Thanks to all for your comments and reference to eligible woofers.
@scottG.: the 15W500 of 18sound exhibits indeed a fabulous Mms of 55g. Sadly, they seem to have sacrificed other parameters (the Fs is rather high, the Qts is more appropriate for a sealed enclosure and the BL is surprisingly low - weak engine)
@GM: Altec/GPA: 39-42g sounds awasome! do you know of any official figures comprising the moving mass values? I've never found them for the current Iconic/GPA production.
@Patrick Bateman: I agree that leightweight moving mass leads in principle to extended bandwidth in the medium range. Low inductance is probably the result of a moderately sized voice coil (up to 75mm or 3 inches in diameter), and short excusrsion is usually limited to a a few millimeters. Perhaps a reason why the Altecs traditionnally have a nominal power of 75 to 150W max. But I think the extended bandwidth and low inductance are a further consequence / inherent factor of low moving mass (relatively small voice coil compared to the boombastic 1000W+ monsters available nowadays), rather than the reason for it.
@Frode and others: the BD15 is indeed impressive. It seems that the high sensitivity is due to the 16 ohms nominal impedance (measures at 1W = 4V input under this impedance, as opposed to the classical 2,83V or 2V for 8 and 4ohm speakers, respectively).
@el'Ol: the W416 Neo is interesting; I'll keep an eye on it!
@Tinitus : the PD153 is nice too, but Mms = 101g...
@Goto discussants: same as the Precision Device: moving mass seems rather high; but agree that the sensational BL compensates for that. I'll look at the other Gotos...
@scottG.: the 15W500 of 18sound exhibits indeed a fabulous Mms of 55g. Sadly, they seem to have sacrificed other parameters (the Fs is rather high, the Qts is more appropriate for a sealed enclosure and the BL is surprisingly low - weak engine)
@GM: Altec/GPA: 39-42g sounds awasome! do you know of any official figures comprising the moving mass values? I've never found them for the current Iconic/GPA production.
@Patrick Bateman: I agree that leightweight moving mass leads in principle to extended bandwidth in the medium range. Low inductance is probably the result of a moderately sized voice coil (up to 75mm or 3 inches in diameter), and short excusrsion is usually limited to a a few millimeters. Perhaps a reason why the Altecs traditionnally have a nominal power of 75 to 150W max. But I think the extended bandwidth and low inductance are a further consequence / inherent factor of low moving mass (relatively small voice coil compared to the boombastic 1000W+ monsters available nowadays), rather than the reason for it.
@Frode and others: the BD15 is indeed impressive. It seems that the high sensitivity is due to the 16 ohms nominal impedance (measures at 1W = 4V input under this impedance, as opposed to the classical 2,83V or 2V for 8 and 4ohm speakers, respectively).
@el'Ol: the W416 Neo is interesting; I'll keep an eye on it!
@Tinitus : the PD153 is nice too, but Mms = 101g...
@Goto discussants: same as the Precision Device: moving mass seems rather high; but agree that the sensational BL compensates for that. I'll look at the other Gotos...
elac310 said:
All the others cost considerably more. 18 Sound hasn't sacrificed other parameters with this driver. Really it depends on how you want to use the design. It *could* be sealed, but it could also be ported to a lower freq. limit depending mostly upon enclosure volume. Try modeling it, both sealed and "vented".
Remember that bl is "wrapped-up" in the coil. 16 ohm coils have an advantage here. Of course 16 ohm coil designs often have more mass as well.
Finally, don't forget sd in relation to mms. For instance it's tough to beat the Supravox 285 GMF vented for it's mms vs. sd. About 8 cubic ft of enclosure volume with a vent tuned to 29 Hz is pretty substantial (..8 inch cylinder vent 14 inches long).
