Blast from the past! SpeakerWorks/USD Audio A-6.0 Testing

I was loaned this set of SpeakerWorks/USD Audio A-6.0 horns by a friend some time ago and recently came across them when shuffling some things around in a closet.  Even though these are circa 1995 (maybe earlier), I thought it might still be fun to test them out for “old times sake” to recapture some nostalgia.  Because, heck, reminiscing is fun and we can learn a lot from old designs.

Before moving too far ahead, I would like to address this specific horn and application given it’s age.  I contacted USD Audio to see if they could provide any insight on the product.  Eric Holdaway was kind enough to respond with some vital information that is crucial to understanding the implications of the preceding test results:

They are “A” models with the fiberglass body which are really, really old.  These should only be used with the original supplied EQ and compensation circuits or comparable devices for them to perform at their best.

Eric also added:

It sure was fun to “invent” the HLCD’s in the car thing with my Dad (Roger), Brother (Pat) and Great friend R.E Greene. Our U.S. Patent was amazing to get and lock in that we had created an original idea. This and the A-periodic subwoofer enclosure were a thrill to create.

 

I have to thank Eric for being kind enough to provide some info on a product that has been obsolete for nearly 2 decades and understanding the desire to still want to learn and revisit some nostalgic items back when car audio sound quality competition was in it’s “heyday”.  As Eric noted, these were designed to be used with an EQ/Compensation circuit.  However, this was not provided so please understand that while these results show the performance of the raw horn… that’s exactly what you are getting; you are not seeing the results as they were intended to be used from the factory as the above mentioned circuit is not tested as part of the kit here.  The owner said he might have this circuit somewhere so this test may be revisited later and updated accordingly.

 

With that said, let’s get started…

IMG_3972 IMG_3967 IMG_3979 IMG_3982 IMG_3980

IMG_3978As you can tell, these horns were treated with CLD (constrained layer damping – commonly known as “dynamat”, etc).  This was popular among competitors as it was used to reduce the horn body from resonating at higher frequencies.

 

Measurement Information

This horn was measured free-air.  This was not measured in a car nor was any sort of baffle used to mimic the bottom half of a dash, as these would typically use in an install to ‘extend’ the horn’s effect in the vertical plane.  It was attached to a 6×6 beam and measured both horizontally and vertically from -90 to +90 degrees.  For Frequency Response measurements, a signal of 2.83v was fed to the driver with the mic placed at 1 meter distance from the horn mouth.

 

Impedance Sweep

Results provided are obtained via Dayton’s DATS v2.

  • f(s)= 1325 Hz
  • R(e)= 5.789 Ohms
  • Z(max)= 14.54 Ohms
  • Q(ms)= 4.164
  • Q(es)= 2.754
  • Q(ts)= 1.658
  • L(e)= 0.8925 mH

USD Horn impedance

Frequency Response – Horizontal

I measured the A-6.0 horizontally, with the magnet side facing upwards from -90 to +90 degrees.  My 0 Degree axis was dead on the straight side of the horn.  Positive (+) degree measurements were performed going from 0 degrees to 90 degrees to the flare-side of the horn.  Negative (-) degree measurements were done going from 0 degrees to 90 degrees to the straight-side of the horn.  The polar mapped image below gives further illustration to help make this clear.

The second and third image are simply the 0 to +90 and 0 to -90 degree measurements broken out for easier viewing. Following these are some ‘comparison’ images at varying axes (i.e.; +15 vs -15 degrees).  Read the legends.

Horizontal Polar

0 to 90 hz 0 to -90 hz

15 vs -15 hz 45 vs -45 hz

Frequency Response – Vertical

I measured the A-6.0 vertically, with the magnet side facing upwards from -90 to +90 degrees.  My 0 Degree axis was dead on the straight at the horn.  The “bottom” is referred to as the compression driver side.  Positive (+) degree measurements were performed going from 0 degrees to 90 degrees to the top side of the horn (CD facing down side).  Negative (-) degree measurements were done going from 0 degrees to 90 degrees to the bottom side of the horn.  The polar mapped image below gives further illustration to help make this clear.

The second image is the 0 to +90 degree (top side) measurements broken out for easier viewing.

Vertical Polars 2

Vertical "top"

Harmonic Distortion

The following was done in the nearfield simulating 98dB @ 1 meter (1khz reference).  Note: Input voltage was 2.83v.

HD 2.83v 98dB @ 1m equivalent

The follwoing was done in the nearfield simulating 104dB @ 1 meter (1khz reference):

HD 104dB @ 1m equivalent

PS:  If you would like to help me keep up funds for testing, there’s a little ‘contribute’ button that goes through Paypal all the way at the bottom of every page.  Any little bit helps.

Hybrid Audio L1 Pro R2 Ring Radiator Tweeters


Up for test is the Hybrid Audio L1 Pro R2 Ring Radiator Tweeter.

Information from the manufacturer can be found here: http://hybrid-audio.com/le/

IMG_2475 IMG_2474 IMG_2482

 

Small Signal Parameters and Impedance

Results as measured via Dayton’s DATs measurement tool.  Which is a very little handy tool to have.  😉

  • f(s)= 639.90 Hz
  • R(e)= 3.48 Ohms
  • Z(max)= 6.84 Ohms
  • Q(ms)= 1.641
  • Q(es)= 1.702
  • Q(ts)= 0.835
  • L(e)= 0.48 mH

l1pro imp

Frequency Response

Frequency Response and the following Harmonic Distortion measurements were taken using Dayton’s OmniMic measurement system.

The frequency response measurements below are on-axis (0 degrees) and off-axis (15, 30, 60 degrees), measured at 2.83v/1m.

l1pror2 FR

To get an idea of the off-axis response vs the on-axis (0 degrees) response, I normalized the above.  What you get is the relative output level of each axis vs the on-axis level.

l1pror2 normalized

Harmonic Distortion Testing

Legend:

Maroon – Fundamental

Blue – THD

Red – 2nd Order Distortion

Pink – 3rd Order Distortion

Green – 4th order

Teal – 5th order

Testing done in the nearfield to emulate 90dB and 96dB output at 1 meter.

l1pro r2 hd90l1pro r2 hd96

Impressions/Results

The Fs is measured at approximately 640hz.  To get an idea of what this means on the high-pass crossover, let’s evaluate the HD results.  At 96dB output the THD (blue) is 1.70% at 1khz.  The THD is less than 0.50% down to 1.8khz though there is a peak in THD of about 1.0% THD at 2.8kHz, which corresponds with the dip/peak shown in this region on the frequency response as well as a bump in the impedance at this same point, which means this could possibly be a chamber resonance.

