| VanJerry |
| quote: | Originally posted by GM
Until the cab is audibly too big sounding ('bloated', i.e. under-damped), I prefer bigger since it yields a more relaxed, 'live' sound, but the difference will be subtle and most obvious with singers like Julie London, at least to me.
GM |
Thank you GM,
You mentioned 3 sizes to me in total which I've listed below. When you're mention you prefer the bigger yielding a more relaxed live sound would you be referring to #3, or the original #1? ie. Could #3 yield a subtly more relaxed sound than the smallest #2 or to get that do you have to go all the way to the biggest, #1?
1.| quote: | Originally posted by GM
L = 85.468"
CSA = 335.121"^2
zdriver = 32.197"
All dims approximate and sim assumes 1.091 lbs/ft^3 of polyfil. |
2.| quote: | ...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" |
3.| quote: | | doubling the two areas at the same length makes whatever the smaller one's width, depth dims 1.4142x larger = ~4.066 ft^3. |
-Jerry |
|
|
| VanJerry |
Hi Scottmoose,
Below I have summarized all I know about the box you first suggested for the AN cast 12. It is a traditional BR stuffed to the point of being nearly aperiodic.
The frequency chart shows this box to provide a bit lower extension than GM's tapered TL.
Can you please tell me how else, in general, such damped vent traditional BR's might differ from a stuffed tapered TL?
| quote: | Originally posted by Scottmoose
It's not exactly a transmission line (although it shares some characteristics) |
And what characteristics would it share with a transmission line?
Thank you,
-Jerry
| 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. |
| quote: |
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. |
frequency chart
| quote: | | 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.... |
| quote: | | 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. |
| quote: | | 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. |
| quote: | | AFAIK, aperiodic just means without period. The only way to genuinely achieve it is with a horn, but you can get ~close enough with a max-flat impedance aligned cab, which was & is the primary object of the heavily stuffed, so called 'classic', non-resonant TL. However, the term has also been appropriated to refer to a flattened out, underdamped box alignment, where you use a resistive vent to lower the Q at Fb. |
|
|
|
| Scottmoose |
| quote: | Originally posted by VanJerry
Below I have summarized all I know about the box you first suggested for the AN cast 12. It is a traditional BR stuffed to the point of being nearly aperiodic. |
It begins as an underdamped BR box with a resistive vent employed (i.e. the vent is stuffed as stated) which lowers the Q at the tuning frequency.
| quote: | | The frequency chart shows this box to provide a bit lower extension than GM's tapered TL. |
Yes, because it's tuned slightly lower. As you're intending to use a sub, there won't be much in it between the two boxes in practice.
| quote: | | ...what characteristics would it share with a transmission line? |
They share similar technical response traits & a reasonably flat impedance (which is the prime object of the classic non-resonant aperiodic TL). Just different (albeit related) ways of achieving a similar object. |
|
|
| GM |
| quote: | Originally posted by VanJerry
Thank you GM,
When you're mention you prefer the bigger....... |
You're welcome!
You asked about #3 Vs #2, so that's what I responded to. Even factoring in an XO that will limit all their BWs, the large one will still sound more 'full'/'relaxed' than the smaller ones due to its much greater acoustic efficiency. Whether or not it's enough to justify the cost in $$/space only the individual can decide.
GM |
|
|
| Kofi Annan |
| quote: | Originally posted by Nordic
Dang!, I realy wanted big horns. Even bigger than that is OK.
Room is 23 x 16 feet (5x7m) |
Yeah! How about a big horn / TL for the rest of us that want the 12 but can't afford none a your fancy subs.
Kofi |
|
|
| GM |
My 16 ft^3 TL example not have enough LF gain BW or big enough? Then maybe the ~18 Hz tuned 80.66 ft^3 BIB will somewhat 'flesh out' your sense of proportion and need to 'shake the rafters'. ;)
GM |
|
|
| VanJerry |
| quote: | Originally posted by GM
My 16 ft^3 TL example not have enough LF gain BW or big enough? Then maybe the ~18 Hz tuned 80.66 ft^3 BIB will somewhat 'flesh out' your sense of proportion and need to 'shake the rafters'. ;)
GM |
I propose a new DIYaudio greeting for BIB aficionados:
"My house is your cabinet."
-Jerry |
|
|
| VanJerry |
rough translation:
"And here is my music room."
But the picture posts a thousand words. |
|
|
| VanJerry |
| quote: | Originally posted by GM
You're welcome!
You asked about #3 Vs #2, so that's what I responded to. Even factoring in an XO that will limit all their BWs, the large one will still sound more 'full'/'relaxed' than the smaller ones due to its much greater acoustic efficiency. Whether or not it's enough to justify the cost in $$/space only the individual can decide.)
GM |
Thank you GM,
I thought the one other difference between the 2 smaller tapered TL's and Scott's is that I read tapering might be better at preventing errant internal sound from bouncing back out through the 12's rather large driver diaphragm.
While there is a resistive vent, Scott's is internally underdamped. But I could use a Matrix approach inside Scott's to offset this.
Am I close to being right?
And the transients would be about the same for either?
Jerry |
|
|
| GM |
You're welcome!
Well, it's true that ideally you don't want the driver to develop standing waves from any boundary, but we're dealing with well damped cabs here that aren't large enough to develop them at a low enough frequency (i.e. high enough amplitude), so it's a moot point.
Oh really?! Looks ~like a well damped prosound alignment to me. All he did was add enough stuffing density to make it semi-aperiodic (over-damped) to get a bit smoother response and lower F3 out of an acoustically small cab.
Either what? I mean I've built plenty of prosound alignment type cabs that Scott's mimics if you damp it like any other BR, but never stuffed them since in these apps acoustic efficiency is pretty much everything. If the various sims are accurate enough to allow direct comparison though, then the small TL is best with each larger size being less so for a given stuffing density since the impedance peak increases with increasing cab Vb, but if you increase stuffing density proportionately they will all be the same, so as I recommended awhile back, build the biggest cab you can 'afford' and then make it as 'tight'/'fast' as you can tell the difference via stuffing density.
Anyway, I'm down to repeating myself as you waltz around this one performance parameter that in the scheme of things is mostly moot unless you're planning to drive them with a high output impedance amp, in which case this would make the smaller cabs larger, so 'color' me done.
