Bose 10″ OEM Woofer


The driver is a 10″ OEM Bose subwoofer which came from a 2008 Cadillac CTS-V ( the year may be off by a couple, but I believe this is the correct year).

 

8e9fe89b 70b6b849 12201852

Small Signal Testing:

  • Re = 0.4625 ohms
  • Fs = 45.6971 Hz
  • Zmax = 2.0756 ohms
  • Qes = 1.2681
  • Qms = 4.4224
  • Qts = 0.9855
  • Le = 0.1834 mH (at 1 kHz)
  • Diam = 215.9000 mm ( 8.5000 in )
  • Sd =36609.6161 mm^2( 56.7450 in^2)
  • Vas = 66.5281 L ( 2.3494 ft^3)
  • BL = 1.9067 N/A
  • Mms = 34.7146 g
  • Cms = 349.4218 uM/N
  • Kms = 2861.8704 N/M
  • Rms = 2.2538 R mechanical
  • Efficiency = 0.4704 %
  • Sensitivity= 88.7426 dB @1W/1m
  • Sensitivity= 101.1220 dB @2.83Vrms/1m

BOSEOEM10inchSubwoofer

 

Large Signal LSI Klippel Testing:

Displacement Limits thresholds can be changed in Processing property page
X Bl @ Bl min=82% 5.3 mm Displacement limit due to force factor variation
X C @ C min=75% 6.8 mm Displacement limit due to compliance variation
X L @ Z max=10 %               3.9 mm Displacement limit due to inductance variation
X d @ d2=10% 25.3 mm Displacement limit due to IM distortion (Doppler)

 img_BlX img_BlSymmetryRange img_KmsX img_KmsSymmetryRange

Kef LS50 Drive Unit


Up for test is the raw drive unit from Kef’s flagship LS50 monitor.

About a year ago I ran the gamut on some Kef drivers: the HTS3001SE concetric, Q100 5.25″ concentric, and the R-series concentric.  Knowing the lineage points to the LS50 drive unit as a mix of the Q-series concetric with it’s Z-flex surround and the R-series concetric with it’s ribbed cone for reducing breakup, I was curious to see the measured performance.  I finally was provided a drive unit to test, so here we go.

Photos:

Stock photo of the LS50 speakers captured from an image search via Google:

ls50lrg

My photos…

IMG_8503 IMG_8504 IMG_8505

 

 

 Woofer Testing:

Small Signal Measurements via Klippel:

Electrical Parameters
Re 3.01 Ohm electrical voice coil resistance at DC
Le 0.197 mH frequency independent part of voice coil inductance
L2 0.474 mH para-inductance of voice coil
R2 2.46 Ohm electrical resistance due to eddy current losses
Cmes 332 µF electrical capacitance representing moving mass
Lces 9.72 mH electrical inductance representing driver compliance
Res 27.62 Ohm resistance due to mechanical losses
fs 88.6 Hz driver resonance frequency
Mechanical Parameters
(using add. mass)
Mms 10.432 g mechanical mass of driver diaphragm assembly including air load and voice coil
Mmd (Sd) 9.706 g mechanical mass of voice coil and diaphragm without air load
Rms 1.137 kg/s mechanical resistance of  total-driver losses
Cms 0.309 mm/N mechanical compliance of driver suspension
Kms 3.23 N/mm mechanical stiffness of driver suspension
Bl 5.604 N/A force factor (Bl product)
Loss factors
Qtp 0.507 total Q-factor considering all losses
Qms 5.107 mechanical Q-factor of driver in free air considering Rms only
Qes 0.557 electrical Q-factor of driver in free air considering Re only
Qts 0.502 total Q-factor considering Re and Rms only
Other Parameters
Vas 2.4278 l equivalent air volume of suspension
n0 0.291 % reference efficiency (2 pi-radiation using Re)
Lm 86.84 dB characteristic sound pressure level (SPL at 1m for 1W @ Re)
Lnom 88.07 dB nominal sensitivity (SPL at 1m for 1W @ Zn)
Madd 9.79 g additional mass
Sd 74.46 cm² diaphragm area

ls50 woofer impedance 1

Large Signal Testing with Klippel’s LSI Module:

Displacement Limits thresholds can be changed in Processing property page
X Bl @ Bl min=82% 6.7 mm Displacement limit due to force factor variation
X C @ C min=75% 2.9 mm Displacement limit due to compliance variation
X L @ Z max=10 % >7.0 mm Displacement limit due to inductance variation
X d @ d2=10% 12.7 mm Displacement limit due to IM distortion (Doppler)
Asymmetry (IEC 62458)
Ak 7.59 % Stiffness asymmetry Ak(Xpeak)
Xsym 0.19 mm Symmetry point of Bl(x) at maximal excursion

Force factor Bl (X) Bl Symmetry Range Mechanical compliance Cms (X) Stiffness of suspension Kms (X) Kms Symmetry Range Electrical inductance L(X, I=0) Inductance over current L(X=0, I)

Frequency Response @ 2.83v/1m:

Note: Due to the rather tall surround and the fact I don’t have the trim ring used to flush mount the driver in a baffle, this driver was not flush mounted.  This will effect the high frequency response to some degree.

  • Black = 0 Deg
  • Orange = 30 Deg
  • Blue = 60 Deg

LS50 woofer 0 30 60

HD at 90dB/1m and 96dB/1m equivalent:

HD @ 90db

HD @ 96db

Tweeter Testing:

Small Signal Results:

Electrical Parameters
Re 3.14 Ohm electrical voice coil resistance at DC
Le 0.013 mH frequency independent part of voice coil inductance
L2 0.01 mH para-inductance of voice coil
R2 0.41 Ohm electrical resistance due to eddy current losses
Cmes 92 µF electrical capacitance representing moving mass
Lces 0.19 mH electrical inductance representing driver compliance
Res 1.02 Ohm resistance due to mechanical losses
fs 1205 Hz driver resonance frequency
Loss factors
Qtp 0.536 total Q-factor considering all losses
Qms 0.709 mechanical Q-factor of driver in free air considering Rms only
Qes 2.185 electrical Q-factor of driver in free air considering Re only
Qts 0.535 total Q-factor considering Re and Rms only

Frequency Response @ 2.83v/1m:

Note: Due to the rather tall surround and the fact I don’t have the trim ring used to flush mount the driver in a baffle, this driver was not flush mounted.  This will effect the high frequency response to some degree.

