HOLY CRAP!!! My wife gave me the green light (Please read and bring suggestions)

[ruseriousclark]

Its a good day my friends!

For those of you with spouses, who do not share your love for music and superior sound, you know exactly how huge the following scenerio is.

We are in the construction phase of building our new home and after much discussion she has conceded to a dedicated Theater in the basement and whole house speaker system all to be installed by yours truly.

Here's the deal. I have one chance not to screw this up so that when I want to make changes later on she'll be less likely to say "no".

I am looking for suggestions/insight on build designs conforming as close as possible to the following parameters.

1st and 2nd floor system

2 Channel systems in 4 rooms - sub optional

I'm looking for form and funtions here. Needs to have an in-wall build configuration and arranged for listening at low to medium volume levels.

Nat P's would be great but I'm unsure even though I know a few in-wall applications have been attempted.

Ideally the system will be condusive to both ambient listening for background purposes but will likewise need to "rock" when the wife cranks it during cleaning or when I'm home alone.

I included the optional sub in the likely hood that someone has a recomendation that met all the aforementioned criteria with the exception of low frequency capabilities.

Dedicated Home Theater

Yeah!!!!!!

Go big or go home! Gentleman fire away. The only bad suggestion is no suggestion.

Lets begin.

This wil be a dedicated room soley for home theater use and the occasional sporting event or tv veiwing. I have ideas but looking for advice and recommendations in line with the following.

7.X surround sound

As with everything we're looking for quality sound here but with one condition...LOUD! Remember its a theater.

LCR

I love the idea of the Nat P's or Madula's here but have read where they may be restrained by their limits where volume is concerned.

I want clarity and detail in a center, timber matched to the L and R mains each with excellent range and depth.

Size is no issue and asthetics are a formality.

Sides and Rear

No suprizes here just well ballance sound for a typical surround speaker.

Sub

WEEEEEEEEEEE!!!

Sonotube? Maybe. Atleast that's not the plan at the moment. I want depth. Bone crushing depth. Key is to have configuration that blends well with the drop off points of the other components.

I'm looking for a system that blends well within each other and has the best sound for the dollar in a hometheater configuration.

I'm ditching my Infinity (Crap) 7.2 system for a DIY. I've built two sets of bookshelves learning the woodworking from a pro. So I feel good about the build just really indecisive about what to build and hoping for some help.

Thanks guys.

Oh, lastly. If any of you are in the Lexington, KY area and would consider getting together or letting a hack like myself take a listen to your work, I'd really appreciate it.

Thanks again. Let the fun begin.

DA

[Gir]

Awe man, that sounds awesome! For the theater, I've always loved the speakers inside the columns, especially the round ones. And for the sub, I'd love to see someone else try a double base array! (DBA) Basically it eliminates all room modes and you get practically a replica of the modeled response curve. It's nuts! More on that here. Thoughts on that anyone?

[augerpro]

All I can say is run Cat5 EVERYWHERE. I mean it. 2 hookups minimum everywhere there is a computer of tv. Terminating in a central junction box where you can hook to a router. Generally the cable and phone line will come into this box also. The future is digital man, evetything will need access to the net, the cable box, the new dvd player, the Xbox, media servers, home theater pc's, everything. Run the Cat5 now when you have the chance. Trust me.

On the AV side. I would run RCA's to several areas in the room. You never know where you may want to put a sub and you don't want to run cables along the edges of the walls do you? Also running some HDMI isn't a bad idea. if you ever want a projector it would be nice to have the cable already in the from the wall to the middle of the ceiling.

[joecarrow]

The Modula MTM should play plenty loud, if you use an active crossover to bass bins. That means that you'll want a 7.1 pre/processor that will give you line outputs so that you can run the front channels "Large" and split the signal to separate amps for a Modula MTM on top and a couple high quality subs beneath. The Dayton RS series of subs should work great for the task, since they have clean output to a fairly high frequency. It'll let you play with crossover frequencies and slopes to get the best sound.

For the sub, you're totally in the green to do infinite baffle. It'll be like nothing you've ever heard before. It'll also let you upgrade the bass without any visible changes later on.

I also recommend an isolated and well ventilated closet to put amps, a server, some crossovers, etc, in. You'll obviously want anything that you regularly adjust to be out in the room- but you really want a rack to hold amplifiers for 8 to 10 channels (two extra from splitting the mains for bass bins), a crossover, some kind of room bass EQ for the subs (thing Behringer Feedback Destroyer Pro), and whatever other tools will let everything else operate at its potential.

