With respect to the slot vrs cyclinder: In theory, there is no difference between theory and practice. But, in practice, there is.
dave
dave
Expanding on what Dave wrote -there is and isn't. The vents behave in more or less the same fashion until the aspect ratio of a slot increases sufficiently for the friction to start damping the alignment (in effect adding acoustic resistance).
Agreed 95db is loud but most music is transient and the sound level varies as much as 20db. When I meant 95db I was taking about peaks of 95db. Another thing, 95db at 200hz is easy, 95db at 50hz is less so. Fortunately, with loudspeakers, we get some assistance from boundary walls in the lower registers.
The reason I am considering WAW (Woofer Assisted Wide range) is to give all the bass duties to a pair of 6.5-8" woofers (like the MarkAudio Alpair 12PW or SB Acoustics SB23CACS45). If the SEAS Excel W22EX-001 produces adequate bass, I assume the SB or MA drivers would do the same.
Bass SPL is a function of how efficient the driver is and how much air it can move. The function is non-linear and max SPL falls dramatically once you are measuring below 50Hz. Hence using my existing SEASW22 as a yardstick, I believe the MA or SB drivers that are listed below will be more than adequate when it comes to SPL.
SEAS W22 - 220cm2 cone area x 0.5cm one way linear xmax, 84db/1w (100-200Hz)
MA 12PW - 147cm2 cone area x 0.85cm one way linear xmax, 89db/1w (100-200Hz)
SB 23CAC45 - 216 cm2 cone area x 0.65cm one way linear xmax, 87db/1w (100-200Hz)
Satori MW19P - 158cm2 cone area x 0.65cm one way linear xmax, 88db/1w (100-200Hz)
This is indeed ideal but we don't live in an ideal world.
Yup, I understand this. If the slot is tall enough there will be less of a difference as the airflow along the walls of the port will have less of an effect.,
Exactly! This again begs the question, why not a PR? It removes the question of the prospect of simulating "airflow" altogether
As shown in the image from Genelec below (source: https://www.genelec.com/key-technologies/laminar-integrated-port-technology)
or detailed in these links
https://www.comsol.com/paper/download/679311/bezzola_paper.pdf
https://www.pearl-hifi.com/06_Lit_Archive/15_Mfrs_Publications/Harman_Int'l/AES-Other_Publications/Maximizing_Performance_from_LS_Ports.pdf
https://audioxpress.com/article/how-good-is-your-port
I think we have gone sufficiently off-topic (apologies to all concerned). The question remains: does a "Tysen style" WAW loudspeaker using say the MAOP 5 or MAOP7 and a pair of either an SB or MA woofer (I am open to suggestions on the model) make sense? And if so which full range and woofer would be recommended?
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As a couple of points:
-Yes, it makes sense just as much as most other reasonable speaker configurations do. If you want the highest practicable dynamic range for your given nominal baseline SPL, I'd suggest a 4in over a 3in midtweeter, assuming side-firing woofers, since notwithstanding their advantages, in most cases it does tend to restrict you to slightly lower crossover frequencies.
-Re PR, go ahead if it makes you happy and you can accurately simulate its behaviour & alignment (remember the same loading conditions apply as a vented cabinet & basic lumped models assuming pure Helmholtz behaviour have the same issue as they do with a regular vent). As noted, their primary value is with acoustically small boxes where for a reasonable CSA, the duct would be excessively long and its 1/2 wave modes would start to cause issues. Beyond that, there's little particular value to them that know of over a regular vent, since in most reasonable conditions (i.e. competent design, which really isn't that hard) they shouldn't have any issues. If they do, it's the fault of the designer.
