Hi guys, this is my first post. (nubiusMaximus) Make Me feel at home! =)
I bought some 6.5" Audax woofers from Partsexpress several years ago. The model # is AT170M0 (Partsexpress# was 296-082 Discontinued.)
The specs that I am able to get are:
Vas 36.2 liters(huge!)
Fs 48 Spl 90db (2.83V)
Qts .69
Response 48-6000Hz
50 watts Xmax 3.5 mm
Has anyone used, or seen this woofer used before? I am getting lousy preliminary results (maybe because I am such a noob) The specs suggest the requirement of a huge enclosure. PeBox from Partsexpress calculates a vented box of 7.51 cf, OR a Sealed enclosure of 17.93 cf for a Qtc of .707 Instead of these huge boxes I tried another route: A U-frame enclosure. Which is a tube roughly twice the length of the woofer diameter, and is about 7 inches in diameter.
This produces practically no bass. None. It is listed as a woofer but performs more like a midrange. I also have the woofer in enclosure that I use for my home theater Center channel. It is sealed .75 cf. Same basic result.
I may be just missing the boat by not building a traditional enclosure, but I don't see much promise in these drivers to push me forward.
Any ideas? Or any reference to previous projects, either failed or successful.
I think I wasted some money here. Thanks for any help
Jon King
I bought some 6.5" Audax woofers from Partsexpress several years ago. The model # is AT170M0 (Partsexpress# was 296-082 Discontinued.)
The specs that I am able to get are:
Vas 36.2 liters(huge!)
Fs 48 Spl 90db (2.83V)
Qts .69
Response 48-6000Hz
50 watts Xmax 3.5 mm
Has anyone used, or seen this woofer used before? I am getting lousy preliminary results (maybe because I am such a noob) The specs suggest the requirement of a huge enclosure. PeBox from Partsexpress calculates a vented box of 7.51 cf, OR a Sealed enclosure of 17.93 cf for a Qtc of .707 Instead of these huge boxes I tried another route: A U-frame enclosure. Which is a tube roughly twice the length of the woofer diameter, and is about 7 inches in diameter.
This produces practically no bass. None. It is listed as a woofer but performs more like a midrange. I also have the woofer in enclosure that I use for my home theater Center channel. It is sealed .75 cf. Same basic result.
I may be just missing the boat by not building a traditional enclosure, but I don't see much promise in these drivers to push me forward.
Any ideas? Or any reference to previous projects, either failed or successful.
I think I wasted some money here. Thanks for any help
Jon King
High Q makes it a bit problematic... its not likely to work at all well in a vented box. I wonder if this was designed to go in car doors? Except for limited swept volume it is ideal for an open baffle.
You could try an alphaTL http://p10hifi.net/tlinespeakers/TLS/downloads/aTL-article.pdf
Or model a sealed enclosire with a Q of ~1.1 and then make it aperiodic...
dave
You could try an alphaTL http://p10hifi.net/tlinespeakers/TLS/downloads/aTL-article.pdf
Or model a sealed enclosire with a Q of ~1.1 and then make it aperiodic...
dave
Hi,
Audax do not usually produce drivers with poor specs.
Your problem is not a huge Vas - its a high Qts.
Simply put I don't believe the specs, I think Qts is lower.
Fs and SPL sound typical of a paper Audax driver.
But with Vas of 36L (= lightweight cone when Fs =48hz)
I'd expect Qts to be around ~ 0.3.
Your experiments with a sealed box also suggest this.
WinISD suggests BL = 4.3 = a very wimpy magnet.
If the magnet looks fairly reasonable i'd say specs are wrong.
If they are right it should boom away in any box around 0.75cuft.
Not much point in Q less 1.
/sreten.
Audax do not usually produce drivers with poor specs.
Your problem is not a huge Vas - its a high Qts.
Simply put I don't believe the specs, I think Qts is lower.
Fs and SPL sound typical of a paper Audax driver.
But with Vas of 36L (= lightweight cone when Fs =48hz)
I'd expect Qts to be around ~ 0.3.
Your experiments with a sealed box also suggest this.
WinISD suggests BL = 4.3 = a very wimpy magnet.
If the magnet looks fairly reasonable i'd say specs are wrong.
If they are right it should boom away in any box around 0.75cuft.
Not much point in Q less 1.