Frode said:
Defo said:
Defo said:
It looks plausible to me. I have worked with the Lambda TD15 drivers and they have the same extended reponse. Although I have not worked with the "M" version, I would expect it to have a very similar response to the BD15 under the same measurement conditions. Once you have a system with TD15's you'll be ruined for anything less
If you look at the specifications of the TD15M compared to the BD15 you'll see that they are VERY similar. Overall I would take the TD15M for the much lower inductance - I don't like iron in my inductors!
Definitely put the TD15M from Acoustic Elegance on your list.
Happy Listening!
Not necessarily, motor design plays a large part in the Le and Le(x) of a given driver. My AE TD15X are 2.5" VC, 500W and 0.3mH, all because of the motor design. The AV series are 3", 1000W and similar Le.elac310 said:
It seems to me you are picking one parameter that is not all that relevant on it's own.
BL/MMS = nonsense
Woofer Speed
Mass itself is not much of an issue for anything. Inductance is a much more critical issue in terms of distortion and response variation with excursion. There are many documented experiments showing how additional inductance causes a delay in the impulse response while adding mass does not.
Keep in mind that most drivers with high Mms have this high Mms because of a huge VC. It isn't the high Mms that is causing the issues it is the large coil and large inductance.
It is a 16 ohm driver. That is why the Bl is so high. Bl with respect to Re is really not that high at all.
Thanks for the kind words Edward. The copper sleeve and low inductance of the TD drivers gives them low distortion and smooth response that isn't found in any driver I have seen. Augerpro's testing recently proves much of this. No other driver came close in terms of Le(x) measurements and distortion is extremely low.
The TD15M response time gated to remove reflections is in the yellow curve here. Unsmoothed it is about +/- 2.5dB all the way up to 4KHz. The dip you see at 4KHz is due to mic position. It rolls off very smoothly a without breakup and is only about 15dB down by 10KHz.
![url]](/community/proxy.php?image=http%3A%2F%2F%5Burl%5Dhttp%3A%2F%2Fwww.aespeakers.com%2Fpics%2Fmeasurements%2FTD15M-closemic.PNG%5B%2Furl%5D&hash=0acf97400118a835f5bc60487cc73bf6)
Hi Brett, just one correction. The TD's are actually 2" coil and the AV's are 2.5" coil. We've had people running TD15M's and TD12M's for live sound reproduction of large national bands with upwards of 1000W of Lab Gruppen power on tap. They have not yet managed to burn up a coil, although the JBL and Sonic cabinets they had used short term often didn't make it through a single night.
Inductance is a function of both the windings and the core the windings are around. The full copper sleeve on the pole forces the coil to work as almost a perfect air core throughout it's entire frequency range. It has other benefits as well.
http://www.aespeakers.com/Lambda001-1.php
John
Keep in mind that most drivers with high Mms have this high Mms because of a huge VC. It isn't the high Mms that is causing the issues it is the large coil and large inductance.
CLS said:
Wow! What a motor!
It is a 16 ohm driver. That is why the Bl is so high. Bl with respect to Re is really not that high at all.
EdwardWest said:
It looks plausible to me. I have worked with the Lambda TD15 drivers and they have the same extended reponse. Although I have not worked with the "M" version, I would expect it to have a very similar response to the BD15 under the same measurement conditions. Once you have a system with TD15's you'll be ruined for anything less
If you look at the specifications of the TD15M compared to the BD15 you'll see that they are VERY similar. Overall I would take the TD15M for the much lower inductance - I don't like iron in my inductors!
Definitely put the TD15M from Acoustic Elegance on your list.
Happy Listening!
Thanks for the kind words Edward. The copper sleeve and low inductance of the TD drivers gives them low distortion and smooth response that isn't found in any driver I have seen. Augerpro's testing recently proves much of this. No other driver came close in terms of Le(x) measurements and distortion is extremely low.
The TD15M response time gated to remove reflections is in the yellow curve here. Unsmoothed it is about +/- 2.5dB all the way up to 4KHz. The dip you see at 4KHz is due to mic position. It rolls off very smoothly a without breakup and is only about 15dB down by 10KHz.
