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The Timelapse Theatre - Planning n' Build Log - Page 31

post #901 of 1281
Quote:
Originally Posted by jdanforth View Post

The 5000c and the DSP 5000 tower sound NOTHING LIKE EACH OTHER no matter which way you orient the 5000c. I wouldn't say that the 5000c is "bad" it's just wildly different.

I walked into a $1M demo room and the designer was upset that I pointed out that their front soundstage didn't match. "But that 'center' channel cost $60k." Great, so get three of them and rotate them 90 degrees. Or, get three identicals of the L/R towers. But to accept compromise at that level of specification is nuts. Following basic acoustics will do way more good than price tags. I haven't heard the 5000c, but I can surely appreciate the benefits you found from perfectly matching the fronts.

Quote:
Originally Posted by jdanforth View Post

To combat that I got the LCR as close to the screen as I could stomach (about 4 inches) which split the difference between the speakers being lodged in between two refrigerator-sized subs and right up flush with a ten foot wide ship's sail.

That "sail" won't notice you scooting them forward 2-3 inches. Those refrigerators will, so that's the first thing I'd try.

Quote:
Originally Posted by jdanforth View Post

I added 2 inches of Linacoustic to the face of the subs to help alleviate reflections (just like the back wall behind the subs). The problem with that, of course, is that I'm only really absorbing from 500Hz up...

Yup, and mudbass is below that. I'd encase those and about every other screenwall surface in 4".

Cheers,
Chris
post #902 of 1281
Quote:
Originally Posted by jdanforth View Post

I've been fiddling around a bit tonight and I have made huge improvements.

1. The Meridian DSP 5000c has been replaced with a DSP 5000 tower. This difference is indescribably better. The entire soundstage is cohesive and coherent now. Voices are clear as a bell.

2. I've lost my rear channels in the back of the room so I've reconfigured the system as 5.1 only. The tradeoff is worth it though!

3. The axis adjustment in Meridian DSP speakers is nothing short of magic. I'm shocked at the improvement in vertical imaging by tweaking that just the slightest bit. I don't understand what's happening but twiddling that setting shifts the sound up or down. It's freaky. And awesome.

WOW!

Now to see about buying another pair of DSP 5000s for the rears again!

The axis adjustment Sounds like a delay/distance/phase tweak..... Changing distance/phase/delay settings can migrate the phantom image between speakers without adjusting spl, which IS the way to do it....

Im not surprised you like the tower back in the center, from what i remember the C was configured quite different from the towers.
post #903 of 1281
Thread Starter 
Quote:
Originally Posted by NicksHitachi View Post

The axis adjustment Sounds like a delay/distance/phase tweak..... Changing distance/phase/delay settings can migrate the phantom image between speakers without adjusting spl, which IS the way to do it....

Im not surprised you like the tower back in the center, from what i remember the C was configured quite different from the towers.

They are configured quite differently but no different than other manufacturer's attempts at the center channel.

Tower:


"Matching" Center:


The center is front ported, has a dramatically smaller cabinet volume (but weighs a metric craptonne), and has a different driver arrangement. The LRs are rear-ported (different diameter), larger volume, etc.
post #904 of 1281
Thread Starter 
Quote:
Originally Posted by TMcG View Post

JD - Judging by all this expert advice, I respectfully withdraw my "try tipping it slightly forward to point more at the listening position" comment!! LOL!

No man, don't do that. That's solid advice for any system!
post #905 of 1281
Quote:
Originally Posted by jdanforth View Post


They are configured quite differently but no different than other manufacturer's attempts at the center channel.

Tower:

"Matching" Center:

The center is front ported, has a dramatically smaller cabinet volume (but weighs a metric craptonne), and has a different driver arrangement. The LRs are rear-ported (different diameter), larger volume, etc.

Agreed, those towers are most likely 2.5-way TMM and the Horizontal MTM is most likely 2-way. Completely different crossover topology.

The box size dictates the low end extension and response of the speaker which is likely very different.
post #906 of 1281
Quote:
Originally Posted by TMcG View Post

JD - Judging by all this expert advice, I respectfully withdraw my "try tipping it slightly forward to point more at the listening position" comment!! LOL!


Not at all! That was an excellent suggestion My post had a little to do with yours, but could be accomplished as well!!!

Quote:
Originally Posted by jdanforth View Post

No worries. Catch you next time. Congratulations on the new subs! Which auditorium at Duke? Do you mean the gym?