/sreten.Attachments
Welcome to the club
I bought those drivers for my first return to speaker building project a long time ago. The specs are correct, unfortunately. Even ignoring that it has a bucking magnet, the magnet is small...
I used about 2 cubic feet heavily stuffed in a tower MTM, and it wasn't to bad for the time it took to save up for my next drivers in a HT setup. OK for kid's speakers or garage use. Now they are used for my son's bass guitar practice amp.
I bought those drivers for my first return to speaker building project a long time ago. The specs are correct, unfortunately. Even ignoring that it has a bucking magnet, the magnet is small...
I used about 2 cubic feet heavily stuffed in a tower MTM, and it wasn't to bad for the time it took to save up for my next drivers in a HT setup. OK for kid's speakers or garage use. Now they are used for my son's bass guitar practice amp.
Interesting formula in that alphaTL article;
http://homepage.mac.com/tlinespeakers/TLS/downloads/aTL-article.pdf
Fo=Fs/Qts.
My Goldwoods that I used in my Aperiodic TL came out to be 112" approximately;
And using the above formula it comes out to 105"
The 112" line was calculated using MJK's MLTL worksheet.
The box size was 20"Hx19"Dx9"W....with 5 internal baffles slightly tapered and fully stuffed with a 4"x 3/4" port/terminus.
The Goldwoods were not designed for bass, since the Xmax is only 2mm. The Fs/Qts on these drivers are 85/.81 = 105"...
The box's real purpose is for a very smooth midrange since a TL box is the closest enclosure to an Infinite Baffle.
The Audax comes out to 69.5" So the box could even be smaller than mine. I would still probably use MJK's worksheet to find out for sure, and it's simulated bass response...
http://homepage.mac.com/tlinespeakers/TLS/downloads/aTL-article.pdf
Fo=Fs/Qts.
My Goldwoods that I used in my Aperiodic TL came out to be 112" approximately;
And using the above formula it comes out to 105"
The 112" line was calculated using MJK's MLTL worksheet.
The box size was 20"Hx19"Dx9"W....with 5 internal baffles slightly tapered and fully stuffed with a 4"x 3/4" port/terminus.
The Goldwoods were not designed for bass, since the Xmax is only 2mm. The Fs/Qts on these drivers are 85/.81 = 105"...
The box's real purpose is for a very smooth midrange since a TL box is the closest enclosure to an Infinite Baffle.
The Audax comes out to 69.5" So the box could even be smaller than mine. I would still probably use MJK's worksheet to find out for sure, and it's simulated bass response...
Thanks for the replies guys.
I guess I should have mentioned this earlier, but I am using these for HT and music too. I don't have room for 5 fairly large enclosures......at least according to my wife =)
I did some calulations using the article u recomended. I had decided on an fO of 80 Hz for my calculations. Which nets a lenth of 32 inches, with a cross section of 127 sq inches. So a sample size might be: 10x12.7x32. This also makes for a rather large enclosure. I am aiming for something small if possible.
I miss-guessed my enclosure size for that sealed center channel I am using now. It is .27 cu ft, which should yield a really hi Qtc of 1.65. Even so, bass is very lacking. Surprisingly it is not muddled or thumpy, just sort of non existant. I realize iI am not going to get a large output from a 6.5 inch driver but.....
So, with the Alpha TL, I am likely to net an additional 2-3 db, and if I remember corectly that sounds like twice the outpout for each 3db increase? Even so, I think I may end up dissapointed. I have a Sub with 2 Dayton Series 2 Drivers (no I haven't set the Xo point for certain yet) =)
My hope was to use these as sort of Mid bass/midrange drivers. It looks like maybe I should use them as Midrange only. Or should I make the effort of building the Alpha TL to try it out? I think if I am going with that large of an enclosure, I would rather have something that performs better in the bass range.
Thanks so much for you opinions. Keep em coming. =)
Jon King
I guess I should have mentioned this earlier, but I am using these for HT and music too. I don't have room for 5 fairly large enclosures......at least according to my wife =)
I did some calulations using the article u recomended. I had decided on an fO of 80 Hz for my calculations. Which nets a lenth of 32 inches, with a cross section of 127 sq inches. So a sample size might be: 10x12.7x32. This also makes for a rather large enclosure. I am aiming for something small if possible.
