| VanJerry |
Umm...
How about this DIY?
Using a compressible fibrous or open cell material of initial thickness "a" and circumference "b" which is compressed by tightening an outside nut. Potentially to point of virtually complete seal.
The cross-sectional area of the interface between inner chamber and outer atmosphere seems to be important in this phenomenon so "b" can be larger or smaller to change it.
A high quality compressible material which can "spring back" after being highly compressed over time may allow the sound to be adjusted for some time into the future. |
|
|
| VanJerry |
| quote: | Originally posted by lrntglls
Emspeaker LB12: 12 inch full range , 98db, 16 ohm, qts:0.2
no xover, no tweeter ( good for 15khz, enough:yes)
www.emspeaker.fr/
You can use it in an bass reflex and get to 40hz (+-3db).
or open-baffle ( that is what I have )+ sub.
Hihg spl with very good transient; very involving sound. |
Thank you Irntglls, I'll look into it. |
|
|
| udailey |
| quote: | Originally posted by VanJerry
Umm...
How about this DIY?
|
Thats a really cool idea. Thats DIY :) |
|
|
| VanJerry |
Thanks udaily,
PS
I didn't make it plain the compressive material should be accessible to the exterior side so it can be swapped or resized. |
|
|
| Nihilist |
Quote from my post #87 :
"Aperiodic has a way of sucking the snap/life out of bass transients, at least IME. OVER-stuffing a sealed box can do this too."
I was NOT and am NOT recomending stuffing a cabinet to those levels, but merely pointing out what COULD be done, contrary to popular belief. To me, an aperiodic cabinet does much the same thing as an overstuffed sealed cabinet with regard to sound quality.
I too believe that too much stuffing can make for a non-optimal sound. I believe I mentioned that right away when I recomended a sealed enclosure to VanJerry. I said he should use the largest sealed cabinet he could get away with and stuff it to suit his taste.
"No. I prefer the driver to be mechanically well damped..."
This would refer to the Qms , no ? A lower Qms would translate to a driver with more mechanical damping ?
Perhaps the Cookbook isn't the best book out there, but I found it quite interesting with regards to his testing of stuffing materials in a decently scientific manner.
............................Blake
.......................Blake |
|
|
| udailey |
| quote: | Originally posted by VanJerry
Thanks udaily,
PS
I didn't make it plain the compressive material should be accessible to the exterior side so it can be swapped or resized. |
Maybe half inside and half outside since you dont want to make a tube out of it but also have to remember, or at least consider, that material does not compress evenly just like springs dont compress evenly. But if you can break it down into several discs, or at least two then the compression of the material will be more uniform. Just a guess/idea based off of your unique thought.
Uriah |
|
|
| VanJerry |
Yes, I can see both issues.
Probably all inside for aesthetics anyway. To be swappable from the outside the material would no longer be held by a bolt through its center so I'd add a little inside shelf to keep it from falling down and being hard to reach.
Multiples of smaller units would also be better due to the fact aperiodics need about 10 sq. in. of interface per cu. ft. of enclosure. Makes it tricky though to keep them equally tight. Probably help to mark treads every 5 turns with color coded perm markers. Would take a lot of these in a single multi-holed array for big boxes.
-jerry |
|
|
| planet10 |
| quote: | Originally posted by udailey
at least consider, that material does not compress evenly just like springs dont compress evenly. But if you can break it down into several discs, or at least two then the compression of the material will be more uniform. |
I have found that one large hole does not allow as fine or easy a tuning as a series of holes or a long thing slot. In subs i have used a similar scheme, compressing the resistive material between the bottom of the woofer and base.
dave |
|
|
| planet10 |
| quote: | Originally posted by VanJerry
due to the fact aperiodics need about 10 sq. in. of interface per cu. ft. of enclosure. |
It is more complex than that. I've typically used Sd as a reference when deciding how much hole to make (when i'm working from that direction)
dave |
|
|
| VanJerry |
| quote: | Originally posted by planet10
I have found that one large hole does not allow as fine or easy a tuning as a series of holes or a long thing slot. In subs i have used a similar scheme, compressing the resistive material between the bottom of the woofer and base.
dave |
David,
What do you think of just the enclosure used in World Design's WD25T? (ignoring it's a 2-way)
ie. Any advantage to having an aperiodic within a sealed enclosure when it comes to larger floorstanders using a big woofer component similar to the AN12 besides a final 12 dB/Oct roll-off?
-jerry |
|
|
| VanJerry |
I'm sorry, I gave the right pdf link for the WD25T but called it the WD25A by mistake. [I corrected this in the post] I'm referring to the one that uses aperiodic vents.
The whole cabinet is divided in half by an aperiodic vented upper floor. The idea is that the midrange and upper bass sees the upper chamber but the rest of the bass sees the whole sealed enclosure. A trick used by the WD25T that I see relevant to me because the AN12 forces such a large box, perhaps it's upper bass and midrange could also use help? Sort of a compromise between your position and Nihilist's?
Or, to keep the whole box aperiodic, a second aperiodic vent from the lower chamber to the outside... |
|
|
| planet10 |
I understood that. The A35, A50 used a similar scheme. As do some of the NAIMs.
Trying to get those tuned properly is much more cut & try. With my experience i'd guess i could get pretty close in 4 tries (maybe)
dave |
|
|
| VanJerry |
So David,
When you said you'd aim for a Qtc of 0.6 or so, and without meaning to ask you to run any sim or anything, what size Aperiodic would that ballpark at?
(I really have been trying but can't find anything online that would help me guesstimate myself...)
4 tries = 4 cabinets? or 4 adjustments to the vents? |
|
|
| VanJerry |
| quote: | Originally posted by Scottmoose
As you seem to favour the idea of a large 12in driver, here's one way of using the AN 12in CF in a smaller (these things being relative) box.