Measured sensitivity is right around 86-87dB on average (note the rising response above 4kHz).  The response isn’t flat; it has approximately a 5dB rising response above 4khz, but this response is smooth. There is a 3dB dip (noted above) at approximately 2.4khz trending back up to a 1dB peak at 3.2kHz which correlates to a resonance in the impedance data. Given this is a area is largely comprised of a dip, though, the concern isn’t great.  At 30 degrees off-axis, the response is down approximately 4dB at 10khz.  At 60 degrees off-axis, the response is down approximately 7.5dB at 10khz.  Overall, the on and off-axis response looks quite good up to 10khz where the 60 degree measurement shows a strong dip centered at ~14.4kHz.  This dip doesn’t really concern me because it’s a dip, not a peak, and doesn’t show up in the other axes of measure which indicates this is not a modal issue; rather just a reflection (possibly a reflection off the surround).  While not ideal, I don’t consider it a deal-breaker.

Bottom line:  Really nice polar response.  Good use down to 2khz with a steep crossover.  Though, with the resonance at 2.4khz, I’d think 2.5khz with a 24dB electronic crossover would be a better use for these in a higher output system.  Obviously individual needs/results may vary.

PS:  If you would like to help me keep up funds for testing additional drivers, there’s a little ‘contribute’ button that goes through Paypal all the way at the bottom of every page.  Any little bit helps.

Scan Speak D3004/602000 Tweeter: Take Two!


Up for test is the Scan-Speak Illuminator D3004/6020-00 1″ Textile Dome Tweeter, 4 ohm.
This is the second time I have tested this.  The reason for the second test is simply to have a better apples-to-apples comparison now that I have switched to using Dayton’s OmniMic measurement system.  Product specs can be found here.

IMG_2262IMG_2263

Small Signal Parameters and Impedance

Results as measured via Dayton’s DATs measurement tool.  Which is a very little handy tool to have.  😉

  • f(s)= 737.50 Hz
  • R(e)= 3.17 Ohms
  • Z(max)= 11.60 Ohms
  • Q(ms)= 6.047
  • Q(es)= 2.272
  • Q(ts)= 1.652
  • L(e)= 0.43 mH

d3004 impedance

Frequency Response

Frequency Response and the following Harmonic Distortion measurements were taken using Dayton’s OmniMic measurement system.

The frequency response measurements below are on-axis (0 degrees) and off-axis (15, 30, 60 degrees), measured at 2.83v/1m.

scan fr 0 15 30 60
To get an idea of the off-axis response vs the on-axis (0 degrees) response, I normalized the above.  What you get is the relative output level of each axis vs the on-axis level.

scan d3004 normalized

Harmonic Distortion Testing

Legend:

Maroon – Fundamental

Blue – THD

Red – 2nd Order Distortion

Pink – 3rd Order Distortion

Green – 4th order

Teal – 5th order

Testing done in the nearfield to emulate 90dB and 96dB output at 1 meter.


d3004 HD90 d3004 HD96

Impressions/Results

The Fs is measured at approximately 737hz.  To get an idea of what this means on the high-pass crossover, let’s evaluate the HD results.  At 96dB output the THD (blue) is 1.25% at 1khz.  The THD is less than 0.50% down to 1.3khz where it is comprised almost entirely of 2nd order distortion above 1.5khz.   Above 1.5khz there is about 10-20dB separation between 2nd and 3rd order components.

Measured sensitivity is right around 86.5dB.  On-axis, there’s about a 5dB dip centered around 14khz.  At 30 degrees off-axis, the response is down approximately 4.5dB at 10khz.  At 60 degrees off-axis, the response is down approximately 9.5dB at 10khz.  The trough in response from 1.5khz to 5khz is made to appear worse thanks to the high Qts on the low end and the rising response above 3.5khz.  There’s a 7dB swing from 2khz to 8khz thanks to the upward rising response on-axis.

Bottom line: Okay response linearity with great distortion values.  Great polar response with very low distortion above 1.3khz.  This would make a good option for a tweeter in a 2-way system where there is a need to cross low to mate with a larger woofer.  The response linearity may cause you some headaches here but with DSP and the sensitivity of this tweeter, you have some ‘headroom’ to scaled down the rising response to help smooth it out, if needed.

Comparison Against the Gladen 28mm

For what it’s worth, here are some pictures and data comparing this Scan d3004/602000 to the Gladen 28mm tweeter tested here.

IMG_2260 IMG_2264

Here is the on-axis response of both compared directly to each other.  Black is the Scan, Blue is the Gladen 28mm:

scan vs gladen 28

Here’s a comparison of the Scan, Gladen 28mm, and Gladen 20mm (just for the heck of it):

IMG_2265

And the response comparison of all three.  Again, Scan is black, Gladen 28mm is blue and the Gladen 20mm is red.  You can see from this comparison just how linear in response the Gladen 20mm is compared to the larger sibling and the Scan (but the Gladen 20mm cannot cross as low as these other two).

scan vs gladen 28 and 20

Update 03/18/15: Consistency Check

I recently initiated a Group Buy on these tweeters and with the multitude of tweeters ordered, I wanted to see how well the quality control was for each set.  The below image is of an impedance sweep from (7) different units, all brand new in box.  As you can see, the differences are negligible with the largest delta in Qts being 0.006 and Fs being 0.60Hz.  That’s fantastic!

d3004 consistency

PS:  If you would like to help me keep up funds for testing additional drivers, there’s a little ‘contribute’ button that goes through Paypal all the way at the bottom of every page.  Any little bit helps.

Gladen Aerospace 20 Tweeter


Up for test is the Gladen Aerospace 20mm tweeter.  Product specs can be found here.

IMG_2251 IMG_2252

Small Signal Parameters and Impedance

Results as measured via Dayton’s DATs measurement tool.  Which is a very little handy tool to have.  😉

  • f(s)= 1073 Hz
  • R(e)= 3.41 Ohms
  • Z(max)= 5.87 Ohms
  • Q(ms)= 1.831
  • Q(es)= 2.536
  • Q(ts)= 1.063
  • L(e)= 0.73 mH

gladen 20 imepdance

 

 

Frequency Response

Frequency Response and the following Harmonic Distortion measurements were taken using Dayton’s OmniMic measurement system.

The frequency response measurements below are on-axis (0 degrees) and off-axis (15, 30, 60 degrees), measured at 2.83v/1m.

gladen 20mm fr
To get an idea of the off-axis response vs the on-axis (0 degrees) response, I normalized the above.  What you get is the relative output level of each axis vs the on-axis level.

gladen 20 normalized

Harmonic Distortion Testing

Legend:

Maroon – Fundamental

Blue – THD

Red – 2nd Order Distortion

Pink – 3rd Order Distortion

Green – 4th order

Teal – 5th order

Testing done in the nearfield to emulate 90dB and 96dB output at 1 meter.

gladen 20 aerospace HD90 gladen 20 aerospace HD96

Impressions/Results

Given these are the little brother of the Aerospace 28mm, I can literally copy/paste my thoughts of the build qualtiy:  Let’s start with the build quality… impressive.  These tweeters feel heavy, which one typically equates to build quality.  Though, I’m not a fan of generalizing, that generalization is legitimate in this case.  There is no plastic housing; these are all (some form) of metal.  I’m not necessarily a fan of the large-ish gauge wire.  I do appreciate no terminals (honestly, they usually just cause your cutout diameter to be widdled out even more to accommodate the wire ran to the terminal).  I just think Gladen could have used a tick smaller wire here given most will have to immediately bend the wire in the install to clear whatever pillar or sail panel they install these in.