For the speakers distributed throughout the house, the Dayton RS225 + RS28a two-way by Mark K would be promising. It probably wouldn't need a sub unless you're a real bass head.

Regarding the "double bass array", that could work, or it could flop. I haven't read much about it. It would definitely be worth simulating response in room with FRD tools.

http://www.pvconsultants.com/audio/frdgroup.htm

Maybe someone here can help you with that- a good sketch of the size and shape of the room would help a lot.

Also, make sure you check out Art Ludwig's page, too- it's a good resource. http://www.silcom.com/~aludwig/

[Gir]

Regarding the "double bass array", that could work, or it could flop. I haven't read much about it. It would definitely be worth simulating response in room with FRD tools.

It seems to have worked for Follgott, and apparently others. Just a thought really.

For the speakers distributed throughout the house, the Dayton RS225 + RS28a two-way by Mark K would be promising. It probably wouldn't need a sub unless you're a real bass head.

I just built a pair of these and they sound great! I'm thinking of rebuilding the cabinets to around 2 cu ft and porting it, but even without porting it a little EQ'ing on the lowend turns out great. I'm very pleased with them. On low volume they're not bad, but boy do they shine once you pump some power into them. If you don't boost the lowend too much they go LOUD. I can confirm that someone heard the speakers one floor down on the other side of my dorm :T .

One other thought, go with the starlit ceiling! Look up Sandman's home theater build on avsforums to get a full "how-to" on those. They rock!

[kingpin]

Its a good day my friends!

For those of you with spouses, who do not share your love for music and ...........

DA

Here is the only pic you will need to see.

Image not available

Chris(cjd) and Brian Bunges Dayton RS 3-way.
I think that's Ryan's(K) dual 15" sub underneath those.


Then there is the "Project Overkill" speakers by some crazy ass Canadian.

Image not available


Enjoy
Mike

[ruseriousclark]

All I can say is run Cat5 EVERYWHERE.

Absolutely. Buddy of mine has the largest Media Center I've seen with nearly 5 Terabytes of storage for everything from DVR, to ripped DVD's on demand. Absolutely first rate. He was in the perdicimant you described below running CAT5 to the entire house in an home almost 40 years old. Needless to say it was a nightmare.

-Love the Mark K design suggestion. Any build experince? Anticipated price point?

-The active crossover on bass bins is a great idea. Allows the control of lower freq. in the mains without passive crossover modification on the sub.

-As for power... what's your suggestion on the house. I'm currently with a 7 channel at 125w in 8ohm and 240w in 4. Plenty I suppose for what we've discussed.

Modula's are what I'd hoped to make happen was just a little apprehensive based on some of what I'd read. What kind of power are we talking about for a HT application?

I'll admit I need to do more research on infinite baffle designs for subs...what's the benifit verses DBA or other conigurations?

Thanks for the encouragement guys keep it coming. I'm salivating and my wife is getting P.O.'d.

[Gir]

-Love the Mark K design suggestion. Any build experince? Anticipated price point?

Mark K's design ran me a little over $500 I think. That was my first build, and I'm working on a couple others this summer (Modula MT, Modula MTM center, 18" sonosub, and some of Zaph's BAMTM with bass bins for a friend). Even though it was a first build it wasn't too difficult, but I guess it's no different than any other 2-way build. Just note that it's the RS225S (SHIELDED) and not the RS225, because it wasn't specified specifically in the writeup and I had to get mine replaced. I think Mark may have edit his writeup now to specify the shielded version. I'm curious to see this summer how Mark K's compare to the Modula MT. I'm itching to play with one of the seas tweeters.

I'll admit I need to do more research on infinite baffle designs for subs...what's the benifit verses DBA or other conigurations?

The DBA essentially eliminates all room modes. It sends a flat wave front across the room, and then the drivers in the back cancel the waves since they are in opposite phase and time shifted for the time it takes the sound to travel from the front to the back. The largest problem is usually what happens at the rear walls, so this takes care of a lot of issues. However, the catch is that you need twice the drivers since you're only hearing the drivers in the front, and that includes double the power. You also need equipment to create the delay in the signal. This is a really pricey way to go, but I'm sure the sound is crazy good! Pretty much an infinite baffle without any room modes :O

If I were you just go with the infinite baffle. Pretty simple from what I understand. Just brace up the wall and stick the puppies in. Easier said than done :T

Kingpin, you seem to be a big fan of foot shots... anyways, love the rs 3-way design! Definitely consider those for the mains.

