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Cedar Creek Cinema

99K views 138 replies 53 participants last post by  wes 
#1 ·
It's about time! :sweat: It is finally finished! :jump:

Cedar Creek Cinema Construction Thread.

We can now define new meaning for :hsd: and it's "Cedar Creek Cinema". :bigsmile:

All of the images is this thread are mostly older pics. This room has been updated fifty-eleven times since its creation.

Below is older info, older pics and older equipment that has been updated.



For the most up to date pictures, please visit: http://www.cedarcreekcinema.ws/


With 4 Fi Audio Q18's (Rise of the Eighteens) and a pair of Audiopulse AX15D2 AXIS 15's (Building the Pulse) in a seriously sealed 3800 cubic foot space... what would we expect. :dumbcrazy:

The Pulse subs with the Audiopulse drivers from reside in each front corner. Front speakers are Martin Logan Spire's with the center being a ML Matinee. The Spire's have their own powered woofer that really has remarkable extension down to about 30Hz. The equipment cabinet was built by my local cabinet guy, Steven Ward. Thanks to all the guys in my Equipment Cabinet Design thread for the ideas. The 2.35:1 screen is 125" diagonal.






The equipment consist of the Onkyo 876 Receiver, an Oppo BDP-83 Blu-ray player, four Behringer EP2500 amps bridged mono powering the Audiopulse subs and the Fi Riser Q18 subs... each load at 4 ohms. The Panamax units handle all the power protection requirements and switching everything on. The amps cannot be all switched on at the same time or it pops the 20 amp breaker. They draw a nice surge at start up, but never exceed 3-4 amps during use. We will be adding a Dish Network 612 HD DVR where the Adcom 515 is filling in space for now.




Here's a closer look at the Pulse subs. I used a textured finish on these that turned out fairly well. The build project is located in the The Pulse Subs thread.




It is impossible to notice any imperfections in the velvet... or the screws used to hang the covered panels... when the lights are down and the screen is lit. There is zero reflection where the velvet is located, which even extends out 48" on the ceiling from the front wall. I plan to add another 48" between the current panel and the return air duct. While the ceiling is painted flat black, there is still some reflection where the velvet ends. It is not really a distraction, but I know it's there. :sarcasm:

 
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#36 ·
Sonnie,

Beautiful job on the HT! I'm sure you'll get a lot of enjoyment out of it. Must be an amazing amount of bass output. One question though...do you ever get phone calls from the Cal-Tech seismologists trying to track down the origin of the strange seismic events they seem to triangulate to your location? :bigsmile:

Lester
 
#44 ·
Wow. Very nice Sonnie. Your old theater was nice, but man oh man your new one is sweet!
 
#48 ·
LOL I’m blind as bat
sorry I did notice them. Yes, yes now I see the enclosure is sealed except for the bottom part of the enclosure that mates the sub base raised floor, right gotcha.

That is might large sub how many litters is it including the rest of the flooring area?
 
#50 ·
80 litres :ponder:eek:f water if filled up to the top because I don’t know sod all about speaker building enclosures apart from most are square or cylindrical types, but I catch on.

I think of the top of my head my diy sub is less in litre volume size but then I only need to glance at yours. Is their an additional thread that goes into a bit more detail on the construction of the (diy subs)?

Cheers
 
#52 ·
So it is and I wouldn’t have even guessed that.

I like the look of it and the teeth rattling well I get that each time I travel on Bournemouth buses lots of low end bass vibrating all for a £3.00 all day ticket.:rofl2:
 
#53 ·

Just curious, Sonnie, how does the "EQ all the subs as one" thing work as far as linear response (or a reasonable facsimile thereof) at the various seats?

We are extremely pleased with everything, despite running into several hurdles along the way and it taking what seems like forever to get it all done.

Ultimately, it paid off with what we really wanted after we teased ourselves with the first HT room we built. I am not sure we could do anything any different or make any changes that could make us any happier with the end result. It sounds awesome and meets or exceeds our every expectation.
What's all this "we" business? Does Angie actually come out to this one with you? :whistling:

Regards,
Wayne
 
#54 ·
how does the "EQ all the subs as one" thing work
I've wondered this myself.

Scenario:

Sub #1 has an +8dB peak @50Hz at the listening position.
Sub #2 has an +8dB peak @50Hz at the listening position.
Total peak at listening position @50Hz is +16dB.
Sonnie applies a single -16dB cut and all is well.

Would it have been better to apply a more reasonable -8db cut @50 Hz to both subs?

brucek
 
#66 ·

how does the "EQ all the subs as one" thing work
I've wondered this myself.

Scenario:

Sub #1 has an +8dB peak @50Hz at the listening position.
Sub #2 has an +8dB peak @50Hz at the listening position.
Total peak at listening position @50Hz is +16dB.
Sonnie applies a single -16dB cut and all is well.

