4 dual opposed SSD 15s - Page 7 - AVS Forum
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DIY Speakers and Subs > 4 dual opposed SSD 15s
gpmbc's Avatar gpmbc 02:39 PM 04-27-2012
With the couch normally in place

Attachment 244830



Attachment 244828
LL
LL

gpmbc's Avatar gpmbc 02:41 PM 04-27-2012
Quote:
Originally Posted by exojam View Post

GP,

Did you save those frd files with easy to remember or descriptive names? Thanks.

James

What do you mean?
exojam's Avatar exojam 02:46 PM 04-27-2012
Quote:
Originally Posted by gpmbc View Post

What do you mean?

GP,

What I was wondering is if you saved those frd files or are the screens you showed just snapshots.

The reason for my asking is if you saved them, you could go back in and reload them all together and then do a snapshot for easy comparison between locations. Thanks.

James

Example below
LL
gpmbc's Avatar gpmbc 02:54 PM 04-27-2012
New to this, they are snapshots. Thx for the info.
exojam's Avatar exojam 03:05 PM 04-27-2012
GP,

No problem at all.

Since I have been using this what I try to do for my measurements is the following:
Make a directory called “Measurements Date
Inside make an fdr and curves folder so I can save the files there as needed.
Put in the name of the frd the master volume I was running the test at. So you can see in my example they all start with a _5 which means -5 on the master volume.
Put the level of smoothing in the name, 1_6, 1_24, etc.

Just somethings I do off the top of my head to try and keep organized as much as possible.

James
Scott Simonian's Avatar Scott Simonian 03:07 PM 04-27-2012
No room gain?
gpmbc's Avatar gpmbc 03:27 PM 04-27-2012
Bosso's eq will remedy that. What's crazy is it doesn't feel like it graphs. I'd say one part because the subs are nearfield. The other I would attribute to ulf being very boosted on movies like the hulk. It is very visceral and the good thing is there is still more in the tank.
MKtheater's Avatar MKtheater 05:05 PM 04-27-2012
Quote:
Originally Posted by gpmbc View Post

Bosso's eq will remedy that. What's crazy is it doesn't feel like it graphs. I'd say one part because the subs are nearfield. The other I would attribute to ulf being very boosted on movies like the hulk. It is very visceral and the good thing is there is still more in the tank.

The graphs don't lie, you are feeling strong 20hz and above. Your ULF is way down. Remember you are measuring sealed subs without any EQ or DSP built in so it will look worse. Once you dial them in and get a flat response to single digits you will say O crap! Now I know what ULF really feel like. Trust me on this one!
gpmbc's Avatar gpmbc 05:20 PM 04-27-2012
I didn't include the 4) 18s up front in any measurement, not that that will contribute greatly to ulf. I know what you're saying MK but the thing that doesn't add up is in watching the incredible hulk. When Hulk encounters Abomination for the first time and they are walking towards each other, I know the footsteps are way lower than 20hz. I feel each step distinctly and with lots of impact. As well, the last hit with the cop car is much more pronounced than it was with the DTS 10s. I know it can get better and it will. I'm just saying from descriptions I've read from people experiencing these scenes, this is what I'm feeling as well. Maybe I'm not using omni mic correctly?
Scott Simonian's Avatar Scott Simonian 05:50 PM 04-27-2012
Just wondering what's up with the 25dB drop from 25hz to 15hz. Hmmm...
exojam's Avatar exojam 06:44 PM 04-27-2012
GP,

Not that it will show you what frequency is being produced but you could try the below steps on the last hit with the cop car scene you are referring to check how high it registers.

Turn off all speakers except your subs
In Omni go to your SPL tab
Select the none at the top for response weighting
Select the fast in the range on the right hand side
Click the reset button before you play the scene
Play the scene of the movie like you normally would and afterwards check the Peak and Max values right above the reset button.

Just be aware you will probably not be able to catch the information in the graph area but that is fine.

You can see what I am referring to by checking the thread below.
http://www.avsforum.com/avs-vb/showt...highlight=omni

James
gpmbc's Avatar gpmbc 06:49 PM 04-27-2012
Thanks again James!
LTD02's Avatar LTD02 07:19 PM 04-27-2012
"In the link I posted, the Harman stuff is not the interesting part(add subs, eq your way to flatness...simple enough...). The part about Yates supercomputers crunching out ideal sub locations for your specific room...now that is the cat's meow. I wish I had that knowledge for my own oddly shaped HT. I have lugged subs all over my room to try and smooth things out(and yes I have stacked in a corner, to no avail). If someone had measured the dimensions of my room and said "place subs here", it would have been sweet. It would especially be welcome for smoothing across two rows. I could get the front seats perfect at one point, but I had huge suckouts at various frequencies in row 2. Yates work would have been great during the HT build phase."

there is a simple version of that called "room response calculator" by yavuz aksan. it runs in excel. i forget where my copy came from. he may have updated it or might be willing to update it for oddball shaped rooms. i haven't checked.
A9X-308's Avatar A9X-308 11:30 PM 04-27-2012
Quote:
Originally Posted by bossobass View Post

Man, I wish you'd post more around here. Your posts are always top notch. Nicked quite a bit from them. Much appreciated.