-Be very careful when you write 'linear Xmax'. There is no such thing. Xmax is a nebulous concept at the best of times that is supposed to be a rough (rough) guide to linear motor range. But 'linear motor range' is unspecified, and there are many different methods of generating a number that can be called Xmax, most of which give different values if applied to the same drive unit. In its simplest form, it's simply used as another way of writing Xmech. Which may simply be taken as such, or an indicator that the motor remains within unspecified limits defining 'linear' to the limit of mechanical travel. And that's just one example. Few manufacturers state which method they use -some provide sufficient data that you can tell, but not all. Even then, its value is open to question; Xmax largely dates from a period when measurement equipment was not widely available & was meant purely as a rough & ready guideline, no more. The real information is in the individual (not a lumped total) HD plots at different drive levels.
-Yes, it makes sense just as much as most other reasonable speaker configurations do. If you want the highest practicable dynamic range for your given nominal baseline SPL, I'd suggest a 4in over a 3in midtweeter, assuming side-firing woofers, since notwithstanding their advantages, in most cases it does tend to restrict you to slightly lower crossover frequencies.
-Re PR, go ahead if it makes you happy and you can accurately simulate its behaviour & alignment (remember the same loading conditions apply as a vented cabinet & basic lumped models assuming pure Helmholtz behaviour have the same issue as they do with a regular vent). As noted, their primary value is with acoustically small boxes where for a reasonable CSA, the duct would be excessively long and its 1/2 wave modes would start to cause issues. Beyond that, there's little particular value to them that know of over a regular vent, since in most reasonable conditions (i.e. competent design, which really isn't that hard) they shouldn't have any issues. If they do, it's the fault of the designer.
-Be very careful when you write 'linear Xmax'. There is no such thing. Xmax is a nebulous concept at the best of times that is supposed to be a rough (rough) guide to linear motor range. But 'linear motor range' is unspecified, and there are many different methods of generating a number that can be called Xmax, most of which give different values if applied to the same drive unit. In its simplest form, it's simply used as another way of writing Xmech. Which may simply be taken as such, or an indicator that the motor remains within unspecified limits defining 'linear' to the limit of mechanical travel. And that's just one example. Few manufacturers state which method they use -some provide sufficient data that you can tell, but not all. Even then, its value is open to question; Xmax largely dates from a period when measurement equipment was not widely available & was meant purely as a rough & ready guideline, no more. The real information is in the individual (not a lumped total) HD plots at different drive levels.
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Almost no added R and an additional suspension resonance make a PR quite different.
Thanx for the genelec pic. The Red is the key bit. Added R to the vent pushing it more aperiodic and making the box less sensitive to dynamic T/S changes.
Absolutely YES!!!
dave
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is there a write up or side by side comparison of the features / functions and ideal use scenarios for MA's drivers?
Not as far as I know. The former would need to be written by MA; the latter would essentially be opinion that will vary from person to person depening on how you define 'ideal use', the rest of the system and requirements for it.
MA provide a range of enclosure suggestions for each driver on their site in the resources section; most of them however were done by muggins here, so I leave it to others to judge their merits or otherwise. In the latter case, if used at all (not generally the case with MA units) they will as noted necessarily vary with requirements; as far as I am aware there is no extended write-up on this for the case in question, outside single-situation scenarios, although I may be wrong.
4" it is. Now the toss-up would be between the MAOP 7 or another other 4" (from Mark Audio or anyone else) that is recommended. What about the Pulvia Seven HD, Alpair 7MS, pr Alpair 6.2?
Agreed. If I can get a port to fit, I'll avoid PRs.
Granted, if it is "MAX", it cant be linear. I think it is just a term used for "maximum linear travel" at least that's how I interpreted it.
Given that the port in the Tysen has very little height are you implying that the "resistance" of the air in the port is integral to the bass response in the Tysen?
Great I have 3 "designs" in my head. Each of them involves a 4" full range on the front baffle. I have made some crude sketches by editing the original Tysen PDF to help you visualise my thoughts.
