full range box size when using a subwoofer

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So many choices, each one changes what the other best choice might be!
I was planning on using either a AN super 10 or Fostex unit, but I wanted to use an active subwoofer with it.
If I use a subwoofer, and the AN super 10, do I need to worry about which one of "their boxes" to use (one port, two ports, as suggested by scottmoose- lengthening the port(s) on the double port, or is this a non issue
Also If I am using a sub, and instead of using a BSC, couldnt I tune the box a little higher to raise the output of the upper bass, lower mids?
I'd rather get the highest sensitivity speaker I can and not lose any more than I have to b/c I will be running them with a low powered triode
Thanks,
Paul
 
I`m not the most helpful guy to give an answer, but if you read customer comments on CSA website, you`ll find the most enthusiatic one is for a pair of AN 10 openbaffle crossed to active sub, you can probably ask david dicks about that one too.

i was thinking of doing it myself with my pair of super 8, but have no time these days...

btw if one has an appropriate room, and doesn`t plan to take bass out of the fullrange units, what advantage can come from building boxes for them?? i`m asking this because i never heard a serious horn design, would one miss something going OB? something that can`t be done from an appropriate sub, maybe horn loaded one?
 
Unless I've missed something obvious, he's not asking for one Horst, or for any self-promotion: he's simply saying he hasn't heard a serious example of the breed, and asking if there are any reasons to run monopole rather than dipole if the wide-band unit is not expected to handle bass frequencies.

Anyway, it rather depends. Not everybody likes the sound dipoles provide, and even when crossing to bass units you still have to be a bit careful. Baffles are the least mechanically efficient way of running a driver, and most FR units don't have a whole load of linear excursion to play with. If you need fairly high SPLs, you'll likely need to hand over to supporting drivers at a higher frequency than a simple subwoofer can be / should be run to keep distortion within acceptable boundaries, especially for heavier material (orchestral, prog rock etc).

If I use a subwoofer, and the AN super 10, do I need to worry about which one of "their boxes" to use (one port, two ports, as suggested by scottmoose- lengthening the port(s) on the double port, or is this a non issue?

Don't go bringing me into this! At least, not without a strict context... 😉

FWIW, as a personal choice, I'd probably look at going with an AN10 or FE206E, sealed, and cross to 15in HE woofers either at 200Hz or 500Hz depending on where your priorities lie, at least 2nd order. Assuming that's a little OTT for you, then I'd probably end up with an AN10 or FE207E in a BR, and support with (preferably) twin subs. That way you won't need an especially low tuning for the main units, which is all to the good.
 
Scottmoose said:
Out of interest, which box were they in -2.8?

Yes. John just brought out his AN10 & AN12 for measure TSP. Here is the modeled response using measured parameters of the AN2.8 cab with AN10 with 6" port (2 3" ports have a less dramatic bump). I sent John home with a length of 6" PVC pipe. I suggested extending the port to 10 1/2".

dave
 

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planet10 said:
The impedance curves were revealing... that ripple train has to be quite audible... they could explain the need i felt for a tweeter... it could well be that the top end is there but very confused.

dave


As I recall the whizzer cone material looked rather thick, and the phase plug a bit short ?
 
Ha! That coincides almost exactly what I've been predicting for the past year or so, with a ruddy great peak at Fb. I don't have the exact dimensions for the 2.8 box, but this is what MathCAD predicts, with the dimensions fudged from the site, a 6in vent, & the claimed driver specs...

Welcome to the house of fun. 🙄
 

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Scottmoose said:
Ha! That coincides almost exactly what I've been predicting for the past year or so, with a ruddy great peak at Fb. I don't have the exact dimensions for the 2.8 box, but this is what MathCAD predicts, with the dimensions fudged from the site, a 6in vent, & the claimed driver specs...

Welcome to the house of fun. 🙄

Here is what we measured today....

dave
 

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Thanks Dave. 🙂

Hmm. Well, that's just resoundingly confirmed my dark suspicions about the manufacturer's claimed driver parameters.