Oh, and another thing I was thinking of. Go for the stealth system in the theater! There's nothing cooler than walking in the theater, seeing no speakers at all, and then BAM! they blow you out of your seat! Try an acoustically transparent projection screen with an IB behind it, and mains on either side behind some GOM. Then put the surrounds in some nice columns with a section cut out and GOM placed over that. SEXY.

[Scottg]

FIRST - be *very* critical of air quality for yourself and your family - LOTS of good filtration AND designed for good air pressure.

Second - (..if you can swing the expense), install a natural gas emergency generator for critical areas (..like emergency lights, phone line, security system, fridge/freezer, at least one computer, etc..)

(Note: See if your utility company has rebate programs for energy savings devices like special water heaters/solar/etc., IF interested, if so - see if they can be incorporated in a visually unobtrusive manner.)

In addition to proper cabling - use tubing conduit in areas where you might need to thread different cable for the future.. it DOES happen.

Put in very high quality grade surge suppressors AND arrestors. Also, good "hospital" grade electrical outlets with good cabling for locations known (and likely) to have expensive electronics. With VERY expensive electronics (like some projectors and flat panel tv's), consider their own dedicated UPS. IF using "Cable", make sure it is boosted and filtered properly to accommodate several "runs". IF it is also used for a high speed internet connection then the booster/divider/filter should also have a UPS and be connected to generator outlet, ..along with the modem of course.

"Centralize" a home server (computer) and consider this as a place for other electronics rack mounted and properly air conditioned (..cooling and moisture), with a dedicated interior AC unit vented appropriately. Purchase a decent UPS that will give plenty of time for the backup generator to work for that server (or servers) AND AC system. The server can include things like Home Automation, Back Up for user computers (with a massive RAID array for its own fault tolerance), etc.. I'd also setup another similar server system, a media server, just to handle a personal TV/Cable substation that is all "TIVO" like with Windows VISTA specifically sold with cable card rights AND enough pci slots for potential tuner cards - making sure that its all 1080 hi def capable. It could of course also include other forms of media like audio and family pictures, etc.. Finally (on the computer "front"), I'd also use one computer to strictly handle the home theater system - Audio, Video, AND Lighting (forget individual components - you can get better performance with a well thought-out HT computer).

Make sure in your theater that your AC/Heating duct system is low pressure and makes virtually no noise in operation. (..it would be nice if it was visually unobtrusive as well (for the entire home) - cheap vents are f-ugly AND noisy!) Additionally, make sure that the theater is well sealed acoustically and for light transmission (around the door, between the above floor joists, etc.). Unlike a dedicated listening room, the theater should be well dampened with lots of insulation. Consider riser/stadium seating for the theater.

Consider coaxial pro units for all in-wall installations including your theater.

..these are nice (contact Assistance Audio for more info.):

http://www.bmspro.info/index.php?show=item&usbid=10283&id=5059989

..with good dispersion 90 degrees (+/-45 degrees), for multiple listening positions.

Ditch the crossovers (if provided) and make use of multiple Behringer digital crossovers for all loudspeakers.. (each of which has 3 "legs" per channel, 2 channels). These devices have the ability to eq., phase adjustment, and time delay - to get that perfect response for the entire audience. Amplification could be as simple as DIY chip amps (digital or not, user assembled or supplier assembled), or some cheap pro amps (again, Behringer) as long as the amplifiers are in their own isolated room (..perhaps the "server" closet).

Note that the Behringer crossover can effectively add additional surround channels with its time delay ability. You could have surround speakers every 4 feet along the walls, its mostly a matter of splitting out the surround channels and adding delay where appropriate. And yes, it would make a very noticeable difference if done well.

Consider a 4 corner (corner of the room) IB sub bass system for the theater. Again, the Behringer crossovers will handle the details for you. The driver is the Dayton IB 15", you would need 4 and a lot of volume for the "enclosure" which can easily be a built-in dedicated partition in the basement for each driver. Other rooms in the house can have more typical in-wall subs for party music and the like.

Use cheaper tactile transducers for each theater seat AND one good one for the floor or riser section if possible:

http://www.partsexpress.com/webpage.cfm?&Webpage_ID=3&CAT_ID=49&ObjectGroup_ID=634

Think a LOT about proper lighting for the theater..

For a more "dedicated hifi loudspeaker system".. well, you have TONS of options there! :T Try for something near fullrange in bandwidth and avoid the use of a sub (or use a sub as well but keep the crossover VERY low in freq.). These are all good sites for DIY loudspeakers:

http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm

http://www.humblehomemadehifi.com/

http://www.zaphaudio.com/

..and of course you have numerous designs on this board to choose from! For a dedicated listening sub consider a RythmikAudio servo sub. Try to "shoot" for something domestically acceptable lest you quash your recent good fortune.