Bosso

Cheers, likewise, I've referenced a lot of your ideas over time.

I've become a bit bored with forums, especially audio, as I'm more or less settled on my designs and am slowly realising them, whenever I can eke out a few $ towards it - tough these last couple of years. Plus I have other interests and a new puppy.

After I mentioned your fan cooling to a friend a while back, he's keen on trying something like a heat exchanger system on the 18"ers when I get them. Cool idea, but I dunno if it'll work. I'm also in an apartment, so I realistically wonder how hot they'll ever get, especially as there'll be 8 12" and 2 15" to go with them (already own these). More than 12 litres of volume displacement in 51m³ of room should be enough to go deep and loud on occasion and with the enclosures spread out, I should be able to have something at almost all of the nodes in the sub range (1H, 1L, 2L, 1W, 2W) but measurements will tell.

Pity I won't be able to attend a get together to hear your system.
FOH's Avatar FOH 06:18 PM 04-28-2012
gpmpc,

Some good points being raised. I'm looking forward to more and more measurements, experiments with your subs. Again, congrats so far, good lookin' out

I've got many points to make and questions to ask. but first about the room modeling stuff;

Whether it's some free shareware room mode calculator for subwoofers, or Yate's et al Cray supercomputer crunching,....it's only going to be as accurate as the input data. Merely examining modal activity with Height, Width, and Depth, is myopic.

I've found (obviously I'm not the first) that room mode calculating is only a very rough draft of what may, or may not occur. Boundary impedances of the floor, walls, ceiling, etc., ultimately play a heavy role in determining exactly what will occur in our HT's modally. Furniture occupying significant cubic quantity, both impacts PVG onset, but also affect time domain behavior of the subwoofer spectrum.

Not just wall material, however ceiling joist size, spacing, adjacent load sharing vertical stiffening members, doors, headers, you name it,...every conceivable element all sums in a nearly infinite set of variables and forms your acoustic environment. Sure some of these elements weigh more heavily, however the sum of many seemingly insignificant components could easily skew an otherwise intuitive result, into an acoustic environment that's subsequently counter-intuitive.

I mean this effects stick built/woodframe construction perhaps more than a concrete bunker style room. Mine for example; not my mix room, but in my non-dedicated HT space, I've got so many odd ball architectural elements. I've got three pocket doors in the room, which really compromise a walls structural integrity. I've got a ~10' sliding glass door to the outside, a kitchen at the far end, a floor to ceiling brick fireplace along one wall, etc., etc.

My point is the modeling is great, but measurements trump all the conjecture.

So these individuals that have Yates, for example, custom stealth build in a multi-sub install, may be locked into their proposed design. However those of us that actually measure every element and move the subs and affect the response accordingly, possess the distinct advantage over the mega buck number crunching. Just sayin


Also, I've enjoyed the advantages of a multi-sub rig since the early/mid 90's. I've planned a new multi-sub approach spanning the vertical with both a multi manifold attic IB, and small sealed balancing subs employing selective mode cancellation for a couple years now. Problem is, my cardio-thoracic rig been falling apart, and it's a bit out of warranty This has made the attic crawl a real bitch,.... however,...significant progress has been made as of late.

Thanks
A9X-308's Avatar A9X-308 06:51 PM 04-28-2012
Quote:
Originally Posted by FOH View Post

My point is the modeling is great, but measurements trump all the conjecture.

So these individuals that have Yates, for example, custom stealth build in a multi-sub install, may be locked into their proposed design. However those of us that actually measure every element and move the subs and affect the response accordingly, possess the distinct advantage over the mega buck number crunching. Just sayin

I could not agree more. Measurement trumps simulation every time.
nube's Avatar nube 07:23 PM 03-26-2013
I remember following this thread last year, and I'm curious whatever became of it.

What happened to the system after you got the Bossobassis? Got any measurements, gpmbc?
gpmbc's Avatar gpmbc 08:18 AM 03-27-2013
Hey Nube, I wanted the Bossobassis but it wasn't made available when I was ready to pay, supply issues I believe. I honestly wouldn't have utilized the SSD 15s if I would have known I wouldn't have been able to obtain that piece of the puzzle. They worked well near field in spite of but far (when I switched my room) I wasn't getting the same ulf dominance. I'm soon to be selling my house so I'll see what makes the final cut in terms of LFE once I'm all in the new setting.
gpmbc's Avatar gpmbc 09:03 AM 03-27-2013
And just for clarification Nube, I didn't want my statement to suggest a knock against the drivers . I was just trying to duplicate a proven recipe from drivers, to the amp, to the eq implemented and I began the project with all 3 factored in.
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