FoLLgoTT's build: 18 x Peerless XXLS12 - Page 7 - AVS Forum
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post #181 of 204 Old 03-16-2014, 01:06 AM - Thread Starter
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I forgot to mention that most of the electronic devices are now located in the neighbour room. This means I don't have to slow down the fans of the FP14000. smile.gif

From top to bottom:
  • Onkyo PR-SC5507
  • 2 x Alto Maxidrive (crossovers for the 3 front speakers)
  • Klein + Hummel Pro C 28 (equalizer for the subwoofers)
  • Sanway FP14000

Only the amplifiers for the front speakers are still in the home theater room. But they are class D (Hypex) and are cooled passively.

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post #182 of 204 Old 03-16-2014, 01:55 AM
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nice work!

what radius did you end up choosing for your screen curve?

Listen. It's All Good.
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post #183 of 204 Old 03-16-2014, 02:01 AM - Thread Starter
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Originally Posted by LTD02 View Post

nice work!

what radius did you end up choosing for your screen curve?

Thanks! smile.gif

The radius is 7.3 m. This gives a curvature that most digital projectors should handle in terms of focus at the sides. I want to correct geometry (trapezoid, pincushion) with a Geobox. Maybe later I upgrade to a second projector and use passive 3D with this box(es).
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post #184 of 204 Old 03-19-2014, 12:26 PM
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Hey Nils,

It's a pleasure and very refreshing seeing a contributor submit decay and ETC measurements, likely two of the most important metrics to determine how "good" a room will sound. Outstanding.
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Behind this fabric I want to put the necessary absorbers/diffusers. I don't have an exact plan for this treatment. I'll have to measure and place them iteretatively. This means I place them where they are needed. E.g. this is mostly in height of the ear. There must be left some reflective surfaces, because I don't want to overdamp the room. It shall sound "alive" and "open". RT60 shall not be too low, especially in the highs. Unfurnately many home theaters are overdamped in the highs.

This ^ ^ ^ ... again, spot on.

So important to approach a room's needs via measurement. In these "bass race" times in which we live wink.gif (I've got 16kw+ redface.gif ), it's so nice and refreshing to see this approach. I've recommended this approach, but it often falls on deaf ears. Everyone wants a rule of thumb, "just tell me what to do" ... etc. There are a few safe bets as far as the low hanging fruit of acoustical treatment. But measurements should guide one's approach to placing treatment, just as you've done.

You're right, some HTs are MF/HF over-damped. But it seems most rooms do need more bass damping/trapping (most are really upper bass traps anyway), and if a room becomes over-damped, it can be brought back with facing/covering of treatment.

Great build. Love everything you've done (maybe I would gone with a cloud), also very cool device you made with the moveable sidewall absorption at the door, nice. I like Rockwool too.

What a screen! My Kung Fu is weak, on the video side ... but my vision is fine, .. and so is that screen!


Most importantly, congratulations and continued good luck. always great reading your contributions.

------------------------------------
Flat, Deep, Clean, Linear, and Loud
------------------------------------
Active 16.8kw, 7.3 system
(3)Seaton Cat12C up front, (4)QSC K8 sides/rears
(2)Seaton SubM-HP, (4)18" IB
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post #185 of 204 Old 03-20-2014, 01:43 AM
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Hi Nils,

why do you prefer the Klein + Hummel Pro C 28 equalizer for the subwoofers over the in HT applications more popular budget ones. Is it for the use of FIR filters? And if so, then I bet that somewhere you wrote about the pros and cons and how you proved with own measurements but I missed that part.

best regards
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post #186 of 204 Old 03-20-2014, 03:22 AM - Thread Starter
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Originally Posted by rumpeli View Post

why do you prefer the Klein + Hummel Pro C 28 equalizer for the subwoofers over the in HT applications more popular budget ones. Is it for the use of FIR filters?

No, I don't use the FIR filter section. In fact it is not possible to use it without a parameter set from Neumann. And I don't need it in the low end. Group delay is so low that it is just not necessary.

The initial reason to use the Pro C 28 was that its IIR parametric equalizer can be configured down to 10 Hz. Beside that this device is extremely flat down to 2 Hz and has a high dynamic range of +26 dBu. So clipping will never occur.
I bought the Pro C 28 second hand for a good price. I would never pay the new price for this application, since I use only 10% of its capabilities. wink.gif
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post #187 of 204 Old 03-20-2014, 03:37 AM
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That confirms my guessing, also since you elaborated elsewhere about the audibility of phase and group delay. However, some say this could be relevant <200 Hz. In case you don't know it already, a google research on the pro C28 lead me to this paper on phase distortion http://forum2.magnetofon.de/bildupload/goosphase.pdf (german content, sorry guys).
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post #188 of 204 Old 03-24-2014, 07:32 AM
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Originally Posted by markus767 View Post

In the next version REW has a checkbox "Room is sealed".

I see the beta 18 of REW 5 was now released and includes a bunch of room simulation changes. It will be interesting to see how the DBA and SBA model now that you can delay the subs.

