VanJerry said:
I think they are both expert sims by expert designers, but one is 3.3 cubic feet, and the other is 16 cubic feet! That outweighs any (subtle) sonic differences in my mind!
Check out Scott's comment in post #128:
In other words, at loud volumes, if the FR has to produce the bass, it runs out of excursion and distorts. It just gets overtaxed. So you cross over and reduce the amount of energy (work) that the FR has to handle, to keep the FR sounding sweet.
(P.S. That's why, in my newbie opinion, you don't really need big drivers if you're going with helper woofers, or subs crossing over high).
If folded:
24"x 28" x 42.75"
Straight line :
24"x 14" x 85.5"
As has been noted already, the above TL is 16cu. ft. !
I thought we were talking about a cabinet that was pushing the size limit at 3.5 cu.ft.
Did I miss something ?
Scott's Aperiodic design could be easily built , and a simple method could be used to seal the Aperiodic venting to provide a Sealed/Stuffed version to compare to the Aperiodic sound .
It also has the benefit of being reasonably sized and a simple build.
Scott,
Perhaps some might find they need more than a 10"-12" driver to mate to a sub @ 80Hz , but considering his room size and some of the much smaller drivers people have suggested for use, I would venture a guess that most people (and VanJerry,based on his writings) would find a 10"-12" driver more than adequate .
There IS alot of bass energy at 80hz, or even 100hz for that matter. A small driver will be hard pressed to provide a real , full reproduction at that frequency , at any decent volume. A 10"-12" unit will have plenty of area to provide the visceral impact at those frequencies , especially in a small-medium room.
VanJerry, IMO go for the 12" AN with a 3 to 3.5 cu.ft. cabinet, perhaps Scott's exact build, with the optional sealing method . This WILL provide you the bass weight you want, excellent transient response , it will be pretty dang efficient (reduces amps workload and provides better headroom) , and will offer you an adjustable cabinet for comparison.
Simple and sweet.
Good luck. I'm done. You know what I think.
....................................Blake
24"x 28" x 42.75"
Straight line :
24"x 14" x 85.5"
As has been noted already, the above TL is 16cu. ft. !
I thought we were talking about a cabinet that was pushing the size limit at 3.5 cu.ft.
Did I miss something ?
Scott's Aperiodic design could be easily built , and a simple method could be used to seal the Aperiodic venting to provide a Sealed/Stuffed version to compare to the Aperiodic sound .
It also has the benefit of being reasonably sized and a simple build.
Scott,
Perhaps some might find they need more than a 10"-12" driver to mate to a sub @ 80Hz , but considering his room size and some of the much smaller drivers people have suggested for use, I would venture a guess that most people (and VanJerry,based on his writings) would find a 10"-12" driver more than adequate .
There IS alot of bass energy at 80hz, or even 100hz for that matter. A small driver will be hard pressed to provide a real , full reproduction at that frequency , at any decent volume. A 10"-12" unit will have plenty of area to provide the visceral impact at those frequencies , especially in a small-medium room.
VanJerry, IMO go for the 12" AN with a 3 to 3.5 cu.ft. cabinet, perhaps Scott's exact build, with the optional sealing method . This WILL provide you the bass weight you want, excellent transient response , it will be pretty dang efficient (reduces amps workload and provides better headroom) , and will offer you an adjustable cabinet for comparison.
Simple and sweet.
Good luck. I'm done. You know what I think.
....................................Blake
rjbond3rd said:
Wow 16 cu. ft. Yes, I cannot lay down that much space for the cause, or my wife would plant me in it. Uh... - that's not to say "wack" me - she's a garden designer.
Now I have an even better appreciation for the difficulty, beyond size, that my constraints placed on possible solutions. I mean I did say I wanted to play at lower volumes, didn't I? Well, at least I'm getting things better.
So, it's true, I still don't have any intention of ever going to THX or Dolby ref levels but who's to say how less loud will cause the FR to get overtaxed.
