What would experienced speaker builders use for a dedicated theater?

[Mandroid]

A bit of a ramble here while I'm stuck at home contemplating projects to build.

My inexperienced criteria that don't necessarily need to apply:

Acoustically transparent screen for ideal speaker placement.
Seated around 10-12 feet from the screen in a room <5000ft^3.
Reference level appropriate to room size: I've seen 78dB suggested for screen and surround channels instead of 85dB.
Multiple subwoofers painstakingly placed and aligned to cover <80Hz.
Sealed speakers with second order rolloff to integrate better with typical AVR bass management.
Room treatments as necessary.
No dipole or quasi-dipole.
Would prefer to avoid diysg.

I see high efficiency speakers with large woofer and waveguide/cd suggested by default on some other forums, but I have not had great experiences with such speakers.
Budget is flexible to obtain more performance, but I certainly couldn't afford outfitting my theater with dual woofer, dual mid designs using Revelators for example.

A few configurations I had been considering:
WMTMW with RS225/FW135H/DA25TX
WMTW with SB23NRX/MR16P/Augerpro waveguide SB26ADC
MTM or MMTMM with SB17NBAC/some tweeter

Thoughts on my rambling would be interesting to hear, but I would also be very curious to know what speakers you might build for a dedicated theater space.

[Scottg]

..this sounds like it's going to be "in-wall" or "on-wall". Both require a designed spec.ed for that use.

[JonMarsh]

This reminds me of the Issac Asimov story, "The Last Question" - "Insufficient data for a meaningful answer".

what tends to happen is that we unconsciously fill in the gaps and make suggestions based on our own "reasonable" assumptions which may not be reasonable to you....


For example, are built-ins practical in your home setup? Do you have the skills and experience for in wall wiring? Are you willing to design for on wall with slope sides and bottoms/tops? Scottg makes appropriate observations about that.

If you plan to go with more conventional boxes with conventional BSC, I have to remind you that the room acoustics and boundary interactions are a big deal- they can be ameliorated with using a Cardas style setup with golden mean ratios for the distances between midwoofer and floor, rear wall, and side wall, but can you comfortably setup that way for your planned or existing furniture setup? Setting up my old GF's system, in a room a little bigger, with fairly high ceilings, we had the mains and rears in the upper corners by the ceiling, and the center on the front wall above the Plasma screen. At the viewing distance and setup she preferred, that worked out fine. But it was a largish family room open to the dining and kitchen area.


Do you have a measurement setup and do you have experience with loudspeaker measurement and filter design? If so, the world is your oyster, and any of those configurations could be made to work well, within the notion of the reference levels you're quoting- 78 dB wouldn't require much drive.

Were I pursuing this concept, I'd also suggest considering an MT or MTM with the Anarchy 554 or 558 and the DA25 if you want a solution that will be use an interesting approach for LF to midrange IM distortion reduction (XBL2), and have a disgustingly low driver BOM cost. In an MTM, you could configure as a MMT and use a 2.5way crossover. If you recoil at the low price of the DA25, consider a BlieSMa T34A-3, possibly with a Visaton waveguide.

Otherwise, just to stir the pot, why not consider MT's or MTM with the PuriFi PTT6.5W04-01A, a BlieSMa T34A or T34B, and to save some time, with Visaton waveguide?

It's a good point to remember that with three ways, the crossover price climbs along with the complexity... I can easily suggest good budget three way combinations for which the crossover implemented with mid tier components would cost more than the drivers. Your first proposal would probably come in that way... and there's nothing wrong with that proposal, other than perhaps being the biggest? If that's not a problem for you, then give it a shot.

[Bear]

Were I pursuing this concept, I'd also suggest considering an MT or MTM with the Anarchy 554 or 558 and the DA25 if you want a solution that will be use an interesting approach for LF to midrange IM distortion reduction (XBL2), and have a disgustingly low driver BOM cost. In an MTM, you could configure as a MMT and use a 2.5way crossover. If you recoil at the low price of the DA25, consider a BlieSMa T34A-3, possibly with a Visaton waveguide.