Not sure, it went through one other guy before it got to me, but he did say the main auditorium? It certainly wasnt cameron if I had to guess...
post #907 of 1281
Thread Starter 
Quote:
Originally Posted by NicksHitachi View Post

Agreed, those towers are most likely 2.5-way TMM and the Horizontal MTM is most likely 2-way. Completely different crossover topology.

The box size dictates the low end extension and response of the speaker which is likely very different.

That's important too when you configure your DSP to make that speaker "small" and, thus, push the low end back to the subs which have a different sonic character altogether. That setting may have had a lot to do with the intelligibility problems.

There's a lot of bass in the male character's voices in 'Star Trek' that was really hard to understand before but last night it sounded great.
post #908 of 1281
Thread Starter 
Quote:
Originally Posted by chriscmore View Post

I walked into a $1M demo room and the designer was upset that I pointed out that their front soundstage didn't match. "But that 'center' channel cost $60k." Great, so get three of them and rotate them 90 degrees. Or, get three identicals of the L/R towers. But to accept compromise at that level of specification is nuts. Following basic acoustics will do way more good than price tags. I haven't heard the 5000c, but I can surely appreciate the benefits you found from perfectly matching the fronts.

I've been in my fair share of $250k+ rooms that sounded pretty bad too.

Quote:
Originally Posted by chriscmore View Post

That "sail" won't notice you scooting them forward 2-3 inches. Those refrigerators will, so that's the first thing I'd try.

Really? You think that an inch of clearance would be OK?

Quote:
Originally Posted by chriscmore View Post

Yup, and mudbass is below that. I'd encase those and about every other screenwall surface in 4".

Not a bad idea. I've got some leftover Linacoustic. I may just add some more to see how I like it. I'm reluctant to do too much treatment before getting Nick back over to do some measurements though.

I forgot to mention that I set up the LCR speakers for "Boundary" mode which, according to the manual, should be used if the speaker is within 24" of a wall. I can only assume that this setting curbs the low-end response to reduce boomy performance.
post #909 of 1281
Quote:
Originally Posted by jdanforth View Post

I've been in my fair share of $250k+ rooms that sounded pretty bad too.


Really? You think that an inch of clearance would be OK?



Not a bad idea. I've got some leftover Linacoustic. I may just add some more to see how I like it. I'm reluctant to do too much treatment before getting Nick back over to do some measurements though.

I forgot to mention that I set up the LCR speakers for "Boundary" mode which, according to the manual, should be used if the speaker is within 24" of a wall. I can only assume that this setting curbs the low-end response to reduce boomy performance.

Would you be willing or able to do something like this?>>>>

http://www.avsforum.com/avs-vb/showt...7#post22078377

That would be the best way to handle everything where the entire front wall is one big flat piece. This is exactly why movie theaters do it the same way Then there is no need for "boundary mode" or any other lining of other speakers etc.

If nick comes up there, he can bring me my 4648 down in new bern and ill meet up with you guys!! haha
post #910 of 1281
Quote:
Originally Posted by beastaudio View Post


Would you be willing or able to do something like this?>>>>

http://www.avsforum.com/avs-vb/showt...7#post22078377

That would be the best way to handle everything where the entire front wall is one big flat piece. This is exactly why movie theaters do it the same way Then there is no need for "boundary mode" or any other lining of other speakers etc.

If nick comes up there, he can bring me my 4648 down in new bern and ill meet up with you guys!! haha

Boundary mode likely dials back the baffle step compensation when closer to boundaries.....

Another benefit to having speakers mounted in wall is no backwave from the mains arriving out of phase and jacking up the response ......

Now Brandon, what you should have done is made a little excursion over to my place with one of those babies in tow.... I would have held onto it until my next adventure to Raleigh!
post #911 of 1281
Enough of all this technical mumbo jumbo, lets see a new VIDEO! THAT'S what is REALLY important!

Regards,

RTROSE
post #912 of 1281
Quote:
Originally Posted by jdanforth View Post

Really? You think that an inch of clearance would be OK?

Yes, it would be fine. Our screen material was designed to hang right over in-walls without any audible effect. You can measure a bit more raggedness up around 20kHz by shortening the spacing, but it only shows up at 1/24 octave resolution. Such narrow bandwidth high frequency effect isn't audible and I'd much rather take that than midrange/mudbass early transient-smearing reflections. Remember, this isn't some 90%-non-AT-perfed-vinyl-POS you have.

