, 08:45 AM
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Quote:
Originally Posted by MrGrey View Post
John WiCK (CLUB SCENE)
Time Stamp
00:47:29 - 00:54:42



So it makes sense that I'd like 8 sealed better than the 4000 ported for that, the JW scene doesn't even give the 4000 a chance to stretch it's legs down low where it has it's biggest advantage.
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post #1247 of 1408 Old 03-01-2017, 08:57 AM
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Quote:
Originally Posted by carp View Post
So it makes sense that I'd like 8 sealed better than the 4000 ported for that, the JW scene doesn't even give the 4000 a chance to stretch it's legs down low where it has it's biggest advantage.
WAHT!?!

Dude, that whole sequence is loaded with full bandwidth bass. Look at the PvA you just posted. Yeah, more peak energy is in the 20-50hz range (as it should) but the <20hz is pretty flat with a shallow rolloff. Not even 10dB down. PLENTY of content for the 4000 or sealed.
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post #1248 of 1408 Old 03-01-2017, 09:24 AM
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@MrGrey , you rock sir.




So I ran this scene with my setup to see how it compares...well, it didn't.

I then ran in +10db hotter (+14db total), and it was closer...but still not there.

I then moved my MBM 1200D (tuned at 50-60hz or so) right up against the couch...nope.

After seeing this graph, it makes sense now. Check out the avg curve, and the area I circled. There is a spike in the avg curve between 30 and 45hz. This is outside of the passband of the MBM, and thus why moving it as close as possible didn't really add that much.

My 2 FV15HPs are nearfield, but not firing directly at the MLP. They are probably 3ft away.

The experience during Carps demo really demonstrates to me how important PR (pressure response) is to the overall experience. Remember, PR is the waves directly impacting your body and is not the shaking of the couch (TR).

While I might be able to recreate the TR, it's the PR that is most impressive. The only way I could recreate that is to have one of my FV's directly behind me.

Crowsons and other transducers can create TR...but will never create PR. I'm convinced PR is really the true benefit of a nearfield sub...TR just happens to come with it.

More to come on this topic as I have VS graphs of Carp's crowsons without the nearfield sub, and vice versa.
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post #1249 of 1408 Old 03-01-2017, 10:06 AM
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Quote:
Originally Posted by Scott Simonian View Post
WAHT!?!

Dude, that whole sequence is loaded with full bandwidth bass. Look at the PvA you just posted. Yeah, more peak energy is in the 20-50hz range (as it should) but the <20hz is pretty flat with a shallow rolloff. Not even 10dB down. PLENTY of content for the 4000 or sealed.


Yeah... well... I should have said I have no idea how to comprehend those graphs. I assumed since the peaks were in the 30hz range that it was weak down low. Carry on, nothing to see here.
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post #1250 of 1408 Old 03-01-2017, 10:26 AM
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Quote:
Originally Posted by dominguez1 View Post
@MrGrey , you rock sir.




So I ran this scene with my setup to see how it compares...well, it didn't.

I then ran in +10db hotter (+14db total), and it was closer...but still not there.

I then moved my MBM 1200D (tuned at 50-60hz or so) right up against the couch...nope.

After seeing this graph, it makes sense now. Check out the avg curve, and the area I circled. There is a spike in the avg curve between 30 and 45hz. This is outside of the passband of the MBM, and thus why moving it as close as possible didn't really add that much.

My 2 FV15HPs are nearfield, but not firing directly at the MLP. They are probably 3ft away.

The experience during Carps demo really demonstrates to me how important PR (pressure response) is to the overall experience. Remember, PR is the waves directly impacting your body and is not the shaking of the couch (TR).

While I might be able to recreate the TR, it's the PR that is most impressive. The only way I could recreate that is to have one of my FV's directly behind me.

Crowsons and other transducers can create TR...but will never create PR. I'm convinced PR is really the true benefit of a nearfield sub...TR just happens to come with it.

More to come on this topic as I have VS graphs of Carp's crowsons without the nearfield sub, and vice versa.
How is pressure response different than frequency response? Frequency response is measured in SPL... (Sound Pressure Level)

I agree with the fact that transducers can create tactical response but not PR.
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post #1251 of 1408 Old 03-01-2017, 10:38 AM
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Quote:
Originally Posted by carp View Post
I did set it up so that the back of the 4000 was in the "corner" - meaning where the stack of subs and side wall meet - and facing the drivers right at my main LP. Subjectively I liked it better this way because I could feel the wind from the ports, but it measured lower on vibsensor.

I agree that there is really no way to do an exact comparison. Even if I moved a sub stack I couldn't get the 4000 in the same position as the sealed because it's so deep. I think it would be cool if there was a tall version of 4000. The way I have my 8 subs setup is very footprint size friendly.
Would encounter some problems with rocking I would imagine.