GM |
|
|
| Scottmoose |
| Right, although it's actually my fault here -the underdamping was in reference to the original box I'd had in mind, with a 6in diameter vent, similar to the existing CSA BR boxes. Pillock that I am, I completely forgot that I'd changed it, and the alignment, by shifting to a 3in vent diameter before posting, which ~follows a damped pro-audio alignment as you say. Must've been having a 'senior moment' a few decades early. As-is, the resistive vent & some of the internal damping / stuffing are optional depending on whether you want to completely flatten the first impedance peak & a theoretically inaudible amount of ripple. |
|
|
| udailey |
Hey Jerry,
I just downloaded an audio test cd last night and played it a few minutes ago. It goes from 16Hz to 20kHz in 44 steps. Let me get the link...
http://binkster.net/extras.shtml
Okay so you can go there and see what I am talking about. I played all tracks. Wow thats annoying. But it was neat to. I posted what I heard on another forum and here is what I said there:
"So, Anyway I just played the audio cd. Actually was sitting down to see what frequency I was listening to. I have to go to the guys site and get the TOC for the disc. Tracks 11-44 are frequencys and my Audio Nirvanas may have been producing track 44 but I couldnt hear anything. I could hear up to 43. They play all but 44. So as far as low end I get everything on the disc but at track 15 is when it really has authority in that tone. Tracks 11-14 play but is more like rushing air than a audio sound. When I cranked the volume a bit tracks 13 and 14 were more obviously there and 12 a bit but 11 is just the driver moving and pushing air but not me hearing much of anything. So I will be right back. I have to check what the frequency of those are...........................................................
Okay. Neat :) Looks like I can hear 16kHz. The ears are not failing me yet. I should go find some 17, 18, 19kHz. The driver is supposed to take a nosedive at 17kHz so I suppose that might not do me much good to try. Could test it on the Fostex I think though just to see what I can hear. Then we have
#11 16Hz
#12 20Hz
#13 25Hz
#14 31.5Hz
#15 40Hz
So the driver in the Bass Reflex box is producing 40Hz with authority and it specs state that the Fs is 37Hz I think. Lemme check.... Nope, I am wrong. The Fs is 33.8Hz. Pretty believable from what I just heard and it tries to go lower. It actually plays the 25Hz. Hmm, maybe I need to read up on what Fs is. My definition may be different than reality. I wonder if the BR enclosure is helping it get lower than its Fs. Guess it depends on how they tested it.
So there you and there I have it. I am satisfied :) That was cool."
So it plays something I can hear from 25Hz up but has authority at somewhere between 31.5Hz and 40Hz.
Uriah |
|
|
| VanJerry |
That's pretty cool Uriah,
And great timing, as I'm having to decide on enclosures now for the Super Cast 12. It's Fs = 36.427 - just a bit higher than the Super 12. Maybe this information you're reporting can mean something to GM and Scottmoose.
For a second till I visited the site I thought maybe #1-#10 were like 5Hz up... Gee, you might get flak on "hearing" 16Hz though - What does the unhearable sound like? :)
Yes, CSA made a point of having their BR's go to 40 with authority. However it's supposed to be the nature of a BR to enable that. The question then becomes: at what cost to quality? Apparently, not much in this case - you're quite happy with all the frequencies.
I was wondering, though, what would happen if you put damping in your vent? Have you tried that already?
Jerry |
|
|
| VanJerry |
| quote: | Originally posted by Scottmoose
Right, although it's actually my fault here -the underdamping was in reference to the original box I'd had in mind, with a 6in diameter vent, similar to the existing CSA BR boxes. Pillock that I am, I completely forgot that I'd changed it, and the alignment, by shifting to a 3in vent diameter before posting, which ~follows a damped pro-audio alignment as you say. Must've been having a 'senior moment' a few decades early. As-is, the resistive vent & some of the internal damping / stuffing are optional depending on whether you want to completely flatten the first impedance peak & a theoretically inaudible amount of ripple. |
Thank you Scottmoose,
I have to apologize to GM and yourself. I feel I've been tiresome in asking if there is any significant difference in sound quality between these options. I have to reveal that my sig other has claimed the right that if there is none she be allowed to have the smaller of the choices. So far that's GM's 1.8 cu.ft. TL.
The 3.5 cu.ft damped vent BR goes down a lot more than 80Hz. It delivers wonderfully on my original request that I be able to cross not just at 80Hz but even 60Hz if possible and I've always appreciated any difference in size this necessitated. It also seems the easier build for a 1st-timer - including messing with the vent damping by ear.
Only recently, after much reading, have I come to appreciate the value of relieving the driver, as GM describes it, of the majority of the high excursion BW when crossing closer to 80Hz. I feel I have no choice but to give up being able to cross my sub any lower than that. I was too idealistic about FR drivers... Or maybe "ignorant" would be the word.
That said, in post #151 after describing his 1.87 cu.ft. TL, GM said of the 3.5:
| quote: | | 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......... |
Before I place myself at the mercy of my spouse, may I ask about this possibility? Or whether it would be bad form to ask if, relieved of the requirement for a lower extension than 80Hz altogether, you would have originally preferred a different approach?
Jerry |
|
|
| Nordic |
| Kofi, it seems we will have to wait for someone to design nice horns for these things some day... I'm not sure 40Hz is going to do it for me, and I'm reasonably sure I do not want the adultaration, complexity and added cost of subs...yet. |
|
|
| udailey |
I never said I heard 16Hz :) I said I could SEE the driver and it is whooshing some air.
Here is what I said
" So as far as low end I get everything on the disc but at track 15 is when it really has authority in that tone. Tracks 11-14 play but is more like rushing air than a audio sound. When I cranked the volume a bit tracks 13 and 14 were more obviously there and 12 a bit but 11 is just the driver moving and pushing air but not me hearing much of anything."
Driver moving but me not hearing much of anything...
If you meant 16kHz then I would retort that I DEFINITELY hear 16kHzl. Without a doubt its there. TVs make a super high pitch when they power on. I have been able to hear that all my life. So I can walk in a house with the TV muted and tell if a TV is on. The old TVs anyway. The plasma doesnt make that noise.
Uriah |
|
|
| VanJerry |
I'm sorry, I just wanted to be the first to ignore your precise description that you in fact did not hear anything and give you a hard time for even mentioning anything below 20Hz - seems that was the custom at some speaker manufacturer's forums I've visited in the past.
...Personally, some of my favorite melodies are played entirely with whooshing air. (Will I be banned for saying that on DIYaudio.com? :) )
jerry |
|
|
| udailey |
When I hooked up the Fostex it will play 40Hz and above but obviously not with the authority of the AN. And I can hear the 20kHz but its hard to find it. I have to put my ear within a few inches and move my ear around a bunch til I find the frequency and then it hurts so I wont be doing any more of that.
I was frankly very suprised to have the Fostex play those notes but it did and this is on the FE127e, a 4.5" speaker. Now, I tried to go lower and it made noise but it seemed it was higher frequency than the 40Hz plus if you got your ear real close I could hear a high frequency in there that I suspect, and dont know for sure, that it was the voice coil rubbing. Just a guess but maybe not a good thing to do, maybe fine. I dont know about the mechanics of it and what is/isnt okay.