Cheers,
Chris
post #913 of 1281
Quote:
Originally Posted by NicksHitachi View Post


Boundary mode likely dials back the baffle step compensation when closer to boundaries.....

Another benefit to having speakers mounted in wall is no backwave from the mains arriving out of phase and jacking up the response ......

Now Brandon, what you should have done is made a little excursion over to my place with one of those babies in tow.... I would have held onto it until my next adventure to Raleigh!

Exactly my point, the backwave/sidewall-wave is exactly what SBIR is and thus why a fully flat screen wall with speakers flush prevents this

I know I know I know, I was close by!!!! But I might have feared for my other cab in a fellow bass-head's possession!! Haha j/k between driving back into new bern from the river house just to pick them up and taking time away from the water, my hands were already tied
post #914 of 1281
Thread Starter 
Quote:
Originally Posted by chriscmore View Post

Yes, it would be fine. Our screen material was designed to hang right over in-walls without any audible effect. You can measure a bit more raggedness up around 20kHz by shortening the spacing, but it only shows up at 1/24 octave resolution. Such narrow bandwidth high frequency effect isn't audible and I'd much rather take that than midrange/mudbass early transient-smearing reflections. Remember, this isn't some 90%-non-AT-perfed-vinyl-POS you have.

Cheers,
Chris

Haha, quite right! I'm really impressed with your product. I can barely look at those Da-lites we install now. Blecch!

I'll experiment with moving the LCR closer. Thanks for the encouragement!
post #915 of 1281
Thread Starter 
Quote:
Originally Posted by RTROSE View Post

Enough of all this technical mumbo jumbo, lets see a new VIDEO! THAT'S what is REALLY important!

Regards,

RTROSE

Oh, OK. If you insist!

post #916 of 1281
Quote:
Originally Posted by jdanforth View Post

Oh, OK. If you insist!

Ha! Video On Demand, now available from the JDanforth Network.

Great video as usual, John! I really like how your carpet turned out. Also, it's funny to see the screen along the side wall look SOO big at the end because of the wide angle lens.
post #917 of 1281
Thread Starter 
Quote:
Originally Posted by stevegravley View Post

Ha! Video On Demand, now available from the JDanforth Network.

Great video as usual, John! I really like how your carpet turned out. Also, it's funny to see the screen along the side wall look SOO big at the end because of the wide angle lens.

Thanks! Yeah, I laughed too when I saw the footage. You forget how much that little lens distorts the perspective. I correct for geometry but the angle changes all the time so I found it too time consuming to tweak the perspective too.
post #918 of 1281
Excellent Video !
Screen's pretty nice too
post #919 of 1281
Wow! Another great video, thanks for finally getting to the important stuff! Your room is starting to come together and look like a theater. Exciting times my friend, exciting times!

Regards,

RTROSE
post #920 of 1281
Thread Starter 
Thanks, guys!

I can't wait until after Maker Faire NC so I can work on the rear wall design!
post #921 of 1281
Really nice video, JD! I always crack up when your son is in the room building different things and just generally being a kid - really top work!

I saw your post on Mario's build about the LED lights and the hum you experienced when they were dimmed - and I recalled a hum you were getting through the audio of your system when you first hooked it up. It sounds to me like a grounding issue - namely a difference in what's called ground potential. What did you ever find out about your electrical hum issues?

So when is the furniture being delivered? Cheers!
post #922 of 1281
Now that you're almost done, if you need any help let me know
post #923 of 1281
Great vid John! I really like the tracking. I think I saw your dolly/track in one of the earlier shots.

Isn't it amazing how much time we spend sitting/kneeling on the floor?
post #924 of 1281
Thread Starter 
Quote:
Originally Posted by TMcG View Post

Really nice video, JD! I always crack up when your son is in the room building different things and just generally being a kid - really top work!

I saw your post on Mario's build about the LED lights and the hum you experienced when they were dimmed - and I recalled a hum you were getting through the audio of your system when you first hooked it up. It sounds to me like a grounding issue - namely a difference in what's called ground potential. What did you ever find out about your electrical hum issues?

So when is the furniture being delivered? Cheers!

Thanks for checking in. I'm fairly sure that the sub hum was due to a dodgy amplifier. I haven't noticed the hum since I upgraded to the Behringer 1000DSP for the subwoofers.