..and I'm sure there is a LOT more to consider.. , but its time for me to :Z

[Paul W]

Be sure to provide easy access to the backside of your equipment alcove via a door etc. I've done this in two houses and it makes wiring access easy rather than a nightmare.

Also, run a dedicated circuit (or two) from the main breaker box directly to the equipment rack.

[Gir]

Consider a 4 corner (corner of the room) IB sub bass system for the theater. Again, the Behringer crossovers will handle the details for you. The driver is the Dayton IB 15", you would need 4 and a lot of volume for the "enclosure" which can easily be a built-in dedicated partition in the basement for each driver.

I dunno, you could probably do better than the Daytons. I would definitely keep the Mach5 IXL-18.4 in mind. Those should be good for an IB setup. Not to mention the specs look absolutely amazing for that price. I just preordered mine for $175 shipped to my door. 4 - 8 of those would really kick your butt :T

[cjd]

So, if the larger 3-ways don't work for you, I've been commissioned to do a "mini" version of them this summer... Mini being a relative term only...

In-walls, don't worry too much about them really being able to rock. I think you're going to find you'll do your serious music listening in the HT. As such, Modula MT's might just do the trick, Nat P's if you want a little more headroom. Either can get quite loud when you're doing the cleaning or your wife is home alone...

Oh yeah, I vote for IB sub also.

While everyone is spending all your money...

Ok, I won't add to the pile of suggestions, but if either of you have allergies or other environmental sensitivities holler - I may have a few ideas. And not all of 'em cost. :P

C

[ruseriousclark]

Excellent suggestions all. I am really encouraged by the 4 corner IB scenerio.

Couple of questions.

What issues are created in the 4 corner IB approach if we intend to form stadium seating? Any chance there is a link to some build examples? I'd like to see how the different design facilited the free air approach in an enclosed space (i.e. false walls, etc.)

What issues are created with in-wall applications of sealed enclosure designs such as the one by Mark K already discussed.?

[Gir]

What issues are created with in-wall applications of sealed enclosure designs such as the one by Mark K already discussed.?

Baffle step becomes the issue (or lack thereof). Try one of the Modula MT inwall designs, they should work well.

[joecarrow]

I'd just like to add- it's really nice to be able to have the same sound playing out of speakers distributed throughout your house. For parties and that kind of thing it lets you enjoy the same music from room to room without having to blast it crazy loud. Likewise, if you're cleaning or doing chores about the house you can listen to music as you go without blasting it and creating a disturbance.

I noticed this tonight in my relatively small apartment. The stereo is in the living room and I was doing dishes in the kitchen. It's midnight now, and it would be really nice if I could get high quality sound in the kitchen without disturbing the neighbors.

Oh yeah- and another thing! Intercoms are good. I don't know how large your house is, but it sure is nice not to have to shout all the way across the house for someone. Also, if somebody is sick in bed or if you have a guest staying with you with a mobility impairment, it comes in handy if they need something. Heck, I'm thinking of coming up with an intercom from one side of my 600 sq ft apartment to the other!

[Scottg]

The Dayton IB driver is the ONLY driver I know of that has the right spec.s for infinite baffle operation. (correct TS param.s and decent excursion). Basically its a sealed design with a LOT more low freq. extension. (I.E. while other excellent designs are petering-out at around 14 hz, the IB keeps on going lower in freq. without a tremendous loss in spl's.) Each driver (unless compound loaded), requires at least 25 cubic feet for really low freq. operation, as you might imagine - this is NOT a typical subwoofer enclosure. Most of the time people will simply use their attic space as the "enclosure", thats not an option here.. but you are still in the construction phase. If you are going to use walls - then you need to make sure that from one stud to the next you have some holes in it to extend the volume to the next stud partition (..and so on). You will also need to seal off that wall with caulk to prevent air leaks (especially near your ceiling/floor joists for the room above). Basic construction of a basement wall is often cinder block wall/studs/sheetrock.. here you want something like cinder block wall/studs with holes/plywood panels/air space/sheetrock. The air space in this case can be something as easy as cheap carpet padding (with a moister barrier facing the plywood) glued to the plywood and sheet rock glued to the carpet padding. It makes for a nice dead wall. (If you personally do this then be sure to wear air filters when spraying the contact cement - its nasty stuff.) Oh, also screw the plywood sheets to the studs - do NOT use nails (..and of course caulk the panel edges to make sure its sealed).