Uriah
BTW what I was hearing on 12 and 13 with the AN ( so this would be frequecies 20 and 25Hz may actually be noise generated by the air passing the ports. I have to go back and listen again, but the Fostex making a noise that seemed to be higher frequency than what was supposed to be playing on 11, 12, 14, 15 made me think to listen again to the AN and now suspect that it might be "port noise?" I dont know, like I said I have to listen again. |
|
|
| udailey |
Okay, so conclusion, kinda..
track 14 is definitely being reproduced just not at the volume that 15 is. So it is reproducing 31.5Hz and I can hear it for sure. When I go down to track 13, 12, 11 the speaker is flexing and when you increase the volume the reflection of the light off of the surround shows it almost flattening out. Its definitely moving a lot and if you put your hand on it you get slapped a bit. The sound, though, and its not the "port noise" I suspected... it seems higher pitch/frequency than what it is supposed to be. Maybe it is some artifact of the enclosure. I dont know whats going on. So the woofer moves like mad and I hear a tone but it just seems that the tone is higher than tracks 14 and 15. You will see what I mean when you get yours and maybe you can help explain it better especially if you have an spl meter or better yet a scope that can show if more than one frequency is being generated.
Uriah |
|
|
| rjbond3rd |
| quote: | Originally posted by udailey
So it is reproducing 31.5Hz... The sound, though, and its not the "port noise" I suspected... it seems higher pitch/frequency than what it is supposed to be. |
Hi udailey, the fundamental is "missing" but the overtones are still there. So you're hearing only the harmonics of the (missing) fundamental. Sometimes this is done intentionally.
If it's really high, maybe it could be bell resonance (where anything circular resonates at a tone where the wavelength = the circumference). That seems like a longshot though. |
|
|
| Scottmoose |
| quote: | Originally posted by udailey
Hmm, maybe I need to read up on what Fs is. My definition may be different than reality. I wonder if the BR enclosure is helping it get lower than its Fs. Guess it depends on how they tested it. |
Fs is just the free-air resonance of the driver. Depending on the design, you can go lower.
| quote: | Originally posted by VanJerry
Maybe this information you're reporting can mean something to GM and Scottmoose. |
Nothing that hasn't been known for the best part of 9 decades or so.
| quote: | | Yes, CSA made a point of having their BR's go to 40 with authority. However it's supposed to be the nature of a BR to enable that. The question then becomes: at what cost to quality? Apparently, not much in this case - you're quite happy with all the frequencies. |
True, I believe they usually tune their larger boxes to ~40Hz, although not everyone would necessarily agree with the way they go about it, or the advisibility of this with all their drivers. I certainly don't.
As for the quality question, depends who you ask, the design, circumstances & a myriad of other factors. Like any vented, back-loaded box, a BR cabinet reverses the phase of the output from the rear of the driver cone (that's why they're called phase inverting cabinets) & use that to provide more gain in the lower registers. There is a delay involved naturally, which can be audible or inaudible depending on the design.
| quote: | | I was wondering, though, what would happen if you put damping in your vent? |
You'll reduce cabinet output & lower the first impedance peak.
| quote: | ...I have to reveal that my sig other has claimed the right that if there is none she be allowed to have the smaller of the choices. So far that's GM's 1.8 cu.ft. TL.
Only recently, after much reading, have I come to appreciate the value of relieving the driver, as GM describes it, of the majority of the high excursion BW when crossing closer to 80Hz. I feel I have no choice but to give up being able to cross my sub any lower than that. I was too idealistic about FR drivers... Or maybe "ignorant" would be the word. |
No. Many users of FR units are quite happy with them run full range, with no support. Fine for some types of acoustic music for e.g., especially if you don't crank the volume up, but not ideal for your use.
| quote: | | Before I place myself at the mercy of my spouse, may I ask about this possibility? Or whether it would be bad form to ask if, relieved of the requirement for a lower extension than 80Hz altogether, you would have originally preferred a different approach? |
I'd build GM's TL, if I wished for this sort of system & couldn't go bigger. However, since you ask about a smaller / higher tuned aperiodic box, for interest's sake, you could use the standard 2.8ft^3 CSA cab., with a 6in diameter x 2.25in long vent. Stuff a la a TL with ~0.8lbs ft^3 of material & stuff the vent too (same density), with a grill of some sort at each end to keep the damping in. See attached.
| quote: | Originally posted by Nordic
Kofi, it seems we will have to wait for someone to design nice horns for these things some day... I'm not sure 40Hz is going to do it for me, and I'm reasonably sure I do not want the adultaration, complexity and added cost of subs...yet. |
GM's BIB not nice enough for you? |
|
|
| Scottmoose |
| I wouldn't make too much of the comparisons if you're comparing a 4 1/2in FE127E to a 12in AN. ;) |
|
|
| udailey |
| quote: | Originally posted by rjbond3rd
Hi udailey, the fundamental is "missing" but the overtones are still there. So you're hearing only the harmonics of the (missing) fundamental. Sometimes this is done intentionally.
If it's really high, maybe it could be bell resonance (where anything circular resonates at a tone where the wavelength = the circumference). That seems like a longshot though. |
Thanks RJ I appreciate the explanation. No its not really high just higher than, for instance, the 31.5Hz which is clearly audible so I knew something was amiss with the others below that.
Uriah
That tone/circumferance/wavelength is interesting. Audio waves do some weird things. |
|
|
| udailey |
| quote: | Originally posted by Scottmoose
I wouldn't make too much of the comparisons if you're comparing a 4 1/2in FE127E to a 12in AN. ;) |
Much less a comparison and much more just "I have this nifty disc now lets see what the speakers I own will do."
Uriah |
|
|
| VanJerry |
| quote: | Originally posted by Scottmoose
I'd build GM's TL, if I wished for this sort of system & couldn't go bigger. However, since you ask about a smaller / higher tuned aperiodic box, for interest's sake, you could use the standard 2.8ft^3 CSA cab., with a 6in diameter x 2.25in long vent. Stuff a la a TL with ~0.8lbs ft^3 of material & stuff the vent too (same density), with a grill of some sort at each end to keep the damping in. See attached.
|
Thank you kindly, Scottmoose.
Last, about stuffing:
I know for BR you actually line the sides with varying thickness between say, an inch or two. By a la TL stuffing do you mean where stuffing is fluffed out and evenly dispersed and it's dense enough to stay where it is - perhaps in a larger cab with the help of bracing? Would this density of stuffing make Matrix bracing unnecessary?
jerry |
|
|
| Scottmoose |
Yes. Stuff the thing as per the density mentioned. Which will damp down almost the entire BW. This assumes hollow-fibre stuffing like dacron BTW.