Beta 18 changes (23rd March 2014):
Room sim: Added option to show anechoic response
Room sim: Added enclosure type selection (sealed/ported)
Room sim: Added delay and gain adjustments for each speaker/sub
Room sim: Levels are automatically adjusted to maintain 75 dB at main listening position regardless of number of speakers/subs selected
Room sim: Changed response graph range from 45..105 dB to 35..95 dB
Room sim: Added a check box to indicate whether room is well sealed (if room is sealed response is boosted below lowest mode)
Room sim: changed -3 dB defaults for subs to 30 Hz and speakers to 80 Hz
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post #189 of 204 Old 03-24-2014, 08:04 AM - Thread Starter
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Originally Posted by desertdome View Post

I see the beta 18 of REW 5 was now released and includes a bunch of room simulation changes. It will be interesting to see how the DBA and SBA model now that you can delay the subs.

That's great! I posted a sreenshot in the DBA thread. Maybe we can discuss it there.
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post #190 of 204 Old 04-07-2014, 10:17 AM
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Originally Posted by Adhoc1 View Post

A guy I know actually decreased a problem mode inside his HT by making openings through the walls at the corners towards another rooom / closet which acted as a large Helmholtz resonator. (My opinion:With windows closed, you have a sealed speaker with some losses but there is also some room gain + some pressure gain (less than 12 dB for the ideal fully sealed room). Combined these more or less even out the natural roll off of your sealed speakers.Noah is right about the open windows being perfect absorbers, not for a 6 Hz wave length but for all those close to or smaller than the windows dimensions.

I've always wondered why room designers go to great lengths to contain sound within the room, only to have it bounce around and cause problems, which then takes even more money to fix. Why not have a thin wall and let the low frequency "leak" out into the woods?

 

 

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post #191 of 204 Old 04-07-2014, 10:55 AM
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^
Why not charge double if you can wink.gif Two better reasons for acoustically isolating a room:
- Don't disturb neighbors
- Keep environmental noise out of the listening room

Markus

"In science, contrary evidence causes one to question a theory. In religion, contrary evidence causes one to question the evidence." - Floyd Toole
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post #192 of 204 Old 04-07-2014, 05:37 PM
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Originally Posted by Adhoc1 View Post

Noah is right about the open windows being perfect absorbers, not for a 6 Hz wave length but for all those close to or smaller than the windows dimensions.

Missed this until I saw it quoted.

I don't believe the size of the opening relative to a wavelength is related to the wavelength.

A hole is hole; where there was a boundary that would develop pressure and reflect energy, there is now nothing.

Noah
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post #193 of 204 Old 04-08-2014, 03:12 AM
 
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Excellent thread! I have some questions regarding your baffle wall & subwoofer configuration.

First, are those subs setup as an IB or do you just use sealed enclosures mounted flush to the baffle wall?

Second, I see that you have your baffle wall angled to toe in the Left & Right mains instead of curving the way you made actual angles. I am curious if those angles in the baffle wall are going to cause any issues with reflections off each wall that each speaker is pointing at?

I would imagine that doing a curved baffle wall would be very difficult, yet, ideal. I plan to start on my baffle wall this coming week as soon as I get moved into our new home. I have never built a baffle wall, but, I want to do something similar to yours with the mains being toed in.

Can you explain how you came up with the proper angle of toe in on each side of the wall? Also, are your subs mounted at the 1/4 point in between each wall?
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post #194 of 204 Old 04-08-2014, 03:59 AM - Thread Starter
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Originally Posted by Martycool007 View Post

First, are those subs setup as an IB or do you just use sealed enclosures mounted flush to the baffle wall?

The subwoofer enclosures are mounted on the wall.
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Second, I see that you have your baffle wall angled to toe in the Left & Right mains instead of curving the way you made actual angles. I am curious if those angles in the baffle wall are going to cause any issues with reflections off each wall that each speaker is pointing at?

I chose the angle which let the speakers point to my reference seat. This was my only criterion.

I investigated a bit toward possible reflections on the baffle wall, but I could not measure any significant effect. I used absorbers to cover the points of possible reflections. But my speakers have waveguides and thus a high directivity. Which means even if there were reflections on the baffle wall they would be attenuated.
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Also, are your subs mounted at the 1/4 point in between each wall?

1/4 is not possible with 18 drivers. wink.gif

I used the formula I posted here. The distance between the drivers is 1/6 of wall width and 1/3 of wall height. The placement depends on the number of drivers. smile.gif
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post #195 of 204 Old 04-08-2014, 04:13 AM
 
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Originally Posted by FoLLgoTT View Post

The subwoofer enclosures are mounted on the wall.
I chose the angle which let the speakers point to my reference seat. This was my only criterion.

I investigated a bit toward possible reflections on the baffle wall, but I could not measure any significant effect. I used absorbers to cover the points of possible reflections. But my speakers have waveguides and thus a high directivity. Which means even if there were reflections on the baffle wall they would be attenuated.
1/4 is not possible with 18 drivers. wink.gif

I used the formula I posted here. The distance between the drivers is 1/6 of wall width and 1/3 of wall height. The placement depends on the number of drivers. smile.gif

Any particular reason behind using those locations for the subs? Do those positions offer any similar benefits to mounting at the 1/4 points?