Corner loading provides a boost of around 9-12 additional db at all sub freq.s (even the lowest). Thats a LOT of free "gain" and it will help keep excursion down, thereby reducing distortion. Similarly each corner sub represents an additional 3db over and above that limit. Corner subs are usually not a good idea unless they are kept below 40 Hz.. BUT here we have access to both eq. and phase adjustments, via the Behringer crossover, that will help the sub system "gel" with the coaxial midbass drivers.

The only issue with the stadium seating is that you do NOT want a simple box type riser that can "drone" (resonate badly). This is almost entirely dependent on the riser walls.. if they are "lossy", (allow low freq. waves to penetrate it), then it shouldn't be a problem.

In wall loudspeakers do not have a baffle step loss in spl's that traditional speakers have, nor do they have diffraction issues that would alter the freq. response of the drivers (note - if they are recessed slightly then be sure to use felt padding around the drivers so that no reflections screw with the sound). If you want to see the effects of baffle loss and diffraction then play with the "Edge" here (real easy to use):

http://www.tolvan.com/edge/

Point source speakers (like coaxials) are particularly "enviable" for use with an in-wall application. Additionally, I like a bit more "punch"/"dynamics" that a more eff. driver with somewhat higher Bl can provide - especially for HT. Also, BMS makes drivers that are a LOT better constructed than your usual HiFi offerings.

[cjd]

Scott, there are a lot of other drivers out there. FiCarAudio's Q18 (he'll customize to IB spec if you order 4 and tell 'im!) and Mach5's IXL-18.4 are the current favorites I think.

4 corner takes serious planning with a lot of room to flop, if I remember correctly. It's not what I would recommend. At all.

Riser should be sand filled. Duh. :P I believe a solid buildup with constrained layer will also do the trick.

C

[Gir]

4 corner takes serious planning with a lot of room to flop, if I remember correctly. It's not what I would recommend. At all.

I agree with cjd. Wouldn't you have a lot of issues with cancellation? I haven't seen a 4 corner setup, but it just seems like an iffy idea.

Oh, and I'm definitely all over the IXL-18.4's 15.4Hz fs :T I'm putting that guy in a 20-24 cu. ft. enclosure. My neighbors are gonna hate me

[BobEllis]

The Harmon white paper on multiple sub placement suggests that for a typical rectangular room, overall response will be smoother with four subs placed in the center of each wall than in the corners. They assumed the same signal to each sub. My room responded quite well to one sub centered on the front wall and one centered on the rear wall. Front center and side center was almost as good.

Sorry I don't have time to search for the link.

[Lindahl]

Use a Sonos system for whole house audio distribution (www.sonos.com). It's incredibly simple to setup and the controllers are amazing pieces of equipment to use. Way more flexible and fun than any of the more "custom" solutions on the market (Niles, Speakercraft, etc.). For background music for the inwalls, a ZP100 for each pair is sufficient. Use ZP80s feeding good DACs for your theater and any dedicated 2-channel rooms you may have. While Sonos is a bit more expensive, once the wife gets her hands on it, she won't care how much it costs. It supports music synchronization throughout the entire house, and line-in devices as well (CD players, Turntables, etc.). It can run through a dedicated NAS (network attached storage), so you don't even need a computer on all the time - just make sure to back it up often enough. Rip the files to FLAC (lossless), and you'll have CD-quality music throughout the house, on top of Rhapsody support (subscription service, where you can pick to listen to any song from a huge list at any time - good for checking out which CDs are worth owning).

[Scottg]

Scott, there are a lot of other drivers out there. FiCarAudio's Q18 (he'll customize to IB spec if you order 4 and tell 'im!) and Mach5's IXL-18.4 are the current favorites I think.

4 corner takes serious planning with a lot of room to flop, if I remember correctly. It's not what I would recommend. At all.

Riser should be sand filled. Duh. :P I believe a solid buildup with constrained layer will also do the trick.

C

custom drivers are another matter.. (good to know that you can get them with a minimum of 4, ciare does them in a minimum order of 20, HOWEVER I've seen several cases where a small manufacturer doesn't deliver a custom order for a VERY long time.. so caveat emptor. )

Indeed the Mach 18's model nicely, but they don't model as an IB (near flat response). Still, they do model well - particularly because the driver's fs is listed around 15 Hz which does provide increased extension over the Dayton. Funny thing is - the Daytons often measure about 15 Hz (after break-in), require less current, and produce a "flatter curve" with similar extension at about the same 25 cubic feet. HOWEVER, you can't ignore the Mach's need for less volume, its greater sd, and its greater linear excursion. Also though, IF you can spare 3 times that volume (AND the Daytons have an fs around 15 Hz), then the Daytons still go lower and at greater spl's for a given input. But again, you will certainly be able to "drive" the Mach's a bit more to compensate somewhat, BUT that will increase distortion significantly. Also, increasing volume (beyond the 25 cubic feet mentioned) on the Mach's nets you nothing.