The Fs is measured at just above 1kHz.  To get an idea of what this means on the high-pass crossover, let’s evaluate the HD results.  At 96dB output the THD (blue) is 2.25% at 1khz.  The THD is less than 0.50% down to 2.5khz where it is comprised almost entirely of 2nd order distortion above 1.5khz.   Above 1.5khz there is about 15dB separation between 2nd and 3rd order components.  Given the fact this is a smaller tweeter physically, the Fs, and the THD results, you can expect to cross this in the region of 2.5khz-4khz, depending on crossover slope.  If you want to use a shallow slope, 3.5-4khz high-pass may be a good safe area with at least a 12dB/octave slope.  If you use a 24dB/octave slope, I’d say 3.0-3.5khz is OK but below 3khz is beginning to push it for a tweeter of this size for high output.

Measured sensitivity is right around 85.5dB.  On-axis, the response is good.  The response exhibits a wide trough centered at about 5khz, resulting in a 2.5dB drop in output.  Otherwise, the response is quite linear.  There’s also about a 1dB dip centered around 11.8khz that fades out the further off-axis you go.  At 30 degrees off-axis, the response is down approximately 3dB at 10khz.  At 60 degrees off-axis, the response is down approximately 6.5dB at 10khz.  Above 12khz the 60 degrees off-axis response drops quickly.  However, 30 degrees is only 3dB below 0 degrees even at 20khz which is quite remarkable.

Bottom line: Very good performance in a compact tweeter.  Great polar response with very low distortion above 2.5khz.  Perfect for a 3-way system with a 3-5″ midrange.

Below are some comparison pictures between this tweeter and it’s bigger brother mentioned earlier:

IMG_2257

PS:  If you would like to help me keep up funds for testing additional drivers, there’s a little ‘contribute’ button that goes through Paypal all the way at the bottom of every page.  Any little bit helps.

AudioFrog GB15 1.5″ Dome Tweeter


Up for test is AudioFrog’s GB15 1.5″ Dome Tweeter.

It’s worth noting this review is based on mostly objective data.  These drivers – as well as the others from the AudioFrog GB series speakers – include a LOT of installation hardware to make installs quicker and easier.  I simply don’t have the time right now to really delve in to the facets of this, but I will include some of the hardware in the following pictures.

IMG_2215 IMG_2209 IMG_2210 IMG_2213 IMG_2211 IMG_2205

 

Small Signal Parameters

Results as measured via Dayton’s DATs measurement tool.  Which is a very little handy tool to have.  😉

  • f(s)= 1183.00 Hz
  • R(e)= 2.92 Ohms
  • Z(max)= 9.32 Ohms
  • Q(ms)= 4.810
  • Q(es)= 2.195
  • Q(ts)= 1.507

AF GB15 Impedance

 

Frequency Response

Frequency Response and the following Harmonic Distortion measurements were taken using Dayton’s OmniMic measurement system.

The frequency response measurements below are on-axis (0 degrees) and off-axis (15, 30, 60 degrees), measured at 2.83v/1m.

GB15 FR 0 15 30 60pngNow, normalized to show the relation of the off-axis response to the on-axis response:

GB15 FR 0 15 30 60 normalized

 

Harmonic Distortion

The following HD graphs are done in the nearfield, emulating the 1 meter output of 90dB, 96dB, and 102dB in order.

GB15 HD 90dB GB15 HD 96dB GB15 HD 102dB

Thoughts

Let’s take this step by step…

In terms of build quality, these are very nice.  The body is made from some thick metal.  There is a slew of install related optioned hardware provided (such as mounting tabs, screw ring to clamp the tweeter, removable grille that you can custom paint, etc, etc).  Just extremely high build quality here.

The Fs shows an Fs of 1183Hz.  Pairing this up with the distortion plots, it’s easier to get an idea of where an appropriate high-pass crossover point for a tweeter is.  In this case, above 2khz, distortion is at about 0.50% THD at 96dB output and below 0.80% THD at 102dB output, so I’d say this is probably a safe low-frequency crossover with at least a 12dB slope.

While that may seem like a (relatively) high cross over point for a 1.5 inch tweeter, take a look at the average sensitivity above this point: 90.5dB @ 2.83v/1m measured.  Compare that to the Gladen Aerospace 28mm tweeter I recently measured – which is only a couple millimeters smaller in each dimension – and you’ll see, while the Gladen looks like it can also take this same crossover point, that tweeter has an average sensitivity of approximately 87.5dB @ 2.83v/1m.  The Gladen 28mm is just a hair more compact, by a couple millimeters in the various dimensions, but the AF has about 3dB higher sensitivity.  So, in terms of output, I’d say the AF is slightly above the Gladen thanks to it’s similarly low distortion but 3dB higher output.

That’s a lot of talk about crossover point, so let’s look at frequency response which is more important to me…

You’ll notice a broad peak on the low end near resonance.  Scan’s D3004/60000 has this as well, though steeper.  I’m not saying it’s bad… I’m just doing some comparison against a well-liked product.  There’s an off-axis dip And it’s worth pointing out here this testing was done without flush-mounting the tweeter (which is the same way I have conducted all of my tweeter tests over the past few years).  As you can see the in the photo at the beginning of this review there is a pretty deep trough between the tweeter dome and the side of the housing that I believe is causing some of the combing pattern you see in the high frequency area.  With that said, I prefer to look at on-axis to get an idea of the smoothness but I focus more on what happens off-axis to see how the trend behaves.  Are the same bumps/dips there or do they differ quite a bit.  According to my measurements the dip at ~10.5khz is due to a reflection from the dome center to the surround (this is a educated guess; doesn’t mean I’m right ;)).  Overall the response on and off-axis trends well in relation to each other.

Overall, the on-axis response isn’t flat and it shows some combing in the high frequencies.  The polar response (how the off-axis behaves relative to on-axis) tracks pretty smoothly.  The sensitivity is 90.5dB @ 2.83v/1m which is pretty high and the distortion levels are very low. This tweeter should be able to handle a 2khz crossover point with the right slope (12dB or greater).