Hm... if I wanted to keep this single driver, I wonder which would let me go louder down low? It may not necessarily be the Cast 12". I mean, they're pretty close in Fs at 36.427 for the Cast 12" and 34.227 for the Cast 10" and have the same xmax and the exact same large magnet.
However on a physical level, as much as the 12 has more cone area and could move more air, that's more for the same size magnet to control.
Is there a way to use some TS parameters to see which is more likely to distort at larger SPL's down low? This suddenly becomes a very useful piece of the puzzle.
Subs crossing high need two due to localization etc (I'm one of those sensitive to it) - I've got the one. It's gets complicated but I thought of using a second amp (I have an all digital HK 50W 7.1 and an old stereo receiver) to bring up the full time helper woofer would be better than making the main FR driver undergo a high pass crossover. Maybe I could even somehow use the built in bass management of the 50W HK...
I'd only want to go louder for HT. And I bet I'd only want to go so loud I'd justify all the added complexity for action films ...and they only make so many a year.
-jerry
Nihilist said:
For both. Though just subtle levels for music - basically fill. Nothing raunchy.
The worry only came in for HT as I realized some types, like action films - even the lame ones - can be quite intense above the target 80Hz well up past 250Hz.
And it's not actually about localization above 80Hz because the Rythmik isn't really designed to be used much above 80. It's virtue is speed and accuracy flat from 80 down to the low teens since so many films actually have intentional content that low nowadays.
I could commit to Scott's design and just see if I can get away with it. The problem is whether I've left enough flexibility if it doesn't make it in certain HT situations such that I'm forced to add a modification that's even messier - defined as involving a greater and greater deviation from the the single driver ideal.
Nihilist said:
BTW, I don't know what to make of the earlier stuffed sealed vs stuffed aperiodic debate. I know the stuffed aperiodic is going to have some trade offs and the stuffed sealed would too. My needing things to be pretty small isn't a big help - I know your advice on sealed is to build the biggest cabinet my wife would allow. Seems I wouldn't have any problem sealed if I had a few more cu. ft. to play with but that's not likely to change unless I can make it shaped like Robert Redford.
If it were pretty much any other driver it wouldn't be a debate. I'd choose a lightly stuffed sealed if for no better reason than as a newbie it'd be the most idiot proof. (As was my first instinct. Especially due to the part about the idiot.)
-jerry
Of what? That ~3.3ft^3 box? Not exactly rocket science. It's a box, stuffed with the quantity of damping material I suggested with uniform density throughout. It has a vent in it, a la a BR, but the vent is also stuffed with damping material, in this case to the same density as the cabinet is. It'll just need a grill of some kind at either end to keep the stuffing in place.
GM's TL will be a better performing cabinet. The price is it's much larger. Personally, if I couldn't go large, then I wouldn't use these 12in drivers, & settle on something else, but if you want to, & you can't go to the size of that TL, then this is probably the best way to do it, and should satisfy those who want the AN12s but can't afford the space.
The AN 10in will go a whole lot lower & with more gain for a given box size, or thereabouts as you have other alignments (BR for example) open to you where you can't use them with the 12in. The cone area is less of course, but it's still quite substantial for an FR driver, so in a smaller room it would be my choice of the two, as I've said before.
GM's TL will be a better performing cabinet. The price is it's much larger. Personally, if I couldn't go large, then I wouldn't use these 12in drivers, & settle on something else, but if you want to, & you can't go to the size of that TL, then this is probably the best way to do it, and should satisfy those who want the AN12s but can't afford the space.
The AN 10in will go a whole lot lower & with more gain for a given box size, or thereabouts as you have other alignments (BR for example) open to you where you can't use them with the 12in. The cone area is less of course, but it's still quite substantial for an FR driver, so in a smaller room it would be my choice of the two, as I've said before.
Scottmoose said:
I'm sorry Scottmoose,
I wasn't familiar with the terms Zdriver and Zvent. The results I obtained by googling them indicated a TL. Most TL's I saw had various channels but you're right, they can also be nothing more than a box and not rocket science indeed. So as it turned out this plain box type is the one you calculated for me.
I imagine I've allowed my support for the AN12 pretty much tie your hands to help me to achieve what I claimed I came for: the best large single driver solution. I feel like I've been a poor student.