As for bracing, bracing is to help control panel resonances, rather than internal, so they go hand in hand. |
|
|
| VanJerry |
I forgot Scottmoose, before I leave you alone for a while,
Will these need a baffle step correction? Or is that standard these days as long as not a bipole, regardless of cab?
Jerry |
|
|
| Scottmoose |
Depends where you put them, and the amp used.
In free space, expect a -3db frequency through step-loss at 314Hz, which is about right to ~start blending into room gain, especially if near a rear wall. TBH, I doubt you'd need any. |
|
|
| VanJerry |
Great.
Thank you. |
|
|
| Kofi Annan |
| quote: | Originally posted by GM
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 |
I see... so this is really a BIB, right?
I'd need to fold this mother as I have 8' foot ceilings and a 7' BIB with an open terminus at the top would likely cause acoustic / aesthetic / marriage issues.
I've managed to find this, courtesy of Godzilla, so I'm assuming this would be the way to get the 24" x 14" x 42.75" dimensioned model.
I'll need to figure out how to dimension the folds to keep the 85.468" L, so any shove in theright direction would be appreciated.
Lagging behind as usual...
Kofi |
|
|
| VanJerry |
Scottmoose or Anyone?
I've been thinking about 3.5 ft^2 giving a more relaxed realistic sound. It's been suggested to me I be better off with the larger BR than the 2.8.
using standard 3/4 in. material, the Commonsense's regular 2.8 ft^2 box is 39in. Tall x 14.5in. Wide x 12in. Deep
For WAV's sake I would have wanted to keep the Width the same and increase height and depth to accommodate any larger volume. Height would also help bring the AN 12's center closer to ear height - as Udailey did with his pedestals.
I'd rather not go above 42in tall, but at 42T x 14.5W x 13D (which gives 3.5 ft^2) the depth is approaching the width.
Question: I recall reading that equal dimensions is a no-no. Is 14.5 x 13 approaching a square enough to be a problem? If so I can make it 15 x 13 or kick the height up some more.
Jerry |
|
|
| Scottmoose |
Methinks you're having a problem making your mind up.
When we say reflex, are we talking reflex or aperiodic?
Square dimensions are not ideal, but it depends how much damping is in the enclosure. Both of the examples I did assumed a fairly reasonable quantity of damping / stuffing so it's not going to be much of an issue. Undamped or more lightly damped, it starts getting to be a problem. |
|
|
| VanJerry |
Hi Scottmoose,
I wasn't clear.
No, I was referring in both cases to your very own damped vent semi-aperiodic BR. The original as suggested being 3.5 ft^2 and the more recent smaller version being 2.8 ft^2. The thing is that someone who's advice I hold in esteem emailed me that the original 3.5 ft^2 would appear hardly any larger than the 2.8 ft^2 but be worth the sound quality.
I started to mess around with some dimensions. I felt I could go as visually tall as 42in. which would also improve the driver center ear height. (44in. would be better but too visually imposing as seen from the front.)
For WAV the dimension I could play with the most was depth but I was concerned about approaching a square section - hence my question.
Actually, I would like to take this opportunity to ask if significant sound comes out of these semi-aperiodic damped vents? I'm asking on behalf of the Center.
I've attached 2 possible configurations for a 12in. center based on the 2.8 ft^2 volume with one 6in. aperiodic damped vent. I'd like to be able to use "Center A" which is much deeper than it is wide allowing a smaller front face.
Jerry |
|
|
| GM |
| quote: | Originally posted by VanJerry
I'd rather not go above 42in tall, but at 42T x 14.5W x 13D (which gives 3.5 ft^2) the depth is approaching the width. |
'Circling the drain' of indecision are we? ;)
Rearranging the larger of my two TQWTs (~4.066 ft^3) yields a 14.875" depth and enough bottom end 'bloom' to probably not need any BSC:
GM |
|
|
| Scottmoose |
Bingo. :)
Re output from an aperiodic cabinet of any description, by nature, it's extremely minimal. |
|
|
| Nordic |
No man Scott, we look up to you for clever designs.
Any chance of a metronome with these drivers?
Or is there a specific quality to these drivers that only make them suitable for those sqaure coffins? |
|
|
| VanJerry |
| quote: | Originally posted by GM
'Circling the drain' of indecision are we? ;)
GM |
| quote: | Originally posted by Scottmoose
Bingo. :) |
Not sure quite how to take that. |
|
|
| VanJerry |
| quote: | Originally posted by GM
Rearranging the larger of my two TQWTs (~4.066 ft^3) yields a 14.875" depth and enough bottom end 'bloom' to probably not need any BSC:
GM |
Thank you GM,
I appreciate that tweak. But I've had a few thoughts on my way around - or down - the drain. :)
Scottmoose doesn't believe BSC will be an issue in his design, especially with wall reinforcement - which I would expect to have in (over) abundance due to the small room:
| quote: | Originally posted by Scottmoose
In free space, expect a -3db frequency through step-loss at 314Hz, which is about right to ~start blending into room gain, especially if near a rear wall. TBH, I doubt you'd need any. |
When I was considering the helper woofer direction for HT earlier I grappled with the fact that I might underestimate the room gain for my small 11x15 basement room. I must say, I've simply never purposely sought to own anything but flat response speakers in the past. And then most recently, I learn from Udailey that the AN 12 inch class have ample - if not alarming - authority in the LF.
So, while an even elevation across the whole bottom end could be desirable for HT I find myself both tempted and timid at the prospect of a more concentrated and isolated bump below 200Hz. One that I fear may actually accentuate the slight dip I see between the critical 200-300Hz in this case - which itself may be accentuated by any step-loss from 314Hz not improved by room gain. I would feel safer at a broader bump that spanned closer to 300Hz, but I gather that's not how TL's work.
I've begun to appreciate the role lack of experience has in this decision making process. I am certainly guilty of having proposed some wild schemes over the course of this thread. The fact is all but the bold operate from knowns. In my case what I know has never included a bump. And I will have 3 x 12in drivers in the small room, with another 2 x 8in, so I think I prefer not to add any further complexity than what I will face with room gain. In the worst case scenario what I planned to use is appropriately sized hinged baffle extensions on either side of the towers that would be folded away when not in use. And if that's not enough, the addition of bipolar with cast 8's augmenting each 12. Because by then I will have already begun to look like Nordic's avatar. ;)
The other aspect that appeals to my inexperienced self is that the 3.5 ft^2 aperiodic damped vent BR provides some flexibility to go lower. Scottmoose has told me that the issue of running these drivers FR may not be so terrible except for HT (I presume at higher volumes.) So this design would allow me to better experiment with what kind of sub crossover I might like for music and lower volume HT and basically help me define the envelope of these AN cast 12's.
