My house is finally done and it includes a 19'x27'x10' dedicated HT room! So now slowly it will begin. I'm starting the move on 2/15/08 but will have only about 7 or 8 days in the US so I probably will not get much done on building the theatre. At least I will take some photos while there.

For the moment I will just describe the plan...

Equipment List

DVD: Denon 5900
Bluray: Sony S300
Pre-Proc: Anthem D2
Main speaker amplifiers: (2) Anthem P2’s
Subwoofer amplifiers: (2) Anthem MCA30’s
Surround amplifiers: TBD Existing options: Usher (1) R-0.8, (3) R-1.5, (2) R-6.0
Center amplifier: TBD
Main speakers: DIY near infinite line dipole two-way bi-amplified DIY crossover.
(36/line, 18 front + 18 rear) Dayton Reference 6” truncated frame.
(84/line, 42 front + 42 rear) Aurasound NSW2 2”
Subwoofers: DIY infinite line dipole (2)
(12/line opposed mounting in pairs) Dayton Reference RSS390HF 15”
Surround speakers: DIY dipole TBD
Center speaker: DIY dipole TBD
Projector: JVC HD1
Anamorphic Lens: Prismasonic FE1500M
Screen: DIY 2.35:1 144” diagonal with Da-lite Cinema Vision (1.3 gain)
Seats: (11) Berkline 13174 (Blue or Burgundy??? Thoughts, suggestions?)

I'm attaching a photo of the room but it's old. I have not seen it in person for about a month. The carpet is in now but I understand some of it has to be redone due to poor workmanship on the install. The carpet is a shade of burgundy so I wonder if ordering burgundy seats will be too much? I can't decide between blue and burgundy so any suggestions will be welcome.

All the speakers will be dipole starting with the subwoofers and going right through the surrounds. Also, the subwoofer will be effectively infinite line at 9' tall with a 10' ceiling and the mains will be near infinite line at about 8' tall.

The subwoofers will be modular with each module containing four of the 15" drivers wired series/parallel. One pair of drivers will face in and one pair will face out to gain the advantage of this push pull configuration. Each of the three modules per line will be driven by one Anthem MCA30 amplifier channel. This is more than enough power given that 25 watts/driver can push them near linear excursion limits below 20 Hz. The plan is to EQ the woofers down to around 12 Hz and then roll them off below this. Most likely I will include a switch to shift the roll off up a bit to perhaps 18 ~ 20 Hz so I can select this option for any material that threatens to bottom the woofers at high output levels.

The main lines will use absorption material in the rear of the speaker and also behind the curtain behind them to eliminate the rear wave. The only purpose of making them dipole is to control the polar pattern, not to have a rear wall reflection as in the Orion ++. I'm afraid I am in disagreement with my friend and mentor Siegfried Linkwitz on the rear wall reflection. My goal is a speaker with a cardioid or perhaps a better description would be a half figure 8 polar response. If I could somehow dump the rear radiation into a black hole behind the speaker, that would be ideal. So, the off axis radiation of the rear mounted drivers will aid in canceling of the off axis radiation of the front mounted drivers and the on axis radiation of the rear mounted drivers I will attempt to discard.

Given my work travel schedule this project is going to take awhile. There will be periods of many weeks where I have no opportunity to work on it because I will be sitting in an Asian hotel room like this one here in Malaysia. The house includes a 23'x40'x10' four car garage so at least when I am home I will have room to work on building the speakers.

Monte

My house is finally done and it includes a 19'x27'x10' dedicated HT room! So now slowly it will begin. I'm starting the move on 2/15/08 but will have only about 7 or 8 days in the US so I probably will not get much done on building the theatre. At least I will take some photos while there.


Monte

Monte:

That is one large home theater, mine is 15' x 20' x 9' always wanted one a little longer and wider.

Monte:

That is one large home theater, mine is 15' x 20' x 9' always wanted one a little longer and wider.

Well it's been said that I'm not building a house with a dedicated home theatre...I'm building a theatre with a dedicated living quarters below.

