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post #151 of 876 Old 03-10-2013, 11:37 AM
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I'm a total noob when it comes to REW, so forgive my totally TARD of a question, but will the mic being so close the back of his recliner have anything to do with it or affect the graph in any way?
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post #152 of 876 Old 03-10-2013, 11:40 AM - Thread Starter
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Cool. Yeah, where we had them last night sounded so smooth, just missing low end so that may be where I end up. I'm still going to tinker more though... cause it's fun. smile.gif
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post #153 of 876 Old 03-10-2013, 11:58 AM - Thread Starter
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Sorry guys if the placement pics/graphs is tiresome, part of why I'm doing it is so I'll have a record of everything.

Ok, so here is all 4 under the screen:



And how it measures compared to the placement from last night, which I am going to use as my bassline (front corners and one under each side surround)





Wow, midbass is killer in last nights setup but low bass much better with all 4 under the screen.
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post #154 of 876 Old 03-10-2013, 12:00 PM - Thread Starter
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Quote:
Originally Posted by ratm View Post

I'm a total noob when it comes to REW, so forgive my totally TARD of a question, but will the mic being so close the back of his recliner have anything to do with it or affect the graph in any way?

I don't know if it does much to bass or not, the mic is about a foot from the couch.
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post #155 of 876 Old 03-10-2013, 12:18 PM
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OK noob question part doo, if you could have your druthers and draw a perfect graph, what would it look like (i need a reference).

BTW, graphs be damned, those look bad ass like that. smile.gif
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post #156 of 876 Old 03-10-2013, 12:24 PM
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That black trace in your last graph really isn't all that far off. Have you run Audyssey yet? I suspect that even as configured, and even with you using half your subs, Audyssey will make that response much better. Add in an LT, additional subs to smooth out your response, and you'll be golden.
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post #157 of 876 Old 03-10-2013, 12:42 PM
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RATM,

You want a flat response graph. meaning that no frequency plays louder than any other frequency.
6dB is twice as loud. carp's y axis is 10dB measuremnts which some say subjectively is what our ears hear as twice as loud.

The reason you want a flat graph is that in a song with various bass notes you don't want some of your bass notes twice as loud as other. Here is a nice little hz to note chart conversion.

http://bass-aholic.com/basics/piano/PianoLayout.jpg


So using the picture above taken from bass-aholic, we can see what notes are what frequencies on a piano keyboard.

Looking at carp's graphs - if a bass note played at 30hz is 20dB louder than a bass note played at 20hz, then the 30hz note would be > = 4x's as loud. That's no good. Think of it like this. In the Black Eyed Peas song the bass notes go boom boom pow, and each of these notes are different frequencies.

You don't want to hear BOOM boom POW, or boom boom POW, or boom BOOM pow.

You want to hear what was intended. boom boom pow. Where all of the unique notes are played at the same volume. A flat frequency response allows different frequencies (IE hz) (IE notes) to be played back at their expected and appropriate volumes.
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post #158 of 876 Old 03-10-2013, 12:45 PM
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carp, those graphs will all be meaningless when you get eight of them setup. tongue.gif

I'd expect with eight you are going to further smooth out your response so much that precise placement won't even particularly matter.



Don't spin your wheels too much until you get them all setup.

OR measure them each individually and find the best placement for each sub (moving it a foot or two left or right on the wall from your intended location) then you'll have a fairly ideal combined location as well in all likelyhood, assuming distance delays are close/accurate.

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post #159 of 876 Old 03-10-2013, 12:54 PM - Thread Starter
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Quote:
Originally Posted by Archaea View Post

carp, those graphs will all be meaningless when you get eight of them setup. tongue.gif

I'd expect with eight you are going to further smooth out your response so much that precise placement won't even particularly matter.



Don't spin your wheels too much until you get them all setup.

OR measure them each individually and find the best placement for each sub (moving it a foot or two left or right on the wall from your intended location) then you'll have a fairly ideal combined location as well in all likelyhood, assuming distance delays are close/accurate.

I know, but my plan is to just find out where the 4 sound/measure the best and then just stack the next 4 on top or place right beside the first 4.

Here is subs stacked up front compared to all 4 under the screen:




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post #160 of 876 Old 03-10-2013, 12:57 PM
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Quote:
Originally Posted by Archaea View Post

RATM,

You want a flat response graph. meaning that no frequency plays louder than any other frequency.
6dB is twice as loud. carp's y axis is 10dB measuremnts which some say subjectively is what our ears hear as twice as loud.

