Seaton Sound SubMersive1 - Page 8

Mark do you know when you will have your web site up and running.
Allen

NOW THATS WHAT I"M TALKING ABOUT

Man, I can not wait until i get this sub in my room. Plus I am looking forward to the
Calibration of my system as well.

That's pure sex!

looks good Mark and Art.....and btw Mark, two of those Submerssives stacked up like that are almost as big as my Sonotube, so dont make fun of my size anymore!

Sherv - I think Art moved on to making fun of your dome ...

Damm I look like a little person back behind those subs

Art

I really wished I could have stayed for all the demo stuff the other day.

art can take a number.....We now serving # 876

Are there any close-ups of the amp and driver?

Kevin,
Thanks for lugging subs up and down the stairs with Mark and me that day !


Were you there for the Tokyo Drift HDDVD demo ? If not, I honestly think that this might be at least one to beat now.

I wish we had taken a shot of the Submersives set up behind the screen with the screen off but we did not.

Art

if it wasn't so freakin cold, I would take the trip to your place too Art ......unfortunately, as it is well documented, Cold weather is my Kryptonite! .............

Mark and you did a superb job looks like....if Mark himself was impressed, then it must be goodness

watched "open range" again last night with my wife I just cant get over the slam the submersive has, Mark says that adding another one to my room would bring it to the performance of what Art has in his theater , this is because of the smaller size of my theater, im tellin ya now......its gonna happen and you heard it here first folks

Do you have a specific chapter in mind?

the best chapter is the last one when they have the big shootout, the submersive puts the gunshots right through you

Art

I left after the first movie demo, after the 2 demo disks. I hated to leave but there is always a first for everything ( me being the first to leave a gtg). Just didnt want it to be this one.

I took some pics that day but dont think I got one before the screen went back in either .... I will check later.

Nice Fit...................



Looking down over XLs to four Submersives below........


Art

Art,

Great fit! Eight 15" woofers doing some serious air moving,I think this configuration(subs and sats above them)can be used to great effect in music systems as well.

Art here is the best I could do.... it was so dark you couldnt even see the subs but I played with the contrast/brightness and turned everything kind of grey

You know, my room is so small that if the numbers Mark told me are right, I will be very very close to Art level with only one sub

Mark,
Looking at Art's sub placement, is there any advantage/detriment to having drivers facing each other so close together? And is placing the subs in the channel like that have any detrimental affect on sound?

I hope Mark will jump in and discuss this. We actually just set them in fairly symmetrically across the front. There was no experimentation despite the fact that several stacking options could have been done including near the corners or between the LCRs. Right now the drivers are about two feet apart.

Art

I just tried a quick look for the pics of the subs in place. No luck. If I recall, they are placed into a "U" channel (trench) that looks like the sides are about 8 to 12" high. Does this add an acoustic challenge? Even more so with the down-firing +/2s?

With drivers facing each other, does this increase the compression wave or is there some air turbulence caused that has to be compensated for?

Small points since it appears the sound is awesome. Just curious.

Randy

The front part of the U (under the screen) is actualy just framed and covered with cloth so its not as constrained as you are probably thinking. its not like they are sitting down in a hole or something.

Thanks, that answers that question.

I may be misapplying the law of physics for solids to gasses, but air does have mass. If you consider a line that is perpendicular to the diaphragm as 0 degrees, I would guess that the strongest sound wave is along the 0 axis. Since two opposing air masses are colliding into each other along this axis, don't they cancel each other. I know that the sound wave is also coming off the diaphragm at other angles up to +-90 degrees. This part of the two waves should augment each other. Maybe I just answered my own question. Since the air molecules that are traveling at 0 degrees towards each other are not going to collide exactly on the same axis, but more than likely a little off axis, they would just be deflected and not stopped. Solids are so much easier to understand.

Randy,

I have many subs facing(acrive drivers) eachother,there are no issues at all.There can be no buildup of pressure and since it is an open area and the subs are two feet apart no problems will result.

I even tried as close as 8-10inches apart,no issues to report. If there is a loss it is minute and not a concern.

I am just trying to get a basic understanding of sound waves. I just thought about it some more and realized that the compression wave does not propagate by propelling molecules unimpeded, but by the the propelled molecules colliding with stationary molecules causing them to move and collide with other molecules. Each collision reduces the force and that is why the SPL is reduced with distance. I still have to believe there is some wave cancellation going on along the 0 axis.

I need to find an animation of sound propagation and what happens at boundaries. Where's Don Herbert or Bill Nye when you need them?

Hi ransac,

You did mostly answer your own question.

The drivers facing eachother have very little effect on eachother, other than having another subwoofer increases the sound pressure level created. A variety of subwoofers have been built with drivers facing eachother, and there is no distructive interaction. Every subwoofer does need some amount of breathing room around it though. A suitable amount of air-space and area open to the room to not significantly impact performance are both inter-dependent and dependent on the specific subwoofer in question.

Obviously ports require room to not affect airflow and tuning frequency. Woofers need free enough space to not significantly change the air load on the front of the driver from what was intended. A very light cone sealed woofer with a larger box and soft suspension behind it will be affected by confinement (small space in front of the woofer) before a system with a relatively small box and heavier moving mass woofer. A compact sealed box (for the size woofer used) with a heavier woofer (required to get deep bass from such a system) like the SubMersive will be very tolerant to confinement.

While there are other effects at work too, in simplest terms we are looking at how significant the resistance of the air is relative to the mass of the cone and the restoring force of the box and suspension of the woofer. If the trapped chamber in front of the woofer presents no significant change to these factors, the response should show minimal change. Of course there are always exceptions. In the case of the SubMersive next to a corner, the amplifier can be pushed to the wall and the woofer can be pushed within about 3-4 inches of the wall with very little change in response where it may start to pull down the range above 100Hz as you push things super tight or only have a small area to allow the air to radiate into the room.

I had originally done a good bit of measuring and experimentation with the different locations using the PB12-Plus/2s, and while the shape of the response changed, the trends to the frequency response were very similar. I have measured from each one of the subwoofer locations as well as in pairs. There is a recession to the response of the subwoofers in the 50-70Hz range that is helped by having the multiple locations across the front, but I did not have time to push a sub into the corner and measure from there. Based on what I have observed and measured in the room, multiple locations are certainly the best solution, 2 or 4 being better always has room for debate. Fortunately it's pretty easy to save the EQ settings for the DSP-30 (from QSC) and do some experimenting. I also put the 3, 10" Triad subs in his side and rear columns to work in combination with the SubMersives, only allowing them to augment the 45-80Hz range where they lend a helping hand nicely and smooth things out over the seats a bit.

I also wasn't very motivated to move the subwoofers much after the first measurements quickly showed a wonderfully smooth response with no EQ from 10-30Hz. What I did do a little different is push the outer two subwoofers away from the center more than the previous subwoofers were. The measurements co-incided with my earlier findings that there was a very small improvement above 50Hz with nothing else lost. With the great results we have had, I am only mildly curious to experiment with pushing two of the subs into the front corners I somewhat expect to find other problems creeping in over the ranges that are behaving so well right now.

How do you guys think the Submersive would compare to the JL Fathom f113? I'm assuming that the Submersive can go much lower with two 15" drivers.

Mark, any updates yet?

Mark has been swamped with some other projects as of late....

getting a few things ready for a GTG in the detroit area tomarrow(sat).