All the above...at least in free air I can say I believe I used the dats correctly....Fs is not where it should be. When I measured the 18h+ the specs not only lined up, but were a little better than advertised.
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You can try and exercise the driver by playing 10Hz tones through it for a while.
Didn't you take delivery of these over a year ago? Why in the 
are you just now running impedance sweeps???
35ish Hz expected and 55Hz received could just be new stiff woofer parts. I would manually massage the spiders and give the cones a good few solid manual pushes both ways to loosen things up. Maybe this on top of fluids 10Hz suggestion?
Qts will drop with the loosened soft parts but 0.9 delivered down to 0.33 expected may not happen but IDK.
A call to John should have happened within weeks of delivery...
are you just now running impedance sweeps??? 35ish Hz expected and 55Hz received could just be new stiff woofer parts. I would manually massage the spiders and give the cones a good few solid manual pushes both ways to loosen things up. Maybe this on top of fluids 10Hz suggestion?
Qts will drop with the loosened soft parts but 0.9 delivered down to 0.33 expected may not happen but IDK.
A call to John should have happened within weeks of delivery...
First off, imho it is not ok to publish screenshots of mail conversations. Normally this is a no go except you have the explicit approval to do so from the other side.
Where I live after 6 months there is a reversal of evidence that you have to prove that any potential defect of malfunctioning was already existing at the time of delivery. One year later? Your duty as customer is to check what have been delivered in time. Maybe this is different where you live.
Where I live after 6 months there is a reversal of evidence that you have to prove that any potential defect of malfunctioning was already existing at the time of delivery. One year later? Your duty as customer is to check what have been delivered in time. Maybe this is different where you live.
I believe you are mistaken. The time frame expectation tickles me...I think I waited 8 months to receive my first order...not complaining...just saying there should be no complaints on time frame for me either lol..
After some more investigation it seems that qts lowers as fs lowers...how much? Hard to say right now...
I was able to get a correct reading for BL on the 18H+ but the 15m is reading 17tm...it should be near 27 for the 16ohm coil...John pointed that out...I have confidence that either my readings are wrong or if not, this issue will be resolved. No worries
After some more investigation it seems that qts lowers as fs lowers...how much? Hard to say right now...
I was able to get a correct reading for BL on the 18H+ but the 15m is reading 17tm...it should be near 27 for the 16ohm coil...John pointed that out...I have confidence that either my readings are wrong or if not, this issue will be resolved. No worries
I think the first thing I need to do is explore this theory of "breaking in". I'm reading that Bl can increase with break in...Fs can decrease, thus decreasing Qts....John said that they design the woofers to reach target spec after breaking in more or less. Though it was himself who seemed to find the BL reading of concern...I believe that the DATS is throwing off the calculation due to Vas being off due to CMS being off due to new parts...
This..and maybe some tunes to calm my nerves...I'm pretty sure I just had a melt down for no reason, other than ignorance to the topic. Rather than down play that aspect, I'm going to eat some humble pie and move forward with a positive attitude that I have a set of some of the best woofers made.
In other news...It is looking like my Horn resp sims are holding true....The slot has a resonant note at approximately 150hz.....and my crazy threaded bracing has a resonate note as well....lol
This..and maybe some tunes to calm my nerves...I'm pretty sure I just had a melt down for no reason, other than ignorance to the topic. Rather than down play that aspect, I'm going to eat some humble pie and move forward with a positive attitude that I have a set of some of the best woofers made.
In other news...It is looking like my Horn resp sims are holding true....The slot has a resonant note at approximately 150hz.....and my crazy threaded bracing has a resonate note as well....lol
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Right, Vas increases and Qes, Qms, Qts shifts downward: Thiele Small parameters equations - How each one affects the others
I've been playing 10hz signal through the woofer for a good 10 minutes. The amp is something like 90 watts in 8 ohms...who knows whats that in 16ohms...45 for good measure...volume on max. The sensitivity of the 15m is so low at 10hz...I can't call how much excursion I was getting....The phase plug warmed up though.