And only a few posts ago I wondered if the AN10 might not in fact provide better usable LF output. Thank you for confirming this. For my needs the AN Cast 10 is superior.
Well, that's it. I can't fight it any more. I'm enlightened. I get it. The 12 just isn't smart. It can work, but aside from being propped up by my fixation, it just isn't the best choice for my large FR. Not without relaxing the the size constraint. And if I can better avoid helper woofers and the lot...
I want good transients. And as you say, the 10 should open the door to other alignments but it's been hard for me to categorize what to do with it. I didn't think BR was known for transients. Consulting X factor (Fs/Qts = 134.7) and EBP (Fs/Qes = 124.5) indicates Horns. They've been used for theaters - not sure about HT. Especially in near-field. And I thought using a large driver demands large enclosures for Horns and BVR's.
Plugging the ANCast10 into a sealed calculator gave a range of quite small enclosures but I could find no values that would allow sufficient bass, no matter what the Qtc. Perhaps aperiodic might extend this a bit further? Only this time it wouldn't be about stuffing the box to force a smaller box. Hmm... could the 10 be a candidate for a single driver variation of the World Designs WD25T Only instead of a smaller aperiodic chamber inside a larger sealed box: a smaller aperiodic chamber inside a larger BR!
Without troubling with calculations, did any particular type of enclosure leap to mind at the time you judged the AN10 the canny choice?
-jerry
VanJerry said:
Greets!
You're welcome!
Well, I don't know about 'inspired', it's just my opinion as to what will best meet your originally stated performance goals with a specific driver EXCEPT FOR SIZE as I prefaced my suggestion, so presented as an example only (or for anyone less space/whatever challenged) to show how much you must pay for it in bulk. Truth be told, I 'pumped up' the 12's specs a bit to make it bigger than it technically needs to be to get the stuffing density down to what I consider the absolute max before it 'sucks' too much 'life' out of the driver's TL BW, i.e. WLs that 'fit' on its diaphragm between the surround and whizzer. Designed to the 12 CF's specs it's 'only' 12.348 ft^3 net, yet with an identical FR, but it takes a theoretical 1.783 lbs/ft^3 stuffing density to do it. This much and more is fine for a 'sub' thru mid-bass alignment, but not 'FR' IMO if not a very high Qts driver.
WRT your sub, I assume you mean use it to the HT's standard 80 Hz XO point, so sure, you can shrink it up by tuning it higher, but then it doesn't meet any of your other goals unless you can get an excellent FR and phase match to them in-room which will require considerable effort, especially if there's only one (some claim impossible with current technology). As I recommended in your other thread, you really need a high SQ headphone system to meet such stringent goals, though feel free to try anyway as many others before you have done.
WRT 'extra LF capacity go towards more damping', this makes no sense to me (at least at the moment) since as you raise the TL's Fp it must be made 'fatter' (increasingly larger CSA) with proportionately greater stuffing density due to it taking 'X' amount of acoustic resistance to smooth out the pipe's harmonics. Bottom line, the cab doesn't get proportionately smaller with increasing Fp as one would assume. This is just one of many things in audio design that's counter-intuitive.
All the above refers to TLs (i.e. a constant CSA pipe), but if we were to 'morph' (so to speak) Scott's semi-aperiodic stuffed vent BR into a reverse tapered 1/4 WL pipe (AKA TQP, TWQP, TQWT) and further accept a theoretically inaudible amount of ripple in the FR to keep the stuffing density to ~1 lb/ft^3 max (though historically folks tend to use < simmed), then we can reduce it to a ~1.8733 ft^3 adjustable floor loaded tower to help fine tune it in-room both to it and the sub system:
L = 47.75"
So = 100"^2 (the wider the baffle, the better to lower the baffle step)
SL = 50"^2 (open bottom terminus)
zdriver = 6"
You could of course work out a smaller version of Scott's damped BR based on the max stuffing density to get similar results, I just prefer to simplify wherever practical. Plus, there's just something about the perceived 'slam' of a big vent (even stuffed) that's a sizeable percentage of Sd Vs a small one.........