Brett said:
Hi Brett, just one correction. The TD's are actually 2" coil and the AV's are 2.5" coil. We've had people running TD15M's and TD12M's for live sound reproduction of large national bands with upwards of 1000W of Lab Gruppen power on tap. They have not yet managed to burn up a coil, although the JBL and Sonic cabinets they had used short term often didn't make it through a single night.
Inductance is a function of both the windings and the core the windings are around. The full copper sleeve on the pole forces the coil to work as almost a perfect air core throughout it's entire frequency range. It has other benefits as well.
http://www.aespeakers.com/Lambda001-1.php
John
To conclude on this thread and if I follow the interesting advice which was given, to look in priority for a low Le and extended high frequency response, and bearing in mind the discussion about woofer speed and BL/MMs ratios (http://www.diyaudio.com/forums/showthread.php?p=1802244), it seems that I could end up with....the woofer I currently have namely the Ciare PW388 (or 15.64W)
http://seeburg.net/1564W1_dt.pdf
I had chosen this one for the low Mms and Rms but it exhibits a very low Le as well (0,91) and frequency response is constantly rising up to 2kHz and stable up to 3kHz.
Back to square 1 or end of quest. In any event, thanks again to all posters for the tips, advice and hints on woofer brands I did not know.
Chris.
http://seeburg.net/1564W1_dt.pdf
I had chosen this one for the low Mms and Rms but it exhibits a very low Le as well (0,91) and frequency response is constantly rising up to 2kHz and stable up to 3kHz.
Back to square 1 or end of quest. In any event, thanks again to all posters for the tips, advice and hints on woofer brands I did not know.
Chris.
I just measured a Pyle PPA15 using the 'destroy it and plop the remains on a jewelry scale' method
And Fs for that 89gr Pyle ?
This Faital has 85gr mms and Fs 32hz, which is quite good fore a standard pro 15" http://www.usspeaker.com/homepage.htm
Mind you, its at 99db
The cost is low Xmax
This PD has 90gr mms and 35hz Fs http://www.precision-devices.com/showdetails.asp?id=79
But fore a driver of this kind a relatively big Xmax of 16mm(p-p)
Cost is lower 96db SPL
With 700watt power handling it will take a bit of EQ
Back and forth
Mostly a matter of what you expect from it
Also, you have no use of 99db at 1khz, if its 95db at 200hz
Last edited:
Could someone please clear up moving mass for me? Is it everything? I mean the cone and spider and surround and vc assembly?
I just measured a Pyle PPA15 using the 'destroy it and plop the remains on a jewelry scale' method
That is usually close. Typically it will be a portion of the surround, spider, and lead wires plus everything else. The reason is that not all of the spider and surround are active (moving) while the cone is moving. 1/3 to 1/2 would be a good estimate.
Mms is the actual weight of the moving assembly PLUS the air load on the cone, which is based off the cone diameter for the most part. Obviously the bigger cone will inflate the Mms figure all else being equal.
Mmd is just the weight fo the moving assembly, but it usually isn't listed my manufacturers.
Mmd is just the weight fo the moving assembly, but it usually isn't listed my manufacturers.
Here's another nice contender with low moving mass and interesting further parameters
P-Audio WN-15S:
Fs 39,8
Mms 65 g
Qms 7,55
Qts 0,25
Vas 286,8
Le 0,81
xmax 3,5 mm
BL 18,34
Neodym magnet
Flat up to 4kHz
http://www.intertechnik.de/module/1411508.pdf
P-Audio WN-15S:
Fs 39,8
Mms 65 g
Qms 7,55
Qts 0,25
Vas 286,8
Le 0,81
xmax 3,5 mm
BL 18,34
Neodym magnet
Flat up to 4kHz
http://www.intertechnik.de/module/1411508.pdf
Seems I didnt understand the question
This Faital specs show, Mms 85.2gr and Mmd 72.5gr
http://www.faitalpro.com/products/schede/ps.php?id=101060100
Im sure that with most drivers surround and spider are "left out" in mms calculation
How else would a small driver be specced with 3gr mms
Maybe sometimes even the voice coil is "forgotten"
Would this "screw up" some other specs ?