Would it have been better to apply a more reasonable -8db cut @50 Hz to both subs?
And, if I have two signal peaks @50Hz in a room of +8 dBSPL, then the resultant peaks SPL level is +14.02 dBSPL (result is double = +6.02dB higher).
Math is the same 20 log [10^(SPL1/20) + 10^(SPL2/20)].
Nothing like a "real live" experiment; maybe this will help clear things up. My DIY sub has two drivers, each powered by an independent amplifier channel. So, I can run both drivers together, or only one at a time. Does this meet the “all things being equal” requirement? :D Ideal to the discussion, I have a honkin’ peak at ~42 Hz.

Here’s a graph I took today. The blue trace is both drivers running (no EQ). The red trace is one driver only. As you can see, the only thing that changes running both is overall gain. I suppose you could say the peak is “worse,” but its relation to the rest of the curve is the same.


Text White Blue Plot Line


Regards,
Wayne
 
#57 ·
If sub 1 and sub 2 both have an 8db peak around 50hz, assuming no cancellations between them, the summed response would be an 8db peak around 50hz, not 16db
So, at the listening position, if sub #1 has a peak of +8dB @50Hz and sub #2 has a dip of -8dB @50Hz, is there not a cancellation?

Do acoustic signals not cancel and reinforce?

Is signal reinforcement not how we enjoy extra headroom by adding a second sub, allowing the volume of each to be reduced?

brucek
 
#58 ·
Sorry guys... Angie and I were on a road trip yesterday to pick up yet another set of speakers. :drive:

Wayne... the "we" stuff is mostly pointing to the design and finish of the room, however, Angie has spent more time in this room since it was built than she did all total in the other room. Still yet... "we" might as well be me and my imaginary friend. :blink:

I have tried the equalization for all the seats and I do not care for it. I do not know if it is psychological because I can see the huge differences in the measured responses or if I really notice a difference, but I do not like it.

I can equalize for the main listening position only... running three Audyssey measurements from that seat and from that seat it looks good. The other seats really do not look or sound any better or worse than they do when I use averaging and measure multiple seating locations... BUT at least I get one position, the main one, looking and sounding good.


As far as the eq'ing all subs as one... I do not know the technical aspects of it, but I do know it works regardless of the location of the subs. I also know that any time I have tried (and I have tried many times) to equalize two subs independently, that while the individual responses have looked very good, once they are combined, the overall response looks awful. It has never... and I emphatically repeat "NEVER!" worked when I have tried to equalize subs independently for an overall smooth combined response. Quite frankly, I do not recall anyone ever succeeding at doing so... and it does not make sense that it can be done either.




In this situation you are measuring the independent responses to see the peak and dip. I believe if you measured them together that your response would be flat at 50Hz and there would be any need of eq'ing. However, trying to equalize them independently, you will apply two unnecessary filters.
 
#63 ·
Sorry guys... Angie and I were on a road trip yesterday to pick up yet another set of speakers. :drive:
What?? More speakers?? Well, if I recall - from where you are, it’s a “road trip” to anywhere! :laugh:


As far as the eq'ing all subs as one... I do not know the technical aspects of it, but I do know it works regardless of the location of the subs. I also know that any time I have tried (and I have tried many times) to equalize two subs independently, that while the individual responses have looked very good, once they are combined, the overall response looks awful. It has never... and I emphatically repeat "NEVER!" worked when I have tried to equalize subs independently for an overall smooth combined response. Quite frankly, I do not recall anyone ever succeeding at doing so... and it does not make sense that it can be done either.
Understood, you EQ’d all the subs as one, presumably from the sweet spot. What I’m trying to find out is, does that technique also gets decent response at the other seats as well?

Regards,
Wayne
 
#59 ·
brucek said:
So, at the listening position, if sub #1 has a peak of +8dB @50Hz and sub #2 has a dip of -8dB @50Hz, is there not a cancellation?

Do acoustic signals not cancel and reinforce?

Is signal reinforcement not how we enjoy extra headroom by adding a second sub, allowing the volume of each to be reduced?
Yes, they cancel and reinforce each other. Regarding reinforcement, the most that can be gained by doubling displacement is 6db, and that's if everything is perfect. If both subs have roughly the same FR - even if that means a 35db peak around 50hz - the combined FR will stay the same (assuming no new room effects from the position of the second sub), it will just be increased 0-6db across the entire range.

If one sub is +8db at 50hz and the other -8db at 50hz, then yes, assuming no new room effects from placement of the second sub, they would cancel each other out and you would be flat at 50hz. The magnitude of the "flat" FR at 50hz would still be 0-6db higher though.
 
#60 ·
the combined FR will stay the same (assuming no new room effects from the position of the second sub), it will just be increased 0-6db across the entire range.
Not that this is my field, but is there a confusion here between absolute and relative levels.

As an example, if I introduce two +8dB filters at 50Hz into an equalizer, the result will be absolute +16dB at 50Hz.

That's a doubling of the single +8dB level, which is relative +6dB higher (20 log 16/8).

brucek
 
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