40in x 13.5in x 10.5in (HxWxD). Zdriver 16.375in. Zvent 37.5in. Vent 3in diameter x 6in long. Stuff cabinet & vent 0.5lbs ft^3 of hollow-fibre damping. Gives a quasi aperiodic damped vent alignment. The vent would need some form of grill at either end to keep the damping material in place. Basically, this is what those Seas vents are; just larger & tuned for a specific box / driver. Just cross to a pair of subs to support the LF. |
Hi Scottmoose,
Are those inside dimensions and is that a form of TL?
It's so compact! What would be the equivalent Qtc of something like that?
-jerry |
|
|
| udailey |
When David Dicks recommends a BR he recommends using 40"x14"x11.5" so this is pretty close. I know I know he recommends it for the whole range of ANs and thats odd, but it sounds good. I do believe it could sound better to, but the fact that it sounds good right now and that Nelson Pass is experimenting with the AN12 in OBs makes me to content right now to try anything else.
Going off of what Dave said about using more than one hole.... You could get around the weird compression of damping material this way. The more holes you make then the more uniform your compression could be. It solves the problem of compressing multiple layers by allowing to use one layer over many holes. On the other hand the air doesnt have to try very hard to get to the outermost holes and it does have to try harder to get to the innermost holes, so it might actually seem like a cone shaped port that is stuffed. Not sure but it makes sense that way to me.
Uriah |
|
|
| lrntglls |
Emspeaker LB12....
Michel Fertin has plans for the cabinet:
a small ported bass-reflex and also a TL
he can help tune it.. |
|
|
| VanJerry |
Hi udailey,
Well, I kinda knew going into this in the land of Thiele and Small that if I did want anything much better than Dick's infamous BR, pleasant as it may be to those who've heard it, getting guidance on the biggest AN wasn't going to be simple. My fall back was always the Cast 10" but after all the work the helpful people here have put into the 12" I'd be a tad worried of being tarred and feathered for starting up on that one :)
| quote: | | ... You could get around the weird compression of damping material this way. The more holes you make then the more uniform your compression could be. |
It's why I visualized a few separate multiples of the design - allowing air to get directly through each hole equally from all directions. Actually, having more than one such independently controllable unit makes for a powerful aperiodic experimentation platform as it allows you to open one more than another. It thus can simulate a variety of virtual materials that may not even exist yet by using pretty much a single standardized material.
But, I should mention that this aspect is a bit secondary right now as I struggle to even see which basic enclosure etc is even doable. I agree indications are the OB way wouldn't be anything as complicated for the large AN's. Too bad I don't have an extra few feet to accommodate this...
-jerry |
|
|
| Scottmoose |
| quote: | Originally posted by VanJerry
Are those inside dimensions and is that a form of TL?
It's so compact! |
Yes, and no, respectively. It's just a variation on an aperiodic cabinet -basic damped / resistive vent approach, that's all, with a net volume of ~3.3ft^3 & is absolutely the smallest I'd consider going with one of these drivers & if you want to go this small, it's about the only available option while maintaining a reasonable FR. Trust me, you don't want to know how large a TL would need to be for these drivers.
Guidance on the AN12in isn't difficult. It's a driver & conforms to the laws of physics. Period. The principal issue is that it really does want a very big cabinet indeed. Doesn't matter if it's T/S based or anything else -it wants a big box. That last BR (with the peak at Fb) that I showed you for e.g. had nothing to do with Theile & Small -that was a trad BR alignment in use many years earlier.
OTOH, the AN 10in will work nicely in a much more manageable volume than the 12in (these things are relative) so is the canny choice of their entire range IMHO. |
|
|
| VanJerry |
That is pretty darn good! Could you hazard a comparable Qtc on this? If it's not quite 0.6 how close can it get if size could be increased?
I was thinking of difficulty more in the sense of:
1. How unreasonable or insane was the size constraint I gave considering the VAS etc
2. The personal embarrassment I risked bringing it up.
Yes, that Cast AN 10in is looking pretty clever indeed. You know, with it's ample LF and HF response - I considered it sealed or aperiodic for the role of the 8in driver in a pair of mains featuring your 15 + 8 suggestion since then it would make an ideal matched timbre HT center on it's own. (Especially if I could nudge it towards an aperiodic roll-off of 80Hz as sealed I could only figure out an F3=97.75, Fc=80.85 and Qtc=0.6 at 34 liters.)
And thank you for your post on my new thread: How much can you add to a single driver design before risking its unique qualities? I appreciate how well it was on target and I hope it will help set the tone for other responders that follow. If you don't mind some very temporary duplication for a post or two, for the benefit of other newbies, I might ask you similar things in both threads.
Actually, it was your earlier suggestion to me below that inspired my starting it. I thought it was a very interesting solution indeed for the constraints I first stated: low volume weight/presence. I assume you were referring to the woofer sealed, but I imagine the 8in could be sealed for additional excellence in the midrange clarity needed in HT.
I'm not sure, now, in which thread it's best to ask you but might a crossover at 500, or 400, be just low enough to be minimally distinguishable from a crossoverless design? (This is just where I need that HT weight.) And secondly, again because it would only serve a very narrow and low freq range, would such a woofer only minimally impact the single source virtues like coherence of the single driver experience?
| quote: | | TBH, given the value you place upon transients, I'm surprised you're wanting to mess around with FR units in the LF anyway. A better bet would be a lowish Q 15in woofer crossed to, say, an 8in in a sealed box at ~500Hz. |
-jerry |
|
|
| Scottmoose |
You're welcome.
Depends on the ultimate design really. In an ideal world, you don't want an XO in the telephone band or an octave either side of it at all. But we don't live in an ideal world.