The reason you want a flat graph is that in a song with various bass notes you don't want some of your bass notes twice as loud as other. CHT has this nice little hz to note chart conversion.

http://bass-aholic.com/basics/piano/PianoLayout.jpg


so using the picture above taken from bass-aholic, we can see what notes are what frequencies on a piano keyboard.

Looking at carp's graphs - if a bass note played at 30hz is 20dB louder than a bass note played at 20hz, then the 30hz note would be > = 4x's as loud. That's no good. Think of it like this. In the Black Eyed Peas song they bass notes go boom boom pow, and all of the works/notes are different.

You don't want to hear BOOM boom POW, or boom, boom POW, or boom BOOM, pow.

You want to hear what was intended. boom boom pow. Where all of the notes are played at the same volume. A flat frequency response allows different frequncies (IE hz) (IE notes) to be played back at thier expected and appropriate volumes.

best example of any question I've posted on AVS!!!

Carp, you're getting one hell of a workout today.
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post #161 of 876 Old 03-10-2013, 01:23 PM - Thread Starter
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Final placement measurement - 1 next to each center and 1 in each corner.




All measurements taken with 4 subs:



The 3 curves that are way down below 30hz are placements with subs in the back of the room, the 3 curves that have a lot more low bass are all subs at the front of the room in different configurations.

For bass above 30hz I like the green line the best, which is subs under the side surround speakers and 1 in each front corner.

For bass below 30 it looks like it's a wash between all 3 up front placement options.

I know all this could change when I have the minidsp since this is no eq, no Audyssey, no nothing - but still - look at that difference at 20hz!! I gain at least 10 db's of headroom if I put all 4 subs up front!! I guess it's a good think I'll be putting 4 up front!!
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post #162 of 876 Old 03-10-2013, 01:25 PM - Thread Starter
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best example of any question I've posted on AVS!!!

Carp, you're getting one hell of a workout today.

Ha, yeah I was planning on doing a brutal pull-up workout today... we'll see. smile.gif
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post #163 of 876 Old 03-10-2013, 02:27 PM
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Carp - Nice measurements and the subs look awesome. You're well on your way to a great base before any EQ-ing. I agree with Jonathan once you get all 8 setup things are going to change a bit for the better. biggrin.gif

Do some critical listening with your favorite config now that you've put in all that work! biggrin.gif
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post #164 of 876 Old 03-10-2013, 03:48 PM - Thread Starter
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Carp - Nice measurements and the subs look awesome. You're well on your way to a great base before any EQ-ing. I agree with Jonathan once you get all 8 setup things are going to change a bit for the better. biggrin.gif

Do some critical listening with your favorite config now that you've put in all that work! biggrin.gif

Thanks man - well, I've been doing exactly that.

I don't want to go all crazy an use all caps like tend to do... I also tend to get really excited and say, "its better than ever now!!"

but wow. I have the subs in the same locations as Kevin and I did yesterday but yesterday we only had time to listen to like 3 song clips and 3 movie clips. Today I did some more music listening and it's so crazy good. The bass is so tight, controlled, and EVERYWHERE!! Oops, there goes the all caps. tongue.gifredface.gif

I don't have the MBM on, and I don't know if I'm going to need it. I still might use it for fun, but this is so good.

Something else really cool, I did a little pull up workout and usually when I'm walking around the room in between sets the bass gets stronger and weaker as I move I can hear the bass coming from the sub(s) at the front of the room if I wander over towards them.

Today the bass stayed the same no matter where I walked!! Now I'm not saying it would measure exactly the same, but subjectively that's what it is like. As I got closer to a sub I couldn't tell that sound was coming from it. It's better than ever!! haha...tongue.gifbiggrin.gif

I turned the front corner subs, it changed the frequency very little but I like how I can see the drivers now. Gotta see those drivers!! biggrin.gif




Thanks everyone for the help so far, it's been fun and it's so rewarding to experience the improvement of multiple sub locations.
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post #165 of 876 Old 03-10-2013, 08:12 PM
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Here's a thought. 5 subs dedicated to the LFE track (.1), 3 at the rear, 1 on each side wall,

And then your front stage has a sub dedicated to each front channel with no crossover set up for the front 3. I suppose this would require 3 channels of external amp along with a 3 or 4 channel minidsp handling active crossover duty.

Might just overcomplicate things for no gain...
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post #166 of 876 Old 03-11-2013, 08:15 AM
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I like this:
Quote:
Originally Posted by carp View Post


+ this

Quote:
Originally Posted by carp View Post


+ this

Quote:
Originally Posted by carp View Post


So 6 in the front and 2 in the rear. At least from an aesthetic standpoint. On the flip side to that, if you went that route I think another amp would be in order so you could eq the nearfield (rear) subs to your liking.