I stand by my recommendation.. UNLESS you have less space to work with OR can really procure in a timely manner a custom driver that exceeds the Daytons (..while not being terribly expensive).

As to the placement..

You didn't read what I was shooting for did you?

The corners net you G A I N at low freq.s. This decreases distortion levels DRAMATICALLY.

The studies that been presented are all shooting for flat (spls) in a given room for broad bandwidth (to "swamp" room modes). They DON'T have precision eq., OR precision phase adjustment, OR precision time adjustment (..let alone FOR EACH DRIVER).

No, the 4 corner loaded IB with proper "eq" is a whole 'nuther beast.

By the way, you do NOT want to sand dampen the riser section (..or anything like it). Think basic "deck" construction with the risers. You DO want it capable of resonating.. you just don't want it to resonate significantly because of the subwoofers output, rather you want it to resonate when you attach a tactile transducer. :T

[cjd]

yes, I know what corner loading does. Gain is only part of the equation. EQ tends to be rather positionally accurate when it's room problems it's used for, so I prefer setting things up where less is required. If I want lower distortion I'll just add more drivers...

While sand would not be a particular problem if a completely inert riser were your goal, you understand the silliness of hauling that much sand into the house? :P You want a floppy riser? One that won't resonate for anything other than tactile transducers? Good luck with that...

C

[Scottg]

yes, I know what corner loading does. Gain is only part of the equation. EQ tends to be rather positionally accurate when it's room problems it's used for, so I prefer setting things up where less is required. If I want lower distortion I'll just add more drivers...

While sand would not be a particular problem if a completely inert riser were your goal, you understand the silliness of hauling that much sand into the house? :P You want a floppy riser? One that won't resonate for anything other than tactile transducers? Good luck with that...

C

when its 4 corner and you have access to the kind of eq. I was referring to - position can be compensated for even across a large area. Again, its DIFFERENT.

(..I was thinking you were suggesting something like sand bag-ing sections of the riser.., not having a basement beach.. 8O )

The "deck" construction will resonant some from the subs - even if you have some good isolating footers for the floor connection. They won't however resonate much because they shouldn't be physically "containing" any low freq. waves from the sub. In other words we DON'T want something that will generate audible low freq.s..

Of course because it is a medium with much greater density than air, the riser's beam & floor will transmit vibration fairly effectively WHEN a transducer is directly connected to it. You WILL need to filter-out freq.s above about 30 Hz though for that transducer (again the Behringer) - otherwise the transducer and riser section could create audible sound (depending on the amount of power and the construction of the riser).

[Dennis H]

The Dayton IB driver is the ONLY driver I know of that has the right spec.s for infinite baffle operation. (correct TS param.s and decent excursion).

BUT here we have access to both eq. and phase adjustments, via the Behringer crossover, that will help the sub system "gel" with the coaxial midbass drivers.

Errrrr, if you have an EQ, T/S parameters are really quite irrelevant for an IB. EQ the in-room response to whatever you want it to be. Go for max Vd with minimum distortion for the buck. While not a terrible driver, the Dayton IB doesn't really qualify on either the max displacement or low distortion requirements. There are much better drivers available for very little more $$/liter. Either the Dayton RS series or one of the TC drivers will be a better choice if you're looking for max displacement for the buck while maintaining low distortion.

[Scottg]

Errrrr, if you have an EQ, T/S parameters are really quite irrelevant for an IB. EQ the in-room response to whatever you want it to be. Go for max Vd with minimum distortion for the buck. While not a terrible driver, the Dayton IB doesn't really qualify on either the max displacement or low distortion requirements. There are much better drivers available for very little more $$/liter. Either the Dayton RS series or one of the TC drivers will be a better choice if you're looking for max displacement for the buck while maintaining low distortion.

Yes and no.. And it IS a good thought, however:

First off - we aren't looking for max displacement. That path leads to distortion.. At the same time though, we don't want to skimp on excursion for those few extraordinary transients (..so no 4mm drivers). Now the Dayton IB is in fact a rather good driver distortion-wise.. (surprisingly so.) Is it bettered by the 15 "high quality" Dayton reference? Well, that all depends on what specific freq., the loading, and the level of power the the driver is receiving. Though I don't know what the distortion levels are like for the Dayton reference, I'll almost certainly grant you that they are lower at higher freq.s (say 50 Hz up). Near each respective driver's resonance? I'd bet the IB (..properly loaded), is better (..assuming the same spl's and freq. - not that it is the case). (..of course thats just a comparison with 1 driver, and there are a lot of alternative designs out there to contemplate.)