Otherwise, just to stir the pot, why not consider MT's or MTM with the PuriFi PTT6.5W04-01A, a BlieSMa T34A or T34B, and to save some time, with Visaton waveguide?

I'd agree wholeheartedly with the spirit of this. There are a several good woofer options out there that can handle the crossover requirements in a TM configuration that will transition well to an 80Hz crossover (-6dB @ 80Hz, -3dB @ 100Hz) at these volume levels. The SMJ Calliope with the MW19P would be one of those options, and it could be made quite a bit smaller in a sealed alignment. After my current build, I'm planning to try my hand at SB17NBAC-based TMs that should hit these targets (SB17 + SB26ADC in a waveguide). For MTM, even more options open up, but you still have to have enough piston volume (cone area * Stroke) to hit your reference SPL targets. Now, whether you use Xmax or Xmech for "stroke" is a function of how clean you need your transients.

Let's touch on that for a second....

The 85dB THX standard is too loud as a target (which leads to the "The audience is now deaf" jokes), but the 20dB of headroom is probably a decent target. At 10 - 11 feet, you'll lose about 10dB at your listening positioning (room volume is less relevant for this calculation), so 85dB at 1m may be right for you and your room. Getting a design to 105dB 1W/1m, should be doable with 100 - 200 watts, depending upon the sensitivity of the total speaker (those Purifi woofers will need more power). Going much louder, though, and the population of options is going to drop off rapidly, especially ones that have "reference-level" performance (e.g., maintaining a noise floor at -40dB or lower at the loudest reasonable playback level), and the SPL requirements will increase both if you decide that you want a louder target SPL at your seating position OR if you move the seating position farther away from your speakers. This second pathway is one that shouldn't be ignored because the inverse power law can be a harsh taskmaster here.

[Mandroid]

For example, are built-ins practical in your home setup? Do you have the skills and experience for in wall wiring? Are you willing to design for on wall with slope sides and bottoms/tops? Scottg makes appropriate observations about that.

Do you have a measurement setup and do you have experience with loudspeaker measurement and filter design? If so, the world is your oyster, and any of those configurations could be made to work well, within the notion of the reference levels you're quoting- 78 dB wouldn't require much drive.

Were I pursuing this concept, I'd also suggest considering an MT or MTM with the Anarchy 554 or 558 and the DA25 if you want a solution that will be use an interesting approach for LF to midrange IM distortion reduction (XBL2), and have a disgustingly low driver BOM cost. In an MTM, you could configure as a MMT and use a 2.5way crossover. If you recoil at the low price of the DA25, consider a BlieSMa T34A-3, possibly with a Visaton waveguide.

Otherwise, just to stir the pot, why not consider MT's or MTM with the PuriFi PTT6.5W04-01A, a BlieSMa T34A or T34B, and to save some time, with Visaton waveguide?

It's a good point to remember that with three ways, the crossover price climbs along with the complexity... I can easily suggest good budget three way combinations for which the crossover implemented with mid tier components would cost more than the drivers. Your first proposal would probably come in that way... and there's nothing wrong with that proposal, other than perhaps being the biggest? If that's not a problem for you, then give it a shot.

Front speakers and subwoofers will be mounted in a purpose-built baffle wall. Construction and wiring is not a problem.

I have some experience with measurements, and intended to build a large, angle adjustable test baffle to perform outdoor measurements for this project. I am inexperienced at crossover design, but optimistic given the software tools and resources available for their design.

As fantastic as a Purifi/Bliesma MTM would be, it is a bit excessive for my budget sensibilities. Those woofers sure are tempting, though.
Would the small Anarchy have enough output capability? Not alot of info available on it, and given that it is only available from diysg, it is likely a no-go.
I would be really interested to hear what other budget-ish drivers are on your short-list that might be appropriate for this project.