As extra, I also did some ‘grille on’ vs ‘grille off’ measurements below because I know some may wonder what effect there is.  I DO NOT recommend using them in this manner because you surely run the risk of voiding a warranty claim if the dome gets damaged and being exposed makes it certain that Murphy will strike you…  😉

The following results illustrate the effect of the grille for both 0 degrees measurements and 30 degrees measurements, respectively.

GB15 FR 0 grille GB15 FR 30 grille

As you can see, there is ~1dB additional output between 3khz-8.5khz with the grille on, but with the grille off, there is a maximum of ~2dB higher output above 8.5khz to about 16khz.  So, it seems the grille impedes the high frequency output some amount while helps the lower tweeter range out.

That’s all…

PS:  If you would like to help me keep up funds for testing, there’s a little ‘contribute’ button that goes through Paypal all the way at the bottom of every page.  Any little bit helps.

Gladen Aerospace 28 Tweeter


Up for test is the Gladen Aerospace 28mm tweeter.  Product specs can be found here.

IMG_2189 IMG_2191

 

Small Signal Parameters and Impedance

Results as measured via Dayton’s DATs measurement tool.  Which is a very little handy tool to have.  😉

  • f(s)= 794.70 Hz
  • R(e)= 3.55 Ohms
  • Z(max)= 8.19 Ohms
  • Q(ms)= 2.900
  • Q(es)= 2.216
  • Q(ts)= 1.256
  • L(e)= 0.67 mH

gladen aerospace 28mm impedance

 

 

 

Frequency Response

Frequency Response and the following Harmonic Distortion measurements were taken using Dayton’s OmniMic measurement system.

The frequency response measurements below are on-axis (0 degrees) and off-axis (15, 30, 60 degrees), measured at 2.83v/1m.

gladen aerospace 28mm FR large

To get an idea of the off-axis response vs the on-axis (0 degrees) response, I normalized the above.  What you get is the relative output level of each axis vs the on-axis level.

gladen aerospace 28mm FR normalized no notes

Harmonic Distortion Testing

Legend:

Maroon – Fundamental

Blue – THD

Red – 2nd Order Distortion

Pink – 3rd Order Distortion

Green – 4th order

Teal – 5th order

Testing done in the nearfield to emulate 90dB output.

gladen aerospace 28mm HD 90dB

Testing done in the nearfield to emulate 96dB output.

gladen aerospace 28mm HD 96dB

Impressions/Results

Let’s start with the build quality… impressive.  These tweeters feel heavy, which one typically equates to build quality.  Though, I’m not a fan of generalizing, that generalization is legitimate in this case.  There is no plastic housing; these are all (some form) of metal.  I’m not necessarily a fan of the large-ish gauge wire.  I do appreciate no terminals (honestly, they usually just cause your cutout diameter to be widdled out even more to accommodate the wire ran to the terminal).  I just think Gladen could have used a tick smaller wire here given most will have to immediately bend the wire in the install to clear whatever pillar or sail panel they install these in.

The test data shows a mighty fine tweeter.  The Fs is measured at just a tick under 800hz which indicates a lower crossover point can be used; for instance, to mate up with a 6.5″ woofer (keep a check on center-to-center spacing here).

Measured sensitivity is right around 87.5dB which jives well with the Gladen spec linked at the top of this review.  Linearity is pretty good with about -2/+2.5dB.  These numbers seem large, but the 2.5dB delta comes from the upward swing starting above 4khz.  So, while it’s not as ‘flat’ as I’d like, I’ve come to expect this kind of upward tilt in response from dome tweeters.  What’s as important, if not more important, is how well behaved the off-axis response is relative to the on-axis.  If you look back at the normalized plot you see the off-axis responses follow along very well.  At 30 degrees off-axis, the response is down approximately 5dB at 10khz.  At 60 degrees off-axis, the response is down approximately 12.5dB at 10khz, which is pretty much par for the course for a 1″ dome tweeter.

The real shining point here is the HD results.  What else can I say but they are fantastic.  At 96dB output the THD (blue) is less than 0.50% down to 1.5khz where it is comprised almost entirely of 2nd order distortion above 1.5khz.   Above 1.5khz there is nearly 15-20dB separation between 2nd and 3rd order components.  Most people would cross this tweeter in the 2-3khz ballpark, and from what I’m seeing, it’s certainly capable (though, the slope order plays an important factor here).

Bottom line: very impressive.  I honestly have no idea how much these cost but the data shows a very nice tweeter.  The FR could be flatter above 4khz but the off-axis response is very well maintained and the HD is exceptional.

As mentioned in the opening paragraph, I also tested the 20mm version of this tweeter here as well.  Here is a comparison picture.

IMG_2257

Additionally, I have tested the ScanSpeak D3004/60200 here.  For a comparison of the two and also with the 20mm Gladen, here you go…

IMG_2260IMG_2264

Here is the on-axis response of both compared directly to each other.  Black is the Scan, Blue is the Gladen 28mm:

scan vs gladen 28

Here’s a comparison of the Scan, Gladen 28mm, and Gladen 20mm (just for the heck of it):

IMG_2265

And the response comparison of all three.  Again, Scan is black, Gladen 28mm is blue and the Gladen 20mm is red.  You can see from this comparison just how linear in response the Gladen 20mm is compared to the larger sibling and the Scan (but the Gladen 20mm cannot cross as low as these other two).

scan vs gladen 28 and 20

PS:  If you would like to help me keep up funds for testing additional drivers, there’s a little ‘contribute’ button that goes through Paypal all the way at the bottom of every page.  Any little bit helps.

Arc Audio “Black 1.0” 29mm Dome Tweeter

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The Arc Audio Black Series is a series of speaker drivers made by a well-known Denmark OEM. Arc has put their tweaks on some of this company’s products and released their own line of drivers geared toward the car audio community, known as the Black Series. From this series is a set of tweeters called the 1.0.

You can find more information from Arc’s product information page here.

The Black 1.0 Tweeter caught my eye for a couple reasons. It has:

  • Removable flange
  • Small mounting depth
  • Nice aesthetics

The flange itself is a twist-lock attachment which makes it easy to remove. Also included are mounting cups (not pictured).

All in all, physically, I really like these tweeters.

I quickly took down some dimensions found below. Please see manufacturer specs linked above for more information.

