Full range on wall for home theater?

Audibility of HF narrow band dips

Good point XRK,

Most high frequency narrow band dips are not too much of a problem as they are not easy to detect by ear.

Also if the dip is even across all axis ie on axis as well as off axis it can be compensated with some gentle Eq.
But avoid sharp Eq compensation unless you are using a very good studio grade DSP which takes care of the phase errors most Eq's introduce when using sharp filters.

Cheers
Derek.
 
The driver arrived. I had also ordered a Seas FA22RCZ. Here're some measurements of each driver in a 48l test box. Impulse response window is 4ms.

The Dayton looks great. The only flaw seems to be the dip at 11.5kHz. Any thoughts?..........

Thanks measurement in 0,5-5kHz Seas look fine, but maybe the whizzer HF imprint is there too.

..........Anybody measured the Alpair 12P, Betsy K, Audio Nirvana?

Not personally but if you like to see only on axis plot here two links................http://www.diyaudio.com/forums/markaudio/234406-m12-a12-2.html#post3466676...............http://www.diyaudio.com/forums/markaudio/239793-comparing-three-different-alpairs.html#post3573319.
 
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Thanks measurement in 0,5-5kHz Seas look fine, but maybe the whizzer HF imprint is there too.

You're welcome. By the way, the drivers were measured at a distance of 1m.


Thanks. For evaluating the driver the measurements should show the free field response. Other than that, measuring just a single axis is rather meaningless. Earl Geddes wrote up his approach lately in this paper http://gedlee.azurewebsites.net/downloads/On Measureing loudspeakers.pdf

The second set looks like it is not gated in any way and therefore contains a lot of room. Not much can be derived from the measurements regarding the raw driver performance.

The first set shows a rather substantial difference between the manufacturer data and the data by Bob Brines. Maybe the mic was too far away and the data still contains a substantial amount of reflections or the driver has some serious issues with resonances the manufacturer data doesn't show.
 
Yeah, narrow dips like that in the top octave will not be audible. However, that rise at ~3500hz will be. However, it should be easy to attenuate with EQ. I suggest considering some light cone treatment as well.

Yes, the driver needs LOTS of EQ but that's easy to do these days. I rather like to have a driver with slowly changing but larger magnitude response variations than a rather flat looking driver with lots of small resonances that might even change with angle.
 
Hi!

Sorry for digging up an old thread, but this design seems to be exactly what I was looking for. ;) Some questions remain though:
Use with a second order -12dB/oct high pass filter at 120Hz to prevent cone over excursion.
[...]
And by the way, if you make the vent 4 in long and remove the HPF, you can use this as a fullrange speaker but at lower SPL's and get some pretty good bass extension to 45Hz:
Is a variant between those possible, e.g. down to 80 Hz?

How could one make the vent 4 in long while the depth of the enclosure is only 2.75?

The frequency response plot is amazingly flat. Has anyone actually build these and measured? Are the Alpairs really this good?

Thanks!
 
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Hi!

Sorry for digging up an old thread, but this design seems to be exactly what I was looking for. ;) Some questions remain though:

Is a variant between those possible, e.g. down to 80 Hz?

How could one make the vent 4 in long while the depth of the enclosure is only 2.75?

The frequency response plot is amazingly flat. Has anyone actually build these and measured? Are the Alpairs really this good?

Thanks!

You can have a BR vent going out the side as I have shown in the drawing. I have not built this yet but you can probably be sure that the sim is good as it is a MLTL that I have pretty good confidence in. The A7.3 has lots of bass capability as it has a large xmax. It may be a rather fragile driver though so be careful not to drive it past xmax. Another option is to use a more durable proaudio driver like the Dayton PA130-8. Less xmax (2mm) but more sensitive so gets you there too. Would need to recalculate the MLTL dimensions though.
 
You can have a BR vent going out the side as I have shown in the drawing.
Sorry, I don't exactly know which drawing you are referring to – are there any others than in posting #6?

The A7.3 has lots of bass capability as it has a large xmax. It may be a rather fragile driver though so be careful not to drive it past xmax. Another option is to use a more durable proaudio driver like the Dayton PA130-8.
I'm sure the A7.3 would do the job nicely in my living room. ;) I was just wondering if there is a variant possible which would work fine with a -12dB HP at 80Hz instead of 120Hz.
 
Having lots of experience with the A7.3....