Jerry |
|
|
| Scottmoose |
| quote: | Originally posted by Nordic
No man Scott, we look up to you for clever designs.
Any chance of a metronome with these drivers?
Or is there a specific quality to these drivers that only make them suitable for those sqaure coffins? |
You're in trouble then if you think muggins here is a source of clever design...
AN12CF metronome? Easy enough if you have the space. 60in tall, So = 6in x 6in square, Sl = 20in x 20in square. Zdriver 30in. Vent in centre of the base, 4in diameter x 1in long. Stuff from the top 35in down, 0.5lbs ft^3 of dacron or similar. Another quasi prosound alignment to keep the LF damped -I doubt they'll be lacking. |
|
|
| rjbond3rd |
| Pardon my intrusion, but may I ask what a prosound alignment is? Thank you in advance! |
|
|
| VanJerry |
| quote: | Originally posted by rjbond3rd
Pardon my intrusion, but may I ask what a prosound alignment is? Thank you in advance! |
At least based on my earlier research to understand the reference:
|
|
|
| rjbond3rd |
| Ah, thank you VanJerry. I got to meet Wayne a few months back (Lone Star Audio Fest) and he is an incredibly friendly guy with some very cool-sounding speakers. Brighter, beefier and they could play really loud, but very different from the single driver "midrange magic" fetish. Thank you for the link! |
|
|
| Scottmoose |
| quote: | Originally posted by VanJerry
Scottmoose doesn't believe BSC will be an issue in his design, especially with wall reinforcement - which I would expect to have in (over) abundance due to the small room. |
I have to point out here that neither would GM's original TL for that matter.
| quote: | | The other aspect that appeals to my inexperienced self is that the 3.5 ft^2 aperiodic damped vent BR provides some flexibility to go lower. Scottmoose has told me that the issue of running these drivers FR may not be so terrible except for HT (I presume at higher volumes.) |
Eh? Where did I say that? You need to keep in mind the context in which remarks are made.
Some (quite a lot) of people find FR drivers, especially large ones, OK for their needs sans any support, particularly at lower volume levels & on relatively undemanding material. But certainly not everyone, and as already mentioned, there are some types of music that are far more demanding than HT can be, particularly in quality terms. |
|
|
| VanJerry |
Hm... maybe brighter, beefier, play really loud is what Scottmoose had in mind for a HT purposed single driver! Sounds about right. And thank you for that bit of info, rjbond3rd.
jerry |
|
|
| Scottmoose |
| Yes, although FR units are not generally the first type of driver that comes to mind if you want bright, beefy & the ability to blow your walls out. The larger units & the odd exception like the Babb drivers get as close as you're likely to get IMO, given the somewhat conflicting requirements of trying to do all that with a single cone. FR drivers typically have a somewhat different set of priorities to units with a narrower operating BW. |
|
|
| VanJerry |
| quote: | Originally posted by VanJerry
Only recently, after much reading, have I come to appreciate the value of relieving the driver, as GM describes it, of the majority of the high excursion BW when crossing closer to 80Hz. I feel I have no choice but to give up being able to cross my sub any lower than that. I was too idealistic about FR drivers... Or maybe "ignorant" would be the word. |
| quote: | Originally posted by Scottmoose Post #322
No. Many users of FR units are quite happy with them run full range, with no support. Fine for some types of acoustic music for e.g., especially if you don't crank the volume up, but not ideal for your use.
|
Which I took to mean not ideal for HT. But if OK for some music - not cranked up, I extrapolated to include some low volume HT as in "girl movies" which I get a lot around here and actually appreciate ...most of the time. :)
And keeping context in mind, I must say again, that I rarely play music loud at all. The loudest would be action movies and I'll bet though it seems loud to us, not half as loud as most would consider moderate.
However, that is me, and it's true - my comments may seem to misrepresent you Scottmoose - to the more typical user.
-jerry |
|
|
| VanJerry |
That someone would be Scottmoose again I would expect.
Hm... That's only about 5.9ft^3 for the Cast 12.
The Super 12 was 7.67ft^3 - quite the difference. |
|
|
| Nordic |
| The dimentions for the cast 12 seems to have alot of even lenght sides i.e. 6x6 and 20 x 20, isn't this supposed to be "bad"? |
|
|
| VanJerry |
| Not if the the sides are all part of a tall pyramid - no parallel surfaces here. (except the bottom and tiny top.) Neat, huh? |
|
|
| Nordic |
Grin, I like it when I get a firm Idea of what I want and find something that is pretty close :D.
I see there is a Partition running down the centre, is this from front to back? i.e. two side by side open top and bottom pyramids?
About the AN-12's, I see the cast frame does not go so low... what is gained in exchange for it giving up the few Herz before the smaller models and non-cast 12"? |
|
|
| planet10 |
| quote: | Originally posted by Nordic
I see there is a Partition running down the centre, is this from front to back? i.e. two side by side open top and bottom pyramids?
|
Not a partition, holey driver brace. For abox that size you'll need side-to-side bracing too... i'd suggest pairs of braces near the bottom.
dave |
|
|
| Nordic |
| Thanks Dave, I'm quite mechanicaly inclined, will keep your suggestions in the back of my head. |
|
|
| Scottmoose |
| quote: | Originally posted by Nordic
The dimentions for the cast 12 seems to have alot of even lenght sides i.e. 6x6 and 20 x 20, isn't this supposed to be "bad"? |
Ever see a cone? ;) Well, this is a (mass loaded) conical horn.
| quote: | | About the AN-12's, I see the cast frame does not go so low... what is gained in exchange for it giving up the few Herz before the smaller models and non-cast 12"? |
Grand total of 3Hz in free-air resonance. Assuming the published specifications are correct. I wouldn't get too worked up about it. For a start, you're excessively unlikely to hear it. Then, 3Hz is well within typical sample variability. And finally of course, it's free-air resonance. How low in practice it will go depends on the cabinet.
