Small Full Range Driver for HT?

rebelvox

Member
2016-01-25 4:48 am
Hi All:

Have been lurking on this site for some time, but this is my first post. Could use some help on a possible home theater design using full rangers.

I am in the process of a home remodel. I would like to convert a medium sized room (approximately 15 x 15 feet) into a home theater. I am contemplating some DIY full range drivers in boxes designed to fit between wall studs.

I'd like to use either Fostex FE83en or Alpair 5, both of which are 3-inch drivers. Here are my questions:

1. Will either of these drivers work? Or are they too small?

2. Will off-axis performance of single drivers be an issue since each speaker will be flush with the walls and can't be towed in like regular box speakers?

3. I assume the boxes have to be sealed since they will be covered by drywall, except for the driver of course. Will these drivers work in a sealed box? If so, how do you determine the volume? I have not seen any sealed box options after searching online.

I will be using a sub. So the the lack of bass from the fronts and surrounds is not an issue I believe.

Appreciate any feedback or guidance from the experts on this forum can offer.

Thanks.

Jim
 
The goal with HT is to try to hit 80 Hz before XO to the woofers. Newer HT receivers allow more flexibility but higher might start to get noticable as you move from 3 channels to mono.

The A5.2 is a very good driver, but it is hard pressed to get near even the higher number (see sims) sealed -- it will get there vented. The FE83 doesn't do anywhere near as well.

Dispersion is pretty good, i wouldn't worry too much about that.

You might consider the slightly larger A6.2s, the paper reaching the lowest, could be XOed at ~105 Hz.

Whether they will do depends alot on how loud you want to play.

dave
 

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Greets!

1, 2) For stereo or any audio app and especially HT, driver size is a function of desired peak SPL and coverage angle at the listening positions [LP] and 3" drivers are going to 'spray' the room over a very wide BW from approximately ~SoS/driver effective diameter or ~5740 Hz on down, so ideally requires either sitting fairly close and/or treating the room to keep early reflections from ruining the sound-field the producer desired and/or you desire a modest peak SPL due to it being in an apartment/whatver and/or focus its output with a waveguide [WG]: https://www.google.com/search?q=hom...KEwiCpYri68bKAhXjnIMKHT2IAU4Q_AUIBigB#imgrc=_

So, what's the floor plan you're considering and how loud at the LP you desire? 75-81 dB avg./95-101 dB peak per channel is what most folks choose, with the avid HT enthusiasts opting for the 85 dB/105 dB cinema reference.

Note that the LFE channel ideally is designed for an additional 10 dB and ideally is much more if all channels are set to 'small', routing all the bass from them to the LFE which can add up to 21+ dB total for a 5.1 system IIRC and of course much more for more channels.

Few folks do this though due to the generally high cost and peak noise levels outside the room and into neighbor's homes, etc., not to mention can do some serious structural damage with the extremely low infra/sub-bass of an increasingly number of movies if the system is capable of reproducing it at the correct level referenced to the mains.

3) They can be vented, just need to be some form of vented [ML] TL alignment or blocked off between the studs as required to create a tightly sealed cab for the vent to work properly and of course can be designed using freeware programs and the driver's T/S specs.

GM
 
I assume you don't desire THX spec'd SPL levels for HT? If so, no standard full range driver (like Fostex, MA, Tang Band, Vifa, Scanspeak, Peerless, etc) can do it except for the pro audio 5in fullrange/mids, serving as full range. For example the PRV 5MR450NDY or the Galaxy SN5N-8 to hit 105dB at the listening position. Other way is a pro audio coaxial like a Beta 8cx in a 0.25 cu ft. box with a vent will hit 100Hz and be capable of 123dB with a HPF.
 

perceval

Member
2014-02-21 8:17 am
Taiwan
I am a HT buff (amongst other things) and unless your room is something like 5x5x5, a couple of 3inchers will not do.

HT is about impact, these says, so how would a couple of sealed 3inchers be up to he task?

Even drama/romantic/comedy have sizeable soundtracks.