Furniture is here already but I haven't shown you yet... I want to catch up with the videos first AND I loaned my wide angle lens to a friend anyway.
post #925 of 1281
Thread Starter 
Quote:
Originally Posted by rabident View Post

Now that you're almost done, if you need any help let me know

Hahah, how generous!
post #926 of 1281
Thread Starter 
Quote:
Originally Posted by andymo View Post

Great vid John! I really like the tracking. I think I saw your dolly/track in one of the earlier shots.

Isn't it amazing how much time we spend sitting/kneeling on the floor?

At least I have new, comfy carpet and padding to sit/kneel on!

Thanks for the compliment. Some of that tracking is good old fashioned Pan and Scan (but reverse since I'm going 4:3 to 16:9!) footage shot with a static GoPro micro camera. The better looking footage is shot with a Canon 7D on a Dynamic Perception Stage Zero motion controlled dolly track.
post #927 of 1281
Thread Starter 
This weekend was a whole lot of fun. Friends came over on Friday night to have dinner and a movie but we wound up just tossing the kids down to the theatre with "Despicable Me" so the grownups could gossip and drink.

Nickshitachi drove up and brought all of his fancy analysis gear. We spent long hours on Saturday night measuring, listening, and tweaking settings to dial in the subwoofers and LCR array.

In case you missed it I was having a lot of trouble with my center channel... it sounded terrible. I replaced it with a full-range speaker that's identical to the left and right. I did this at the cost of going from 7.1 to 5.1 but I'll live.

Here are the before and after measurements that we did.

The room started out with a rather uneven response in the low frequency (as expected). You can see the room modes fairly clearly especially down there around 30Hz. You can also see the steep 20Hz rolloff that I installed due to the poor performance of these subwoofers below that frequency.

(Blue is the post-adjustment; purple is the pre-adjustment)



First we tweaked the "distance" parameter in the Meridian processor for the subwoofer channel to find the best performance and then we applied three or four PEQ adjustments by way of the Behringer 1000DSP amplifier used for the subs. Not bad considering there are no purpose-built bass traps in the room yet.

The important thing is that it sounds great!

Adjusting the subwoofer helped to smooth out response in the high end as well as you can see from this center-channel only graph. These graphs sure look bumpy but it really does sound exceptional in the room. Vocal clarity is excellent. You can see in this graph where the 120Hz rolloff down to the subwoofer takes place.



Now check THESE out. Look at the change in decay that has occured in the room since we first measured vs. now. The green waterfall is with nothing in the room except carpet... no Linacoustic, no furniture.



And this is what we measured this weekend (new carpet, 2" Linacoustic on screen wall, giant couch, giant ottoman, no other wall treatments)



Ideal? No. Better? Oh yeah!


Attention Defecit Version: The room sounde even better now thanks to tweaks and measurements after a visit from Nickshitachi!
post #928 of 1281
Nice results. Thanks for sharing these before/after examples! Nickshitachi also consulted me (via my thread) on REW and some related suggestions. So I assume you are planning to add some bass-trapping?
post #929 of 1281
Man I had a great time. Always good to spend some time with a fellow HT hobbyist.

First off John has a really comfortable theater to spend some time in. His choice in seating really has me re-evaluating my choice for recliners.... The screen size and aspect I thought were very well though out and executed. Both 16:9 and 2.40 looked good. I was also particularly impressed(jealous) with the black levels of his projector.

On the audio side, starting at the bottom(subs). This was the first time I'd heard both the F20s working in the room. Two F20s carried the room admirably with plenty of headroom to spare.

The mains were clear, crisp, and well integrated. We evaluated the imgaing with some pink noise and confirmed what we already knew, they were setup to image proper. I was particularly impressed with the vocal clarity of the center. It was really spot on IMO. I'm really picky when it comes to dialog but the Meridians sounded nice.

Measurement Comments: The room has come a long way both aesthetically and acoustically. The ringing was significantly lower this go around as evident in the waterfall. The problem areas in the sub FR are room related confirmed by coincidence of major group delay swings at the sharp dip frequencies. Every bit of bass trapping will pay major dividends for those areas. I do wonder though how they(subs) would measure with the mouths on the floor or one mouth up and one mouth down...... Maybe next trip!?

Overall Nice Job man, cant wait for the Next time!
post #930 of 1281
Quote:
Originally Posted by NicksHitachi View Post

We evaluated the imgaing with some pink noise and confirmed what we already knew, they were setup to image proper

Can you explain how you do that?

Fred
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