Anyway, the eleven Berkline's have been ordered through the power buy. I went with blue.

Also, the twenty four RSS390HF woofers are on order. There are 100 custom 6" truncated frame RS150's already sitting in my living room waiting for me. The extras are going in the whole house audio system.

Most of my upcoming short trip home will be spent moving so I'm not sure I will get much done toward this project. Ideally I will slip in a trip to NC in the not too distant future so I can cut the parts for the subwoofer baffles on the CNC. That will save a lot of time!

Monte

Monte,

You're obviously very into dipoles, and have thought about them a lot. But one practical thing to consider with dipole subwoofers if you want to "use absorption material in the rear of the speaker and also behind the curtain behind them to eliminate the rear wave." Elimination of subwoofer reflected waves is very difficult, and requires a lot of absorber depth to even do a partial job.

I've designed bass traps which go down to the 20's of hertz. But these have been 3 feet deep, and haven't eliminated all reflection but have been tuned to single room modes. I doubt if one could do broad band attenuate of all subwoofer wall reflection by more than about 6 dB (absorption coefficient of around 0.7).

Regards,
Terry

...Elimination of subwoofer reflected waves is very difficult, and requires a lot of absorber depth to even do a partial job.

Terry, you are absolutely correct. The good news is that I'm not even going to try to absorb the rear wave of the dipole woofer system. Ideally I would dump the entire rear wave into a black hole but as you mention, this would be a very difficult task at low frequency. So, low frequency must be treated as a lumped sum end equalized accordingly. The combination of rear reflected low frequency and the forward wave will have to be accepted as it is.

I disagree with Siegfried Linkwitz in his assertion about rear wall reflections. To me the Orion ++ creates an artificially deep sound stage which does not just create a deeper space but also tends to elongate the depth of individual vocals and instruments. Avoiding this does not require absorption of low frequency so this should not be the issue of greatest concern.

The real problem is, how do you avoid destruction of the dipoles uniform polar response? Absorption, how much ever you use, tends to always absorb more energy with increasing frequency. One of the nicest things about a dipole is that off axis energy tends to have the same frequency response as on axis resulting in reflections that are more similar to the direct sound field. If you absorb the rear wave non uniformly this advantage of the dipole is partially destroyed. That's where the real challenge is going to be! Low frequency isn't that critical because it's going to all lump together anyway.

I still have a lot of experimenting to do on this project. I've heard a dipole where efforts have been made to accomplish this with surprisingly good success so I believe I can accomplish an acceptable approximation of the goal.

The problems in the approach are certainly not trivial and the ideal goal is not really obtainable so an approximation is all that can be expected. As the project progresses, I will post measurement results.

Monte

May as well do an IB sub. It has the same benefits of dipole (no cabinet coloration) but without all the cancellation.

I had a pair of 18" Avalanche dipoles in my little theater and they could barely muster 105db. They sounded great but had no balls at all.

May as well do an IB sub. It has the same benefits of dipole (no cabinet coloration) but without all the cancellation.

I had a pair of 18" Avalanche dipoles in my little theater and they could barely muster 105db. They sounded great but had no balls at all.

I thought about IB but it loads the room in a different way than dipole. There is an interesting article here... http://www.musicanddesign.com/roomgain.html that talks a lot about how different woofer types load a room. I'm planning to experiment with the author's cardioid approach at some point but will try to avoid any system that pressurizes the room in the same way as monopole. IB is not a bad approach to bass however. I would opt for it over any small box any day! I think the cardioid approach may be a better solution however.

Monte

I think a dipole sub can work fine for a music system. But your thread says theatre and that means high SPL/deep extension.

The drivers you listed have about 2L of displacement each, for 24L total. My dual Avalanches have about 13L so at best you'd get almost 3db more SPL than I did. I fed mine 700 watts to each driver and they came close to and did bottom out very easily. The most I could ever get out of them was about 105db in a very small, sealed room (10x12).

With EQ I got them to extend to ~25hz where they fell off pretty hard. Also I used a 12db/octave highpass filter at 20hz to protect the drivers. Without that the deep bass in recent movies could guzzle the excursion while creating very little SPL since the wavelengths could easily diffract around the baffle and cancel.