Action? Sci-fi? even bigger and wider.

My 8" full-rangers are barely up to the task.
Best sound I ever had was with my line arrays.

If there is one place where bigger is better, it's HT.

Check out a few threads at Home Theater Forum - Home Theater Systems - HomeTheaterShack

I have a projector for video (some of them cheaper than a TV these days), and you need a sound that is just as big.

Don't skimp on that important part of the enjoyment either.
 
I am a HT buff (amongst other things) and unless your room is something like 5x5x5, a couple of 3inchers will not do.

HT is about impact, these says, so how would a couple of sealed 3inchers be up to he task?

Even drama/romantic/comedy have sizeable soundtracks.

Action? Sci-fi? even bigger and wider.

Depends on how loud he wants to play…

dave
 
I had run a 5.1 system with A7s quite happily for a couple of years, crossed over at 100 to the LFE channel.

Out of boredom and desire to test drive something else in the same room (340ft^2), I supersized that to A10P a while back.



A6 metals continue to serve adequately as rear surrounds, and I'm now running CHP70s in front height effect - was rather surprised how much more that opened things up than the front width .

FE83 is a cute little driver, and the new A5.2 is quite nice as well, but I think either would be hopelessly underrated for this application.

Bigger might be better for some, but count me as one of those not looking to crack the plaster by reaching THX levels at 20Hz at home, so frankly even the smaller system noted above was quite satisfactory. When I want the full body immersion of 20,000 or whatever watts of digital surround sound and laser 3D, I'll go to the cinema - so far that's happened only about 4 times since installing my little TV system. I must admit that the latest Star Wars, and the Martian in 3D were each a helluva ride in their own quite different ways - Interstellar was a bit of a mushroom trip, and Prometheus was 2hrs (felt like twice that long) that I'll never get back.
 

pnix

Member
2014-10-16 5:09 pm
Hi All:

Have been lurking on this site for some time, but this is my first post. Could use some help on a possible home theater design using full rangers.

I am in the process of a home remodel. I would like to convert a medium sized room (approximately 15 x 15 feet) into a home theater. I am contemplating some DIY full range drivers in boxes designed to fit between wall studs.

I'd like to use either Fostex FE83en or Alpair 5, both of which are 3-inch drivers. Here are my questions:

1. Will either of these drivers work? Or are they too small?

2. Will off-axis performance of single drivers be an issue since each speaker will be flush with the walls and can't be towed in like regular box speakers?

3. I assume the boxes have to be sealed since they will be covered by drywall, except for the driver of course. Will these drivers work in a sealed box? If so, how do you determine the volume? I have not seen any sealed box options after searching online.

I will be using a sub. So the the lack of bass from the fronts and surrounds is not an issue I believe.

Appreciate any feedback or guidance from the experts on this forum can offer.

Thanks.

Jim

Get a 8" full range driver. Everything else is just a toy and will produce massive amounts of distortion in a home theater application where you want the satellites to go down to about 80Hz. Reduced distortion would require a 2-way. Be aware that a 8" has a pretty narrow beam width, i.e. it will work for 1-2 seats max. On the other hand you get controlled directivity that is otherwise hard to come by.
A single 8" has the advantage that you can keep electronics at a minimum. Like any full range driver an 8" needs to be equalized though. So get prepared to do your own acoustical measurements (Google UMIK-1 and REW). The Seas FA22RCZ is quite good and has a decent listening window. I've seen promising measurements from a Gradient AX 8 but haven't measured one myself yet. Should have it in about a week though.
 
I am a HT buff (amongst other things)

Me too, big time, far more than just music listening, so it's cinema reference for me and a lot lower than the THX 20 Hz LFE lower limit as well as up to a lot louder for certain musical concert BDs, etc., but so many folks live somewhere [or with someone] that there's no way they can listen at anywhere near even the 81 dB TV movie reference and one major reason why those horrible performing little HTiB systems are so popular.