Yes, you can cross 2nd order at 80Hz, but not with much SPL. 4th order would be better. Without reading back five pages, I presume that you are doing a 2.1 setup, i.e., a single sub. This is always problematic with small mid-tweets. Speaker localization can be a problem above 100Hz. Corner mounting the sub helps, but brings up other problems. Always a trade-off.

I find the A7.3 sounds best if crossed above 150Hz. I am currently using 300Hz, but that is with collocated stereo subs.

If you don't already have the drivers and can stand the cabinet size, I highly recommend go in up to the A10.3 It can much more easily stand an 80Hz cross.

Bob
 
Yes, you can cross 2nd order at 80Hz, but not with much SPL. 4th order would be better.
My AVR only does 2nd order (so do many AVRs, AFAIK). It is expected that sats have a 12 dB / oct rolloff themselves, so together with the 12 dB electrical HP this should sum up to 24 dB / oct.

Without reading back five pages, I presume that you are doing a 2.1 setup, i.e., a single sub.
I just jumped into this thread because I find the design intriguing, I am actually looking for surround speakers for my 5.1 system. But yes, there is only a single sub for now.

If you don't already have the drivers and can stand the cabinet size, I highly recommend go in up to the A10.3 It can much more easily stand an 80Hz cross.
I bought nothing so far, I'm just evaluating the possibilities. ;) Curious, the A10.3 is even a little bit cheaper (we are talking about the 'Alpair 10M A Generation 3', don't we?). While I wouldn't mind it, I assume this would need a different enclosure / MLTL design.

By the way, is there a technical difference between the 'grey' and 'gold' types, or is it really just the color?
 
Why do you have to XO so low?
Actually I don't have to, it would just be nice. First because it would comply with the reference design, second it would fit to my main speaker settings, which are crossed at 80Hz.

If you have a sub, 100Hz fine and pretty non directional.
100Hz would work with the design meant for 120Hz? I was quite impressed by the second design which goes down all the way to 45Hz, even if at lower SPL, that's why I was curious if a version between 120Hz HPF and no HPF is thinkable – which would make it the perfect™ surround speaker. ;)
 
Second to everything on Bob's #51 above-
If you have the ability to run collocated woofers* with the 7.3 ( or even the 6.3 that doesn't get as much mention) crossed over in the 250 - 300 neighbourhood and a "real" sub below 100 or so, you can have a pretty decent system

Yes, I realize that makes it a multi-way, but it definitely works

* they don't need to be in the same box- within a wavelength of the XO should fine.

I quite like the very affordable Silver Flute 6 or 8" woofers for this type of application
 
If you have the ability to run collocated woofers* with the 7.3 ( or even the 6.3 that doesn't get as much mention) crossed over in the 250 - 300 neighbourhood and a "real" sub below 100 or so, you can have a pretty decent system

Yes, I realize that makes it a multi-way, but it definitely works
Forgive my ignorance, but I fail to see the advantage of such a set up over a simple 2-way speaker. It would require floor- and wall space, not to mention an active setup.

The most remarkable feature of xrk971's design (from my point of view) is being a single wall mount 'pizza box' with a single driver, so it doesn't occupy floor space and has no need for an internal XO.
 
Perhaps we're getting way too wrapped up in convoluted terminology? Bob's "7.3 with collocated woofers" is a 2-way - the chosen XO frequency/slopes and space available for enclosures are among factors that determine the simplicity of the implementation. They needn't be active, but component values for speaker level XO at the frequencies under discussion can get to be costly.

I think several of us are saying the same thing in a roundabout fashion - that any small fullrange driver will have some limitations in compact wall mountable enclosures, most particularly attainable SPL and extension into the bottom octave for both music and the generally even heavier duty cycle of movie sound effects.

XRK's pizza box certainly looks like a clever design, and if you have the wall space in exactly the right locations to suit the listening area (not always as easy as it sounds!) by all means. It is worth noting that as of the date of posting that design ( August 2014) he had not heard the 7.3 - several of us quite familiar with the driver might recommend a higher XO to LFE channel than given, and that 102dB with extension flat to at 80 might be optimistic - but then I've not built that particular enclosure, so who knows?

I'd personally be inclined to avoid very shallow enclosures (2 1/2" internal), certainly with a driver such as the Alpairs under consideration.

Reading "home theatre", I always assume dedicated LFE sub(s) - below 100 or so

In the final analysis, a successful speaker system is a balance of compromises with which you can live - us experts here be damned :D.