  • OD – 64.5mm (with flange)
  • OD – 48.2mm (without flange)
  • Mounting Diameter – 44.6 (taking in to account the leads)
  • Mounting Depth – 26.5mm (with mounting cup)
  • Mounting Depth – 20.0mm (without mounting cup)

Thiele-Small and Impedance Data

Electrical Parameters
Re 3.47 Ohm electrical voice coil resistance at DC
Le 0.014 mH frequency independent part of voice coil inductance
L2 0.014 mH para-inductance of voice coil
R2 0.58 Ohm electrical resistance due to eddy current losses
Cmes 116 µF electrical capacitance representing moving mass
Lces 0.22 mH electrical inductance representing driver compliance
Res 2.91 Ohm resistance due to mechanical losses
fs 1005.4 Hz driver resonance frequency
——————
f ct 1003.5 Hz driver resonance frequency in enclosure
Mechanical Parameters
(using test encl.)
Mms 0.117 g mechanical mass of driver diaphragm assembly including air load and voice coil
Mmd (Sd) 0.094 g mechanical mass of voice coil and diaphragm without air load
Rms 0.345 kg/s mechanical resistance of total-driver losses
Cms 0.215 mm/N mechanical compliance of driver suspension
Kms 4.65 N/mm mechanical stiffness of driver suspension
Bl 1.002 N/A force factor (Bl product)
Loss factors
Qtp 1.164 total Q-factor considering all losses
Qms 2.135 mechanical Q-factor of driver in free air considering Rms only
Qes 2.551 electrical Q-factor of driver in free air considering Re only
Qts 1.162 total Q-factor considering Re and Rms only
Other Parameters
Vas 0.0164 l equivalent air volume of suspension
n0 0.63 % reference efficiency (2 pi-radiation using Re)
Lm 90.19 dB characteristic sound pressure level (SPL at 1m for 1W @ Re)
Lnom 90.8 dB nominal sensitivity (SPL at 1m for 1W @ Zn)
rmse Z 2.18 % root-mean-square fitting error of driver impedance Z(f)
Series resistor 0 Ohm resistance of series resistor
Vbox 0.296 l volume of enclosure
Sd 7.35 cm² diaphragm area

A fairly nice resonant frequency (Fs) of about 1khz. The delta from the nominal impedance of 3.60ohm at 3.0khz to 20khz is only 0.80ohm (approximately). Le is low at 1.4mH.

;

Frequency Response and Harmonic Distortion at 2.83v/1m

The nominal measured SPL at 2.83v/1m is about 83.382, averaged from 1khz to 10khz. This is about 1dB down from the Scan D3004/602000 I tested recently.

Like some other tweeters, there is a dip in response from 1.5khz to 5khz made more apparent by the boosted response in the top end. I assume this is to help off-axis performance which it does well at 30 degrees. However, at 60 degrees there’s a more distinct rolloff. While the response at this angle is only down 5dB from the 30 Degrees measurement at 10khz, you can see the difference is more apparent at this angle compared to the on-axis measurement than the difference between on-axis and 30 degrees off axis.

To achieve a more real-to-the-source response, the top end should be more flat and not curved. But, there seems to be a strong trend in many tweeters I’ve seen lately (and tested tweeters) that have this same profile of an increased top end. I’m not sure if this is tied to trying to achieve an off-axis response that still has more off-axis content to it or not. For car audio use when off-axis mounting is typically used, this is likely the case.

Response smoothness is pretty good. There’s a peak in response at 15.6khz which shows up in all axes which means it is likely a cone breakup issue. But, at nearly 16khz I can’t say it’s something I would really fret.

You can see non-linear performance is dominated by 2nd order distortion near Fs. This dips below 1% (relative to the mean fundamental) at ~1.6khz. In my opinion, a non-issue at this volume level.

Let’s ramp up the voltage input to see what happens at higher volume…

Harmonic Distortion at 5.5v in the Nearfield

Note: This measurement was taken at 4.75″, equating roughly to 96dB at 1 meter.

Since this is a tweeter, I zoomed in on the HD response to focus on the area above 700hz (notably, response above 1khz).

My personal THD ‘caution zone’ is 3%. 1% is detectable by some depending on the listener and source material along with other factors. I feel 3% is a good all around number so I’ll evaluate based on that.

The areas where you cross the 3% threshold are:

  • Below 1.6khz
  • 2.3khz to 2.9khz (up to 4% THD)
  • 8.8khz for a small instance (up to 4% THD)

These crossing points are comprised of 2nd order distortion almost exclusively.

Third order distortion is kept below 1% above 2khz.

Based on this data, you can likely cross these tweeters down to about 2.5khz without significant distortion. This would attenuate the 4% THD in the 2.5khz area. Power levels will need to be considered and you may find you’ll need to go higher in crossover. Overall, however, I don’t see anything that is a red flag for typical 1″ dome tweeter crossover points and these will probably do well to mate with just about any standard mid/woofer in the 5 inch to 7 inch range. However, the points passband between 5khz to 7khz do make me curious as to what the audible effect may be. As usual, let your ears be a guide.

Since HD testing is only one small aspect of non-linear distortion testing, let’s look at some more data.

Intermodulated Distortion (Voice Sweep at 5.5v)

This measurement was done in the nearfield as well. The bass tone was fixed at ~100hz (0.1*Fs) and the “voice” tones were swept from 800hz to 10khz.

As seen with the HD testing above, the contributing factor to non-linear distortion with this driver is 2nd order distortion. Without measuring with the LSI, I can’t say for sure what this is caused by but my guess is there is assymetry in the suspension, causing the rise in 2nd distortion at Fs, which tapers off below Fs. This decline would give the appearance of higher distortion at frequencies near Fs. In this case, if the driver’s Fs were shifted to be a bit below, you could likely get away with an even lower crossover point. However, I don’t see this as a staunch hindrance simply because most don’t want or need a standard sized tweeter to cross below 2.5khz. This driver does a good job overall of mitigating the 2nd order distortion at Fs; keeping it to below 6%.

Like with the HD plots above, you can see issues at 2.4khz and 8.9khz in the IMD measurements.

This essentially tells you how much power you can expect to lose due to compression from the initial voltage measurement to the last. At 4khz the initial 1v measurement has a measurement of 98.9dB. At 4v, the measurement is 98.44. There is roughly 0.46dB difference here, which isn’t bad considering the level is essentially going from 83dB at 1m to 96dB at 1m. Also, note the compression is minimal at Fs.

Conclusion

A nice looking tweeter, with some nice features when it comes to installation options for the car audio consumer.

A smooth FR with a rising response to help with off-axis response. If aimed on-axis, these may have to be tamed a bit on the 6khz to 8khz, depending on your tastes and goals. I’d personally like to see this tweeter without a rise and a bit more lift at 60 degrees off-axis to keep up with the other on/off axis measurements. However, it performs well on and off-axis as a whole and does a good job at extending the off-axis response rather than falling off sharply, so it’s not a huge knock.

The distortion parameters look pretty good. There is nothing outstanding to me as a limitation, based on my current understanding of transducer design and subjective experience. A crossover of >; 2.5khz is needed and you may be served well to cross a bit above this if you listen loud. With tweeters, I try to stay above 2.5khz even when the tweeter can handle going lower. YMMV (your mileage may vary).