Since the roll off slope between F3, Fb (p) defines a TL's, BR's Qtp, the steeper it is the higher it is just like a sealed alignment's Qtc, but the XO will alter it (usually for the worst), ergo the price you pay in impulse response when shrinking cabs so much, though combined with the Rythmik's feedback control and the TL's well damped ~flat BW it will in theory seen compression horn 'fast' if you can dial it in 'close enough'.
AFA folding, you normally place the driver somewhere around seated ear height and choose a width/depth ratio, then fold it up as required. Note that if you use a 1.0:1.4142 bend width:depth ratio, then the divider board(s) winds up equidistant from all three walls in the bend. For other ratios you'll either need to scale it out as I do or use a CAD system to calc it.
GM
Attachments
rjbond3rd said:
The overall performance of the two will be anything but subtle if there's any signal of note below ~80 Hz. Regardless, mine assumes no sub system except possibly to fill in below ~35 Hz for action movies while I assume Scott's is based on a full time sub system XO'd higher, making it an apples n' oranges comparison if true.
Something usually lacking in these threads including this one is the effect of increasing directivity with increasing driver Sd, a big deal once you move away from small room/near-field apps if you can't control the room's interaction due to WAF/whatever and why folks like me prefer at least a 15" for < ~1200 Hz XOs and tandem or stacked pairs depending on room placement for < 500 Hz.
Harry Olson had a clue when he chose a 15" frame size for RCA's 'flagship' FR driver circa mid 1930's, arguably the best overall performing wide BW driver offered to date in its final LC-1A iteration when loaded into its 20 Hz corner BLH, needing only a super tweeter today to fill in the top ~half octave for those that can still hear above ~16 kHz. In today's US dollars it would sell for ~$2794/pr. + tax & delivery, so while not for 'everyman', it's still a relative bargain compared to the FR drivers available today that can potentially compete with it.
GM
GM said:
Thank you GM,
1.8733 is very very small for what this is doing, isn't it. Incredible.
But you have this at one extreme and the 12-16 cu.ft. at the other. The latter is obviously too large, but the former infers that perhaps one could have just a bit better performance if not constrained to be quite so astoundingly small? I feel a lil' bit like Goldilocks
Perhaps I needed to emphasize that at this point I am in no way attempting to "enjoy" the design aspect of DIY audio in and of itself. Though I have a long inclination for design in my history I am not at risk of suffering any loss if anyone here deprived me of any of the challenge of selecting the right approach - the satisfaction of determining the best dimension - or the thrill of discovering a better way to do something than has been done before. Though I understand all these things, the status of my health is actually rather lacking and I needed the easy lift I think I can get from some organic acoustic medicine. Hence the single driver; hence, for now, any concern over making it a slightly less risky and experimental effort - though of sufficient quality to make it as medicine. As I get stronger, which I very much anticipate, I can already tell I will want to leverage what I'm learning in this process presently to pursue an involving and rewarding hobby in the future.
So a few Questions:
I've begun to notice how there can be counterintuitively diminishing returns but if you had the size budget to go up to double that of the 1.87 cu.ft. above, could there be a differently dimensioned tapered TL for the AN Cast 12" that has some better combination of speed, coherence, detail and - yes - even HT slam? And restoring some of that lost impulse response?
And turning to the AN Cast 10". With the issue of cabinet size mostly removed, can you imagine an effective HT solution for it? My wife would like me to mention it'd be all right to even consider the unusual such as the Metronome worked out for the similar AN Super 10" which though tall strikes my wife's fancy, and which particularly for the 10 more than almost any other driver shows an impressive curve.
By the way, I'm beginning to acquire a sense of the apprehension of the difficulty of integrating a sub that you've been hinting at and so I can actually see advantage to a XO nearer to 60 than 80Hz as perhaps a valid trade off necessitating a lower volume ceiling including for HT.
Gratefully,
-jerry
VanJerry said:
Hi VanJerry, if that's the case, you should build a proven design! Just speaking honestly, I'm not sure why you are so keen on these two particular drivers, especially for home theater.