I got the effective Diameter from John...Mmd should be close (1 gram less than 8 ohm version)...his predicted Mms, as a result, is on point. Sd is good...He commented about the squiggles in the impedance, suggesting that "something" is moving...Those squiggle are in the woofer that is mounted in the box....and in the complimenting woofer that I tested unmounted in free air. So if "something" is indeed moving where do you think that "something" is? The "something" is showing the same trend as well so whether in the box or on the floor the same "something" is moving.
Dats is calculating a lot of these specs based off of specified MMd, Re, fs, Q, le...
Cms is incorrect compared to listed...Vas is off....Bl should be near 27 according to John... The formulas and math are over head. I need the help of the board to get to the bottom of this.
Since the woofer in the box (no damping material) stands the best chance of being broken in...I've started with it. The other woofer can be the control...
8ohm version for comparison...most specs should end up identical in the end of this experiment.
I don't know if I should hook up a bigger amp to reach higher excursion or what...no idea how long "break in" should take...please advise.
Latest piece of evidence....Fb is about matching according to Hornresp (51hz)....In free air Fs should be 34hz but is reading as 49hz
I got the effective Diameter from John...Mmd should be close (1 gram less than 8 ohm version)...his predicted Mms, as a result, is on point. Sd is good...He commented about the squiggles in the impedance, suggesting that "something" is moving...Those squiggle are in the woofer that is mounted in the box....and in the complimenting woofer that I tested unmounted in free air. So if "something" is indeed moving where do you think that "something" is? The "something" is showing the same trend as well so whether in the box or on the floor the same "something" is moving.
Dats is calculating a lot of these specs based off of specified MMd, Re, fs, Q, le...
Cms is incorrect compared to listed...Vas is off....Bl should be near 27 according to John... The formulas and math are over head. I need the help of the board to get to the bottom of this.
Since the woofer in the box (no damping material) stands the best chance of being broken in...I've started with it. The other woofer can be the control...
8ohm version for comparison...most specs should end up identical in the end of this experiment.
I don't know if I should hook up a bigger amp to reach higher excursion or what...no idea how long "break in" should take...please advise.
Latest piece of evidence....Fb is about matching according to Hornresp (51hz)....In free air Fs should be 34hz but is reading as 49hz
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wire the other woofer opposite phase and try to dampen the vibration so that the whole house is not shaking if you have them on the floor. might be possible to sleep at the same time
put small white dot (dust, sugar, paint, piece of masking tape, whatever) on the cone and you can visually approximate the excursion. Have fun!
put small white dot (dust, sugar, paint, piece of masking tape, whatever) on the cone and you can visually approximate the excursion. Have fun!
[Fc] is box tuning, differing driver's specs only changes the response. Same with vented box [Fb].
In theory, only the manufacturer and whoever has experience with the brand/model # knows how long it takes to break a driver in with 'x' procedure.
For consumer apps would just drive them hard enough to hear audible distortion at the published Fs with a tone generator and get it as close to it within the +/- 10% norm of the times and not a consideration for prosound apps.
Hmm, looks like they 'dropped the ball' big time on this one, the reference efficiency's are way too different to ever line up.
FWIW, specs are normally off, but if its reference efficiency is +/- some reasonable percentage from the ideal at QC testing, then you can count on them breaking in/working as designed per the ideal specs, but 3.64% Vs 1.3942%? No way!
Yours are already down to ~ the Fs, Vas specs, so obviously there's no way Qt is going to plummet down to a much more powerful motor.
FWIW, specs are normally off, but if its reference efficiency is +/- some reasonable percentage from the ideal at QC testing, then you can count on them breaking in/working as designed per the ideal specs, but 3.64% Vs 1.3942%? No way!
Yours are already down to ~ the Fs, Vas specs, so obviously there's no way Qt is going to plummet down to a much more powerful motor.