I miss-guessed my enclosure size for that sealed center channel I am using now. It is .27 cu ft, which should yield a really hi Qtc of 1.65. Even so, bass is very lacking. Surprisingly it is not muddled or thumpy, just sort of non existant. I realize iI am not going to get a large output from a 6.5 inch driver but.....
So, with the Alpha TL, I am likely to net an additional 2-3 db, and if I remember corectly that sounds like twice the outpout for each 3db increase? Even so, I think I may end up dissapointed. I have a Sub with 2 Dayton Series 2 Drivers (no I haven't set the Xo point for certain yet) =)
My hope was to use these as sort of Mid bass/midrange drivers. It looks like maybe I should use them as Midrange only. Or should I make the effort of building the Alpha TL to try it out? I think if I am going with that large of an enclosure, I would rather have something that performs better in the bass range.
Thanks so much for you opinions. Keep em coming. =)
Jon King
If you only need 80 Hz, i'd throw some aperiodic boxes togther... you could even just try it with your existing centre... it will bring the Q down at least a bit...
Try something like Dynaco used on the A 25 (maybe best to put it out of the way on the back of the box)
http://www.t-linespeakers.org/classics/dynaco.html
dave
Try something like Dynaco used on the A 25 (maybe best to put it out of the way on the back of the box)
http://www.t-linespeakers.org/classics/dynaco.html
dave
14G-Dutch^ said:
Aperiodic design is still a black art... (i'm sure with some port stuffing data it could be modeled in MJK)... my receipe is to build a big a box as you can live with (but Q no lower than 1.0-1.1) and then add an aperiodic port. My experiments have lead me to the Dynaco style port as the easiest to actually implement... a long skinny port, with a rebate. You put a piece of plastic gutter mesh on the bottom of the rebate, add 1-3" of suitably shaped fiberglass insulation, and then squish it down flat (the Dynas have a 3/8" rebate -- a convienient size for 3/4" material) using another piece of gutter mesh.
The variables in your control are the size of the vent, the depth of the rebate, and how thick the fiberglass you are squishing. Unless you build a bunch of boxes or a removable port panel, the first two become more or less fixed at build time.
GM has described a click test, or you can use repeated impedance measures (you are aiming to just kill the bottom impedance peak of the BR saddle that happens when you put a hole in the box), but you can get pretty close by ear.
dave
14G-Dutch^ said:
0.707 gives maximally flat... Qs down to 0.5 give better transient response.... 0.5 < Q < 0.6 is really good if your woofer is reaching down to where room gain takes effect (room dependent)
To expand on what Bob said, a driver with Q=0.69 needs to be in a very large box to get Q= 0/7 -- totally impractical here. So given that how do you get a smallish box that doesn't have a bass hump... The idea behind the aperiodic box is to start with a smallish box which has a higher Q than desired then lower the Q with the resistive port. Might not be perfect, but it uses the driver at hand and gives a reasonably small box.
dave
planet10 said:
Hi,
As I said in an earlier post there not much point going lower than Q=~1.
This occurs when Vbox ~= Vas, making the box bigger than Vas
will just mean Vas will dominate and the box will have less and
less effect as its gets bigger.
Most speakers have light stuffing nowadays (BAF/Poyfill), but this
is definetely the case where you should go for maximum stuffing.
I'd go for rockwool (stuff that comes in blocks to go in wall cavities).
This would also work for the resistive port as outlined by p10.
So a 30L to 35L box, stuffed to be ~ 25% bigger + resistive port.
/sreten.A step back if u don't mind. In an alpha tl, is the x-section result attained in the formula an absolute requirement? Could it be narrower and longer? Or some other route?
Btw is the 30-30 liter box someting u arrived at with a formula, or is it kind of subjective?
Thanks again for the help. Btw I am going to try your recommendations on the aperiodic design, Just kind of foreign to me though. I LIKE formulas =)
Here is my listening (READ ...LIVING) room, and a Picture of the cener channel, and of the driver. The tweeter is a VifaD27TG-05
Jon King
Btw is the 30-30 liter box someting u arrived at with a formula, or is it kind of subjective?
Thanks again for the help. Btw I am going to try your recommendations on the aperiodic design, Just kind of foreign to me though. I LIKE formulas =)
Here is my listening (READ ...LIVING) room, and a Picture of the cener channel, and of the driver. The tweeter is a VifaD27TG-05
Jon King
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