The whole single-driver midrange magic is for jazz, acoustic, chamber music, female vocal etc. Home theater is a different beast -- anyway, just one person's opinion! In no way do I mean to discourage anybody who is having fun at this, nor have I heard the drivers in question.
VanJerry said:
Hi rjbond3rd,
Hmm... I guess that can read cold... Let me explain.
I didn't wish to raise eyebrows on this DIY forum for saying that. For me efforts of design which I've undertaken in the past normally involved two aspects:
- Being energized and immersed in a new topic to understand;
- And the sense of adventure and achievement at meeting a challenge.
Unfortunately, with my present degree of wellness it'd be best I didn't take on additional challenge or adventure. And so I am instead enjoying the fact that I've found a topic that both energizes and immerses me. And I'm looking forward to being able to use what I'm learning here so that when I am feeling better I can personally attempt to enjoy the actual design aspect as well.
However, I find myself in need of something which hasn't yet been created. So I am moving to obtain it as best I can.
rjbond3rd said:
It may seem strange, but I still am not aware of any drivers particularly suited as single drivers for HT. So I'm going by what was established from the 70's and earlier hinting I should bet on the largest FR's I can afford. There are far better ones I'd prefer but nothing remotely this cheap. (Maybe I should have checked vintage.)
Otherwise, there's 2 parts to my answer for that:
1. As far as I know, there is no reliable design for single driver home theater, commercially or DIY. There are some quite expensive musical speakers using exotic FR drivers that would work very well I'm sure. But I'm far from affording those. Instead, when it comes to HT with it's demand for dynamics the affordable choices mostly involve bipole FR's and those using crossovers and multiple drivers - but these aren't single driver.
Then there are the single driver satellite and subwoofer systems. I'm sure these can be very pleasant. But here's my concern with them:
Film, and film sound, is incredibly important to me. I don't just mean as a consumer of action blockbusters or the like. I mean all film. From (well, yes, ironically...) the silents on up. And I mean it as a creator, as well as a consumer... Yes, I'm one of those closet screenwriter types. So for me film sound is every bit as I imagine people here feel about their music: Though quite many could manage to enjoy their music on a satellite/sub system, most would rather not rely on them to experience each emotional nuance. Or to experience the pace and the rhythm. I hear all this in film too.
Not to gripe, but on top of my acoustic brain dealing with decoding a recorded sound, the effects of an enclosure and multiple point sources - each potentially getting in the way of the sound, at the same time my movie brain is similarly dealing with the writing, acting and direction or the sound aspects of ambiance, mood and dialog texture - any of which can also get in the way of the filmic experience. So actually I demand as much or more from speakers for HT than I do for music. Probably the same way an audiophile demands more from speakers for music than they do for HT.
2. Affordable drivers can do a fair job by using a smaller xmax, but this requires a larger cone for the HT output I needed. Though affordable, the AN's carry very large magnets. I wanted this reserve even if it wouldn't always be necessary, in case I wanted to start over. Especially as I could not afford the higher end drivers from Japan or Europe. There are some dynamic coaxials but they introduce a crossover. And the good ones are over my budget. As far as anything smaller: I'd risk insufficiency and having to add reinforcing drivers later. I've decided I'd rather risk distortion and ceilings on my SPL's than having to give up the single driver quality.
rjbond3rd said:
Yes, but it's magic to you is actually courtesy of the willingness of these genres to allow the listener space to enter the experience. A smart film does the exact same thing and so it too should favor the single driver midrange. A lot of mediocre films, included some big budget films, don't respect this, have a way overly complex soundscape which achieves little, and help give HT it's bad rap as a waste of fine speakers. The only main difference is the emotional use of bass. Though the violence, force and excitement is admittedly in the upper bass, the foundations for most of the emotionality is in the lower subwoofer range. So if you have the midrange and the low bass you can access most good films at least at their core. Still, our culture is shaped by those addictive action flicks and I'd rather not go cold turkey without them. These of course do need the mid and upper bass.
-jerry
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