Option 1. 2 x 8" push-push woofers placed slightly higher up than on the Tysen V2
Cabinet dimensions: 46" H x 7" W (front) 8" W x (rear) 15" D
Which of these 8" woofers would suit this configuration best?
https://www.madisoundspeakerstore.c...oustics-sb23cacs45-8-8-ceramic-woofer-8-ohms/
https://www.madisoundspeakerstore.c...stige-l22rn4x/p-h1208-8-aluminum-cone-woofer/
https://www.madisoundspeakerstore.c...19p-8-7.5-egyptian-papyrus-cone-woofer-8-ohm/
https://www.madisoundspeakerstore.c...pair-12pw-8-paper-cone-bass-wide-band-driver/
Option 2. 2 x 8" woofers placed as close to the floor as possible to eliminate floor bounce (http://www.troelsgravesen.dk/BOOKSHELF-1/RoyAllison.pdf)
Cabinet dimensions: 46" H x 7" W (front) 8" W x (rear) 15" D
the same choice of 8" woofers as above. Maybe the port at the bottom can be moved to the top and face the rear instead of the front.
Option 3. Clone of KEF Blade (using a port instead of ML-TL) using 4 x 5-6" woofers instead of 2 x 8" woofers.
Cabinet dimensions: 46" H x 17" D x curved front baffle 7" front, tapering to 5" in the rear. I can make a small conical enclosure from fibreglass for the 4" full range.
Choice of 6" woofers.
https://www.madisoundspeakerstore.c...e-l16rnx3-6-aluminum-cone-woofer-h1869-8-ohm/
https://www.madisoundspeakerstore.c...l16rnx-6-aluminum-cone-woofer-h1488-08-8-ohm/
https://www.madisoundspeakerstore.c...coustics-sb17cac35-8-6-ceramic-woofer-8-ohms/
https://www.madisoundspeakerstore.c...5-8-6.5-woven-carbon-fiber-cone-woofer-8-ohm/
https://www.madisoundspeakerstore.com/satori-woofers-6-7/satori-mw16p-black-egyptian-reed-cone/
Hope this helps.
Thanks
Navin
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Yes, I do see "ports" in Dave's designs.
I haven't worked out any of the details. I am trying to wrap my head around the concept first. I don't even know which of the woofers would be the best option to go with.
If I can't find an ML-TL calculator on the internet (I made a feeble attempt at finding one) I can always default back to a ported box.
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Tha MAOP is the pinnacle. The A7ms might do some things betetr due sto the monoSuspension, and one certainly entetains the thots that an A7ms MAOP would be a killer midTweeter, the Pluia 7HD an evolution of the A7 the MAOP is based on, the metal cone Alpair 6.2 is a sleeper but if you can find one, sort of between an A5 and an A7. And teh cheapest of teh lot. I would choose the MAOP 7.
Yes. Based on one of Scott’s TLs, the slot gives a bit less quantity, but a bit more control.
Woofer placement in n ML-TL is usually determined by the designers choosen Zd. Not taking advantage of this means the TL typially needs more damping.
One of the goals of a WAW is to get the midTweeter and teh helper woofers within a quarter wavelength at the XO. This approach will greatly compromise that. I in fact have never had an issue with, or obsessed over floor bounce.
The only difference in concept with Blade versus Tysen is that the Blade mirrored an extra set of woofers so as to make a symetrical )push-push) woofer, midTweeter, PP woofer in an MTM arrangement. Flip a tysen woofer upside down and put it on the top, gives a Blade configuration. While thot experiements outlined the concept, the blade beat me to the puch and is a brilliant design over all. (althou i would not be surprised if they have soem KEF-ness to them).
We did this with the facets, adding a second set of Peerless 830870 to this design, and then jumping thru hoops to get a quarterwave load for the woofers.
Not easy to build.
(now veneered with Vancouver Island Yew and working on swapping out the FF85 for A5.
dave
The ones that work best within the design constraints you have to live with. Some cut and try required (in a modeler).
dave
Allen,
Of which box do you refer Allen, i believe we have what, 5 potentials you could be referring to, from the last few posts.
dave
Of which box do you refer Allen, i believe we have what, 5 potentials you could be referring to, from the last few posts.
dave