Will you hear the transition? Maybe. Maybe not. More pertinently -would you care? That depends on what you happen to focus upon when listening. We all basically hear the same thing (physiological losses aside) but we tend to listen differently & value specific things. Those who value total midband transparency & tie themselves up in knots at the suggestion of anything at all other than 1 driver even near that region are unlikely to be thrilled. Although I suspect it's more the idea of having another driver in that region than the sonics they'd object to. OTOH, people who place value on low-distortion, high SPLs & massive LF transient swings at ~live levels won't be happy with one driver, however it's loaded, period. They'll want that extra capacity in the LF from a big woofer.
FWIW, (& assuming the design allows for it!) 500Hz is probably one of the least evil places within the midband to cross, for reasons I've noted above. View it as Credit / Debt sheet. Which side the balance falls upon is down to individual preference. Minimal interference is how I'd tend to categorise it, with more advantages in some situations (assuming you aren't obsessed with total transparancy across the entire midband irrespective of the cost) than disadvantages. If it worries you & you can sacrifice some power-handling, you can always cross lower, below 200Hz, should you wish. Both work well, they just have different compromises.
Looking at your rough requirements, the 10in or 12in suitably loaded should do you for mains in a room that size. I'd be inclined to go with the former, for simple size reasons as the 12in really would prefer a larger box than most people can stomach to start giving of its best, but YMMV as always. |
|
|
| VanJerry |
Thanks for the assurance, Scottmoose.
And a concise reality overflight.
Roger least evil 500Hz. :angel: Big time research tonight as this opens a legitimate front along with a new struggle with my single driver demons :devilr:
But it would save me hours if you gave a few sentences to expand on typically expected compromises.
| quote: | | & you can sacrifice some power-handling, you can always cross lower, below 200Hz, should you wish. Both work well, they just have different compromises. |
What I can imagine a little better than crossing at 500Hz is the effect of crossing lower: such as for every 100Hz I go below 500 means a lot of acoustic energy the smaller driver would need to use up in the same range, causing it to be what - ? - Not just poorer in transients but possibly impacting what kind of enclosure can be utilized? HF extension... Seems in this case like a good job for the AN Cast 10. It already wants to roll off in the 90's sealed and has a surplus in the HF it can stand to lose. Might there be a way to force it to roll off a little higher without too much of a real crossover? That would be a plus.
vs
Staying at 500Hz and aside from some minor(?) coherency issues and the demand for a more robust and proper crossover - what ? - it will only be more wonderful? ...Tell me a little more?
And..
| quote: | | Looking at your rough requirements, the 10in or 12in suitably loaded should do you for mains in a room that size. I'd be inclined to go with the former, for simple size reasons as the 12in really would prefer a larger box than most people can stomach to start giving of its best, but YMMV as always. |
So actually, the ~3.3ft^3 is the "absolute" smallest... That begs for a drop of exposition. What is gained is a reasonable FR. Could you offer a rough Qtc equivalency or what is lost?
Perhaps I should ask, at what number of cu. ft. does the 12 become well clear of the term "absolutely" and enter into the realm of "pathetically" smallest. Or better :)
-jerry |
|
|
| tinitus |
Fostex FF225K has low Qts and roll off "early" at 175hz with -6db around 130hz in 4liter closed, but it will need a supertweeter above 10khz ... appears to be a pretty smooth middriver with very high sensitivity
Wonder if used in surround whether only main speakers need the additional woofer and supertweet and the rest could do with only the FF225K, and no xo on any of them ? :cool: ... well, then theres the BSC issue :confused:
btw, AN 8" CF seems to do exactly the same thing |
|
|
| tinitus |
| quote: | Originally posted by tinitus
... well, then theres the BSC issue :confused:
|
Maybe double drivers in 1.5way :D :rolleyes:
btw, the additional woofer on mains will need to be driven by adjustable plateamps or maybe reckhorns A-401 which has some nice features, like adjustable satelite xo
Well, its probably not that easy :cannotbe: |
|
|
| tinitus |
| Well, I actually question whether BSC is needed or even wanted on the surround channels, but only on the mains ... but thats only theoretically |
|
|
| VanJerry |
Hi tinitus,
Thank you for the variations on Scottmoose's theme.
What I like is the idea that if a crossover is used that it is in, to use his language which I like, "a least evil place." However, I haven't by any means given up on a totally single driver solution. What is certain though, is that now as I judge any single driver approach I want to be sure at the very least there's room in the design for augmenting woofers. (If anyone's frustrated and said, "It's about bloody time," I try to address that in the next post below.)
I understand a crossover above 6K or 7K or 10K would also be out of the way of critical listening but I feel if I were to use a crossover at all I'd only want to use one. Of the 2 options: high and low, I feel the HT and low level requirements make this choice for me - down low.
| quote: | | Maybe double drivers in 1.5way.... the additional woofer on mains will need to be driven by adjustable plateamps |
I have to look into the advantages and disadvantages of these things. But, gee, a separate amp for augmenting woofers? I wouldn't mind for later, but do you really think I can't use the 120W I have in SS now to drive everything?
-jerry |
|
|
| VanJerry |
To all,
I just also want to add that understanding what will and what will not so much take away from the single driver experience is clearly my fulcrum point.
That's why I starting a parallel thread on the matter: How much can you add to a single driver design before risking its unique qualities?
I hope any surprises and revelations there will allow me to make the best use of the efforts of all the people here. It's something I should have done very early however I didn't know if it would be appropriate forum behavior to do so. But weighing that against the risk of frustrating or otherwise exhausting your generosity I've decided to do what I can to protect it. Plus they are two legitimately different subjects.
Besides, the double research I was doing all along was getting to me anyway. :) |
|
|
| Scottmoose |
This is what happens when things get taken out of context.
'One of the least evil places in the telephone BW.' Not 'least evil.' And that, as I've kept harping on about, is design dependant. Nothing is a panacea. You select the compromise that will work best for you & design a system based upon that; ergo if any XO is going to be done, where & how will be part of the design from the start.