FWIW, again, fudging the cabinet dimensions (they'll be close enough), 3 FR plots for a 6in diameter vent: top = 0.75in long, middle 6in long, lower 10.25in long. The 6in diameter vent is a bit OTT IMO; certainly at anything less than a 6in length. Ferret owners best exercise extreme caution... 😀
 

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Scott-
Those modelled curves don't look much like the ones I saw on Dave's screen yesterday. The problems with the shorter vent tubes were more dramatic in Dave's models.
It looks like different software can make a big difference, so best to leave the final judgment to real ears!
BTW, my drivers had 100+ hours on them, so that may account for some of the differences from the published numbers at commonsenseaudio.

John
 
could you explain why a port can give benefit? isn`t the 2.8 a quarter wave design and not a bass reflex cabinet?

really the 2.8 would only go that low? i`m going to build them for the super 8 when i got the time, but then from my actual really unbalanced spiral-horn design i heard some good 35hz tone... and it`s completly a wrong design, since it was for the 206, as scott helped me figure out on another thread...

dave why don`t you give a try to a spiral-horn with a little fostex unit? so we can have a trustworthy comparison of the design purpose?
 
VictoriaGuy said:
Those modelled curves don't look much like the ones I saw on Dave's screen yesterday. The problems with the shorter vent tubes were more dramatic in Dave's models.

The last curve is very close to what i generated. My 3/4" curve looked to have a bigger bump, i'll have to do an overlay to see if it is just a graph scale artifact.

dave
 
Edit -you beat me to it Dave. Had a bit of a problem, halfway through writing my post, with a lump of Aberdeen Angus steak getting caught in my throat. 😱 Not recommended, I assure you.

VictoriaGuy said:
Scott-
Those modelled curves don't look much like the ones I saw on Dave's screen yesterday. The problems with the shorter vent tubes were more dramatic in Dave's models.


I dunno -the short-vent graph I did above are pretty similar to the one Dave posted above, with a ~ +5 - 6db lift at Fb. I was feeling charitable & damped the box quite heavily, plus, as I mentioned, I don't know the exact dimensions of the cab itself, so I fudged it slightly. ~close enough to give a good idea of the general trend though.

BTW, my drivers had 100+ hours on them, so that may account for some of the differences from the published numbers at commonsenseaudio.

No chance. I'm not sure which units you have, the Super, or Cast Frame models, but it doesn't really matter; 100 hours of use isn't going to dramatically reduce the total damping / motor power and Vas, or add ~ 20Hz to their respective resonant frequencies. The Super 12 measurements also corrolate quite well with some others I've seen, so my conclusion is that Audio Nirvana's published specs are as ficticious as those from most other FR driver manufacturers.
 
human.bin said:
could you explain why a port can give benefit? isn`t the 2.8 a quarter wave design and not a bass reflex cabinet?

really the 2.8 would only go that low? i`m going to build them for the super 8 when i got the time, but then from my actual really unbalanced spiral-horn design i heard some good 35hz tone... and it`s completly a wrong design, since it was for the 206, as scott helped me figure out on another thread...

dave why don`t you give a try to a spiral-horn with a little fostex unit? so we can have a trustworthy comparison of the design purpose?

It's a bit of both. Most supposed bass reflex cabinets are in fact hybrids. Technically, a BR requires an even air-particle density within the enclosure and no standing waves at all, and very few cabinets meet that criteria. In this case it's a badly designed BR / MLTL.

Anyway, yes, the 2.8 with the short vent & AN10 really will only go that low -it's just basic physics / box tuning, so expect a cut-off around 50Hz.
 
To the OP's point

If you're going to assume stereo subs, I'd go with a small sealed box. You'll lose something in transient response near box cut-off, but if you tune it to where you want to bring the subs in, you can save yourself the HPF, and even potentially mitigate baffle step with the sealed box bump.
 
Scottmoose said:
That's certainly one way, although I'd be looking at stereo woofers, rather than subs per se. Most sub drivers can't get up high enough, & don't sound as good. Ouch. Controvertial perhaps, but I know I'm not alone in thinking that. YMMV as ever of course.


In my limited experience with FR, it seems the last thing one wants is a sub that goes boom. Dayton has the reference series subs that are musical, but I would consider going with something as small as a 10 inch woofer. Dayton has a continuum of woofers to subs, with some models clearly borderline.
I find it's a bit tricky with dayton woofers to determine the highest xover that's going to be smooth and musical.
I'm hoping we get more extended range designs, rather than FR. But perhaps I'm wrong in assuming there's an musical advantage in designing extended range instead of FR.
 
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