A large 3-way speaker still holds a certain appeal, but is it providing much benefit when the high-excursion content is already being covered by subwoofers? I want big three-way speakers, but at the same time, I wouldn't mind saving the cost of all those extra crossover components.

The 85dB THX standard is too loud as a target (which leads to the "The audience is now deaf" jokes), but the 20dB of headroom is probably a decent target. At 10 - 11 feet, you'll lose about 10dB at your listening positioning (room volume is less relevant for this calculation), so 85dB at 1m may be right for you and your room. Getting a design to 105dB 1W/1m

This is spot-on how I feel about reference level. 105-108dB output @1m is entirely adequate.

[Scottg]

1st thing I'd do is determine the dispersion pattern (horizontal and vertical angles) needed for nearly identical pressure for EACH LISTENING POSITION.

Then I'd look to the location where each speaker would go and what the wall presents relative to that dispersion window. In other words, most walls aren't angled to the center of your listening space. Basically you are looking for problems here with dispersion pattern when trying to achieve the same freq. response for all listeners. And IF you go nearly "omni" (well, half-space "omni") to solve this problem - you'll then need to work harder on working with reflections (..which doesn't mean absorbing them altogether).

If you can do an inset treble-*waveguide that can be angled in the wall, then you'd be in better shape. Even then though, you need to look at the lower-freq. limit and use for that waveguide (and of course the resulting dispersion window relative to each listener). Some waveguide that bottoms-out (becomes nearly "omni") around 2 kHz or higher isn't going to do you a lot of good in this instance.

*and very likely an angled large woofer as well.

With respect to inset angled designs, you'll also need to know about your wall-space available: like are the supports/studs 16" on-center, or 24" on-center? What's the usable wall depth? Obstructions (wire/pipes) in that wall cavity where you want to place the speaker? Etc..

[technodanvan]

Would prefer to avoid diysg.

Would the small Anarchy have enough output capability? Not alot of info available on it, and given that it is only available from diysg, it is likely a no-go.

Far be it from me to question one's brand preferences as I have my own weird 'no-buy' lists, but I'm curious as to the rationale for avoiding DIYSG? I have only seen praise for their kits and such, and their prices are certainly competitive. I have no experience with the little Anarchy, but I have a few boxes of the 708s and they all (so far) seem well made with consistent parameters. I'd love to do something with the little guys sometime.

[Bear]

A large 3-way speaker still holds a certain appeal, but is it providing much benefit when the high-excursion content is already being covered by subwoofers? I want big three-way speakers, but at the same time, I wouldn't mind saving the cost of all those extra crossover components.

Simplistically, a 3-way crossover is 2x as expensive as a 2-way crossover (2*HP + 2*LP). Realistically, a 3-way is even more expensive (to a given build level) because the high pass and low pass networks on the midrange will interact, and you will want/need some extra parts there. Then you layer in a perfectionist approach since you're trying to match phase/DI/FR in two places, rather than one....

You get the idea.

Take a look at HiFiCompass for measurements of various drivers. Then take a look at various completed designs that are published or available as kits. Very few in-wall designs are out there in my limited experience. You may want to design your HT around being able to remove/replace the in-wall speakers, as well. One thing of note, once you start building, you may not be able to stop.

My current project is the Helios from Jeff Bagby, one of his last designs. It's a good all-arounder as a two-way, but it requires a fairly large (~35L) cabinet. And it's not cheap. For my surrounds, those will be ones that I can work on over time, though the drivers in question (SB17NBAC + SB26ADC) should work very well together (Troels Gravesen has a design for these). I'm also looking to build a center channel, but that will likely be last in the sequence. I've got my eye set on the new Bliesma T25-series of tweeters, but those are not available yet.

With a waveguide, then there are a number of 8"-class woofers that might also work, but you're likely deep into doing the crossover yourself at that point.