We'll see how the end result plays out when you have all eight up and running man. Looking great thus far!
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post #167 of 876 Old 03-11-2013, 11:12 AM
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Yep. Like legos, but with glue. Or in Edoggs case, getting a completely assembled Lego Death Star and adding the Darth Vader lego man on top. Don't worry man, nobody cares "how" the boxes were constructed when you go full attack mode with the Quads!
Hey come on now! It took a little bit of work to unpack all the stuff, not to mention the cabs are freaking heavy. Give me a little credit! biggrin.gif
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post #168 of 876 Old 03-11-2013, 11:31 AM
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Hey come on now! It took a little bit of work to unpack all the stuff, not to mention the cabs are freaking heavy. Give me a little credit! biggrin.gif

For sure man! Edogg is strong and can lift very heavy pieces of furniture.
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post #169 of 876 Old 03-11-2013, 11:54 AM - Thread Starter
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So 6 in the front and 2 in the rear. At least from an aesthetic standpoint. On the flip side to that, if you went that route I think another amp would be in order so you could eq the nearfield (rear) subs to your liking.

We'll see how the end result plays out when you have all eight up and running man. Looking great thus far!

I was thinking about that, but yeah you're right I'd need another amp. Last night I was thinking it would be pretty cool to have 12 up front - 4 under screen and 4 stacked in each corner and then 4 in the rear but then I came to my senses. Seriously though, the major drop off makes me nervous since I'll only have twice the fire power I have now up front, I'm hoping the minidsp can take care of it. If not.... I may have to get crazy.

In the end I want basically no limits to 10 hz. By no limits I mean that when I crank it up I give in before the subs do. I normally don't listen to a movie like this, but I love occasionally cranking it and it ALWAYS happens during a demo or a GTG which seems to be somewhat often or at least that's what my wife says.

More importantly if I have that kind of output I'll have crazy amounts of headroom so that 99 percent of the time the system will just be coasting and in doing so will sound great.
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post #170 of 876 Old 03-11-2013, 12:14 PM
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I was thinking about that, but yeah you're right I'd need another amp. Last night I was thinking it would be pretty cool to have 12 up front - 4 under screen and 4 stacked in each corner and then 4 in the rear but then I came to my senses. Seriously though, the major drop off makes me nervous since I'll only have twice the fire power I have now up front, I'm hoping the minidsp can take care of it. If not.... I may have to get crazy.

In the end I want basically no limits to 10 hz. By no limits I mean that when I crank it up I give in before the subs do. I normally don't listen to a movie like this, but I love occasionally cranking it and it ALWAYS happens during a demo or a GTG which seems to be somewhat often or at least that's what my wife says.

More importantly if I have that kind of output I'll have crazy amounts of headroom so that 99 percent of the time the system will just be coasting and in doing so will sound great.

+1 My goals exactly.
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post #171 of 876 Old 03-11-2013, 12:22 PM
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Quote:
Originally Posted by carp View Post

I was thinking about that, but yeah you're right I'd need another amp. Last night I was thinking it would be pretty cool to have 12 up front - 4 under screen and 4 stacked in each corner and then 4 in the rear but then I came to my senses. Seriously though, the major drop off makes me nervous since I'll only have twice the fire power I have now up front, I'm hoping the minidsp can take care of it. If not.... I may have to get crazy.

In the end I want basically no limits to 10 hz. By no limits I mean that when I crank it up I give in before the subs do. I normally don't listen to a movie like this, but I love occasionally cranking it and it ALWAYS happens during a demo or a GTG which seems to be somewhat often or at least that's what my wife says.

More importantly if I have that kind of output I'll have crazy amounts of headroom so that 99 percent of the time the system will just be coasting and in doing so will sound great.

BOOM!
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post #172 of 876 Old 03-11-2013, 04:21 PM
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carp...

I'm staging an intervention.

notice no smiley...
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post #173 of 876 Old 03-11-2013, 05:18 PM
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Quote:
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Seriously though, the major drop off makes me nervous since I'll only have twice the fire power I have now up front, I'm hoping the minidsp can take care of it.

When tested by Ricci, and similar to most any small-sealed, the native response plunges like a rock in the low 30's ... just as does yours. However, when examining your measurements, you can see the native plunge all the sudden take a detour upon the onset of PVG around 24hz or so. Which, doing some simple calculations, 1130/24hz=47.08 You take that and divide it in half, 47.08/2=23.54hz. This is the calculated approx. onset of PVG.