  • Black = 0 Deg
  • Orange = 30 Deg
  • Blue = 60 Deg

LS50 tweeter 0 30 60

 

HD at 90dB/1m and 96dB/1m equivalent:

HD @ 90db

HD @ 96db

Pioneer S-IW691In-Wall Speaker: Individual Drive Unit Testing


Pioneer S-IW691In-Wall Speaker: Individual Drive Unit Testing

A friend of mine ordered the Pioneer S-IW691 Elite® EX Series speakers for his home theater setup and sent one to me because he was curious just how well the individual drivers perform; namely the concentric mid/tweeter.  The same drivers are also used in Pioneer’s in-wall center channel.

The following is taken from Pioneer’s product information page:

Designed around our award winning EX floor-standing platform, the new Elite® EX Series not only redefines the entire architectural category, but also now offers an even more comprehensive solution for the most refined of audiophile tastes.

With an experience that blends seamlessly within any environment, the EX Series offers exceptional sound with all but complete invisibility.

Built with only the finest of hand picked materials, our patented Coherent Source Transducer (CST) driver technology offers every home cinema connoisseur the most enveloping and accurate “sweet spot” available today. To fully appreciate our Elite EX Series speakers, they simply must be experienced to be believed.

The S-IW691 is designed for custom home cinema and the demands of 2 channel critical listening applications. It features a 6 1/2” woven aramid/carbon composite bass driver, a 5 1/2” magnesium midrange and a 1 3/16” ceramic graphite tweeter built into a laminated MDF baffle. Add customizable features like Treble Contour Control and exceptional sound is always at your fingertips.

 

I always am interested in seeing how raw drivers in ‘kits’ like this perform, so let’s get to it…

 

Photos

Entire Unit

IMG_8380

IMG_8401 IMG_8402

Concentric Mid/Tweeter

IMG_8389

IMG_8381

IMG_8386

IMG_8387

Woofer

IMG_8394 IMG_8395 IMG_8396 IMG_8397

Test Results: Tweeter

TweeterSmall Signal Parameters:

Electrical Parameters
Re 4.46 Ohm electrical voice coil resistance at DC
Le 0.03 mH frequency independent part of voice coil inductance
L2 0.022 mH para-inductance of voice coil
R2 0.6 Ohm electrical resistance due to eddy current losses
Cmes 74 µF electrical capacitance representing moving mass
Lces 0.24 mH electrical inductance representing driver compliance
Res 21.99 Ohm resistance due to mechanical losses
fs 1186.9 Hz driver resonance frequency
Loss factors
Qtp 2.067 total Q-factor considering all losses
Qms 12.174 mechanical Q-factor of driver in free air considering Rms only
Qes 2.467 electrical Q-factor of driver in free air considering Re only
Qts 2.051 total Q-factor considering Re and Rms only

tweeter imp

Tweeter Frequency Response:

2.83v @ 1m, 0, 30, and 60 degrees

Note: The strong dip in response shown in the on-axis (black) is likely due to not flush mounting the drive unit (unfortunately, I don’t have the tools on hand to create such a flush mount).

  • Black = 0 Degrees (on-axis)
  • Orange = 30 Degrees
  • Red = 60 Degrees

tweeter 0 30 60

Tweeter Distortion:

Harmonic Distortion at 90dB and 96dB equivalent output:

  • Blue = THD
  • Red = 2nd Order
  • Pink = 3rd Order
  • Green = 4th Order
  • Teal = 5th Order

tweeter HD @ 90

tweeter HD @ 96

Intermodulated distortion and 90dB and 96dB equivalent output:

tweeter IMD @ 90 tweeter IMD @ 96

 

 

 

Test Results: Midrange

Midrange Small Signal Parameters:

Electrical Parameters
Re 4.54 Ohm electrical voice coil resistance at DC
Le 0.227 mH frequency independent part of voice coil inductance
L2 0.326 mH para-inductance of voice coil
R2 4.48 Ohm electrical resistance due to eddy current losses
Cmes 205 µF electrical capacitance representing moving mass
Lces 8.75 mH electrical inductance representing driver compliance
Res 20.1 Ohm resistance due to mechanical losses
fs 119 Hz driver resonance frequency
——————
fm 85.1 Hz resonance frequency of driver with additional mass
Mechanical Parameters
(using add. mass)
Mms 9.213 g mechanical mass of driver diaphragm assembly including air load and voice coil
Mmd (Sd) 8.413 g mechanical mass of voice coil and diaphragm without air load
Rms 2.241 kg/s mechanical resistance of  total-driver losses
Cms 0.194 mm/N mechanical compliance of driver suspension
Kms 5.15 N/mm mechanical stiffness of driver suspension
Bl 6.712 N/A force factor (Bl product)
Loss factors
Qtp 0.567 total Q-factor considering all losses
Qms 3.073 mechanical Q-factor of driver in free air considering Rms only
Qes 0.693 electrical Q-factor of driver in free air considering Re only
Qts 0.566 total Q-factor considering Re and Rms only
Other Parameters
Vas 1.735 l equivalent air volume of suspension
n0 0.405 % reference efficiency (2 pi-radiation using Re)
Lm 88.28 dB characteristic sound pressure level (SPL at 1m for 1W @ Re)
Lnom 89.49 dB nominal sensitivity (SPL at 1m for 1W @ Zn)
Sd 79.46 cm² diaphragm area

mid impedance

Midrange Large Signal Parameters:

Displacement Limits thresholds can be changed in Processing property page
X Bl @ Bl min=82% >2.0 mm Displacement limit due to force factor variation
X C @ C min=75% 1.4 mm Displacement limit due to compliance variation
X L @ Z max=10 % >2.0 mm Displacement limit due to inductance variation
X d @ d2=10% 9.6 mm Displacement limit due to IM distortion (Doppler)
Asymmetry (IEC 62458)
Ak -87.89 % Stiffness asymmetry Ak(Xpeak)
Xsym -0.01 mm Symmetry point of Bl(x) at maximal excursion

mid bl mid bl symmetry mid cms mid kms mid kms symmetry mid lx mid li

Midrange Frequency Response:

2.83v @ 1m, 0, 30, and 60 degrees

  • Black = 0 Degrees (on-axis)
  • Red = 30 Degrees
  • Blue = 60 Degrees

mid 0 30 60

 

Midrange Distortion:

Harmonic Distortion at 90dB and 96dB equivalent output:

  • Blue = THD
  • Red = 2nd Order
  • Pink = 3rd Order
  • Green = 4th Order
  • Teal = 5th Order

mid HD @ 90 mid HD @ 96

Intermodulated distortion and 90dB and 96dB equivalent output:

mid IMD @ 90 mid IMD @ 96

 

 

Test Results: Woofer

Woofer Small Signal Parameters:

Electrical Parameters
Re 4.79 Ohm electrical voice coil resistance at DC
Le 0.505 mH frequency independent part of voice coil inductance
L2 0.62 mH para-inductance of voice coil
R2 3.01 Ohm electrical resistance due to eddy current losses
Cmes 541 µF electrical capacitance representing moving mass
Lces 14.5 mH electrical inductance representing driver compliance
Res 24.9 Ohm resistance due to mechanical losses
fs 56.8 Hz driver resonance frequency
——————
fm 42.9 Hz resonance frequency of driver with additional mass
Mechanical Parameters
(using add. mass)
Mms 20.235 g mechanical mass of driver diaphragm assembly including air load and voice coil
Mmd (Sd) 18.605 g mechanical mass of voice coil and diaphragm without air load
Rms 1.501 kg/s mechanical resistance of  total-driver losses
Cms 0.388 mm/N mechanical compliance of driver suspension
Kms 2.58 N/mm mechanical stiffness of driver suspension
Bl 6.114 N/A force factor (Bl product)
Loss factors
Qtp 0.778 total Q-factor considering all losses
Qms 4.813 mechanical Q-factor of driver in free air considering Rms only
Qes 0.925 electrical Q-factor of driver in free air considering Re only
Qts 0.776 total Q-factor considering Re and Rms only
Other Parameters
Vas 8.9472 l equivalent air volume of suspension
n0 0.171 % reference efficiency (2 pi-radiation using Re)
Lm 84.52 dB characteristic sound pressure level (SPL at 1m for 1W @ Re)
Lnom 85.5 dB nominal sensitivity (SPL at 1m for 1W @ Zn)
Sd 127.68 cm² diaphragm area

woofer impedance

Woofer Large Signal Testing:

Displacement Limits thresholds can be changed in Processing property page
X Bl @ Bl min=82% >3.2 mm Displacement limit due to force factor variation
X C @ C min=75% 1.7 mm Displacement limit due to compliance variation
X L @ Z max=10 % >3.2 mm Displacement limit due to inductance variation
X d @ d2=10% 19.5 mm Displacement limit due to IM distortion (Doppler)
Asymmetry (IEC 62458)
Ak 64.93 % Stiffness asymmetry Ak(Xpeak)
Xsym 1.82 mm Symmetry point of Bl(x) at maximal excursion

woofer bl woofer bl symmetry woofer cms woofer kms woofer kms symmetry woofer lx woofer li

 

Woofer Frequency Response:

2.83v @ 1m, 0, 30, and 60 degrees

  • Black = 0 Degrees (on-axis)
  • Red = 30 Degrees
  • Blue = 60 Degrees

woofer 0 30 60

Woofer Distortion:

Harmonic Distortion at 90dB and 96dB equivalent output:

  • Blue = THD
  • Red = 2nd Order
  • Pink = 3rd Order
  • Green = 4th Order
  • Teal = 5th Order

woofer hd @ 90Db woofer hd @ 96Db

Intermodulated Distortion at 90dB and 96dB equivalent output:

woofer imd @ 90Dbwoofer imd @ 96Db

Kef R300 Midrange Drive Unit Testing

By now you’ve probably seen my testing of the Kef HTS3001SE and Q100 drive units.  I had read the next step in the Kef Uni-Q line are the drivers in the “R” series.  So, a fella let me borrow the 5 inch midrange drive unit from the R300 speaker to test.  The R300 comes with a separate woofer but I was not sent this.  The only way to obtain these drivers individually is to purchase the speakers they come with (such as the R300 or R500 speaker) and remove them.  Which brings up something worth noting.  I am testing these raw drivers as more or less for knowledge purposes.  These kind of tests tell us exactly what the basis for a speaker is (drive units + enclosure + circuit design).  If Kef is starting with a great drive unit then one can logically assume they have likewise extended efforts to use them as a speaker in a manner which reflects their ‘raw’ performance.  In other words, if the drive unit design is great, odds are so is the complete speaker it’s used in.  Now, let’s get on with it!

 

Kef R300_2 Kef R300_1 Kef R300_3

 

Like the Q100, this driver has a very large motor structure and basket.  For a midrange, this is a HUGE drive unit, relative to other mids I’ve used.  You’ll also notice the motor and frame are a bolt together design.  The spider is below the cone on a tier sitting above where conventional speakers’ spiders are.  The surround of this driver has a curved shape to it, I assume to help it act more like a waveguide as with the cone’s shape.  The voice coil diameter is roughly 45-47mm (I had to spitball this so please take it as only an estimate).  OD is approximately 130mm.  Surface area (minus the tweeter assembly/waveguide) is about 98.01cm².  Actual effective surface area, noting the moving portion of the driver’s cone is 25cm²; the tweeter housing/waveguide is roughly 49mm in diameter.

 Tweeter Testing:

Tweeter Small Signal Parameters

 

Electrical Parameters
Re 2.92 Ohm electrical voice coil resistance at DC
Le 0.012 mH frequency independent part of voice coil inductance
L2 0.011 mH para-inductance of voice coil
R2 0.34 Ohm electrical resistance due to eddy current losses
Cmes 120 µF electrical capacitance representing moving mass
Lces 0.26 mH electrical inductance representing driver compliance
Res 0.94 Ohm resistance due to mechanical losses
fs 907.9 Hz driver resonance frequency
Loss factors
Qtp 0.488 total Q-factor considering all losses
Qms 0.644 mechanical Q-factor of driver in free air considering Rms only
Qes 2.005 electrical Q-factor of driver in free air considering Re only
Qts 0.487 total Q-factor considering Re and Rms only

 

tweeter imp

 

Tweeter Frequency Response

0, 30, and 60 degrees.  2.83v/1m; Nearfield & Farfield merged at 1800hz.

Kef R300 Drive Unit Tweeter Frequency Response 0 30 60

Tweeter Harmonic Distortion at 90dB/1m and 96dB/1m

kef r300 tweeter Fundamental + Harmonic distortion components (90dB1m) r300 tweeter Fundamental + Harmonic distortion components (96dB1m)

 

 

 

 Woofer Testing:

Woofer Small Signal Parameters:

Electrical Parameters
Re 3.08 Ohm electrical voice coil resistance at DC
Le 0.155 mH frequency independent part of voice coil inductance
L2 0.234 mH para-inductance of voice coil
R2 1.77 Ohm electrical resistance due to eddy current losses
Cmes 242 µF electrical capacitance representing moving mass
Lces 3.63 mH electrical inductance representing driver compliance
Res 9.29 Ohm resistance due to mechanical losses
fs 169.5 Hz driver resonance frequency
Mechanical Parameters
(using add. mass)
Mms 7.416 g mechanical mass of driver diaphragm assembly including air load and voice coil
Mmd (Sd) 6.9 g mechanical mass of voice coil and diaphragm without air load
Rms 3.293 kg/s mechanical resistance of  total-driver losses
Cms 0.119 mm/N mechanical compliance of driver suspension
Kms 8.41 N/mm mechanical stiffness of driver suspension
Bl 5.531 N/A force factor (Bl product)
Loss factors
Qtp 0.603 total Q-factor considering all losses
Qms 2.399 mechanical Q-factor of driver in free air considering Rms only
Qes 0.796 electrical Q-factor of driver in free air considering Re only
Qts 0.598 total Q-factor considering Re and Rms only
Other Parameters
Vas 0.5905 l equivalent air volume of suspension
n0 0.348 % reference efficiency (2 pi-radiation using Re)
Lm 87.61 dB characteristic sound pressure level (SPL at 1m for 1W @ Re)
Lnom 88.74 dB nominal sensitivity (SPL at 1m for 1W @ Zn)
Sd 59.26 cm² diaphragm area

woofer imp

Woofer Large Signal Parameters:

It may be pretty obvious that I wasn’t able to resolve all the values here. The limiting suspension resolves first at 1.5mm linear xmax, and to resolve Bl and L(x) would mean pushing on the driver harder than I am comfortable with. Suffice it to say, a high pass filter will help lessen the suspension related distortion, but this driver isn’t intended to cover bass frequencies, either.  If memory serves, it’s crossed above 500hz in the R-series towers where it is accompanied by a midwoofer.

Displacement Limits thresholds can be changed in Processing property page
X Bl @ Bl min=82% >2.5 mm Displacement limit due to force factor variation
X C @ C min=75% 1.5 mm Displacement limit due to compliance variation
X L @ Z max=10 % >2.5 mm Displacement limit due to inductance variation
X d @ d2=10% 7 mm Displacement limit due to IM distortion (Doppler)

Force factor Bl (X) Bl Symmetry Range Stiffness of suspension Kms (X) Kms Symmetry Range Mechanical compliance Cms (X) Electrical inductance L(X, I=0) Inductance over current L(X=0, I)

Woofer Frequency Response

0, 30, and 60 degrees.  2.83v/1m; Nearfield & Farfield merged at 500hz.

Kef R300 Drive Unit Woofer Frequency Response 0 30 60

Woofer Harmonic Distortion at 90dB/1m and 96dB/1m

kef r300 woofer Fundamental + Harmonic distortion components (90dB1m) kef r300 woofer Fundamental + Harmonic distortion components (96dB1m)

Miscellaneous Testing

I took some time to do a bit of additional testing with this driver just for fun using REW software and my calibrated mic.

I used an active crossover with a 3khz/LR2 crossover point between the mid and tweeter.  I then measured the driver at 0, 30, 45, 60, and 90 degrees to see how the response of the driver with this crossover applied measures in all angles.  The results are overlaid below in 1/12 resolution.

NOTE:  SPL is not indicative of any particular test method.  I just applied power to the driver and tested in various axes.  In other words, this is NOT indicative of 1w/1m or 2.83v/1m test standards.  The following is for the sake of seeing the driver’s performance in all axes with a 3khz/LR2 crossover.

drive unit sound power

Now, averaged them together for a single plot average of all the above points:

drive unit average

Same result as above, but in 1/3 octave:

drive unit average one-third

Another bit of testing I did was to see how the peak between 5-6khz could be tamed.  So, I applied some DSP correction and did a comparison.  The result below is a measurement of the raw woofer response vs the EQ’d response taken on axis (0 degrees).

This isn’t to say it’s needed.  It’s just something I did because I had some time and thought I’d share.  😉

r300 woofer raw vs eq

I failed to save the results from the off-axis measurements with the DSP included, but suffice it to say, the EQ cuts added to tame this peak worked and were shown to have diminished greatly in the off-axis measurements as well as the on-axis measurement shown above.

Impulse Response Note

Being this is called a coincident driver and the benefit of these are they are supposed to emanate sound from the sound point, I measured the tweeter and midrange drive units separately and evaluated the arrival of the impulse response.  The two impulse response lined up to a ‘T’.  Unfortunately, I didn’t save this measurement because I simply forgot to before I had to shut down the computer so am unable to post the results.

Parting Thoughts

The benefit of having a coincident design is excellent.  I’ve toyed with a few here and there, though, I felt the companies’ never quite got it right.  So, when I first started testing the Kef drive units I didn’t expect much, to be honest.  However, the previous Kef Uni-Q units I’ve tested (HTS3001SE & Q100) have proven to be very well designed.  My results for the R300 drive unit show the same standard of performance.  I took the time to listen to these along with the Q100 speakers I have and must say that I am now sold on Kef’s coincident driver engineering.  I was extremely impressed by these (two) drive units’ performance in my listening tests.  People tend to get caught up in subjective ‘analysis’ whereas I fall in to a very objective analyzer category.  I tend to ignore subjective reviews in whole and often advise others to use them lightly, unless there is objective data to correlate.  This is why it’s rare I comment on the sound of a speaker/driver.  But, I can unequivocally say, after about 3 weeks of listening to these R-series mids and the Q100 speakers – against my coveted DIY speakers and countless other drive units – these truly are the best drive units I’ve laid ears on.  And, for the price, the Q100 speaker is what I would consider an excellent value for the critical listener on a real-world budget.  In fact, I intended to sell my Q100’s after testing the drive units but I have since decided to use the Q100’s as portable reference system.

Kef Q100 Speaker Drive Unit Testing

As with the Kef HTS3001SE I tested, I ordered a set of the Kef Q100 Bookshelf speakers in order to remove and review the raw Q100 driver itself.  I really wanted to see how this coaxial design performed.  Zaph had already tested this one but I wanted to do Klippel LSI testing on it to see how the suspension performed.  He actually mentioned this in his writeup and I thought it would be cool to provide the results.  Of course, since I had it on the test baffle I did some other standard measurements as well.  The one I was interested in, but didn’t perform on the HTS3001SE driver was tweeter frequency response performance with movement of the woofer.  I don’t necessarily have an easy way to test this so I did something a bit different: I used a 9v battery to statically ‘fix’ the woofer either in the coil out or coil in position and measured the response.  I then compared this to the woofer at rest performance of the tweeter and did a direct comparison.  This is discussed further below.

On to the testing…

 

Up first, obligatory pictures:

 

IMG_5291  IMG_5288 IMG_5289 IMG_5290

This driver is quite the little beast.  A very large motor and pretty substantial surround make this one of the largest 5.25″ drivers I’ve personally seen.  Although I didn’t weigh it, it is fairly heavy due to the woofer’s ferrite magnet as opposed to neodymium.  This results in large and heavy.  I can’t exactly measure the voice coil but comparing it to the tweeter assembly, it appears to be a few mm larger in radius so I’d estimate VC diameter at roughly 55mm.  It is best to rear mount this driver given the very tall surround at approximately 12mm, but for the purpose of my test I front mounted it.