Re your several Qtc queries, it's not a sealed box so the Qtc is somewhat moot. Probably around 0.4 in terms of its roll-off contour, but as I say, it's not a sealed box. WRT 'absolutely' to 'pathetically', that is so subjective as to make any answer I could give worthless.
As for crossing lower -lower you cross the less potentially audible the XO point (although you don't want it in the middle of a couple of instruments BW) but the harder the wide-band unit will have to work, potentially increasing distortion if it needs to do more than it's capable of. |
|
|
| VanJerry |
| quote: | | Originally posted by Scottmoose WRT 'absolutely' to 'pathetically', that is so subjective as to make any answer I could give worthless. |
What do you call something only 30% bigger than "absolute" minimum? I thought it self-deprecating to call it "pathetic." But the humor was obtuse and wasted your time and I apologize for my poor editorial oversight. Got all-nighter punchy. :yawn:
| quote: | | FWIW, (& assuming the design allows for it!) 500Hz is probably one of the least evil places within the midband to cross, for reasons I've noted above. View it as Credit / Debt sheet. Which side the balance falls upon is down to individual preference. Minimal interference is how I'd tend to categorise it, with more advantages in some situations (assuming you aren't obsessed with total transparancy across the entire midband irrespective of the cost) than disadvantages. If it worries you & you can sacrifice some power-handling, you can always cross lower, below 200Hz, should you wish. Both work well, they just have different compromises. |
I've been probably misusing Qtc's to get a comparative sense of transient quality - a way of comparing apples to oranges. It would have been better to ask:
Would the resultant transient quality of this quasi aperiodic be better or worse than what you might expect from a sealed box of Qtc=0.6? (This being Dave's suggested target for this application.)
And if not at this minimal size, at roughly how much larger?
On the crossover at 500: An area of least interference, but I appreciate the delicacy of the situation when checking an instrument bandwidth chart. Still in the thick of things logarithmically speaking.
It won't help relieve the full range driver but is there a name to having a full time woofer run off a separate amp with a simple first order rolloff up top? No crossovers again. Both drivers operating. Would the interference be that much worse to 500Hz with both drivers operating rather than one fully crossed over? That is, avoiding a crossover to get some on-demand HT weight in exchange for sacrificing some quality on the main driver.
Thank you
-jerry |
|
|
| rjbond3rd |
Hi VanJerry, compare Scottmoose's quasi-aperiodic MLTL design he made for you:
http://www.diyaudio.com/forums/show...378#post1566378
With the crude 300-liter WinISD sim (yellow line) with Qtc of .66:
http://www.diyaudio.com/forums/show...700#post1548700
The tradeoffs are in those graphs. Scott's design has the same (arguably better actually) performance than the gigantic sealed box, but in a vastly better-sized enclosure.
In terms of where to cross over from FR to helper woofer, pick any frequency, really. If you listen at low volumes, choose as low an xover point as you can tolerate. If you want high volumes, you'll be forced to use a higher xover point. You might end up adjusting it a bunch of times.
I realize you're just trying to understand the trade-offs. Ultimately, though, this subject has some mysteries which can only be unlocked with your saw! :) |
|
|
| GM |
??? Absolute minimum is a driver suspended in free air from the ceiling. Minimum box size technically is one that seals the basket holes as done on compression drivers, sealed back mids, tweeters, i.e. minimum box size is the one that closest meets the needs of the app WRT its F3, F6, F10, etc. both on and off-axis.
Acoustic bass or similar players and folks who believe they can tell the difference between small variances in Qtc in the LF BW tend to prefer a 0.5 Qtc, which is the largest sealed box size and as it shrinks, its F3, Fb rises. Ditto TLs (AKA ~ 'aperiodic'). Not many 'free lunches' in audio system design.
A max flat impedance TL is considered the best trade-off between BW, impulse (transient) response and box size, providing a benign load to the amp, though due to the vanishingly low output impedance of an SS amp the latter is moot.
WRT where to put an XO point......... the pioneers of audio were only interested in reproducing the human voice BW as accurately as practical, so the majority of early audio was based on Bell Labs' human hearing research, not a musical instrument's BW chart, and when the available movie soundtrack BW had increased enough to require an XO point approaching our acute hearing BW, 300 Hz/2nd order was chosen and as more research was done it was bumped to 500 Hz as an acceptable trade-off to ensure that all of the most dynamic portion of the music spectrum (amp power wise) be covered by the woofers and later still, upped to 1.2 kHz in acoustically small venues. In the near-field of recording, broadcasting studios, 1.5-1.6 kHz became the norm for decades until electronic advances allowed any point to be chosen since the signal can be manipulated in the digital domain.
Point source (cone/dome) drivers can roll off its HF at ~6 dB/octave if it has zero inductance, so an impedance compensation (AKA zobel) filter is required, but in a subwoofer's BW the components are large, expensive and raises its Qts, so EQing its HF response is the usual choice.
Anyway, using the AN12's published specs and assuming a zobel is added, a max flat impedance TL that except for size meets all the criteria of reasonably extended LF BW to allow a low acoustic subwoofer XO point, ~critically damped roll off slope for excellent impulse response, benign impedance if using a high output impedance amp and when properly located in-room may not even need a sub system for the majority of movie soundtracks:
L = 85.468"
CSA = 335.121"^2
zdriver = 32.197"
All dims approximate and sim assumes 1.091 lbs/ft^3 of polyfil. Compared to a sealed version it has a much lower Q Fs impedance, ergo flatter phase and slightly better impulse response, faster roll off below Fs and slightly more gain BW above it. If SS driven I doubt you can hear these subtle differences in-room though since it dominates down low, but you can always seal up the terminus (port) to test it.
Note that if you end load the driver its impulse response further improves a bit with the trade-off of its response mirroring the sealed's down to Fs.