So after the normal small box boosting/LT'ing is added back in, then you'll be fine. Unless you're rocking an IB, or a huge box, you're going to see this drop off.


Back to your room's PVG; when I look at the aggregate graph of all the positioning, I estimated the 24hz point visually. Around this point is the lowest freq of which can propagate freely. Any freq lower than that point, can't fully propagate, hence the pressure vessel gain ... Physically, the longest dimension of the room can no longer support full propagation of the waveform. So somewhere around 23hz-24hz, the normal propagation transitions to pressurization. The wave reproduction changes from a normal cyclic propagation, to pressurization because the wavelengths are too big for the space.

This is key; the frequency at which this occurs is approximately the point whereby half the wavelength of a given frequency is equal to the rooms longest dimension. So looking back to previous post, seeing the longest room dimension is around 23 feet. That said, and after calculation, the transition from propagation to pressurization will occur around 23hz-24hz. This is because a 24hz waveform is (1130/24)= ~47'. Half of that is 23.5', correlating to the longest dimension of your room. This is the point of transition. Any frequency below that point begins to pressurize the room, and any frequency above that point propagates freely.


So the room gives back acoustically. One of the few examples of free lunch in audio; PVG. This reciprocity is theoretically 12db per octave. The percentage of the 12 db/octave gain one achieves, seems to entirely depend on the integrity of the boundary walls and surfaces. For example, a full tilt concrete bunker should yield a full 12db/octave boost. Typically, it seems as if somewhere between 6-10 db octave may may achievable. Also, in addition to the boundary movement/flexing, other elements can affect the onset point. And anything that consumes a certain measure of cubic feet (furniture, cabinets, etc), may slightly alter the transition merely due to occupying cubic volume.


*
Then there's another component at play, and this is very cool. A distortion lowering mechanism is a by product of the vessel gain. It would seem the acoustic reciprocity elicits a greater proportion of acoustic gain to the deep fundamental freq, moreso than that of the harmonic distortion aspects up higher. In other words, it only makes sense that any fundamental occurring below the PVG onset point, would be subject to the normal PVG, however the harmonics of the fundamental land above the transition, thus they receive much less acoustic gain. Sweet, .. have your cake and eat it too.






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In the end I want basically no limits to 10 hz. By no limits I mean that when I crank it up I give in before the subs do. I normally don't listen to a movie like this, but I love occasionally cranking it and it ALWAYS happens during a demo or a GTG which seems to be somewhat often or at least that's what my wife says.

More importantly if I have that kind of output I'll have crazy amounts of headroom so that 99 percent of the time the system will just be coasting and in doing so will sound great.



Context;
You're going to have plenty, I'm sure of it. It's easy to loose context around these parts. Eight eighteens, yeah, (8)18s ... hell, the vast majority of enthusiasts don't even use more than one sub,....of any size. You'll have plenty. Looking at DataBass' system charts, the SI system equated to the Velodyne DD18 @20hz (which by any technical measure is superb). They're $4999msrp, you can equal it's output with one box. Doubling to two yields 6dB, moving to 4 yields another 6dB, escalating up to 8 sums to another 6dB ... totaling +18dB over that of a single sub. That's a single, high performance 18" high excursion sub ... plus 18dB cool.gif


Ample headroom and output isn't the question. The real task at hand is the proper integration of a phenomenal subwoofer system, with those highly capable mains, into the strongly dominant influence that is your room. But you can largely win that one.



Best of luck

edited "@20hz", wrt the Velo DD18 for added clarity

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post #174 of 876 Old 03-11-2013, 06:33 PM
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carp...

I'm staging an intervention.

notice no smiley...

I'd imagine it's more about talking yourself out of going the same route than for carp's wellbeing wink.gif
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post #175 of 876 Old 03-11-2013, 06:40 PM - Thread Starter
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Quote:
Originally Posted by FOH View Post

When tested by Ricci, and similar to most any small-sealed, the native response plunges like a rock in the low 30's ... just as does yours. However, when examining your measurements, you can see the native plunge all the sudden take a detour upon the onset of PVG around 24hz or so. Which, doing some simple calculations, 1130/24hz=47.08 You take that and divide it in half, 47.08/2=23.54hz. This is the calculated approx. onset of PVG.

So after the normal small box boosting/LT'ing is added back in, then you'll be fine. Unless you're rocking an IB, or a huge box, you're going to see this drop off.