This theory of not pressurizing a room is odd to say the least. Part of it is the near impossibility of stopping the cancellation. The wavelengths get so long at low frequencies that to stop the backwave getting to the initial frontwave would require a baffle so big that you either need an enormous room or it just ends up becoming a wall.

If you're ok with limited SPL in the deep bass range then I guess the plan will work fine.

I think a dipole sub can work fine for a music system. But your thread says theatre and that means high SPL/deep extension.

The drivers you listed have about 2L of displacement each, for 24L total. My dual Avalanches have about 13L so at best you'd get almost 3db more SPL than I did. I fed mine 700 watts to each driver and they came close to and did bottom out very easily. The most I could ever get out of them was about 105db in a very small, sealed room (10x12).

With EQ I got them to extend to ~25hz where they fell off pretty hard. Also I used a 12db/octave highpass filter at 20hz to protect the drivers. Without that the deep bass in recent movies could guzzle the excursion while creating very little SPL since the wavelengths could easily diffract around the baffle and cancel.

This theory of not pressurizing a room is odd to say the least. Part of it is the near impossibility of stopping the cancellation. The wavelengths get so long at low frequencies that to stop the backwave getting to the initial frontwave would require a baffle so big that you either need an enormous room or it just ends up becoming a wall.

If you're ok with limited SPL in the deep bass range then I guess the plan will work fine.

If the article I included the link to earlier is true, the size of your room may have been the problem. According to his results, the smaller the room, the sooner the dipole becomes ineffective. Based on your dimensions assuming an 8 ft ceiling, a dipole would not be effective below about 36 Hz. So you may have evidence that his theory is correct.

One other thing to consider is the effect of the infinite line. This provides about +10 dB increase in output. Because the line runs floor to ceiling it becomes effectively about three times longer. The side wall mounting provides about +6 dB additional gain compared with having the dipole baffles sitting out in the room.

So, it will be interesting to see but listening to various recordings from the lowest notes of large pipe organs to canon shots on a similar smaller system suggest it's going to work very well. That system used six 12" drivers in each column each having only 6 mm peak linear excursion. Even with that limited volume displacement, it had no problems with very demanding low frequency material. It was by far the most impressive bass I've ever heard before or since. My brother was already familiar with this system and he had told me many times, "you may think you know good bass but you have not heard good bass until you have heard Brian's bass". He was right! My hope here is to exceed even that system! (Brian is a not so vocal speaker designer who has been designing speakers for over 60 years and designing dipole woofer systems for over 40 years. No web site, not even e-mail so he is not well known but he knows this stuff better than anyone I've ever known.)

In your situation I have to think the room size was the problem. In that room, attempting to get much output below the mid 30 Hz range with a dipole would probably prove pretty fruitless. In my room, I will begin to experience the same problem but the problem starts below 20 Hz and increases rapidly moving lower.

The good news is that this theatre has huge attic space on three sides and the top. So, If I really want to pressurize the room I will have space to put as many IB woofers baffles behind the walls as I want:D So who knows, maybe one day you will see a new thread pop up..."All dipole Theatre augmented with IB":)

Monte

Monte,

You may want to look at the work of Charalampos Ferekidis. He found that some room mode control is possible with dipole subwoofers. But the technique is selective as to the modes that can be controlled. The basic idea is that you can inhibit excitation of a room mode axis by oriented the dipole so that it provides no energy along that axis (perpendicular to axis of dipole). But of course you still excite modes in the direction of the dipole axis.

Regards,
Terry

Terry

Yes, I think at best orientation can only move the modes around. As Siegfried has pointed out, the dipole will have less room modes simply because no modes are excited in the nulls. So by changing the orientation you only select which modes are and which modes are not excited.

According to Brian, the designer of the system that got me started on this idea, peaks in the response existed initially but they were not particularly localized. Instead, the same peaks were pretty much everywhere so correcting the response with a notch at one location fixed it for all locations. I'm not entirely sure the woofer must be dipole for this, I suspect it may have more to do with the infinite line but this assumption could be wrong. It may require the combination of the two.