GM |
|
|
| GM |
| quote: | Originally posted by rjbond3rd
The tradeoffs are in those graphs. Scott's design has the same (arguably better actually) performance than the gigantic sealed box, but in a vastly better-sized enclosure. |
Yeah, where box size is the primary goal, 'forcing' an under-damped vented alignment into a well damped one is the way to go IMO, but then you're usually forced into adding a (sub) woofer system, so it's a 'pay me now or pay me later' scenario in total box bulk and system budget with the benefit of increased potential performance and shape, placement flexibility.
GM |
|
|
| Eva |
| If the acoustical output from the drivers does not sum properly on-axis, you will always notice it, no matter what crossover frequencies are chosen. There is no way to hide the effects of bad crossover design. On the other hand, a good crossover is hardly noticed at all, but it may have to include compensation like steps, notches, etc... |
|
|
| Scottmoose |
True, in an ideal world, but we're talking about some usefully effective points to place them, reducing the audibility of the transition & which also in some cases may permit simpler topologies.
One would hope that all XOs are well designed for the task in hand. Which sadly, is rarely the case. Active / digital is the way forward IMHO. |
|
|
| Nihilist |
Why are you worried about using "helper" woofers with a 10"-12" main driver that will easily trade off to a sub ?
Is the sub only to be used for HT , or will it be music too ?
..........................Blake |
|
|
| tinitus |
I think the AN10" CF ought to work with a woofer driven by Reckhorn A-410 as it has both high and low pass adjustable up to 300hz along with sub Eq as well as lower midbass Eq
Fore the surround channels the AN10 may work ok on its own
It doesnt need a very big box
A notch from 2khz and up may work wonders
Its not perfect and if its possibel at all to make the connections with a surround receiver I do not know, but doing a passive design takes some experience, a crossover in the midbass is not as simple as it sounds and can be very tricky |
|
|
| Scottmoose |
| quote: | Originally posted by Nihilist
Why are you worried about using "helper" woofers with a 10"-12" main driver that will easily trade off to a sub ? |
Because not everyone will be happy with the performance of just a 10in - 12in FR driver down to below ~100Hz. Some yes. Others no. |
|
|
| udailey |
Looks like David Dicks has updated the box designs. Still BR but he has 3 extra sizes and an OB that now has dimensions.
5 Cubic Foot
(35T x 20W x 20D)
8 Cubic Foot
(38T x 26W x 21D)
13.6 Cubic Foot
(48T x 24W x 24D)
Open Baffle
(30T x 24W x 15D) |
|
|
| VanJerry |
Just got in recently.
Hi rjbond3rd,
Interesting idea to use these two sims to compare. Thank you.
I'm not sure if I'm using your sim properly though to I compare GM's and Scottmoose's sims. Anybody slap my wrists here...
What I observe is that Scottmooses's curve seems to have little or no rise around 100Hz and a subsequent linear roll-off slope similar to something between the green and yellow lines in your sim. This would correspond to a Qtc somewhere in the middle between 0.66 and 0.92.
What I observe with GM's curve is a more rounded roll-off slope but I'm not sure if it has a slight rise around 80 or 90Hz. Still, I'd call it a bit closer to the yellow line corresponding to a Qtc of 0.66 than that of Scottmoose's.
Now, being that these are near aperiodic TL's something tells me I'd be wrong to simply assign Scottmoose's curve, say a... (0.66 + 0.92) / 2 = 0.79. I'm not attempting to do that.
But would it be permissible to hazard that GM's curve would represent a tighter sound, while Scottmoose's would be easier to mate with a sub?
| quote: | | ...If you listen at low volumes, choose as low an xover point as you can tolerate. If you want high volumes, you'll be forced to use a higher xover point... |
Hm... Low xover at low volumes, high at high. Up to now I thought low volumes could use more weight and so it would be useful to turn the sub's crossover up to cover more of the low band. But obviously you know something I'm not aware of yet.
I'd expect it'd be important to keep this sub strategy in mind as any design particulars are worked out. But I have to admit after thinking abut it I can't grasp the basis for this - so I guess it represents a critical hole in my understanding. Can you expand on this?
-jerry |
|
|
| VanJerry |
| quote: | Originally posted by GM
??? Absolute minimum is a driver suspended in free air from the ceiling. Minimum box size technically is one that seals the basket holes as done on compression drivers, sealed back mids, tweeters, i.e. minimum box size is the one that closest meets the needs of the app WRT its F3, F6, F10, etc. both on and off-axis.
Acoustic bass or similar players and folks who believe they can tell the difference between small variances in Qtc in the LF BW tend to prefer a 0.5 Qtc, which is the largest sealed box size and as it shrinks, its F3, Fb rises. Ditto TLs (AKA ~ 'aperiodic'). Not many 'free lunches' in audio system design.
A max flat impedance TL is considered the best trade-off between BW, impulse (transient) response and box size, providing a benign load to the amp, though due to the vanishingly low output impedance of an SS amp the latter is moot.
WRT where to put an XO point......... the pioneers of audio were only interested in reproducing the human voice BW as accurately as practical, so the majority of early audio was based on Bell Labs' human hearing research, not a musical instrument's BW chart, and when the available movie soundtrack BW had increased enough to require an XO point approaching our acute hearing BW, 300 Hz/2nd order was chosen and as more research was done it was bumped to 500 Hz as an acceptable trade-off to ensure that all of the most dynamic portion of the music spectrum (amp power wise) be covered by the woofers and later still, upped to 1.2 kHz in acoustically small venues. In the near-field of recording, broadcasting studios, 1.5-1.6 kHz became the norm for decades until electronic advances allowed any point to be chosen since the signal can be manipulated in the digital domain.
Point source (cone/dome) drivers can roll off its HF at ~6 dB/octave if it has zero inductance, so an impedance compensation (AKA zobel) filter is required, but in a subwoofer's BW the components are large, expensive and raises its Qts, so EQing its HF response is the usual choice.