Combining aesthetics, build quality and measured results, I’d recommend this tweeter. Overall, it performs well and allows you to use a larger dome tweeter in an area most domes of this size won’t fit thanks to the removable flange which I think is the major selling feature. Most 1″ dome tweeters require a decent area to install them in; the removable flange here knocks that real estate down by 16mm; more than 1/2 inch. This is very helpful to tight quarters installs.

Parting Notes

If anyone would like to offer some additional analysis, by all means, feel free to contact me and we will discuss the potential to add your own objective thoughts based on the data presented. This is a community effort and I want everyone’s understanding of what the data is expressing to grow.

If you like what you see here and would like to contribute to the fund toward additional test gear, hardware, or just buy me lunch, it would be greatly appreciated. Just click the “Contribute” button at the bottom of this page and contribute what you feel is worth it. Thanks.

Scan Speak Illuminator D3004/602000 Tweeter Testing

The Scan-Speak Illuminator D3004/6020-00 1″ Textile Dome Tweeter has become a pretty regular staple in the audio community.  Especially for the automotive hi-fi hobbyist due to its Scan Speak name, community based subjective reviews, and small form factor.

* Picture property of MadisoundSpeakerStore.com

 

I have owned a set of these tweeters for a while now and have had great results with them.  At any volume I play them, using a 3.15khz/LR4 (24dB/octave) crossover, they handle it very well.  I wanted to see just how my subjective thoughts and others’ translate in to objective performance.

For dimensions and accompanying manufacturer specs, please see the link above.

 

On to the test results…

 

Thiele-Small Parameters and Impedance

Electrical Parameters
Re 3.21 Ohm electrical voice coil resistance at DC
Le 0.013 mH frequency independent part of voice coil inductance
L2 0.021 mH para-inductance of voice coil
R2 0.45 Ohm electrical resistance due to eddy current losses
Cmes 167 µF electrical capacitance representing moving mass
Lces 0.28 mH electrical inductance representing driver compliance
Res 7.14 Ohm resistance due to mechanical losses
fs 735.8 Hz driver resonance frequency
——————
f ct 756.7 Hz driver resonance frequency in enclosure
Mechanical Parameters
(using test encl.)
Mms 0.189 g mechanical mass of driver diaphragm assembly including air load and voice coil
Mmd (Sd) 0.169 g mechanical mass of voice coil and diaphragm without air load
Rms 0.159 kg/s mechanical resistance of  total-driver losses
Cms 0.248 mm/N mechanical compliance of driver suspension
Kms 4.04 N/mm mechanical stiffness of driver suspension
Bl 1.064 N/A force factor (Bl product)
Loss factors
Qtp 1.714 total Q-factor considering all losses
Qms 5.506 mechanical Q-factor of driver in free air considering Rms only
Qes 2.473 electrical Q-factor of driver in free air considering Re only
Qts 1.706 total Q-factor considering Re and Rms only
Other Parameters
Vas 0.0164 l equivalent air volume of suspension
n0 0.254 % reference efficiency (2 pi-radiation using Re)
Lm 86.24 dB characteristic sound pressure level (SPL at 1m for 1W @ Re)
Lnom 87.2 dB nominal sensitivity (SPL at 1m for 1W @ Zn)
rmse Z 2.41 % root-mean-square fitting error of driver impedance Z(f)
Series resistor 0 Ohm resistance of series resistor
Vbox 0.296 l volume of enclosure
Sd 6.83 cm² diaphragm area

 

 

You’ll note the low impedance.  The common rule of thumb for tweeter crossovers is to double Fs and use a steep slope; typically LR4 (24dB/octave).  Many people who run 2-way setups (a midwoofer + tweeter) prefer to have a tweeter that can be crossed low in order to better match the power response of each driver, giving a nice overall polar response.  Dr. Earl Geddes has a very good writeup regarding the importance of matching directivity, found here:

 

If you’re paying attention, you’ll also see the difference in T/S values measured vs that of the manufacturer spec.  T/S values are to be measured in one given environment, typically at room temperature.  This keeps them all on an even keel for comparison purpose.  Some manufactures adhere to IEC specs for defining T/S parameters and others do not.  If they do, they will state it.  For the time being, I am measuring in my garage and thus am making note of the fact that my results will not always mimic those of a manufacturer when it comes to parameters influenced by the environmental conditions such as humidity and temperature.  Specially, these parameters are Vas, Bl, and Cms.  However, Fs, Qts, Qms, Qes, Le, and Re are not affected by the environment and thus can be compared to that of other sources with more latitude.  This particular test was done in an ambient temperature of approximately 85 degF; humidity undetermined.  The tweeter was mounted on a scaled IEC baffle.  It is important to always be aware of the test methods when making comparisons across different sources.

 

Frequency Response and Harmonic Distortion at 2.83v/1m

At the standard measurement conditions of 2.83v/1m, this driver exhibits a sensitivity of approximately 85.9dB.

The frequency response on axis has a trough from 1.5khz to 3khz dipping to ~81dB and then rises to the height in SPL from 6.2khz to 9khz at 88.2dB before dipping again at 13khz and rising one more time at 15.5khz.

The off-axis response of this driver is smooth with no severe drop off as the driver is angled away from the listener.  The graph above depicts a smooth response at 30 and 60 degrees off-axis with a very nice linear gap between the two response curves.

The corresponding Harmonic Distortion results show a very nice distortion profile.  There is clear separation in 2nd order from third order distortion.  The 1% THD threshold is crossed at 1631hz with a small blip above 1% at 6.25khz.  Realistically, the audibility of 1% THD is a far fetch, so I often adhere to the 3% THD value (which corresponds to -30dB down from the fundamental).  My own personal subjective testing and data points on the internet have shown me this is a fair median value to use.  While some cannot hear 1% THD, others cannot hear 10% THD.  What’s more, the source material being played will cause variance in the audible threshold of distortion.  And going beyond that, it is being stated that masking plays a large role in perception of distortion.  To again point to Geddes, you can read this for further information:

http://www.gedlee.com/downloads/The%20Perception%20of%20Distortion.pdf

Having said all of that, the 3% distortion mark for this DUT does not occur until approximately 1.1khz at this particular output level.  While these values are great, consumers often listen louder than at the standard measurement above, so …

Harmonic Distortion (measured in the Nearfield)

This test was done in the nearfield, with the mic located about 4.75 inches from the mic, with a 5.2 volt output applied.  This equates to roughly 114dB in the nearfield, or 96dB at 1 meter.

Zoomed in Results:

As you can see above the 3% THD mark occurs roughly at 1.5khz.  Notice the clear separation of 3rd order distortion; it’s below even 1% distortion until 650hz.  Well beyond the typical crossover range for any tweeter of this size; below Fs even.

There is a couple areas that have a higher 2nd order distortion, however, at approximately 5.5khz and 6.5khz.  These make up the THD percentage of 1.75% and 2.75%, respectively.

