DATS vs Acoustic Elegance

[camplo]

Thats some interesting reading JRT.....though that design is tempting me to keep my under power (low Bl) drivers.....I did take note to the theory...The way my bass boxes are designed, I have serendipitously created a dual opposing MAPD alignment lol....Its a U shape box where the bottom of the U has a much lower csa than the sides of the U.

[JRT]

Looks like your 15M is a good candidate for the MAPD alignment, which can provide improved linearity.


See the MAPD alignment white paper (at the Internet Archive at the link below) authored by George Short, of what was North Creek Music Systems (now out of business).

https://web.archive.org/web/20100413....com/MAPD1.htm

The MAPD is an acoustic suspension loading with improved linearity provided by the aperdiodic damping of an airflow resistance, and is essentially an advanced sealed alignment, so it exhibits the second order high pass of a sealed alignment with improved linearity. In his MAPD white paper, George Short recommends an acoustic high pass Q of approximately one. Not mentioned in the whitepaper is that Q would lend itself well to use in a third order sealed alignment (eg. exhibiting BW3 acoustic highpass) achieved by cascading a first order high pass with the MAPD's second order highpass.

The succinct white paper at the link above is based on George Short's masters thesis, available at the link below. At 120 pages, the thesis goes into considerably more detail. Start with the white paper.

https://vtechworks.lib.vt.edu/handle/10919/45955

[camplo]

Thanks Chris! I've figured out that my 18H+ woofers are within spec but unfortunately the 16ohm 15ms I have, have qes specs that are double what it should be and this not good.

incorrect Vas is throwing off my DATS prediction.....call it due to break in.....never the less....reverse operations allowed me to get BL numbers for speculation and WInISD prediction made it even simpler to get predictions with different values quickly...

The 18H+ are looking to be fine but my 16ohm 15m have dbl the Qes I am looking for....highly doubt they will drop 50% due to break in....

[DeZZar]

MY DATS doesn't calc. "BL" TIKO.

Should do. Once you measure the driver including VAS open the Driver Editor. BL is listed in N/Amp (which is 1:1 with T/m). This is a V3 unit.


If you plug these numbers into WinISD as you suggest the BL calculated is bloody close...

[Chris Roemer]

MY DATS doesn't calc. "BL" TIKO.
From DATS, I plug these into WinISD: Qes, Qms, Fs, Vas, Re, and Le; also (from other sources): Sd, Xmax, and Pe.
WinISD then calcs: Qts, Mms, Cms, Rms, BL, Vd, and USPL and SPL.

[DeZZar]

Cant really find any specific published materials on how DATS specifically calculates each param but its all based on the impedance curve I think - progressively solving for most params based on their mathematical relationships with each other.

BL seems to have a few different ways to calculate it, and from a manufacturers perspective they are probably basing the physical dimensions approach (length of wire etc). Dats doesn't know this so there's no real surprise its potentially going to come up with a different number based on an electrical estimate.

[camplo]

I was looking at that earlier...I believe the dats uses this approach to figure qes...

How do you think it figures CMS?
I think in your second link is the answer.

[DeZZar]

http://www.wavecor.com/Measuring_driver_Q-values.pdf
https://sound-au.com/tsp.htm
https://www.bksv.com/media/doc/bo0384.pdf (3.3 Qes)

[camplo]

Qes = 2 Pi x Fs x Mms / (Bl2/Re)

Bl2= (2 Pi x Fs x Mms / Qes) x Re

[DeZZar]

Qes is not calculated from BL.

[camplo]

The best question I've had so far....might be an easy one....You need to know BL to know qes and you must know Qes to know Bl...So how is the DATs figuring out Qes without BL?

[DeZZar]

Driver needs break in before you can conclude anything about the Q's.

[scholl]

can you put them in the intended box and measure the FR? If the Qs are so far off you'll see it quick.

[camplo]

I've more so, come to the conclusion that these drivers aren't exactly, bummy....its just that Acoustic Elegance has bloated the hell out of the advertised specs....not a new concept I supose....The part where they really screwed me is that telling me the thiele specs of the 16ohm voice coils would line with the 8ohm so that I wouldn't have to change my design....this is before choosin the 16ohm coils....so now my qts is off and the only way to adjust qts ( with a resistor) will result in a negative impact on efficiency....thats pretty crappy of them to set me up like this....the design is intended to reach critical damping ie qtc 0.5 and I cannot do this with the current box/woofer combo

[dynamo]

I think you are worrying about something not worth worrying about.

100% accurate