Anyway, using the AN12's published specs and assuming a zobel is added, a max flat impedance TL that except for size meets all the criteria of reasonably extended LF BW to allow a low acoustic subwoofer XO point, ~critically damped roll off slope for excellent impulse response, benign impedance if using a high output impedance amp and when properly located in-room may not even need a sub system for the majority of movie soundtracks:
L = 85.468"
CSA = 335.121"^2
zdriver = 32.197"
All dims approximate and sim assumes 1.091 lbs/ft^3 of polyfil. Compared to a sealed version it has a much lower Q Fs impedance, ergo flatter phase and slightly better impulse response, faster roll off below Fs and slightly more gain BW above it. If SS driven I doubt you can hear these subtle differences in-room though since it dominates down low, but you can always seal up the terminus (port) to test it.
Note that if you end load the driver its impulse response further improves a bit with the trade-off of its response mirroring the sealed's down to Fs.
GM |
Hello GM,
Thank you for responding. There is a depth of information in your post that will have me working on it a while.
I wanted to ask you some things but your post stimulated in me a need to come a bit clean on TL's.
I believe in honoring the generosity and effort of everyone who posts to me, but I must confess that despite my best efforts I've not been able to catch up to this recent subject as much as I'd like. Of the reading I've done on enclosures since this thread began much of it was on BR, then sealed, the much simpler "leaky sealed" aperiodic and a bit on horns/BVR's mixed in the middle. Of my original attempts to grasp TL's what impressed me most was the advice warning that it would require some competence to pull off successfully so I thought it wise to invest the reading time I had available on simpler boxes. Thinking back, I'm a little concerned when I mentioned the Metronome earlier that I may have given a different sense of my abilities. Then on top of this I wasted precious time the past few days to finish off my reading of the simpler aperiodic - the use of a controlled leak in an otherwise plain sealed box - to make sure I had no other choice but to dive into the TL world.
So, suddenly I find myself unprepared as I find myself in a relative sweep of suggested TL-based aperiodic solutions. Yet of course, with my size and performance concerns, and that curious AN driver... what else could it have been? But I will make it my priority to get a handle on this over the next few days.
Questions:
I sense what you've suggested to me is inspired. But if I really did have faith in my sealed servo Rythmik sub and wanted to make the fullest use of it, would there be a variation of this enclosure that sacrifices a bit off the LF? ie. If not needed (and I again apologize if I seem an ingrate for your achievement but) could that extra LF capacity go towards more damping etc?
I am ignorant perhaps, whether this would have the effect of also losing, rather than helping the| quote: | | ~critically damped roll off slope for excellent impulse response, benign impedance if using a high output impedance amp |
And secondly, may I ask what HxWxD these measurements would roughly correspond to? (L = 85.468" ; CSA = 335.121"^2 ; zdriver = 32.197")
Thank you,
-jerry |
|
|
| rjbond3rd |
| quote: | Originally posted by VanJerry
But would it be permissible to hazard that GM's curve would represent a tighter sound, while Scottmoose's would be easier to mate with a sub? |
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!
| quote: | | Low xover at low volumes, high at high....Can you expand on this? |
Check out Scott's comment in post #128:
| quote: | | As for crossing lower -lower you cross the less potentially audible the XO point... but the harder the wide-band unit will have to work, potentially increasing distortion if it needs to do more than it's capable of. |
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). |
|
|
| Nihilist |
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 |
|
|
| rjbond3rd |
Hi Nihilist, regarding GM's cab unfolded, alternatively keeping WxD in a 1:1.4142 ratio (1 to square root of 2):
height: 85.468
width: 15.39
depth: 21.767
Or in other words, the refrigerator. Hey, nobody said hifi was easy! |
|
|
| VanJerry |
| quote: | Originally posted by rjbond3rd
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!
|
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. :)
| quote: |
.... 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). |
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.
| quote: |
(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). |
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 |
|
|
| VanJerry |
| quote: | Originally posted by Nihilist
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 ? |
Hi Nihilist,
Nope. 3.5's about the limit. |
|
|
| VanJerry |
| quote: | Originally posted by Nihilist
Why are you worried about using "helper" woofers with a 10"-12" main driver that will easily trade off to a sub ?
Is the sub only to be used for HT , or will it be music too ?
..........................Blake |
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.
| quote: | Originally posted by Nihilist
To me, an aperiodic cabinet does much the same thing as an overstuffed sealed cabinet with regard to sound quality. |
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 |
|
|
| VanJerry |
| quote: | Originally posted by udailey
Looks like David Dicks has updated the box designs. Still BR but he has 3 extra sizes and an OB that now has dimensions.
5 Cubic Foot
(35T x 20W x 20D)
8 Cubic Foot
(38T x 26W x 21D)
13.6 Cubic Foot
(48T x 24W x 24D)
Open Baffle
(30T x 24W x 15D) |
Hi udailey,
Kind of an admission that for the larger AN's - well, the 12's anyway, that Bigger is Better. Nothing wrong with that - as far as the history of the culture of speakers go. If only our wives were still living in the 60's. ...Free Love...! |
|
|
| VanJerry |
Hi Scottmoose,
I have a visual mind. Might you have a link to an image of the kind of design you have in mind? Perhaps a generic section plan view? Or a pic of one in the progress of being built? I'd like to see what the insides look like.
Thank you,
-jerry |
|
|
| Scottmoose |
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. |
|
|
| VanJerry |
| quote: | Originally posted by Scottmoose
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. |
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.
| quote: | | 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. |
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 |
|
|
| GM |
| quote: | Originally posted by VanJerry
Thank you for responding.
I sense what you've suggested to me is inspired. |
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. :smash:
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 |
|
|
| Nihilist |
"I didn't think BR was known for transients."
Their not. Can be made decent, but not as good as a TL, Sealed or Aperiodic design of equal build quality.
"And I thought using a large driver demands large enclosures for Horns and BVR's."
It does.
..............................Blake |
|
|
| GM |
| quote: | Originally posted by rjbond3rd
That outweighs any (subtle) sonic differences in my mind!