So, what do the two sets of data above really tell you?  Not quite as much as you might think.  While HD testing is great, it’s not a stand alone in non-linear distortion testing because it’s a swept sine test.  However, you can often get practical use information out of this data and that’s why it’s still important to analyze a driver in this context.  From the above, you can see that crossing below 2khz at even loud volume (96dB at 1 meter distance) will net you distortion levels well below 3% for a typical crossover passband as low as 2khz.  So, this tweeter can be crossed relatively low.  However, I would not advise crossing below 2.5khz with a 12dB/octave slope simply to play it safe.  I use mine in a 3-way set crossed at 3.15khz/LR4.  Of course, you should use your own judgement.  The data is here only to help you and should not replace your ears and a little common sense.  😉

Intermodulated Distortion (Voice Sweep)

Now that we have some basic non-linear data from the Harmonic Distortion plots above, let’s see what happens when we apply a more real-world situation.  By using the Klippel IMD Voice Sweep, I can play a single “bass” tone (defined by 0.1*Fs) and sweep a nominal passband at the same time.  The output voltage can be dictated by the user.  For this test, I chose 1v to 4v, in 1v increments.  This excites the voice coil with a bass tone while playing higher frequency content and therefore gives a better idea of the performance of the DUT when music is applied and at varying levels.

For this test, the bass tone is fixed at 75hz and the swept tones range from 800hz to 10,000hz.

First, let’s look at the Harmonic Distortion components.  In many ways this data can be used to correlate with the HD above.  The real benefit, however, is the ability to more easily see the effect of increased voltage to the DUT on distortion where in the previous HD test, the applied voltage was singular.

What you can see from the above is, since third order distortion is so low, the overriding factor of THD (1st picture in this set) is from 2nd order distortion.

It’s interesting to note the third order distortion values are not linear with applied voltage.  To be honest, I’m not exactly sure what is the cause of this but will investigate further.

Let’s look now at the intermodulated distortion results.

Second order IMD seems to increase at a linear rate (compared to input voltage), whereas third order seems to increase more non-linearly.

Again, as with the HD results, you can also see that 3rd order distortion is kept to a minimum here.  It is worth nothing that odd-order distortion is often referred to as the distortion that can be most offensive to the listener, whereas even order distortion is acceptable and reportedly sometimes preferred.

Compression of a driver is what happens when the coil is heated and the dissipation of the heat is not very efficient.  This ultimately results in a loss of SPL at varying input voltage.  In an ideal system, if you increased the voltage by 3v you would expect the output of the system to reflect this; essentially input/output linearity.  However, this is not the case with real world drivers.  They all suffer compression.  Some just do a much better job at reducing the effect.  So, it is important to understand the limits caused by compression.  Klippel presents this in a VERY easy way to understand: if the output is linear with input voltage, all result data points should stack on top of each other.  As thermal compression increases, however, these lines will separate and the lines further down (referenced to the original, smallest voltage, measurement) will be shown as the relative SPL difference.  Confused?  It’s harder to explain in type than it is to see, so let’s look at this tweeter’s performance as an example:

Pick a frequency.  Let’s say 2000hz.

The 1 volt input measures about 90.9dB.

The 2 volt input measures about the same at 90.9dB.  This means there is no compression because the output is linear.

The 3 volt input measures about 90.79dB.  Very little compression.

The 4 volt input measures about 90.45dB.  This delta means there is roughly 0.45dB loss from the 1v input.  Ideally, if the driver had no compression, these lines would all stack on top of each other and show the same value because they’re all referenced to the initial measurement.  However, with the little compression suffered here, there is some loss in SPL output from 1v to 4v input.

Think of it like this.  With 1v applied to a 4ohm (nominal) driver – measuring 86dB @ 1w/1m – you would expect to get 80dB output at 1 meter.  If you put in 4v, you would get 4 watts, making your theoretical expected output at 1 meter to be 92dB.  In this particular case, we lose 0.45dB at 4v from theoretical.  So, your final output at 4v would be maxed at 91.55dB at 1m.

Finally, here is the measured voice coil delta Temperature (Tv) from 1v to 4v.

You can see from the above that as the input voltage increases, the temperature of the voice coil does as well.  It’s interesting to note the dip in Tv at 4.5khz.  Compare this to the Frequency Response measurements above and you can see the driver seems to gain efficiency at this point.  I’m sure this is not a coincidence.  However, I will have to explore this further to determine just what the relationship may be.

Conclusion

The Scan-Speak Illuminator D3004/6020-00 1″ Textile Dome Tweeter is great tweeter that can be crossed low enough to mate with most nearly any 6.5″ woofer.  The frequency response on and off-axis is very smooth, while the on-axis rise in response lends to a better slightly off axis response as shown at 30 degrees.  For the car audio crowd where on-axis mounting is not always easy in order to remain ‘stealth’, this is a benefit.  However, I’ve not necessarily been a fan of a driver that deviates from a flat response.  In fact, while using these in the car on-axis, I had the passband of about 6khz to 10khz attenuated via my graphic EQ.  This was without knowing of this near 3dB rise in the same passband from the measured mean of 1khz to 10khz.  Maybe a more off-axis aiming would have kept me from having to attenuate this band, though I prefer the method of having a driver on-axis to gain in the direct vs reflected avenue.  It’s been my experience that a sense of ambiance is more prevalent when this is done.  For the home audio crowd, this is namely a moot point.  Unless, of course, you prefer to toe out your loudspeaker or even cross fire inward.  Some have spoken of the benefits of a wider soundstage in the home when doing this.  Personally, I’m more fundamentally rooted in car audio so my experience toward aiming trickery in the home audio realm is minimal.

The non-linear measurements show this driver to be higher in 2nd order distortion and marginally limited in 3rd, and subsequent, orders of distortion.

Bottom line:  A great driver objectively and my own subjective experiences have resulted in the same conclusion.  I dare not mention “value”.  I’ll leave the data for you to determine that.

If you like what you see here and would like to contribute to the fund toward additional test gear, hardware, or just buy me lunch, it would be greatly appreciated.  Just click the “Contribute” button to the side or bottom of this page.

Alibaba 28mm Tweeter with Black Flange Testing

I’ve recently been provided three different sets of tweeters for testing by a member of the audio community.  Each set of tweeters are from an overseas seller of numerous audio components.  Essentially, what many would call a “build house”.

The first of these tweeters up for testing is the 28mm dome tweeter with a black flange as shown below:

This driver’s approximate dimensions are:

  • Outer Diameter: 60mm
  • Mounting Diameter: 50.5mm
  • Mounting Depth: 10.2mm

Physically this driver looks pretty nice from the from.  A shallow mounting depth and a nice aesthetic black flange.

With that, let’s move on to the data.  If you want to see the graph in full 1600×1200 resolution, simply click on it and it’ll pop up in full-res.