I see you've added the dimensions to the Metronome Table Dave... that was fast. :) |
|
|
| Nordic |
| How do I work out the lenght of the feet part that extends past the bottom...? those bits with the curves cut out... |
|
|
| Scottmoose |
| Imagination. It's not overly critical. 2 - 3in should do it. Steve set the original so that their CSA ~ =Sl. |
|
|
| planet10 |
| quote: | Originally posted by Scottmoose
I see you've added the dimensions to the Metronome Table Dave... that was fast. :) |
:D |
|
|
| Nordic |
| Thanks, I see, if I convert the ratio used in the examples given it works out to 74mm i.e. 3 inches... |
|
|
| planet10 |
| quote: | Originally posted by Nordic
How do I work out the lenght of the feet part that extends past the bottom...? those bits with the curves cut out... |
They aren't even necessary if you run the port out the front, back or sides...
dave |
|
|
| VanJerry |
| quote: | Originally posted by Nordic
About the AN-12's, I see the cast frame does not go so low... what is gained in exchange for it giving up the few Herz before the smaller models and non-cast 12"? |
Hi Nordic,
This is what Commonsense tells me:
"Subjectively, the Cast 10 and 12 have more extension, a more 'open' midrange, and better control and precision."
"The Cast Frame 10 and 12 were a total redesign. Frankly, I was expecting about the same 10% improvement that we got with the Cast 8 over the Super 8. But, if I were to quantify it, I would probably estimate the improvement as more like 25 to 30%."
jerry |
|
|
| Nordic |
Thanks...
the numbers on their site makes the smaller drivers seem more appealing, I knew there had to be more to it, to even make this a viable seller...
The Audio Nirvana 'Super 12 Cast Frame' has a frequency response from 36 hz to almost 20,000 hz.
The Audio Nirvana 'Super 12' has a frequency response from 33 hz to almost 20,000 hz.
The Audio Nirvana 'Super 10 Cast Frame' has a frequency response from 34 hz to almost 20,000 hz.
The Audio Nirvana 'Super 10' has a frequency response from 36 hz to almost 20,000 hz.
P.S. Will someone please tell this guy that it is Hz not hz....
These come close to my current two ways as far as FS is concerned, going from low 30's to where ever a 70's japanese silkdome tweeter goes to. |
|
|
| Nordic |
What level of fudge factor is there with the actual dimensions?
I.e. will a few mm diffirence to the top plate make a big diffirence?
Just trying to make something that can actualy be dialed in on a saw, like 83 degrees as opposed to 83.34.
I guess one could also alter the height by a few mm
Edit:
Scrap that idea... seems it makes a huge diffirence in dimensions.
Angle = 83.34
Hypotenuse Side =1534.7825
Opposite Side=1524.4256
Changeing the angle to 83, would reduce height to 1449.6937 from 1524.4256 i.e. 3 inches |
|
|
| VanJerry |
Have you considered posting these pretty specific questions on The Metronome thread?
It sounds like a great project to contribute to the Metronome family.
Jerry |
|
|
| Nordic |
Lol, well I guess, but it is also relevant here as it is a possible enclosure specificaly for the AN12 Cast frame... :D
Going by Dave's dimensions it is pretty huge, I guess I can tick one item on mylist of requirements
 |
|
|
| VanJerry |
Oh, of course. I just know all the various builders of the Metronome are there, that's all.
The Metro box for the Super 12 was big for me. So I had been looking at the Metronome as a serious option for the Cast 10. It's curve is also amazing. Now that the dimensions for the Cast 12 are out and smaller it is, to my mind, a killer combination if someone would like the option of not using a sub.
Go for it! The looks are outstanding for a 12in too. Very harmonious.
Jerry |
|
|
| GM |
| quote: | Originally posted by VanJerry
Thank you GM,
....I grappled with the fact that I might underestimate the room gain for my small 11x15 basement room.
In my case what I know has never included a bump.
And I will have 3 x 12in drivers in the small room, with another 2 x 8in.......
The other aspect that appeals to my inexperienced self is that the 3.5 ft^2 aperiodic damped vent BR provides some flexibility to go lower. |
You're welcome!
Since higher SQ comes from attenuating too much acoustic gain Vs boosting too little, best to always underestimate the acoustic gain BW needs if you don't have an acoustic map of the room to design ALL your speakers to best blend.
As for the 'bump', all else being equal it's the byproduct of a shorter tuning length, so if it's too much, just bleed it off as required by either gapping the driver away from the baffle or a bleed hole in the top rear.
As for your 'small' room, it's bigger than the one I'm typing in, though down low, a basement will typically yield more gain for a given BW below where the room gets 'on the pipe' so-to-speak, i.e. ~565 ft/longest dim = 36.67 Hz in your case. Above this point there will be boundary gain of course, so how close to a boundary or corner will decide how much of the speaker's roll off BW gets boosted at what gain curve.
Obviously, putting form fitting triangular cabs in the corners yields the most and if along a wall the cab needs to be as flat as practical for best results, so your need for narrow baffles pretty much dictates they be well away from any boundaries for best blend which in turn dictates a sub system if you can't get them ~maximally flat at the listening position down to ~36.67 Hz.
Hmm, at least WRT the mains in a HT app (and in theory each surround channel), each channel has to be designed in isolation due to how the signals are encoded/decoded, so driver requirements are based on SPL and directivity, ergo your driver complement may be anywhere from overkill to woefully inadequate. Since you've yet to put any numbers on your alleged lower than average listening levels there's no way to know where your proposed selections slot in.
Yeah, the stuffed BR does allow for more tuning flexibility as long as you keep the vent reasonably small/short as a baseline, though you can add a vent at the bottom of a TQWT, so a moot point IMO. The BR is potentially a slightly easier build from a panel angle cutting POV though depending on several variables.
Another factor you apparently haven't considered is how we perceive loudness WRT comfortable average/peak levels. The old C-V marketing mantra I use for a signature tells it all 'in a nutshell': Loud is Beautiful if it's Clean! in that the lower in distortion a system is, the louder we tend to listen at, so while a ~62 dB/listening position average is a plenty loud enough SPL sitting here listening to music or a movie through a POS soundcard coupled to a similar SQ computer sub/sat system is at least 85 dB when in the living room through a vanishing low distortion system to get a similar perceived performance, albeit a wider LF gain BW one.
This latter point is very important when considering lower average SPLs in that due to our acute hearing gain curve we must boost the LF, treble BW (AKA 'loudness' control) to compensate, so each channel's low distortion gain BW becomes increasingly important, increasing the potential need for a sub and treble system, not reduce it.
Bottom line, it's always best to design/build the most efficient system practical for your various $$$/size/whatever 'budgets' and if you don't need it all, it just means you get to enjoy an even lower distortion system than predicted, firm in the knowledge that if you ever get a 'wild hair' or just want to impress, you can. I mean how often in the USA (and increasingly around the world) can a Ferrari or similar car owner take advantage of even a sizable fraction of its performance potential other than on a closed course racetrack?
GM |
|
|
| just a guy |
| quote: | In my case what I know has never included a bump.
|
Chasing a perfectly flat frequency response curve is pretty pointless. Sometimes good enough is good enough.