Monte

Very Nice! I like the wood trim and two paint colors you picked out.

I finally moved into the new house and I even got to do a little on the theatre while I was in the states before leaving on this current trip to Japan.

I got a few days to go to North Carolina to visit my brother and borrow his CNC router to cut the baffles for the twenty four Dayton 15" drivers. Cutting these and the complex dado cuts in the tops, bottoms and center pieces on the CNC make life a lot easier!

On my next trip home the goal will be to work on building the giant dipole sub-woofers, and building the curved screen. The four screen support columns in the photo are built up using 5/8" MDF. The screen will be mounted to these which hold it about three feet away from the wall. The door seen in the photo leads to attic storage but should not be consider an access to the storage but rather access to the back stage area from the storage. Another more accessable door is for getting into the attic.

Looks like the woofer modules are not going to be as heavy as I thought, based on the weight of the MDF pieces and the four woofers per module they should come in under 200 lbs each so less than 600 lbs/ea for the stack of three each side of the theater.

I'm stuck in Japan for at least a couple weeks so progress will continue to be slow but I will post more as I am able to continue putting this thing together.

Monte

Hi everyone, here is a progress report as of April 15, 2008. I worked on the woofer modules right up to the end of my stay at home this trip. I do mean right up to the end, the taxi driver showed up and had to help me finish gluing up the last woofer module before taking me to the airport for this trip to Taiwan.

The first project this trip was to build the screen. I did this following tr6’s design approach which I have to say worked very well. The main difference was that I did not use Velcro to attach the screen material but instead used window screen spline inserted into a grove which I had cut into the 2x4. It was somewhat challenging to get the screen stretched smoothly but I did finally get it.

Once the screen was installed I ran into a few more challenges getting the anamorphic lens aligned. With help from others here on the forum I finally got this under control. The primary keys seem to be in mounting the projector completely flat and level and then tilting the lens such that the light path remains centered through all the optics. With the projector and lens aligned I was able to use the lens end stop screws to obtain uniform adjustment left and right with the correct 16:9 and 2.35:1 aspect ratios at each limit.

I also made a lot of progress on the dipole woofer system. Unfortunately in the rush to get things done at the last minute I went off and left the flash card with all the most recent photos in the camera. I do have a few from a few days earlier so I will at least post these. One photo will show me standing next to one woofer stack consisting of three modules. In this photo the side panels have not yet been mounted but at least it will give you some insight into the size of these monsters. Each module weighs about 100 lbs empty and the installation of the four 15” woofers will add an additional 92 lbs. Add in the base, top, and the dividers between each module plus grills and these will easily weigh in at over 600 lbs/ea.

I’m hoping to finish things up here in Taiwan within two or three weeks so hopefully after that I will have enough time at home to finish the woofers. After that I’m going to start concentrating on more mundane details like the equipment rack, routing cables, and various cosmetic issues. The line source main speaker project is likely still quite some time out.

I’ll post another progress report after my next trip home.

Monte

Here a couple photos of the woofer modules. Unfortunately all the later ones are still on the flash card inside the camera 8000+ miles away in Texas. Once I get back home and continue the construction I will post some of these and also some newer photos.

Monte

I'm on the way back from Taiwan but I'm afraid of what kind of update I'm going to have for the theatre projects. Just hours ago the house was hit by a major storm destroying the garage doors and sucking some of the woofer modules I worked so hard on into the driveway:(

Interestingly after sucking these 100 lb modules and some relatively heavy power tools out of the garage it then put the doors back in blowing them into the garage such that I'm told it would be difficult for anyone to get in. I'm concerned the woofer modules are toast. I mean, they are MDF and got sucked out of the garage into a driving rain. The raw mdf had been painted but the cherry side walls didn't have anything on them. It's going to suck if I have to start over:mad:

I know I should be glad it wasn't worse. I'm told the house across the street lost half its roof and one a block away lost most of its roof. Still, I'm bummed out, it's going to be a long flight back!