Quote:
Originally Posted by carp View Post
Yeah... well... I should have said I have no idea how to comprehend those graphs. I assumed since the peaks were in the 30hz range that it was weak down low. Carry on, nothing to see here.
Haha, green line is peaks in the response over that whole scene, Red line is the avg total response over the whole scene by dB spl level on the x axis, frequency on the Y. What it's basically showing is that the highest peak levels of the gun shots are likely those two massive spikes, but along with those, there is excellent information on a slow rolloff all the way down to below 10hz.
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post #1252 of 1408 Old 03-01-2017, 10:54 AM - Thread Starter
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Quote:
Originally Posted by dominguez1 View Post
1) So I ran this scene with my setup to see how it compares...well, it didn't.



2) My 2 FV15HPs are nearfield, but not firing directly at the MLP. They are probably 3ft away.

1) I can't match carp's theater experience on that scene either, despite having ~ double the amplifier power. I've tried. First time I heard that scene at carp's I hadn't even seen the movie. I went home and rented it right away and was really excited. It didn't have the Atmos track on the rental copy, and I couldn't reproduce Sheldon's room tactile/pressure effect and assumed it was because it was stripped down audio on the rental disk. So I bought the retail disk in Atmos, and still couldn't match it. grrr. It's fun in my room too, but not nearly as tactile as it is in his room. I still use it for demo sessions on occasion, as the dynamic gun shots, and bass is all around great cinema audio.

Having his eight front subs corner loaded in two groups of 4 vertical stacked surely helps. Concrete boundary reinforcement too on one wall, back and side, and on the other wall just back. My space behind the AT screen baffle wall (about 8-10 foot) - means my front subs are at about the 1/3 point, and my rear subs are close to the 1/3 point in my room too. Good for a smooth FR, not ideal for absolute max SPL. @carp , when you had the pair of caps, or the pair of submersives did you ever measure the difference between the output where you have two concrete walls vs. the output where the corner only has the concrete wall behind the sub? I'm curious how much difference that made for boundary gain between your two corners, and I'm also curious how much boundary gain in general you get from those concrete walls. I know scrappydue has a ridiculous amount of boundary gain in his basement with his eight SI. He has to cut 20Hz by about 8dB to be flat down low, while many of us have to significantly boost at 20hz. (I am anyway). I basically have a 12dB shelf boost plugged into the iNukes for my setup at 20hz, and that's on top of whatever Audyssey MultiEQ XT32 is doing.

This stuff is interesting!


2) 3' away is not nearfield dominguez1, Move those Rythmik FV-15HP right up against the back of your seat, and try it again. (probably have to adjust impulse response/phase/EQ for the 3' change).
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post #1253 of 1408 Old 03-01-2017, 11:14 AM
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Quote:
Originally Posted by Bassment View Post
How is pressure response different than frequency response? Frequency response is measured in SPL... (Sound Pressure Level)

I agree with the fact that transducers can create tactical response but not PR.
Yeah...We've been using PR because it's nicely abbreviated and flows with FR and TR. But I can see why that would cause some confusion...

The more appropriate name should be SIR, or sound intensity response.

Sound intensity = pressure * particle velocity.

If you look at the first post of the mbm thread, it explains it further and shows some tech on how to measure it with some expensive equipment.
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post #1254 of 1408 Old 03-01-2017, 11:39 AM
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Just for fun, if your system is set at "Reference Level," this is the peak SPL from the John Wick club scene:


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post #1255 of 1408 Old 03-01-2017, 12:05 PM
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Originally Posted by desertdome View Post
Just for fun, if your system is set at "Reference Level," this is the peak SPL from the John Wick club scene:

Which means it should always be played at +2, right?

...Right?
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post #1256 of 1408 Old 03-01-2017, 12:06 PM
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Quote:
Originally Posted by Archaea View Post
1) I'm curious how much difference that made for boundary gain between your two corners, and I'm also curious how much boundary gain in general you get from those concrete walls. I know scrappydue has a ridiculous amount of boundary gain in his basement with his eight SI. He has to cut 20Hz by about 8dB to be flat down low, while many of us have to significantly boost at 20hz. (I am anyway). I basically have a 12dB shelf boost plugged into the iNukes for my setup at 20hz, and that's on top of whatever Audyssey MultiEQ XT32 is doing.

This stuff is interesting!