Not sure if you realize this, but the acoustics of ANY room are going to chop up your pretty graph anyway as soon as the speaker is used in an actual physical room. You are worried about a tiny bump, but when placed in room, the reponse at listening position could have +/- 20 db peaks and dips.
For example, take a picture of your perfect response curve and let a 3 year old draw on it a bit. Then it will look a bit more like in room response. |
|
|
| Kofi Annan |
Nordic already beat me to it, but...
Yes. These are nice and big. They will be mine.
Kofi |
|
|
| planet10 |
| quote: | Originally posted by Kofi Annan
Yes. These are nice and big. They will be mine.
|
|
|
|
| VanJerry |
MetroPicasso
...Picassonome?
...with a Dali twist. |
|
|
| Nihilist |
Funny how after 372 posts and MUCHO bullsh**, we've finally come around to what I've been trying to say from the beginning.
I recommended to build the biggest , most efficient sealed system that VanJerry could tolerate. It would provide the best transient respone, the best quality sound, and the easiest build.
Gee, I guess there is something to K.I.S.S. :dead:
VanJerry, my recommendation is that you stop looking at the CPU , as this will just delay your "Nirvana" .
Just Build it already . . . . .
.......................................Blake |
|
|
| Scottmoose |
| He isn't building a sealed box. |
|
|
| VanJerry |
| quote: | Originally posted by Nihilist
VanJerry, my recommendation is that you stop looking at the CPU , as this will just delay your "Nirvana" .
|
I ordered 3xCast 12's and 2xCast 8's today.
But what is "CPU"? |
|
|
| VanJerry |
| quote: | Originally posted by just a guy
Chasing a perfectly flat frequency response curve is pretty pointless. Sometimes good enough is good enough.
|
Practically speaking, I have to agree. To be honest, I've been caught grabbing at bumps :) because, when the hard information is reviewed, I feel there really is little upon which to base an informed decision except for what I mentioned and that Scottmoose's enclosure allows me more experimental flexibility - to, I suppose, better understand some aspects first hand. In short, I may not as yet deserve a choice. But I know in building the damped vent BR I can see ways I can earn this.
In fact, by careful design of bracing I can include the option of inserting a slanting divider and using the same box to try a smaller tapered TL similar to GM's. (I would use only screws and removable seals in this case.) I can even use the 3.5ft^3 to try Nihilist's true sealed.
I can compare all these. And learn.
Jerry |
|
|
| Nihilist |
"I ordered 3xCast 12's and 2xCast 8's today.
But what is "CPU"?"
Good for you ! ! ! ! Happy building !
CPU is "central processing unit" , or short/slang for computer.
I like your idea of the transformable cabinet. Should provide some insight.
................................Blake |
|
|
| Scottmoose |
| Does sound like a good plan doesn't it. Getting the seals right will be the hardest part I reckon, but not an insurmountable issue. |
|
|
| udailey |
"In fact, by careful design of bracing I can include the option of inserting a slanting divider and using the same box to try a smaller tapered TL similar to GM's."
THAT is a neat idea :)
Uriah |
|
|
| Scottmoose |
Got there in the end, mmm? ;)
Well, sort of. You've got to build & listen & experiment & listen &... yet.
Still, that'll be easy after this. :D |
|
|
| VanJerry |
Aye,
I'll use blue tack as my removable glue/seal. |
|
|
| Nordic |
I have been converting the measurements to actual sizes of cuts,
Looks like it is going to eat plywood.... to the tune of $150 per speaker, with lots of left overs
I looked at another way of cutting them (to the same dimensions), but it is difficult and would probably need some big saws, this would produce 2 full sides and 2 half sides (which can be joined down the centre, which should get both drivers out of the $150 worth of plywood (3 sheets 2440x1220mm), with enough scraps for a subwoofer or some mini monitors left over. |
|
|
| Kofi Annan |
| quote: | I have been converting the measurements to actual sizes of cuts,
Looks like it is going to eat plywood.... to the tune of $150 per speaker, with lots of left overs |
We may want to break this out into a separate thread to not pollute this one, but I have plans to make a pair as well and would love to see your cut plans.
How were you planning to perform the cuts? I'm thinking a circular saw and a guide would work as I have the equivalent of a Fisher Price table saw. Also, the semicircular cutouts on the bottom to form the feet would be a challenge for me. Any advice on that?
Kofi |
|
|
| Kofi Annan |
Here's my version of measurements...
Kofi |
|
|
| udailey |
| I think the semicircular cuts are for looks. You could just put some pegs on each "leg" to make the contact with the floor a little smaller and more direct. |
|
|
| Nordic |
Yep I would make the arch space as big as possible in order for it not to act like a second port restricting the first.
My boards come in 1220x1440mm, which is a bit of a mismatch
It has to first be cut down to 1220 x 1646mm, the top an bottom (short sides then need to be shaved at angle just shy of 2,1:18.
I will use mittred angles, wich makes one side of the cut panel wider than the other, the lower side of the shaved top and bottom is always on the wide side.
I would start the first panel as the line running from top to bottom through the centre of a panel, so the first cut would be half of a side, this cut is done at 45degrees front to back and will be the side of the next headless pyramid witch fits in inverted next to this cut, so from the same board the panels cut next to each other will be face, rear, face, rear., this takes care of the tops and bottoms being angled correctly also...
Our first panel was only half a side, the second one you mark out can be a whole side, as can the third, the forth one will only leave enough space for half a panel again, So you can get up to three sides out of one board
My sketch has some rectangular blocks used as spacers to get the measurements right, I am starting to like the look of this band down the centre, it also shows the cut off piece on the top of the main board |
|
|
| Nordic |
| I attach the sketchup file for closer inspection... |
|
|
| Nordic |
Lol, I seemed to have stunned you into silence :rolleyes:
Question.... anything to be gained (or lost) from non parallel top and bottoms? |
|
|
| VanJerry |
Hi All,
I had wanted to jump right into the next phase: plans and building ...but I'm spending a little more time reading about baffle size and diffraction issues than I expected. Interesting stuff.
However I didn't want to leave it hanging unsaid that I'm grateful to everyone who has helped me get this far.
Over the course of this thread you have allowed me to remain authentic to my fledgling sense of direction. It may have cost you all extra time and patience but I think that says a lot about this DIYaudio forum community and its culture of ethics, high standards, and understanding.
So I think this thread has done more than chronicle the pursuit of one solution. It's also provided a good demonstration of the kind of effort you are willing to make to allow others to evolve their knowledge and hold on to their vision. And that's a good combination for everyone here both new and old.
Jerry |
|
|
| Nordic |
How are you progressing?, please keep us posted and motivated with construction pics....