Back to your room's PVG; when I look at the aggregate graph of all the positioning, I estimated the 24hz point visually. Around this point is the lowest freq of which can propagate freely. Any freq lower than that point, can't fully propagate, hence the pressure vessel gain ... Physically, the longest dimension of the room can no longer support full propagation of the waveform. So somewhere around 23hz-24hz, the normal propagation transitions to pressurization. The wave reproduction changes from a normal cyclic propagation, to pressurization because the wavelengths are too big for the space.

This is key; the frequency at which this occurs is approximately the point whereby half the wavelength of a given frequency is equal to the rooms longest dimension. So looking back to previous post, seeing the longest room dimension is around 23 feet. That said, and after calculation, the transition from propagation to pressurization will occur around 23hz-24hz. This is because a 24hz waveform is (1130/24)= ~47'. Half of that is 23.5', correlating to the longest dimension of your room. This is the point of transition. Any frequency below that point begins to pressurize the room, and any frequency above that point propagates freely.


So the room gives back acoustically. One of the few examples of free lunch in audio; PVG. This reciprocity is theoretically 12db per octave. The percentage of the 12 db/octave gain one achieves, seems to entirely depend on the integrity of the boundary walls and surfaces. For example, a full tilt concrete bunker should yield a full 12db/octave boost. Typically, it seems as if somewhere between 6-10 db octave may may achievable. Also, in addition to the boundary movement/flexing, other elements can affect the onset point. And anything that consumes a certain measure of cubic feet (furniture, cabinets, etc), may slightly alter the transition merely due to occupying cubic volume.


*
Then there's another component at play, and this is very cool. A distortion lowering mechanism is a by product of the vessel gain. It would seem the acoustic reciprocity elicits a greater proportion of acoustic gain to the deep fundamental freq, moreso than that of the harmonic distortion aspects up higher. In other words, it only makes sense that any fundamental occurring below the PVG onset point, would be subject to the normal PVG, however the harmonics of the fundamental land above the transition, thus they receive much less acoustic gain. Sweet, .. have your cake and eat it too.
Context;
You're going to have plenty, I'm sure of it. It's easy to loose context around these parts. Eight eighteens, yeah, (8)18s ... hell, the vast majority of enthusiasts don't even use more than one sub,....of any size. You'll have plenty. Looking at DataBass' system charts, the SI system equated to the Velodyne DD18 (which by any technical measure is superb). They're $4999msrp, you can equal it's output with one box. Doubling to two yields 6dB, moving to 4 yields another 6dB, escalating up to 8 sums to another 6dB ... totaling +18dB over that of a single sub. That's a single, high performance 18" high excursion sub ... plus 18dB cool.gif


Ample headroom and output isn't the question. The real task at hand is the proper integration of a phenomenal subwoofer system, with those highly capable mains, into the strongly dominant influence that is your room. But you can largely win that one.



Best of luck

Holy schmoly, I'm going to be attempting to digest that post for awhile - thanks a ton for the info. smile.gif I don't understand all of it - but SLOWLY I am learning as I go and will be referring to that quite a few times I'm sure.

Haha, yeah that puts it in perspective when you compare to the DD18. Ok, now all I need is for Erich to ship me back the SI driver and finish up the last 4 boxes.
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post #176 of 876 Old 03-11-2013, 06:42 PM - Thread Starter
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carp...

I'm staging an intervention.

notice no smiley...

I thought Luke was the one in need of an intervention?!?!

Don't worry, I'm not buying any more subs. This has to be it, the bass down to 30hz is ridiculous right now with 4 drivers and I trust FOH that all will be well with the minidsp and 4 more drivers for the stuff below 30hz so I'm sure I'm good to go.
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post #177 of 876 Old 03-11-2013, 07:27 PM
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Originally Posted by carp View Post

I thought Luke was the one in need of an intervention?!?!

Don't worry, I'm not buying any more subs. This has to be it, the bass down to 30hz is ridiculous right now with 4 drivers and I trust FOH that all will be well with the minidsp and 4 more drivers for the stuff below 30hz so I'm sure I'm good to go.

Man your room is so sexy. I really have to stop visiting these threads or I'm going to buy new mains.
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Insert Scott's Homer Drooling Picture Here.

Awesome job, really. Your stage looks perfect.
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post #178 of 876 Old 03-11-2013, 07:58 PM
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Man your room is so sexy. I really have to stop visiting these threads or I'm going to buy new mains.
Awesome job, really. Your stage looks perfect.

What are his mains?
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They are the JTR Noesis I believe.
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post #180 of 876 Old 03-11-2013, 08:09 PM
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They are the JTR Noesis I believe.

Yup
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