Monte

6-3-08 update:

The woofer modules cherry sides were all water damaged by the storm. Apparently it was an F2 that didn't touch ground but passed right over between my house and the one next door. Fortunately insurance paid for both materials and labor to rebuild the modules. Also the inner parts were ok due to having been painted so all I had to do was knock the cherry sides off and replace them.

Since I didn't have the photos with me on the previous update I'll put in a couple from the beginning stages of the woofer assembly and then the new progress recovering from the storm damage.

I'm once again out of town, this time Portland OR! Not quite like Taiwan, Japan, or Korea but still out of reach to work on this project. Hopefully I will have a more extended time at home soon so I can finally finish the woofer project and start on the infinite line mains...not to mention all the other remaining projects to get this theatre up and running.

Monte

Monte,

Enjoy your time here in Portland...no F2's in the forcast....

Ray

Montekay, have you posted any of this in the DIY sub forum? I think lots of experts there would be very interested in this sort of sub design.

24 fricking subs? are you trying to go richter scale?

24 fricking subs? are you trying to go richter scale?


There can Never too many subs or too much bass! :D
but there can be too many people that complain about it!. :p

Montekay, have you posted any of this in the DIY sub forum? I think lots of experts there would be very interested in this sort of sub design.

After the storm I put a post on the DIY forum hopelessly looking for advice on recovering from water damaged MDF. I knew the answer would be "MDF + water = toast" but I was hoping someone would have a miracle cure. As it turned out it wasn't that bad to knock the damaged sides off and replace them.

Anyway, in the DIY forum I briefly discussed the design of the sub but not in much detail. I didn't want to run a duplicate of the thread so maybe once I get farther along and can start posting measurement data etc I will put a post in DIY directing people to this theatre build thread.

I'm attaching a photo of the garage door damage. You see the little table router sitting in the driveway in front of the right side door...before the storm it was in the garage, after the storm it was 50 feet away up against the neighbors house along with a wooden crate and misc other items. Twisters do strange things! I wonder what it wanted with my router?

Monte

Well I have the seats in now! Thanks Roman of Ultimate Home Entertainment! Roman is the guy to talk to about theatre seats! http://www.rtheaters.com/

The woofer modules are getting closer to being ready to load drivers. I had to make a quick trip to Japan this past week but will be back in the US Thursday evening so hopefully in a week or so the woofer columns will be done and playing. Next I think I will start on the infinite line mains.

As for the center channel I'm thinking of turning Don Keele's Pair-Wise Symmetric Multi-way idea on its side and using it to obtain uniform polar response in the horizontal plane instead of the vertical. His approach uses symmetrical pairs to control beam width and polar shape in a multi-way M-T-M style driver arrangement. Actually it's more like a W-LM-HM-LT-T-LT-HM-LM-W. The crossover transfer functions are quite unique and would not easily be realized using an analog approach. Because home theatre circumstances inevitably dictate some sort of horizontal driver arrangement anyway I think a horizontal version of Keele's and Horbach's design would be ideal as it would provide uniform coverage without the unwanted lobe effects of conventional horizontal MTM type center channel speakers. My version will of course be dipole which will eliminate the far off axis issues.

http://www.aes.org/e-lib/browse.cfm?elib=14199
http://www.aes.org/e-lib/browse.cfm?elib=14208

Monte

I've been mulling an idea you might find interesting.

I recently got a Lexicon MC-1, which has a feature called bass enhance.

What it does is it takes bass from the front and LFE channel and routes it to the side surrounds, which are then set to "large". It shifts the phase of this bass forward by 90 degrees (1/4 cycle) to simulate bass reverb in a live space and to reduce the mono bass nature of many mixes. Also this can help smooth out bass response since bass is now coming from 2 extra locations.

Now where this ties in with your project; I have small Paradigm dipoles for my side surrounds. To do this bass enhance properly you need 2 extra subwoofers placed with the side surrounds. What I was thinking about was to use say 4-6 of these per side

http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=264-837&scqty=12

Other people have built excellent open baffle speakers using these drivers. Their 6x9" sizing could be used to build a pseudo column that is actually a dipole subwoofer. 6 per side could easily achieve high SPL at low xmax down to about 40hz, which is what the Lexicon needs.