The strange thing here for the IB is that because of the driver's spec.s and the way its loaded, it has less distortion at ultra low freq.s.. Not only is it lower than a normal driver AT resonance, but its also lower beyond resonance in its compliance "controlled" region for a given spl (..and again though, this is assuming proper loading).

What is NOT strange and should have been "picked-up" upon, is that to eq. the lower limit of a sub requires greater power. Greater power creates greater heat. Greater heat alters T/S param.s. And as a natural conclusion, greater heat also increases distortion - significantly. Along with this power issue is also the effect of the additional back emf that is being placed on the field integrity of the magnet, and also the quality of the signal. (..and yes, the Reference version might have an "edge" here because of its design - but why create a problem to fix?)

..as if that weren't enough..

Second - we must also consider the limitations of the "eq" system. :E This one I'm sure you didn't consider (..and its not exactly "apparent" either ) To my knowledge the Behringer has its lower eq. limit at 20 Hz. Now I don't know if thats a "centered" freq. or not, (..i.e. discreet like I suspect it is). Nor do I know if the user can "get around" this potential problem by "working over" the crossover's low pass abilities and eq. settings.. Even if it is a problem, but they can still "get around it" technically, then there is the issue of processing power and its limit on the filter and actually being able to do so. In any event - the thought in my mind is that this *could* be a serious problem (in addition to all the problems above), and should be "factored" in as a potential limitation for boosting the low end of a sub..

BTW, while it is an interesting discussion, I'm not sure its helping Clark any - and thats the point of the thread.

So I guess I'll add this for Clark's sake:

There are a LOT of good designs out there, and what I have suggested is in my mind *one* solution that gives you more extension with less distortion for most playback levels. Also, you don't need really low extension for most movies (..for you, the design I have proposed may be moot). So don't get "mired down" with the details here, and most certainly choose what you think will work best for you. :T

[cjd]

First off - we aren't looking for max displacement. That path leads to distortion.

Low frequency output at low distortion is largely a function of how hard you have to drive your subs to achieve a certain SPL (or rather, how NOT hard). SPL is a function of displacement... You want lower distortion at 120dB at 10Hz, add more drivers or otherwise find ways to move more air more easily.

EQ does require power, but heat shouldn't be a problem? If you're pushing an IB hard enough to cause heat problems, you don't have enough drivers... excursion is THE limiting factor. Not sure, but I have a pair of the Dayton IB15's you love so much... and I drive them to their excursion limits on very little power at 16Hz... They can't handle enough power to heat up.

C

[Dennis H]

Scott, you've told me a lot of things I didn't consider. 'Nuff said that I have considered them all.

I'll just stick to a couple of points. The Behringers do indeed work below 20Hz with an F3 of about 5Hz. Heating is not an issue with an IB because there is no box giving you back pressure so the driver can be driven to Xmax at 20Hz with very little power.

The Dayton IB driver is made by Eminence and (along with the Dayton DVC line) is a klone of the original Adire Shiva/Tempest line. While I haven't seen any published tests comparing the 15" versions, Monte Kay has done lots of tests of the 12" versions using the Linkwitz 3-tone method. The 12" Dayton RS and TC2/TC1000 drivers have lower distortion than the 12" Shiva. They simply have better motors. The old Eminence designs were good in their day, and still not too shabby, but there are better choices available now.

http://www.mfk-projects.com/woofers.htm

[Dennis H]

Just one more comment about driver Q, EQ and power requirements. It is often incorrectly said that you have to 'boost the bass' of a low-Q driver in an IB or OB to get flat response so the driver needs more power from the amp. Really it's the opposite, you have to cut the highs of a low-Q driver to get the response flat and the driver needs less power overall.

Let's take two identical drivers with equal Qms. The way you change Qes and the resulting Qts is to change motor strength Bl, either with magnet strength or the amount of wire in the gap. The driver with the stronger motor will have the lower Qes. Both drivers will require about the same power at Fs where the mechanical properties dominate. But the one with the stronger motor, and the lower Qes, will require less power at higher frequencies where the electrical properties dominate.

SL has discussed this at length when people unfairly criticized his choice of the low-Q Peerless XLS along with hefty EQ. They seem to think that making the motor weaker and boosting Qes would somehow require less power.