If you look at the ‘Tangerine’ waveguide/lens/whatever you want to call it, you’ll notice there’s actually a phase plug on the tweeter.  The HTS3001SE does not have this.

For those who want to read about the Tangerine waveguide, click this link (PDF format).  There’s also discussion on the radial ribbing of the other Uni-Q cones, which this driver doesn’t employ.

 

 

Raw Driver Physical Measurements

First off, given this isn’t sold as an individual driver, I have taken my own measurements.  These are rough measurements taken with my not-so-recently calibrated calipers, but should be good within +/-1mm.

Outer Diameter 143 mm
Mounting Diameter 120 mm
Mounting Depth   83 mm
Effective Piston Diameter* 109 mm
Effective Piston Diameter**   60 mm
Flange Thickness 0.34 mm
Mounting Tab Thickness 0.65 mm
*Half surround to half surround; including space consumed by coincident tweeter.
**Half surround to half surround; NOT including space consumed by coincident tweeter.

Test Results

To make things a bit easier to manage, I’ve broken down the test results in to two sections:

  1. Woofer Testing
  2. Tweeter Testing

Part I: Woofer Testing

Woofer Thiele-Small Parameters and Impedance

Note:  When determining the full suite of T/S parameters, the effective diameter of the driver is needed to calculate Vas, Bl, etc.  Most of the time this can simply be measured by measuring the diameter of the driver from half-surround to half-surround since the motor must control the entire cone area.  However, in this case, the entire cone does not move.  Therefore, the effective diameter (and resulting Sd) is not the entire diameter of the driver.  The effective diameter here is determined by subtracting the static tweeter assembly from the overall effective diameter of the woofer.  See physical measurements section above for all values.

Electrical Parameters
Re 3.09 Ohm electrical voice coil resistance at DC
Le 0.256 mH frequency independent part of voice coil inductance
L2 0.427 mH para-inductance of voice coil
R2 3.39 Ohm electrical resistance due to eddy current losses
Cmes 318 µF electrical capacitance representing moving mass
Lces 18.82 mH electrical inductance representing driver compliance
Res 29.82 Ohm resistance due to mechanical losses
fs 65 Hz driver resonance frequency
Mechanical Parameters
(using add. mass)
Mms 12.834 g mechanical mass of driver diaphragm assembly including air load and voice coil
Mmd (Sd) 12.108 g mechanical mass of voice coil and diaphragm without air load
Rms 1.352 kg/s mechanical resistance of  total-driver losses
Cms 0.467 mm/N mechanical compliance of driver suspension
Kms 2.14 N/mm mechanical stiffness of driver suspension
Bl 6.35 N/A force factor (Bl product)
Loss factors
Qtp 0.365 total Q-factor considering all losses
Qms 3.878 mechanical Q-factor of driver in free air considering Rms only
Qes 0.402 electrical Q-factor of driver in free air considering Re only
Qts 0.364 total Q-factor considering Re and Rms only
Other Parameters
Vas 3.6615 l equivalent air volume of suspension
n0 0.241 % reference efficiency (2 pi-radiation using Re)
Lm 86.02 dB characteristic sound pressure level (SPL at 1m for 1W @ Re)
Lnom 87.14 dB nominal sensitivity (SPL at 1m for 1W @ Zn)
Sd 74.46 cm² diaphragm area

q100 impedance

Woofer Large Signal Analysis with Klippel’s LSI Module

Displacement Limits thresholds can be changed in Processing property page
X Bl @ Bl min=82% >4.2 mm Displacement limit due to force factor variation
X C @ C min=75% 1.9 mm Displacement limit due to compliance variation
X L @ Z max=10 % 2.8 mm Displacement limit due to inductance variation
X d @ d2=10% 17.1 mm Displacement limit due to IM distortion (Doppler)

q100 bl q100 bl symmetry q100 kms q100 kms symmetry q100 cms q100 le q100 li

Woofer Frequency Response

Measured at 2.83v/1m.  Stitched with a nearfield measurement at approximately 500hz.

Kef Q100 Drive Unit (Woofer) 0 30 60

Woofer Harmonic Distortion

kef q100 woofer FR HD 96dB

Part II: Tweeter Testing

Small Signal Parameters:

Electrical Parameters
Re 2.84 Ohm electrical voice coil resistance at DC
Le 0.018 mH frequency independent part of voice coil inductance
L2 0.011 mH para-inductance of voice coil
R2 0.5 Ohm electrical resistance due to eddy current losses
Cmes 110 µF electrical capacitance representing moving mass
Lces 0.28 mH electrical inductance representing driver compliance
Res 1.09 Ohm resistance due to mechanical losses
fs 902.6 Hz driver resonance frequency
Loss factors
Qtp 0.491 total Q-factor considering all losses
Qms 0.678 mechanical Q-factor of driver in free air considering Rms only
Qes 1.769 electrical Q-factor of driver in free air considering Re only
Qts 0.49 total Q-factor considering Re and Rms only

Tweeter Frequency Response

Kef Q100 Drive Unit (Tweeter Only) 0 30 60

Tweeter Harmonic Distortion

Kef Q100 Tweeter FR HD 96dB

Tweeter Response vs Woofer Position

I thought it would be interesting to see how the position of the woofer cone impacts the frequency response of the tweeter.  This matters when you’re listening to music and isn’t captured by a standard sine sweep.  To measure this performance I simply connected a 9v battery to the woofer’s terminals in positive polarity, then negative polarity which resulted in an approximate +/-3mm shift in cone direction.  I ran a sine sweep over the tweeter while the woofer was a) at rest, b) fixed out, and c) fixed in.  The pictures below show illustrate this.

Woofer at rest:

Q100 Woofer At Rest

Woofer fixed out:

Q100 Woofer Out

Woofer fixed in:

Q100 Woofer In

The following results are of the three positions discussed above overlaid on one another.  The lines are labeled per the woofer position.

Note: The SPL level is not absolute here.  I performed the test at the same volume level throughout but it is not intended to reference any set test paraemter such as 2.83v/1m or 1w/1m.

Kef Q100 Drive Unit Woofer Displacement on Tweeter Response Example

End

If you have any specific questions or you have feedback on the performance of this driver, feel free to post to my page.