The drivers could be placed with the null towards the seats or parallel to the wall.

This bass enhance feature is unique to Lexicon however.

http://i27.tinypic.com/1fxsf8.png

That's actually not a bad idea. The little 6.5" TangBand subwoofer is also a really good choice for this. That one in particular is really quite with low distortion at low frequency. Interestingly the 8" version is horrible! I don't know what they did wrong with the 8" but it's really noisy! I'm not sure about the 6x9. I had a set in my hands once for a car audio application but didn't bother doing any real testing on them so I don't know if they are as good as the 6.5". They did work great for car stereo! It's good to hear others have had good experiences with them in open baffle applications. I may have to order some more and take a closer look at them this time.

My Anthem D2 doesn't have "bass enhance" like the Lexicon but I wouldn't think it would be too difficult to create something like this externally.

Monte

Someone on DIY audio forums or open baffle speakers forum (forget which) did stereo mid-bass arrays with the 6x9 driver. They used 10 per and with 2mm xmax they were getting something insane like 117db with very low distortion and that was with a cabinet only as deep as the drivers to avoid resonance. They were $28 each at PE but have recently jumped to $42.

Before I left on this trip to Taiwan I managed to get the woofer system to 2/3 capacity. When I return I will install the third module on each side.

At the moment with just eight 15" woofers per side I can get a maximum of 119 dB at 18 Hz in the center row. The distortion is very high at that point however. By keeping it down to 2.83 volts per woofer I can still get over 100 dB at 18 Hz with less than 1% 2nd harmonic distortion and just a little more 3rd.

As expected distribution of bass in the room is quite uniform. From row to row there are some variations but from side to side the over plots pretty much lay right on top of each other. The back row is about 5 dB higher than the front row but the frequency response curves are almost identical. The center row curve is slightly different but for the most part the room EQ requirements are the same everywhere in the room. Just as Brian Elliot had suggested, with this floor to ceiling line open baffle system, fixing the room modes at one location fixes them for all locations. I'm not sure how much difference there will be in bass distribution once the third set of modules are stacked on top of these but if it improves then that will make his statement even more true.

I'm moving my updates to my web site and don't see the need to double post so for following the progress in the future go here... http://www.mfk-projects.com/home_theatre.htm

Monte

Are you satisfied with ~100db at 18hz?

Are you satisfied with ~100db at 18hz?

Are you kidding??? At 1% distortion...absolutely I am! Don't forget the maximum output at 18 Hz is 119 dB currently and will be about 122 dB once all the woofers are playing. At 110 dB 2nd harmonic is still about 1% and 3rd is just over 3%. At 116 dB 2nd is about 1.5% but 3rd has risen to 35%. Again, this is with just two modules per side so I'll get a bit more once the third modules are in place. So yes I think this will do:D

Monte

Knowing Jesse, he's NOT kidding. :)

That's not so bad then if you can reach 110db with only 3%.

35% with an odd-order harmonic is very high though.

Maybe you should have a 2nd sub setup to bolster movies. An IB or a pair of contras for example :D

That's not so bad then if you can reach 110db with only 3%.

35% with an odd-order harmonic is very high though.

Maybe you should have a 2nd sub setup to bolster movies. An IB or a pair of contras for example :D

Three sides and the top of the theatre are surrounded by huge attic space so I could put another 24 of those 15" drivers in IB if I really wanted to:D I could use those from 18 Hz down:)

Yeah 35% 3rd sucks but at 116 dB @ 18 Hz! I don't think there are any commercial subs that can match even that. Most subs really suck at this at high level at really low frequency. Anyway, the last set of dipole modules will get me another 3 dB. Actually 116 dB is shaking the place pretty well already!

The movie, "The Core", the scene where the guy demonstrates his laser thing by cutting the hole in the mountain...pretty scary on the system as it is! The depth charges on U571 are pretty intense too!

mk