I like your baffle wall! I am about to start my baffle wall and would like to do something similar to yours, but, I am limited on carpentry knowledge and have no idea how you can make those angles like you have. Perhaps you could give me some pointers on how to properly construct a baffle wall with curved sides for toeing in your L+R speakers? smile.gif

I have all the tools and have some decent experience with building subwoofer & speaker enclosures, but, I have never tackled a baffle wall, and to be honest, it scare's me!
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post #196 of 204 Old 04-08-2014, 12:44 PM
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Hi!

Does the angle on the baffle wall mean that you should delay the outer bass drivers in order to have a planar wave? Or doesn't it matter that much for the lower frequenzies?

I try to post this once more since there has been some discussion on angling.
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post #197 of 204 Old 04-08-2014, 01:02 PM - Thread Starter
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Originally Posted by Martycool007 View Post

Do those positions offer any similar benefits to mounting at the 1/4 points?

Yes. It is just a scaling to more drivers. Even one driver at 1/2 works up to a certain frequency.

To the construction of the angle: I have multiple parts. Two big subwoofers with 6 drivers and two subwoofers with 3 drivers. The columns with 3 drivers are placed in that way that the gap could be closed with the main speakers and with boards. I screwed everything directly into the subwoofer enclosures. The space behind the columns is empty to avoid mold. There is no secret trick in this construction. smile.gif



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Originally Posted by jeno View Post

Does the angle on the baffle wall mean that you should delay the outer bass drivers in order to have a planar wave? Or doesn't it matter that much for the lower frequenzies?

It doesn't matter. Furthermore there is no big difference at all in frequency response when the outer columns are disconnected.
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post #198 of 204 Old 04-08-2014, 01:20 PM
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Originally Posted by FoLLgoTT View Post

It doesn't matter. Furthermore there is no big difference at all in frequency response when the outer columns are disconnected.

Thanks!
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post #199 of 204 Old 04-09-2014, 05:29 AM
 
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Originally Posted by FoLLgoTT View Post

Yes. It is just a scaling to more drivers. Even one driver at 1/2 works up to a certain frequency.

To the construction of the angle: I have multiple parts. Two big subwoofers with 6 drivers and two subwoofers with 3 drivers. The columns with 3 drivers are placed in that way that the gap could be closed with the main speakers and with boards. I screwed everything directly into the subwoofer enclosures. The space behind the columns is empty to avoid mold. There is no secret trick in this construction. smile.gif


It doesn't matter. Furthermore there is no big difference at all in frequency response when the outer columns are disconnected.

And you are sure that by having the baffle walls sides toed in with hard angles rather than a smooth curvature will not take away any of the benefits of having a regular more traditional flat baffle wall?
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post #200 of 204 Old 04-09-2014, 05:47 AM - Thread Starter
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Originally Posted by Martycool007 View Post

And you are sure that by having the baffle walls sides toed in with hard angles rather than a smooth curvature will not take away any of the benefits of having a regular more traditional flat baffle wall?

I'm sure that listering to the front speakers without angle is the worst case. wink.gif

And a smooth curvature is much harder to build. Of course I would prefer it if I were able to build it.
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post #201 of 204 Old 04-09-2014, 06:03 AM
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I work with engineers in Austria quite often. The personality when building things is a bit unique (e.g. over the top) on simple things. I knew you were over the top in a sense. However, over there, over the top has many levels. Seeing that junction/terminal block (lower right) just put you at a 9/10. tongue.gif

I must be guilty because people say I am guilty because they chose to call me guilty because they refuse to see the truth. Much easier to be part of the mob..
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post #202 of 204 Old 04-09-2014, 07:06 AM
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Originally Posted by Martycool007 View Post

And you are sure that by having the baffle walls sides toed in with hard angles rather than a smooth curvature will not take away any of the benefits of having a regular more traditional flat baffle wall?

Directivity of you mains is not absolute so, rather than firing straight into the room with a lot of inadvertent "splash" from the sidewalls, angled L&Rs direct sound across the listening area. A smooth curved wall would probably be even better, but more difficulty than benefit...better to put the additional effort into the rest of the room.

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post #203 of 204 Old 04-10-2014, 02:36 AM - Thread Starter
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Originally Posted by Trepidati0n View Post

I work with engineers in Austria quite often. The personality when building things is a bit unique (e.g. over the top) on simple things. I knew you were over the top in a sense. However, over there, over the top has many levels. Seeing that junction/terminal block (lower right) just put you at a 9/10. tongue.gif

Yes, german/austrian engineers are a bit special. My wife could tell you stories, because I'm a Dipl.-Ing. (M.Eng.) myself! tongue.gif


I love those tiny little bastards. It is so easy to reconfigure all the subwoofer connections. No screwing and no soldering necessary. wink.gif

Btw, my main speakers are connected with the big 8-pole speakON connectors. Together with a multicore cable it feels really big, heavy and solid. No comparison to those cumbersome banana plugs...
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post #204 of 204 Old 09-09-2014, 10:45 PM
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