If you like what you see here and what to help me out, there’s a Paypal Contribute button at the bottom of each page.  Every little bit does help.  Remember, I don’t get paid a dime to do this stuff.  I do it on my own for the love and entertainment but it is nice not to have to pay out of pocket to purchase things to test or gear to test with.  I’m looking to buy a new high-SPL capable mic for subwoofer testing so any donations in the near future will go toward that.

 

Thanks!

 

 

EDIT, 01/16/2013:

I was asked for a picture of the crossover that comes with the Q100 speaker.  Here it is:

IMG_5312

 

 

 

Update 01/26/2013:

I’ve been using these Kef Q100 speakers (driver and cabs) as my reference/experimenting setup with dolby, L7, etc recently and I can say unequivocally, these are by far the best set of speakers I’ve heard in their respective size range. The imaging and soundstage along with vocal acuity is incredible. When I first fired them up I was extremely impressed. Walking around the speakers, there is no dramatic drop in response; the sound power response is excellent.

I had every intention on selling these to get funds back but at this point I’m making every effort to not have to sell them. I’d like to make them my new reference setup. A sub to pick up below 50hz mated to these would make a very potent and worthwhile setup rivaling many tower based setups I’ve heard. And this is coming from the guy with a set of Zaph ZRT 2.5’s. the cool part is its extremely portable so I can take it to meets and demo for others.

Kef really nailed this speaker. For its price I have yet to find anything I think could beat it.

Kef’s HTS3001SE… I cracked the Egg!

Note:  This discussion revolves solely around the drive unit used in the Kef HTS3001SE.  For speaker (drive unit+egg enclosure) testing and data, click this link.

 

I recently ordered a set of the Kef HTS3001SE speaker.  The reason wasn’t to have a great set of computer speakers.  Rather, I was interested after reading Zaph’s test of the Q100 driver how much that performance was captured in the smaller 3001SE driver for potential DIY use.  While a set of the HTS3001SE can be upwards of $400, if you consider you’re getting 4 drivers, that brings the cost down to about $100/piece with the benefit of a coaxial design.  Still, that’s not exactly cheap and the results need to be viewed to determine relative worth.  The Q100 driver is noted as a 6 inch driver, whereas the HTS3001SE is a bit smaller.  My measurements (discussed below) show it to be closer in size to a typical 5.25 inch driver.  Zaph’s data on the Q100 driver shows a whole lot of potential and, as far as coaxial/coincident drivers go, it’s the best I’ve seen.  The Q100 features the Z-surround which my guess was to keep the surround out of the wave of the tweeter as much as possible yielding a smooth high frequency response both on and off-axis.  If you look at coaxials from other manufacturers data you’ll find disparaging HF response; especially on-axis.  Like I said, I was really curious how well the “little brother” – the HTS3001SE – would perform.  Unfortunately there wasn’t any data on this and I knew I’d have to measure it myself if I wanted to know.  So, I ordered a set to test and they showed up today.

 

Started off with the full Egg…

 

IMG_5162 IMG_5164

 

 

Luckily, dissecting them was extremely easy and not destructive.  I dismantled the egg simply by removing the rubber facing which revealed two allen heads.  Consequently enough, Kef includes an allen wrench for purpose of positioning the Egg on the swivel mount.  I removed the two allen heads and the shell came apart with ease.  This revealed the driver attached to the front half and the back half which contained the port (what feels like plastic), the crossover, and some acoustical stuffing.  I disconnected the speaker leads from the driver.  This left the driver attached to the front portion via 4 screws.  I removed those screws, applied a small amount of force to ‘break’ the driver free of the mount and voila… raw driver.  🙂

IMG_5116 IMG_5117 IMG_5118 IMG_5121 IMG_5122 IMG_5123 IMG_5127 IMG_5130 IMG_5135 IMG_5136 IMG_5140 IMG_5147 IMG_5150 IMG_5151

IMG_5176 IMG_5167

As you can see above, the driver itself has a plastic frame and basket and (seemingly) a neodymium motor.  The driver features a ribbed cone.  Upon further investigation, the cone and the ribs seem to be one molded plastic piece rather than a paper/aluminum cone overlaid on a plastic ribbed frame.  I would assume the rib design is implemented to prevent modal issues higher in frequency outside of the woofer driver’s passband and hopefully testing will show us how well that worked, though there is no way to compare what the results would be had the cone not been ribbed since I don’t have a version of this.  We’ll just have to guess.  Also, the driver uses the ‘tangerine’ waveguide found in some of the other Uni-Q drivers.  When the cone is traveling forward and rearward with the voice coil, the tweeter assembly stays fixed.  The cone itself is cut to allow the tweeter assembly to fit inside the driver, therefore there is no contact of the cone with the tweeter mechanism.  This implies you would expect strict control of the suspension in order to keep from the cone touching the tweeter and, judging from the suspension measurements illustrated in the Woofer LSI section below, this is in fact the case.

Raw Driver Physical Measurements

First off, given this isn’t sold as an individual driver, I have taken my own measurements.  These are rough measurements taken with my not-so-recently calibrated calipers, but should be good within +/-1mm.

Outer Diameter 119.6 mm
Outer Diameter Including Tabs 144.8 mm
Mounting Diameter* 119.3 mm
Mounting Depth 60.5 mm
Effective Piston Diameter** 102 mm
Effective Piston Diameter*** 70.5 mm
Flange Thickness**** 0.34 mm
Mounting Tab Thickness 0.65 mm
* Note this driver’s mounting diameter is extremely close to the outer diameter excluding tabs.  Look at the picture of the driver and you’ll see the tabs are what allow you to have any bit to a baffle at all.
**Half surround to half surround; including space consumed by coincident tweeter.
***Half surround to half surround; NOT including space consumed by coincident tweeter.
****Flange thickness is not uniform.  At the mounting location the flange is a bit thicker.

 

As noted, the flange isn’t uniformly thick.  The mounting tabs are a tad bit thicker.  To make sure this point is understood, I have taken a few pictures to illustrate:

IMG_5155

IMG_5154

Another thing worth noting to anyone who may want to order these to dissect and use the drivers themselves is this: front mounting these may be more trouble than its worth.  There’s a circle, but there’s not much meat here.  The tabs provide mounting privileges.  The wire lead blocks also stick out a decent bit so you’ll have to notch out your mounting ring.  Which is probably why Kef rear mounts the driver in the egg.  This may be the easiest way to go depending on your plans.

 

Final pictures, featuring the Aura Sound NS3 (left), the Kef HTS3001SE driver (center), and Scan Speak 12MU (right) for comparison purposes.  As you can see, the Kef 3001 driver is a bit larger.  I measured the Scan’s effective diameter to be about 84mm while the Kef’s is approximately 102mm.  Again, ‘effective diameter’ is half-surround to half-surround across the driver.  So, really, this particular Kef driver is much closer in size to a 5.25 inch driver.