You might want to consider an interim solution (back to that "design for replacement" thing...). Zaph has in-wall versions of the ZA5 series of designs. These are budget-friendly and relatively high performance. In an MTM arrangment, they should hit your SPL requirements, as well. Put a three pack of those in your walls, and that will buy you some time to figure the rest out.

[Mandroid]

1st thing I'd do is determine the dispersion pattern (horizontal and vertical angles) needed for nearly identical pressure for EACH LISTENING POSITION.

Then I'd look to the location where each speaker would go and what the wall presents relative to that dispersion window. In other words, most walls aren't angled to the center of your listening space. Basically you are looking for problems here with dispersion pattern when trying to achieve the same freq. response for all listeners. And IF you go nearly "omni" (well, half-space "omni") to solve this problem - you'll then need to work harder on working with reflections (..which doesn't mean absorbing them altogether).

If you can do an inset treble-*waveguide that can be angled in the wall, then you'd be in better shape. Even then though, you need to look at the lower-freq. limit and use for that waveguide (and of course the resulting dispersion window relative to each listener). Some waveguide that bottoms-out (becomes nearly "omni") around 2 kHz or higher isn't going to do you a lot of good in this instance.

*and very likely an angled large woofer as well.

With respect to inset angled designs, you'll also need to know about your wall-space available: like are the supports/studs 16" on-center, or 24" on-center? What's the usable wall depth? Obstructions (wire/pipes) in that wall cavity where you want to place the speaker? Etc..

The baffle wall is built a small ways into the room specifically to accommodate the screen channels and front subwoofers. Parts of the wall are built at an appropriate angle to keep left and right speakers on axis for listeners. I may end up paying for room design services from someplace like Acoustic Frontiers, then do the construction myself.

Very few in-wall designs are out there in my limited experience. You may want to design your HT around being able to remove/replace the in-wall speakers, as well. One thing of note, once you start building, you may not be able to stop.

With a waveguide, then there are a number of 8"-class woofers that might also work, but you're likely deep into doing the crossover yourself at that point.

You might want to consider an interim solution (back to that "design for replacement" thing...). Zaph has in-wall versions of the ZA5 series of designs. These are budget-friendly and relatively high performance. In an MTM arrangment, they should hit your SPL requirements, as well. Put a three pack of those in your walls, and that will buy you some time to figure the rest out.

Can confirm there are very few diy in-wall speakers, and even less information on their design. That's not going to stop me from building a very large baffle for outdoor measurements and designing a crossover, though.

In regards to, "once you start building, you may not be able to stop"...it's too late for me already. Finished speaker cabinets number around 30, and subwoofers 10. I also seem to be developing a collection of drivers. Some might suggest I have a problem.

[oneplustwo]

Have you considered active line arrays? May not work for your room or desired "workflow." But something to consider.

[Scottg]

The baffle wall is built a small ways into the room specifically to accommodate the screen channels and front subwoofers. Parts of the wall are built at an appropriate angle to keep left and right speakers on axis for listeners. I may end up paying for room design services from someplace like Acoustic Frontiers, then do the construction myself.

Cool! 8)

With that in-mind, I'd be looking at a larger waveguide and 15" woofer with the right sort of off-axis pressure below 1.5 kHz. Specifically for overall value, I'd be looking at the compression driver and waveguide that Zvu has here:

http://www.htguide.com/forum/showthread.php?44394-Darth-Modula-MX-Monitor&p=634466&viewfull=1#post634466

For a 15" ideally the Eighteen Sound 15w500:

http://www.eighteensound.com/en/products/lf-driver/15-0/8/15W500

(..Eminence Delta 15A might also work well, but require a bit more from the crossover if it's not a DSP crossover.)

..and target a steep enough crossover near 1 kHz that produces a very uniform horizontal response off-axis.

That should give you a fairly stable +/- 30 degree horizontal "window" to work with, and significantly lower near reflections.