(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). |
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 |
|
|
| Scottmoose |
The price makes me want to...
That said, you get what you pay for in this life. And at todays prices, as you say, moving toward bargin status. Even for those who can't afford it. |
|
|
| VanJerry |
| quote: | Originally posted by GM
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"
|
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 |
|
|
| rjbond3rd |
| quote: | Originally posted by GM
...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" |
Hi GM, so this is big at the top, then tapers to half the top's area at the bottom -- so it would stand on some kind of (strong, wide) adjustable feet? |
|
|
| GM |
Greets!
Well, you can do it that way, but I made them wide/shallow and the back sloping in with a full length triangular brace to create a three point footing. Sometimes I added a straight duct to the bottom if I wanted a lower tuning.
GM |
|
|
| rjbond3rd |
| Wow, that sounds like a really cool and unusual cab, visually! |
|
|
| rjbond3rd |
| quote: | Originally posted by VanJerry
I am in no way attempting to "enjoy" the design aspect of DIY audio... hence, for now, any concern over making it a slightly less risky and experimental effort... |
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 |
| quote: | Originally posted by VanJerry
I am in no way attempting to "enjoy" the design aspect of DIY audio... |
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.
| quote: | Originally posted by rjbond3rd
...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. |
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.
| quote: | Originally posted by rjbond3rd
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. |
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 |
|
|
| VanJerry |
| quote: | Originally posted by GM
Greets!
....I made them wide/shallow and the back sloping in with a full length triangular brace to create a three point footing. Sometimes I added a straight duct to the bottom if I wanted a lower tuning.
GM |
Hi GM,
Roughly like this?
With diminishing returns being what they are, is this actually better sounding than if the same design were allowed to be twice as big? Is that why it's quite this small, or was the objective to see how tiny you can get it? Really, this is an amazing achievement, but it's OK if it were not quite as small if that could achieve anything in sound.
-jerry |
|
|
| rjbond3rd |
| quote: | Originally posted by VanJerry
I still am not aware of any drivers particularly suited as single drivers for HT... As far as I know, there is no reliable design for single driver home theater, commercially or DIY... |
Hi VanJerry, I think that's because it's so easy to mate a FR to a big woofer (and it can even be pretty cheap, too.)
However, I totally appreciate your quest for minimalism! At my house, we're also on a minimalist quest, having ripped out the whole system, to be replaced by in-wall speakers for home theater, freeing up some room for horns for two-channel. I wish you success, sir! |
|
|
| GM |
| quote: | Originally posted by VanJerry
Roughly like this?
With diminishing returns being what they are, is this actually better sounding than if the same design were allowed to be twice as big? |
Greets!
Right, though again my brace/'foot' went all the way to the top to 'kill three birds with one stone' (I hate to do any more woodworking than absolutely necessary).
Well, we've relieved it of the majority of the high excursion BW, so don't need much acoustic efficiency, especially with such a low mass corner (2*Fs/Qts = ~149.3 Hz which will be lower in use), i.e. the cab's BW is < an octave wide.
That said, until the cab is at least as big as its Vas, bigger is better (BIB) rules for the most part, so in a side by side comparison the larger one will in theory sound slightly more 'full'/'relaxed', though impulse response actually degrades a bit due to the cab not controlling the driver quite as much (weaker air spring) and why I gave you the smallest practical version for a ~80 Hz XO point. Personally, the former outweighs the latter until it becomes audibly under-damped, but as always YMMV.
Anyway, doubling the two areas at the same length makes whatever the smaller one's width, depth dims 1.4142x larger = ~4.066 ft^3.
GM |
|
|
| GM |
| quote: | Originally posted by VanJerry
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.
1. As far as I know, there is no reliable design for single driver home theater, commercially or DIY. |
This has been my situation for ~eight years now and there's others here and other forums also with the only difference being I wasn't anywhere near the technical 'newbie' status of most folks who gravitate to the various forums.
There is, or at least use to be, but I don't know if DC Gold is still offering the late (Babb) Loreleis. In a 1 ft^3 sealed cab it's nominally flat from ~ 40-20+ kHz with a ~24 Hz Fs, so with a bit of room gain will have no trouble getting down to 20 Hz with authority at loud enough levels at low enough distortion to outperform Jim Griffin's original ~'infinite' Linus Array in a fairly large Hotel conference room. They probably could have drowned them out, but we only had JG's 250 W amp available whereas Alan (Babb) said he'd reliably tested them with 400 W.
Amazing what a compression loaded ~5.25" can do with a 1.2" Xmax and tiny Vas. ;) Not that it matters though since you claim not to be able to ante up its relatively high 'entrance fee'. :(
GM |
|
|
| VanJerry |
| quote: | Originally posted by GM
This has been my situation for ~eight years now and there's others here and other forums also with the only difference being I wasn't anywhere near the technical 'newbie' status of most folks who gravitate to the various forums. |
So, you understand...
| quote: | Originally posted by GM
There is, or at least use to be, but I don't know if DC Gold is still offering the late (Babb) Loreleis. In a 1 ft^3 sealed cab it's nominally flat from ~ 40-20+ kHz with a ~24 Hz Fs, so with a bit of room gain will have no trouble getting down to 20 Hz with authority at loud enough levels at low enough distortion to outperform Jim Griffin's original ~'infinite' Linus Array in a fairly large Hotel conference room. They probably could have drowned them out, but we only had JG's 250 W amp available whereas Alan (Babb) said he'd reliably tested them with 400 W.
Amazing what a compression loaded ~5.25" can do with a 1.2" Xmax and tiny Vas. ;) Not that it matters though since you claim not to be able to ante up its relatively high 'entrance fee'. :(
GM |
WOW GM!!
I need to do some deep reading elsewhere but I just read everything on dcgoldaudio.com and their Reference Neo beryllium models look fantastic. No TS parameters but these are designed for high end marine so they have low VAS and if the BABB Lorelei is any indication: large Xmax.