IMG_5142 IMG_5141

 

Driver & Speaker Testing

Now, on to the testing.  This will be broken up in to 3 parts:

  1. Tweeter Only (Raw Driver:  no passive used)
  2. Woofer Only (Raw Driver: no passive used)
  3. Coaxial set playing with Kef’s passive crossover in use

 

 

———————————————————————————————————————

Part I: Tweeter Testing

Tweeter Thiele-Small and Impedance Results

Electrical Parameters
Re 2.91 Ohm electrical voice coil resistance at DC
Krm 0.0299 Ohm WRIGHT inductance model
Erm 0.22 WRIGHT inductance model
Kxm 0.0001 Ohm WRIGHT inductance model
Exm 0.86 WRIGHT inductance model
Cmes 147 µF electrical capacitance representing moving mass
Lces 0.06 mH electrical inductance representing driver compliance
Res 1.2 Ohm resistance due to mechanical losses
fs 1757.4 Hz driver resonance frequency
Loss factors
Qtp 1.41 total Q-factor considering all losses
Qms 1.945 mechanical Q-factor of driver in free air considering Rms only
Qes 4.738 electrical Q-factor of driver in free air considering Re only
Qts 1.379 total Q-factor considering Re and Rms only

Kef HTS3001SE Tweeter Impedance

Tweeter Frequency Response

Measurements taken in the neafield and farfield, then merged together at approximately 1200hz, representing a quasi-anechoic response at 2.83v/1m.  On-axis and off-axis measurements are represented at 0, 30, and 60 degrees.

Kef HTS3001SE Tweeter Driver 0 30 60

Tweeter Harmonic Distortion

Measurement taken in the nearfield at SPL equal to 96dB/1m.

Kef HTS3001SE Tweeter Fundamental + HD Kef HTS3001SE Tweeter HD

Tweeter CSD

Obtained from the same nearfield conditions as HD above is used.  In this case, however, I have set a floor equal to that of the lowest in-band response level minus 40dB.  Which means, at approximately 6250, the response of the tweeter was lowest at 107dB.  I set the floor for 67dB.  This chops off any data that might not be needed.  It is common convention to do do this as the thought is ringing audibility is only -40dB within 3 milliseconds.  Personally, that’s about the extent of my knowledge here but to those who find this useful, I have provided it.

Kef HTS3001SE Tweeter CSD

———————————————————————————————————————

Part II:  Woofer Testing

Woofer Thiele-Small and Impedance Results

Electrical Parameters
Re 3.21 Ohm electrical voice coil resistance at DC
K 0.002 LEACH inductance model
n 0.77 LEACH inductance model
Cmes 478 µF electrical capacitance representing moving mass
Lces 6.98 mH electrical inductance representing driver compliance
Res 18.79 Ohm resistance due to mechanical losses
fs 87.1 Hz driver resonance frequency
——————
fm 61.8 Hz resonance frequency of driver with additional mass
Mechanical Parameters
(using add. mass)
Mms 11.986 g mechanical mass of driver diaphragm assembly including air load and voice coil
Mmd (Sd) 11.655 g mechanical mass of voice coil and diaphragm without air load
Rms 1.334 kg/s mechanical resistance of  total-driver losses
Cms 0.278 mm/N mechanical compliance of driver suspension
Kms 3.59 N/mm mechanical stiffness of driver suspension
Bl 5.006 N/A force factor (Bl product)
Loss factors
Qtp 0.735 total Q-factor considering all losses
Qms 4.919 mechanical Q-factor of driver in free air considering Rms only
Qes 0.841 electrical Q-factor of driver in free air considering Re only
Qts 0.718 total Q-factor considering Re and Rms only
Other Parameters
Vas 0.7692 l equivalent air volume of suspension
n0 0.058 % reference efficiency (2 pi-radiation using Re)
Lm 79.84 dB characteristic sound pressure level (SPL at 1m for 1W @ Re)
Lnom 80.8 dB nominal sensitivity (SPL at 1m for 1W @ Zn)
Sd 44.18 cm² diaphragm area

Kef HTS3001SE Woofer Impedance

Woofer Large Signal Analysis (LSI) Results

Displacement Limits thresholds can be changed in Processing property page
X Bl @ Bl min=82% 2.7 mm Displacement limit due to force factor variation
X C @ C min=75% 3.6 mm Displacement limit due to compliance variation
X L @ Z max=10 %            >3.9 mm Displacement limit due to inductance variation
X d @ d2=10% 12.7 mm Displacement limit due to IM distortion (Doppler)
Asymmetry (IEC 62458)
Ak -3 % Stiffness asymmetry Ak(Xpeak)
Xsym 0.34 mm Symmetry point of Bl(x) at maximal excursion

Kef HTS3001SE Woofer Force factor Bl (X) Kef HTS3001SE Woofer Bl Symmetry Range kef 3001 Stiffness of suspension Kms (X) kef 3001 Kms Symmetry Range Kef HTS3001SE Woofer Mechanical compliance Cms (X) Kef HTS3001SE Woofer Electrical inductance L(X, I=0) Kef HTS3001SE Woofer Inductance over current L(X=0, I)

Woofer Frequency Response

Measurements taken in the neafield and farfield, then merged together at approximately 500hz, representing a quasi-anechoic response at 2.83v/1m.  On-axis and off-axis measurements are represented at 0, 30, and 60 degrees.

Kef HTS3001SE Woofer Driver 0 30 60

Woofer Harmonic Distortion

Measurement taken in the nearfield at SPL equal to 96dB/1m.

Fundamental + Harmonic distortion components (Relative to 96dB1m)_1 Kef 3001 woofer Harmonic distortion (Relative to 96dB1m)

Woofer CSD

Obtained from the same nearfield conditions as HD above is used.  In this case, however, I have set a floor equal to that of the lowest in-band+some response level minus 40dB.  Which means, at approximately 10khz, the response of the woofer was lowest at 100dB.  I set the floor for 70dB.  This chops off any data that might not be needed.  It is common convention to do do this as the thought is ringing audibility is only -40dB within 3 milliseconds.  Personally, that’s about the extent of my knowledge here but to those who find this useful, I have provided it.

kef 3001 woofer CSD

Finally, here is the result of the Tweeter’s on-axis response overlaid on the same graph with the Woofer’s on-axis response.  This is raw driver data; no passive crossover used.

Kef HTS3001SE Tweeter and Woofer Drivers

———————————————————————————————————————

Part III:  Coaxial Speaker Testing Using Kef Passive Crossover

Up next is testing the HTS3001SE speaker on the baffle using the supplied passive crossover.