2) 3' away is not nearfield dominguez1, Move those Rythmik FV-15HP right up against the back of your seat, and try it again. (probably have to adjust impulse response/phase/EQ for the 3' change).
For another example in my room with a similar front setup, albeit DO oriented subs as opposed to stacked arrays, I have a ton of gain down to 20hz as well but then it drops off some then plummets at about 10hz. Always has, always will apparently. Only time I "Fixed" it was with the DO RE 18's in the rear of the HT manifold. By itself it added IIRC 9-10dB at 10hz, which was killer fun. I am tossing around the idea of dumping two of my DO boxes in back of the theater just to try it, and if it works that well, then I'll be cutting holes in my rear wall all over again...I just patched them up right before I left for ya'lls lovely state.

Anyways, by the time I get my response flat to below 10hz with my shelf EQ filters (12/9/6 dB LT options, but the 12dB boost shows flattest), I end up having to cut the 20hz to about 40hz area pretty significantly to get it back to flat again.

Jon, you have a lot more space to pressurize down in your HT which is what I think plays a much larger part than the 1/3 placement of your subs, at least for the front 5. There is enough of a wall there that IMO the subs should still present enough of a 2pi space reaction than your thinking of them actually being 1/3 room away from a "Real" sonic barrier.

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post #1257 of 1408 Old 03-01-2017, 12:29 PM
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Originally Posted by desertdome View Post
Just for fun, if your system is set at "Reference Level," this is the peak SPL from the John Wick club scene:

As I understand it, Peak SPL is not an RMS metric...Meaning it is not over time and doesn't translate to what we hear.

I believe max SPL is the appropriate metric to use. In this case, 115.7db.
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post #1258 of 1408 Old 03-01-2017, 12:32 PM
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1) I can't match carp's theater experience on that scene either, despite having ~ double the amplifier power. I've tried. First time I heard that scene at carp's I hadn't even seen the movie. I went home and rented it right away and was really excited. It didn't have the Atmos track on the rental copy, and I couldn't reproduce Sheldon's room tactile/pressure effect and assumed it was because it was stripped down audio on the rental disk. So I bought the retail disk in Atmos, and still couldn't match it. grrr. It's fun in my room too, but not nearly as tactile as it is in his room. I still use it for demo sessions on occasion, as the dynamic gun shots, and bass is all around great cinema audio.

Having his eight front subs corner loaded in two groups of 4 vertical stacked surely helps. Concrete boundary reinforcement too on one wall, back and side, and on the other wall just back. My space behind the AT screen baffle wall (about 8-10 foot) - means my front subs are at about the 1/3 point, and my rear subs are close to the 1/3 point in my room too. Good for a smooth FR, not ideal for absolute max SPL. @carp , when you had the pair of caps, or the pair of submersives did you ever measure the difference between the output where you have two concrete walls vs. the output where the corner only has the concrete wall behind the sub? I'm curious how much difference that made for boundary gain between your two corners, and I'm also curious how much boundary gain in general you get from those concrete walls. I know scrappydue has a ridiculous amount of boundary gain in his basement with his eight SI. He has to cut 20Hz by about 8dB to be flat down low, while many of us have to significantly boost at 20hz. (I am anyway). I basically have a 12dB shelf boost plugged into the iNukes for my setup at 20hz, and that's on top of whatever Audyssey MultiEQ XT32 is doing.

This stuff is interesting!


2) 3' away is not nearfield dominguez1, Move those Rythmik FV-15HP right up against the back of your seat, and try it again. (probably have to adjust impulse response/phase/EQ for the 3' change).


I can check it again, but I think the 2 corners were real close. The concrete only goes up half way because my basement is 1/2 level underground - which is nice because I've never had a drop of water in it in close to 15 years - knock on wood.

My room gain is not good. I crank up a low shelf boost 12 db's for John Wick (same JW curve for lots of other movies) and even more boost for some movies like Lucy and The Shallows, also Sully that I showed for demo's.

If I don't boost my response drops like a rock under 25 hz.
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post #1259 of 1408 Old 03-01-2017, 01:30 PM
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2) 3' away is not nearfield dominguez1, Move those Rythmik FV-15HP right up against the back of your seat, and try it again. (probably have to adjust impulse response/phase/EQ for the 3' change).
How about nearbyfield?

At one time I had one FV right behind me...and it was VISCERAL like Carps. I had a similar "wincing" experience on certain demo clips...it was awesome.

But the other seats were so far off from a TR standpoint compared to the MLP. So I bought another FV and placed them behind the non-lp seats. It was a good comprise, as now all the positions have very good TR and are more even seat to seat.

The other thing that hasn't been discussed yet that bothered me when the FV was directly behind me...I hated getting "slammed" on things that have no business having that effect; things like doors shutting, guitar picks, etc. It was absolutely incredible for those bass demo scenes, but some other films, the Intensity was out of place and sometimes affected the overall experience and perceived sound quality.

@carp or @Archaea , do you run into this problem at all?
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post #1260 of 1408 Old 03-01-2017, 02:13 PM
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A low pass filter will help a lot with that kind of stuff.
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