[cjd]

Dennis, it's really a wash, but yes - generally levels are cut above with EQ, and overall gain adjusted to suit, vs. trying to increase gain below. Same net result. Same total power handling capability in the end.

Regardless, total SPL is 100% excursion limited. Powering to excursion maximums in an IB is not difficult at all, often pathetically low levels of power.

C

[---k---]

Scott, I would be interest to see new threed with some pictures of your system/room. You sound like you have a lot of experance. It would be interesting to see.

[Brian Bunge]

Chris,

Sent you a pm.

[Dennis H]

Regardless, total SPL is 100% excursion limited. Powering to excursion maximums in an IB is not difficult at all, often pathetically low levels of power.

Yup. And the thing is a low Qes driver and a high Qes driver will require about the same (low) power to reach Xmax at Fs assuming they have the same mechanical properties.

[Scottg]

Low frequency output at low distortion is largely a function of how hard you have to drive your subs to achieve a certain SPL (or rather, how NOT hard). SPL is a function of displacement... You want lower distortion at 120dB at 10Hz, add more drivers or otherwise find ways to move more air more easily.

EQ does require power, but heat shouldn't be a problem? If you're pushing an IB hard enough to cause heat problems, you don't have enough drivers... excursion is THE limiting factor. Not sure, but I have a pair of the Dayton IB15's you love so much... and I drive them to their excursion limits on very little power at 16Hz... They can't handle enough power to heat up.

C

Again this is way beyond the bounds of Clark's thread - so this is the last time I'll reply on this subject (..lest a complete hijacking ensue).

Anyway..

In my vernacular "how hard you drive your subs" specifically relates to sinking current to the driver (i.e. power input levels). And yes, heating is a serious problem, but I was talking about power input level and resulting VC heating issues as it SPECIFICALLY relates to eq'ing the low end of a driver that does not have T/S parameters conducive to an IB (and properly loaded of course). (..in other words I wasn't talking about the Dayton IB at all on the subject of heating).

You are absolutely correct though that excursion is the nemesis of a good IB. At the same time it is also a problem (IN ANY DESIGN) when it comes to distortion levels. In fact anything beyond about 8 mms of excursion, (even for a very well designed large excursion driver), is asking for problems. So of course you are correct that you can limit this problem by using multiple drivers. Indeed I spec.ed 4 drivers for this design! Even more importantly I spec.ed the drivers be loaded in the corners of the room, which provides free "gain" at the lowest freq.s without an increase in excursion.

Also note that I do not own the Dayton IB drivers nor do I "like them so much". I have however seen distortion figures (broadband) for several samples driven at varying power levels - and was marginally impressed when looking at the driver's resonance (and near resonance) behavior, (..especially when compared to most other drivers). Why I'm recommending them is that they are pretty good at the lowest freq.s in the right design.

Dennis:

Thats good to know about the Behringer.. I had only the manual to go on at it only lists 20 Hz to 20 kHz. I have their older digital eq. and thought that it had that limitation (..but I haven't played with it in a while so I really couldn't say).

I am aware of the Dayton IB's history.. What I haven't seen is the distortion levels at varying input levels of the Dayton Reference at and near its resonance. It DOES have a better motor.. but how the total driver is DESIGNED *might* mean that it has higher distortion at an near its resonance - but again, I honestly don't know.. I DO know something about design though.. and the higher compliance of the IB (in a design with little compression), almost always has less distortion at an near its resonance because of its "softer" spider. The Reference on the other hand has a much lower compliance figure and as such is "tighter" and will likely become much less linear near its resonance. (i.e. its acting like a tightly wound spring.. near the driver's resonance the "tighter the spring", the more violent and non-linear the reaction when it effectively becomes "un-sprung".)

--k--:

Sorry, no pictures (..and my cobbled together fullrange/supertweeter/dipole midbass/monopole subs are F-UGLY.. :B )

[Dennis H]

In case anyone thinks I'm knocking the IB/DVC drivers, I'm a HUGE fan of PaulW's 18 driver 15" DVC IB. HTGuide motto:

If some is good
more is better and
too much is barely enough.

http://www.geocities.com/pnwright3/Gemini_subs.html

[Scottg]

In case anyone thinks I'm knocking the IB/DVC drivers, I'm a HUGE fan of PaulW's 18 driver 15" DVC IB. HTGuide motto:

If some is good
more is better and
too much is barely enough.

http://www.geocities.com/pnwright3/Gemini_subs.html

..and the interesting thing is, as impressive as that sub design is - it still isn't nearly as impressive as his DIY ribbon linesource mid/tweet!