This Faital specs show, Mms 85.2gr and Mmd 72.5gr
http://www.faitalpro.com/products/schede/ps.php?id=101060100
Im sure that with most drivers surround and spider are "left out" in mms calculation
How else would a small driver be specced with 3gr mms
Maybe sometimes even the voice coil is "forgotten"
Would this "screw up" some other specs ?
Last edited:
No,
mmd is the actual mass of the moving parts taking account of the distances moved by some of the partially fixed components.
mms is the actual mass of the moving parts plus the effective mass of the air that the cone must move.
Looks a bit low, but not impossible; if they publish comprehensive sets of TS parameters and you know a few equivalence formulas, you can test the coherence of data.
For what it's worth, I use the following one rms=(6,28xmmsxfs)/Qms
with mms in kg and rms being the mechanical resistance,
which has helped me find some inconsistencies in the data on 2 or 3 occasions in the past (even of wellknown manufacturers; when I asked them, they acknowledged a possible mistake in their measures). Please, bear in mind this formula (although it comes from a RD engineer of a major speaker manufacturer) is not unanimously valued on DIYaudio and it is not my intention to open a discussion about it (those who are interested may look at http://www.diyaudio.com/forums/showthread.php?t=131739).
Chris
80g mms 15" woofers always seemed "heavy" sounding to me in Karlson - 60g mms should be doable with 3mm xmax w. 2.5" coils and I'd assume Eminence has made them (and I've bought them). AA Craaft advertised 77g mms for their 18s. My lightest Eminence 18" is 103g mms
look at the B&C 15TRX vs JBL M151 in RCA Fan's "half-horn" reflex - some folks may prefer the more midrangey balance of this JBL - some might like the heavy cone B&C
look at the B&C 15TRX vs JBL M151 in RCA Fan's "half-horn" reflex - some folks may prefer the more midrangey balance of this JBL - some might like the heavy cone B&C
An externally hosted image should be here but it was not working when we last tested it.
Last edited:
re: graph - that's a bass reflex with fb~40Hz and no flare to the vents which are gapped ~1.25" from the back panel - I'm not sure where Dr. Geddes tuned for Summa nor his box size - this might be my TBX but IIRC specs aren't real far apart from my TRX - - re:Karlson - dunno if higher mass woofers are appropriate - but maybe for high spl work - - maybe i'll get a 3015 or 3015lf but I wasn't fond of Dayton-Eminence 295-070 - Martin's 1844/15269 would be better if Le weren't 4.1mH :^) - it has a nice cone - sorry to mess up this thread
Last edited:
light cone or low mms 15"
If you can find a pair I would recommend the Yamaha JA3882, it is not easy to use and won't work in Onkens. The magnetic circuit is 13 kG, 4" VC, mms of 52G. The ideal is horn loaded as it has ultra low Qts and reasonably high Vas.
This driver makes any other 15 I have heard sound fat and slow, it leaves the fabled 515 sounding like an 80 year old dog (if it were possible). This, in a pair of Altec 210 cabs. One side running the Yammies the other the 515's.
This is the best there is. Not that I am biased nor in the slightest one eyed. I will dig out the PDF and post it. If possible I will post some pictures as well.
If you can find a pair I would recommend the Yamaha JA3882, it is not easy to use and won't work in Onkens. The magnetic circuit is 13 kG, 4" VC, mms of 52G. The ideal is horn loaded as it has ultra low Qts and reasonably high Vas.
This driver makes any other 15 I have heard sound fat and slow, it leaves the fabled 515 sounding like an 80 year old dog (if it were possible). This, in a pair of Altec 210 cabs. One side running the Yammies the other the 515's.
This is the best there is. Not that I am biased nor in the slightest one eyed. I will dig out the PDF and post it. If possible I will post some pictures as well.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.