Frequency Response

Kef HTS3001SE Coaxial Driver with Passive Crossover 0 30 60

Harmonic Distortion

This test was done to simulate the equivalent level of 96dB/1m.  This usually involves testing at 112dB in the nearfield.  Since there’s a dip in response in the 1-2khz area, likely due to the passive using baffle step compensation here, thus making the lower passband of the woofer have more output, I used the average output from 100hz-10khz and increased the output until I achieved approximately 112dB here, though I wound up closer to 115dB.  You’ll see what I mean below.  Just look at the dashed line labeled Fundamental Mean.  That line represents the mean output level which is approximately 115dB.

Kef HTS3001SE Coaxial Driver total with Passive Crossover HD 96db 1m

Coax Driver Harmonic distortion (Relative to 96dB1m)

Coaxial Driver CSD

Taken in the nearfield with a floor set 40dB below the lowest dip in response below 10khz, which occurred at about 110dB.

Kef HTS3001SE Coaxial Driver CSD with Passive Crossover

Individual Driver Frequency Response with Respective Crossover

This is the result of testing each driver with it’s respective passive crossover implemented.

Kef 3001SE tweeter and woofer individual with passive

———————————————————————————————————————

Summary/End Thoughts

This may be a bit scattered, so forgive me.

Raw driver response:

Woofer:

  • The woofer is comparable to 5.xx” drivers in cone area.
  • The measured Fs is 87hz, with a Qts of 0.718.
  • The linear xmax, as measured by Klippel’s LSI, came in at 2.7mm; limited by Bl.  This is the xmax at 10% THD.  Suspension derived linear xmax clocked in at 3.6mm.
  • As noted in the opening discussion about build quality, the cone is designed to move around the tweeter assembly and there’s really not much wiggle room here.  This means the suspension should not have any tilt or asymmetry while in motion.  Otherwise the cone would crash against the tweeter housing.  And it doesn’t.  The most obvious way to tell this is by throwing some power at the driver and listening for any contact.  Then, if you want to really see just what the suspension is doing, you can do so by analyzing the suspension performance measured by Klippel’s Large Signal Identification (LSI) module provided in the woofer results section.  As shown in the Kms Symmetry Range graph in this section, suspension symmetry is nearly ruler flat.  The delta from the driver at rest (0mm) to peak measured excursion (~4.4mm) is about 0.23mm which is roughly the thickness of a folded sheet of paper.  This is textbook symmetry for a suspension system.  So, by this standard, the driver’s design and build quality are spot on.  Below is a video of the woofer’s movement to show how the tweeter assembly stays static while the woofer cone moves around it.

CAUTION:  You may want to turn down your volume.

  • The woofer exhibits a sharp drop in response just above 2.2khz, as evidenced in all the response charts.  Thinking this may be a function of the hole in the center of the woofer cone (to pass beyond the tweeter) and stem from a phase anomaly.  My first inclination was to investigate via phase comparison of the driver tested at two different levels (90dB/1m vs 96dB/1m).  I thought that if I drove the woofer further in travel it might show a more distinct alteration in the measured response in this area. However, I found no obvious evidence with this method.  All phase and magnitude plots between the two drive levels lined up almost perfectly.  Though, it is clear to see the minimal phase takes a notable dip as shown below.

kef 3001 woofer Minimal phase of transfer function H(f)

 

  • Frequency Response:
    • The average SPL at 2.83v/1m is 83dB from 100hz to 2khz.  Above 2khz, the response diverges pretty rapidly and falls off pretty hard until 4khz which is roughly where the -3dB point is from 0 to 30 degrees.  Overall, if you can determine exactly what the cause of disturbance here is and/or you have the DSP to adjust the response above 2khz (assuming this is possible) you might be able to eek out more usable bandwidth.
  • HD:
    • 2nd order dominates here and rides 1% distortion from about 200hz to 1.5khz.  Above this, there’s significant increase in 2nd order then alternating with 3rd order starting at 2.7khz.  Though, 3rd order is staying around 0.25% from about 150hz to 2khz (with a small blip at 250hz rising to just under 1%).Even order distortion follows the same profile as the FR above 2khz which could be telling… I just don’t know what it’s telling.
  • While there the inductance over excursion plot doesn’t show a symmetrical Le(x) curve, the overall inductance delta represented via Le(x) from -4.4mm to +4.4mm is less than 0.08mH, which indicates possible use of inductance mitigation.

Tweeter:

  • The tangerine waveguide, as it’s called, looks pretty interesting.  Frankly, I’ve not found any white papers or technical documents on the design so I’ll hold my subjective and likely wrong thoughts on this.  But, at the least, it’s an interesting means of controlling directivity and, compared with other coincident/coaxial offerings on the market, it seems to do a pretty good job.
  • Frequency Response:
    • There definitely appears to be a horn loading effect.  Off Axis response seems to look pretty well behaved, though the on-axis response shows potential issues caused by a null at 8khz.  I did some listening and didn’t notice this to stand out but it may require attention should you be interested in using this driver for your own design.  This may be an inherent trait of this type of design as I notice it occurs in the Seas Coaxial offerings as well.  Could just be coincidence, though.
  • Harmonic Distortion:
    • As with the woofer, the HD results of the tweeter is dominated almost solely by 2nd order distortion components.  3rd and subsequent order distortion is almost non-existent below 2khz.

 

Combined driver response with passive crossover:

Remember, I am measuring a coaxial driver with the supplied crossover intended to be used in an enclosure on a raw baffle.

  • It looks very much like there’s baffle step compensation here, evidenced by the boosted response below 1khz.  On the test baffle, the boosted low end shows itself.  There’s hearty low end here.  In the speaker egg, this shouldn’t be as much of concern.
  • Of course, the top end has a boost as well which mean a trough in response between 1khz to 2khz.  I thought maybe I had one of the drivers out of phase but testing the polarity the other way yielded results that showed me that obviously wasn’t the issue.  Furthermore, looking at the individual driver results with supplied passive crossover yield very similar results for the woofer driver.  Someone with speaker building experience may be better able to explain this. This could be intentional design to have this dip in response.  I have yet to have a chance to measure the speaker itself but hopefully I’ll get to soon.

————————————————————————————

End

That’s it.  I’ve tried to cover what I can, but given the breatdh of this test, I’m bound to have missed noting something or possibly mislabeled a graph.  If you notice anything like that, let me know and I’ll correct it.

If you have any specific questions or you have feedback on the performance of this driver, feel free to post to my page or check discussion here.

If you like what you see here and what to help me out, there’s a Paypal Contribute button at the bottom of each page.  Every little bit does help.