And critically, these are affordable versions of those very expensive drivers I knew were beyond reach. I can swing $430 - $475 per pair for a larger 6x9", 7" or 9.5" - that leaves me enough for a timbre matched Reference center and 5" surrounds as well (maybe Classics.)
David from DC Gold:| quote: | | Our speakers are probably more akin to NXT, Jordan, Bandor, Manger than a typical pistonic drivers where the bending wave of the material is utilized for creating the full frequency response |
The Lorelei is on the shelf while being re-designed. They were expecting end '07 so I can tell I shouldn't be counting on that one for a bit yet. But there's all those larger models anyway! Designed for impulse and dynamics at low VAS! This could be the ticket for an ideal single driver HT solution.
Reference Models:
Use aluminum/beryllium cones and vented neodymium magnets
N69R: The 6 X 9 size breaks up cone resonance. 35 - 20 KHz +/- 3 dB 93db
N7R: Utilizes a new open cast aluminum basket. 40 - 20 KHz +/- 3 dB 93db
N9.5R: 35 - 17 KHz +/- 3 dB 95db
The company describes how they used to use Gold Ribbon, Manger, Dynaudio, etc but wanted to do better. Currently built in the USA, they have no spider, use ferrofluid and:
| quote: | | .... the biggest change from Classic [which would have included the Lorelei?- Vanjerry] to Reference is the change from aluminum to beryllium in the most critical place that gives the best sonic bang for the buck. Beryllium is used in some of the finest tweeters made but in our design it adds to the bass, smooths the midrange and extends the highs. |
What d'ya think?
-Jerry |
|
|
| MJK |
I could not find any detailed specs presented for any of the drivers. There are no measured impedance or SPL response plots for any of the drivers. There are only a minimal number of words describing a couple of the key parameters. They may be everything they claim to be, but without any real information presented you would be taking a hige risk spending that kind of money on an unknown driver. Manufacturer's specs should be taken with a grain of salt, it is very hard to tell which are accurate without measuring the driver yourself.
How would you design an enclosure based on the information provided on the DC Gold site?
Also, I believe the prices I saw on the site were per driver. |
|
|
| Scottmoose |
I think it's per pair -certainly for the classics at any rate, but the text isn't particularly clear in the reference line, so it'd need confirming.
It's a heck of a punt to take without any parameters or performance graphs though. Pity the Lorelei's are no longer around -that was a pretty impressive unit by all accounts. |
|
|
| VanJerry |
Hi MJK and Scottmoose,
I understand and appreciate your concerns in this case.
Yes, at least for the N9.5R, N69R and the N4R the prices are per pair.
I'm doing my due diligence with the business and I am emailing David at DC Gold for the specs. I'm not any much less comfortable not having them. And I knew I could not expect any specific assistance from the forum without them.
However, after all the patience you've expended on my newbie behalf thus far, you'll be relieved that being high end marine they are designed for small simple sealed cabinets. In fact, tiny. :)
In their recent newsletter colorful Norh seems to feel that they are powerful for bass and that the F9.5 can be used to effectively displace a subwoofer in a large nightclub:
http://www.norh.com/news.html
-jerry |
|
|
| VanJerry |
Dmason at audiocircle.com states in a post earlier this month:
| quote: | I have a pair of the 7ND Reference, for evaluation, from Gold. These are the first run production units.
It is a VERY powerful driver, with Nd-ring magnet, and two focussing rings, and vented pole-piece.. It has a unique cast basket, and is as open in the back as possible.It has a very light alloy cone, covered in some secret grey compound which smells abit like old polyvinyl, and looks abit like gunite, and likely is doing double-duty as a damping compound, to reduce ringing, and also to weather-proof the driver. As a mere 7 inch driver, it could easily be considered as a high resolution, long-throw device. It clearly is a monster.
I am awaiting their measurements to build an alignment based on those measurements. On an open baffle, 15* off axis, with a Class A triode amp of 10 watts, it really is quite something. In a sealed box, it can take 300 watt peaks. I would like to hear it with a good Class A sand amp or Pass DIY type circuit. Hope this helps abit...
If they dont get back to me with measurements soon, I will send them out. I REALLY want to try these in a purpose-built BIB (Bigger Is Better) folded pipe/horn. |
In reference to the spider, Mike at Norh states:
| quote: | | Another unique feature of the DC-Gold Audio loudspeakers is that they do not have a spider. They use a Teflon ring and ferro fluid in a patented arrangement that eliminate the need for a spider. |
|
|
|
| MJK |
Scott,
Add one to the cart and then recheck the price and quantity. I might be mistaken but it looks like a per driver pricing system. If that is the case, you need to double the cost for a pair.
VanJerry,
I have watched you follow up on a lot of different driver and enclosure recommendations. It must be getting a little frustrating trying to keep track of all the good recommendations and then trying to decide which one will meet your requirements best. It makes my head hurt, I can see option paralysis setting in at some point. So I am going to outline my thinking and make a recommendation, you can take it or leave it as you wish.
1) You have a fairly small room. I doubt you want speakers so big that they dominate everything else in the room. Personally I have that same situation, my big two channel OBs are great but they are killing my ability to change things around and try other speakers in my system. So they will be replaced in the next month with something smaller and hopefully better. If you want 5 channel HT, I am not sure a large set of enclosures make sense.
2) You have a sub which relieves the requirement for producing bass below 100Hz. This really frees up a lot of options, you don't need your full range driver system to cover the deepest bass. I think this will enhance the final performance, the mids and highs will be better and can play more accurately without the need to superimpose bass output using the same cone. This also eliminates the requirement for a large full range driver.
Following that logic, my recommendation is to use a Fostex FE-167E six inch full range driver. It has a great midrange and does a decent job of the high frequencies. An eight inch driver will add more bass at | | | |