 

 

Thiele-Small and Impedance Data

Electrical Parameters
Re 4.11 Ohm electrical voice coil resistance at DC
Le 0.035 mH frequency independent part of voice coil inductance
L2 0 mH para-inductance of voice coil
R2 0 Ohm electrical resistance due to eddy current losses
Cmes 117 µF electrical capacitance representing moving mass
Lces 0.17 mH electrical inductance representing driver compliance
Res 3 Ohm resistance due to mechanical losses
fs 1131.7 Hz driver resonance frequency
——————
f ct 1186 Hz driver resonance frequency in enclosure
Mechanical Parameters
(using test encl.)
Mms 0.372 g mechanical mass of driver diaphragm assembly including air load and voice coil
Mmd (Sd) 0.349 g mechanical mass of voice coil and diaphragm without air load
Rms 1.065 kg/s mechanical resistance of  total-driver losses
Cms 0.053 mm/N mechanical compliance of driver suspension
Kms 18.81 N/mm mechanical stiffness of driver suspension
Bl 1.787 N/A force factor (Bl product)
Loss factors
Qtp 1.436 total Q-factor considering all losses
Qms 2.485 mechanical Q-factor of driver in free air considering Rms only
Qes 3.403 electrical Q-factor of driver in free air considering Re only
Qts 1.436 total Q-factor considering Re and Rms only
Other Parameters
Vas 0.0043 l equivalent air volume of suspension
n0 0.175 % reference efficiency (2 pi-radiation using Re)
Lm 84.64 dB characteristic sound pressure level (SPL at 1m for 1W @ Re)
Lnom 84.53 dB nominal sensitivity (SPL at 1m for 1W @ Zn)
rmse Z 11.62 % root-mean-square fitting error of driver impedance Z(f)
Series resistor 0 Ohm resistance of series resistor
Vbox 0.296 l volume of enclosure
Sd 7.55 cm² diaphragm area

 

The impedance shows an Fs at roughly 1186hz.  Rather high for a dome of its size, relatively speaking.  For example, look at the Scan Speak D3004/602000 I just tested.  Physically, these drivers are very close to the same size.  However, the Scan has an Fs at about 730hz.  Quite a bit lower if you need to cross low.  Of course, Fs isn’t everything, so let’s keep looking.

 

Large Signal Analysis

Displacement Limits thresholds can be changed in Processing property page
X Bl @ Bl min=82% >0.175 mm Displacement limit due to force factor variation
X C @ C min=75% >0.175 mm Displacement limit due to compliance variation
X L @ Z max=10 % >0.175 mm Displacement limit due to inductance variation
X d @ d2=10% 0.919 mm Displacement limit due to IM distortion (Doppler)
Asymmetry (IEC 62458)
Ak -16.75 % Stiffness asymmetry Ak(Xpeak)
Xsym 0.18 mm Symmetry point of Bl(x) at maximal excursion

 

This data, truth be told, isn’t as complete as I would like it to be.  To be honest, the fragile nature of tweeters makes it a bit harder to measure than that of a woofer and since these were donated tweeters to test, I chose not to stress them like I normally would a woofer.

What you can see, however, is that the suspension is the more dominant source of distortion.  The other graphs gives you some idea of the internal workings of the motor, suspension and inductance.  You can see the xmax parameters did not converge.  Again, this is simply due to the fact I did not continue to test these drivers.  I heard audible buzzing during the test and was concerned I was going to damage them so stopped the test at this point.

 

Fundamental and Harmonic Distortion Taken at 2.83v/1m

Nearfield Harmonic Distortion Test Results approximating 96dB at 1 meter.

The fundmaental response curves at 0 and 30 degrees are fairly smooth in a nominal passband of 1khz to 10khz with a mean sensitivity of approximately 84dB at 2.83v/1m.  There is a dip in response in the mid section, likely made more obvious by the increased top end response.  The 30 degree off-axis measurement mimics very closely the on-axis (0 degree) measurement.  At 60 degrees, however, the response takes a relatively sharp decline and at 12khz is roughly 7dB down from the 30 degree measurement and 9dB down from the 0 degree measurement.  So, the polar response of this driver isn’t great when getting to the very high frequencies.

The HD testing shows a very steep increase in non-linear distortion; reaching 10% at 1.6khz and 5% as high as 2khz for the high output testing (5v).  Even at more moderate levels of 2.83v, as shown in the first picture, 1% THD is reached by 3khz with a steady incline in to higher distortion the lower in frequency it plays.

All in all, while the FR looks good, the HD results indicate this is not a driver that should be crossed low.  The imlications are that this driver would likely be best served when crossed above 3khz with a fairly steep filter.  From personal experience, relating objective data to subjective thoughts, this looks to be even better served as a tweeter relegated to a 3-way system where a higher crossover is permitted.

Intermodulated Distortion Testing (Voice Sweep)

Note:  See Klippel Application Note 24 for details of test parameter and setup.

  • Fixed Bass Tone at ~ 0.1*Fs
  • Voice Sweep from 800hz to 10,000hz
  • Voltage Range from 1v – 4v
    • There was audible buzzing of the driver which caused me to not increase the test voltage output higher than 4v
  • Mic was located in the nearfield – approximately 4.75 inches from the driver – to mitigate environmental related anomalies

The data above again indicates a driver not well suited to a low crossover.  It also shows the effect of compression.  Based on the relative 1v test, nearly 1.8dB is lost at 4v due to thermal effects at the voice coil below 3khz.  In other words, there’s a pretty big loss in efficiency the more power you throw at this driver.  Compare this to the Scan Speak D3004 test mentioned above where only 0.45dB is lost due to compression.  However, above this 3khz mark, the compression is only about 0.2dB from the 1v measurement to the 4v measurement.  This is more data that show this driver’s ineffectiveness as a capable transducer above 3khz.

Motor Stability

Note:  See Klippel Application Note 14 for details of test parameter and setup.

Conclusion

As noted above, this driver’s Fs and non-linear performance indicate it should not be used to be crossed low and mate with a larger woofer for a 2-way system.  While I am sure some might say it sounds just fine, all the data points to egregious issues when used below 3khz.  In regards to linear distortion (frequency response), this driver would likely perform well mounted slightly off-axis.  However, the large rolloff in response above 10khz might give me some cause for concern.  If you’re in the hunt for a driver that can be used in a 3-way system with a higher crossover of around 4khz, and can mount it a bit more on-axis than 30 degrees, it’s worth a shot.  If you’re looking for a tweeter to cross below 3khz, I wouldn’t really look at this as a contender.

If you like what you see here and would like to contribute to the fund toward additional test gear, hardware, or just buy me lunch, it would be greatly appreciated.  Just click the “Contribute” button to the side or bottom of this page.

Sample Test Page for Driver X

Here is where and how data will be posted.  Check links.  Check photos.  Things look good?  Cool.