GM
 

rebelvox

Member
2016-01-25 4:48 am
Thank you all for responding. It would seem, based on the replies, that my grand plan would be less than ideal. I am not really interested in THX spec'd SPL levels per se, but I do what the system to have enough impact to be enjoyable. So I will checking out other options, including 5-8 drivers, box speakers, or a combination of both.
 

pnix

Member
2014-10-16 5:09 pm
Thank you all for responding. It would seem, based on the replies, that my grand plan would be less than ideal. I am not really interested in THX spec'd SPL levels per se, but I do what the system to have enough impact to be enjoyable. So I will checking out other options, including 5-8 drivers, box speakers, or a combination of both.

Good decision. Also think about on-wall speakers as this will increase the output a bit.

Remember, movie level is 105dB max. If you're sitting about 7ft away SPL loss over distance and gain due to reflections are roughly the same. Most people listen 10-15dB below reference at home so you'll end up with 90-95dB SPL requirement from the driver. Very hard to do below 200Hz without massive distortion.
 

pnix

Member
2014-10-16 5:09 pm
In a HT app, it's not supposed to ~null out as a major design criteria is to minimize reflections as much as practical.

GM

Quite true but I didn't want to destroy the OP's hopes in an early stage. A 8" can work quite well when done right. One simply needs to get rid of all that esoteric nonsense that dominates most full range speaker discussions. Speaker building is an engineering task not magic.
 
'You're preaching to the choir', so why would it? I mean it's critical to his driver/speaker choices Vs any 'mandatory' WAF/whatever trade-offs, which since we know basically nothing about these or any room or desired overall in room layout details and loudest it may need to play on occasion for a demo/whatever; then even suggesting, much less 'telling', him to buy an 8" 'FR' driver seems premature at best IME, i.e. "More data, less wank" - Zilch

GM
 
Speaker building is an engineering task not magic.

While very true on the surface, even the best speakers are not very good, and many compromises have to be made. The art of speaker design comes in balancing the compromises so that the resulting speaker suits the needs of the user.

Here we know some of the compromises. Medium size room, doesn't need to play very loud, and he wants to build them into the wall preferably in a sealed box (but may have to compromise to get the bass extension needed to reach his woofers).

While you find an 8" FR a minimum size, i have yet to find one i could live with long term. Too much compromise in the mid/top, and lack of dispersion (a generalization). Modified SEAS FA22 or Visaton B200 are my favorite 8s but both need boxes too large to fit into the wall (unless there is a room on the other side you can poach some space from) so they are out.

dave
 
Purely from a minimum SPL level and sufficient diameter to have 150Hz "chest impact" and coaxial since the horn gives better directivity than an 8in fullrange. But you are right in that we don't really know what the OP wants when he says he wants HT speakers. HT for me, means an impactful experience like you get when you sit in a THX certified theatre. Otherwise just call it 5.1 or 7.1 surround sound for TV - not HT.
 
I think we need to be careful about confusing / scaring Jim off with our incessant squabbling / pedantry over this. There are of course "industry standards" of SPLs, frequency response, number of channels, placement, yada yada - any combination of which for many folks may well be overruled by domestic or budgetary constraints.

The room that he described is not particularly large - i.e. 225ft^2? - and as well as they can be made to work for a dedicated HT system with a small listening window, not all rooms can readily accommodate - nor are structural renovations always available for in- or on-wall installations of the larger speakers that are being recommended as "ideal" or "minimum requirements". So for many folks that means floorstanders or stand mounted "mini-monitor" types.

FWIW, over the past decade or so, I've hobbled together several multi-channel video systems with moderate sized FR speakers at which the mavens of "serious HT" would laugh, but it hasn't kept our family from enjoying any of them.

That said, even with full support of subs crossed over much higher than the "THX standard 80Hz" - which I have found to work well, the initial 2 3" drivers mentioned would be hard pressed to serve well in this application.
 
That said, even with full support of subs crossed over much higher than the "THX standard 80Hz" - which I have found to work well, the initial 2 3" drivers mentioned would be hard pressed to serve well in this application.

Yet would very likely perform considerably better than a typical soundbar.

dave