I started thinking the large 'nome just looked too gothic. Ended up adding a rounded rear wing (gonna be hard but I once made a rococo chair), I'll probably fill this with sand to avoid resonance and to provide braceing to the inner panel. And a nice clip on grill. |
|
|
| udailey |
I was reading that grills add dips in your frequency/spl curve. That was in this months AudioExpress magazine.
Uriah
BTW those look really cool |
|
|
| planet10 |
| quote: | Originally posted by udailey
I was reading that grills add dips in your frequency/spl curve. |
It usually isn't the grill material themselves, but the grill frames that cause the problem. It is tricky to do a grill that doesn't get in the way but it is possible.
dave |
|
|
| VanJerry |
| quote: | Originally posted by Nordic
How are you progressing?, please keep us posted and motivated with construction pics....
I started thinking the large 'nome just looked too gothic. Ended up adding a rounded rear wing (gonna be hard but I once made a rococo chair), I'll probably fill this with sand to avoid resonance and to provide braceing to the inner panel. And a nice clip on grill. |
Hi Nordic,
I've been thinking about what is making it look gothic - or at least what we loosely call gothic. To me it's two things which are mutually reinforcing though happening at a subtle level.
First, adding elements of a strong curve approaching a 180 "U" to tapering straight lines in the design. Combining such curves with converging straight lines is a Victorian aesthetic. Sticking with just straight lines has helped the converging lines of the Metronome seem more contemporary perhaps unconsciously borrowing on the crystalline motif.
Combining 180 curves with parallel straight lines avoids this. But the Metronome is defined by it's vertical convergence in both form and function.
Second, the prominent parallel top and bottom in an otherwise converging vertical theme. Tall and thin dominates most other Metronomes allowing the more distant parallel tops and bottoms not to compete for our attention as much. When the top and bottom are compressed as in the 12 inch variation it not only brings these two surfaces closer together, it also lessens the clear aesthetic dominance of the vertical taper. And it is a shape we associate with "gothic" being a common Victorian motif used in architectural roof shapes as well as stone tombs and monuments.
During my analysis it occurred to me that the conventional converging straight line Metronomes could look even more contemporary in a clean and energetic crystalline sense by adding a faux top. Still parallel internally to the bottom in keeping with it's function. But externally with a cosmetic slant upwards from front to back or tilted from one side to another or something organic in between. We find crystals pleasing and this is how many naturally terminate.
However, I do like the large and more gentle visual curve you've added using contrasting color and value. I think the benefit it conveys is to somewhat harmonize or bridge the two effects I've described. But to me it just needs a little help to overcome them. This visual curve would be completely effective if either the top surface were rounded (preferably in an arc vs a large radius edge) or if the rear curve were less prominent. (Perhaps less than 90 degrees.) I'd imagine such a modified rear curve would still help with box regidity, internal reflections and rearward wrapping external diffraction if these were it's functions.
Jerry |
|
|
| Nordic |
Thanks, yes I did try to round the tops, but hit a brain fart, figured out how to do it properly afterwards(was a long time since I did technical drawings at school), I did figure out lots of hidden thingies in sketchup now. Will add the curve later, but it iis going to be even harder to make... the current curve can be made by cutting grooves from top to bottom.
At the moment I listen to music with the covers off, but it is nice to put them on if you have guests over... |
|
|
| Nordic |
| I am worried about the angle of the driver.... It seems to be an afterthought in the whole design, in the 12" cast AN metronome, they are slanted backwards/upwards at just under 7 degrees. At my listening position about 4m away, that means they are pointed up by almost half a meter from the centre of the driver. |
|
|
| Scottmoose |
| No, it's not an afterthought. Like the Cain & Cain Abby, where the driver is also mounted on a sloping baffle, Metronomes are not intended for a listening distance much over ~ 8 - 10ft. They're meant to be used in the nearfield, or for relatively close listening, in modestly sized rooms, where the tilt (in the case of the larger designs) places the listener slightly off-axis, & thus compensates for the naturally climbing FR that many FR drivers, including the AN 12in CF have over ~1KHz. If you want to sit further away from them, & you feel that having the driver angled in this way would bother you in your situation, then I suggest you build something else, or modify it to your own taste. |
|
|
| Nordic |
Lol, they are so pretty I could place them anywhere, but wireing may become dangerous...
If you have have any specific project in mind (even one of your own), I would appreciate it if you drop me a mail.
I am limited to a similar budget +-$250/set of drivers... (from no claims on insurance policy for 4 years) I have a few unused tweeters here, if something like that is needed
I'd like some bass down to AT LEAST the 30s, my current "woofer" has an FS of 30Hz and is only 84db/w, and that is more than enough bass for the melow stuff I listen to mostly.
I have yet to move so I don't know if my current speakers are up to the larger room... but here they go low enough.
the new room is 5m x 7m (from memory) and the roof I guess is about 2.3 to 2.4m high |
|
|
| VanJerry |
Hi Scottmoose,
I noticed you like a good wave launch...
Well, the internals have been established: the drivers, category of enclosure and volumes. Now it's the externals: allowing me to deal with aesthetics and selecting an outer form that best augments what I have on the go here.
After a lot of reading about baffle step and diffraction I've decided to go wide and shallow.
I'm particularly looking forward to the benefits this will give me in the areas of wave launch and to handle enough baffle step loss to meet room gain. I think these benefits will be particularly useful in HT (adding weight, realism and dimensional solidity as well as helping my speakers couple with my smallish room.) I also fancy the look and turns out my wife does too.
I figure 20 inches wide is a minimum. Might swing 22" or better with a curvy WAF shape.
I'd be willing to go semi-elliptical a la PMS (Poor Man's Stradivari.) But in all my reading I haven't come across whether this would be wasted on how a large full range driver is more directional. In which case I'd be just as well off with a truncated pyramidal baffle as Planet10 has described. Either way, I wasn't sure how shallow I can go with a 12 inch FR in terms of internal reflection. Or alternatively need to go in terms of external diffraction.
I think this would be an interesting project to contribute: I don't think anyone has made a single large driver interpretation of a Strad. Well - more of an Eclipsa really. Perhaps I am acting on the fondness I had for the Sonus Concertino's I once owned in my formative years. They were my one organic emotional experience in audio. [sniff]
I'm off on a camping trip for a few days but I thought I shouldn't wait till I got back to ask.
Thank you,
Jerry |
|
|
| planet10 |
| quote: | Originally posted by VanJerry
I don't think anyone has made a single large driver interpretation of a Strad. Well - more of an Eclipsa really. |
Both Demetri & Mileva are in this vien. They would only need fancy cabinet work...
Even with a full-range the wider cabinets don't seem to dissapear as well as their narrow heavily champhered counterparts. EnABL experiments are on-going to see if that can remedy the issue.
dave |
|
|
|
