D3004/660000
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Left: SPL @ 2.8V, 1 m, unit 1 and 2. Right: Distortion measured at 0.25 meter, input 2.8V ~92 dB/1 meter,
unit 1 and 2.

CSD, 2.8V. Left: Unit 1. Right: Unit 2.
D2904/710003
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Left: SPL @ 2.8V,
1 m, unit 1 and 2. Right: Distortion measured at 0.25 meter, input 2.8V ~96 dB/1 meter,
unit 1 and 2.

CSD, 2.8V.
Left: Unit 1.
Right: Unit 2.

Left:
Step response, unit 1. Right: Step response unit 2.

7100 dispersion at
0, 10,20, 30 and 40 deg.
D3004/66400
Beryllium dome
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Click image to view
large. Download specs
here.

SPL normalised for 1 m/2.8V,
unit 1 and 2.

Impulse response, unit 1 and 2.

Step response, unit 1 and 2.

CSD, 25 dB, unit 1 and 2.
Very clean indeed!

Left: SPL unit 1 and 2 (not normalised for 2.8V/1m). Right: Impedance unit 1 and 2. Quite as matched pair!

Distortion from unit
1&2. Measurement at 0.25 m distance, 2.8 V. Black = 2nd harm.,
blue = 3rd harm. These tweeter display significant lower distortion compared to 7100
and 6600.
I
don't think I've ever had a pair of so closely matched tweeters. They
have outstanding performance in my
Jenzen ATS speakers.
D2908/714000
Beryllium dome
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Click images to view large
Measurements,
baffle: 65 x 57 cm, 27 cm from top. All measurements normalised for
2.8V/1m.
My expectations are high on
this new tweeter and nothing below suggests I should be dissapointed.
The Revelator magnet system is stronger compared to the Illuminator
motor, thus an 8 ohms voice coil is used here. On top of this a
titanium voice coil former, not seen before on ScanSpeak tweeters.
Most noticeable is Qm, 7.3 according to specs. My measurements suggest
a little lower, but nevertherless, nothing I've seen before. High Qm
means low mechanical damping and some may fear this will make a too
lively treble. Time will tell. I've heard reservations towards this
7140 tweeter based on the response graphs displayed at SS website.
The use of a 10-100.000 Hz range doesn't make things look better on
paper. Looking at the 1.000-20.000 Hz range alone (see below) display
an usually well behaved response and initial modelling suggest an easy
tweeter when it comes to crossovers. And let me say that I couldn't
care less about the dip above 16 kHz towards 20 kHz. Some people are
obsessed about a flat response to e.g. 30 kHz. There are much more to
good treble performance than a ruler flat response to 30 kHz.

Left: SPL at 0.5 m distence, on-axis. Right:
Tweeter 1 and 2. These units are so much alike that only one will
be shown below except for cumulative spectral decay and impedance.

Left: Impedance of unit 1 and 2. Right: Step
response display better damping compared to 6640!

Left: Horizontal dispersion at 0, 10, 20, 30
and 40 deg., 1000-20000 Hz. Right: Same at 200-40000 Hz. My CLIO
microphone is down 1 dB at 20 kHz and 5 dB at 30 kHz, so please add
some level there. Generally these response graphs look better than
those published in
Voice Coil and
Klang&Ton magazines.

CSD @ 25 dB range. These are seriously clean
and quite better than those made by
Vance Dickason. I wonder if
some work has been done to the tweeter since they were reported in
Voice Coil. Compared to the
6640 tweeter, these CSDs suggest a better rear chamber with fewer
resonances in the 500-1200 Hz region.

Left: Red, SPL as-is and red, 6.8 uF
bypassed by 3R3. Simple equalisation. Right: Orange: Test crossover
@ 2 kHz from 8.2 uF/2R2+0.47mH in front of above equaliser. I don't
think equalising will be necessary in my final set-up.

Left: Distortion at 2.8V input taken at 0.25
m distance. Green = 2nd harm., blue = 3rd harm. Right: Same at 5.6V input. This tweeter can safely be used down to 2 kHz - if you can tune the
frequency response! Not that easy.

Now, all measurements above were done on a
large flat panal, but how does it look when it we use a small baffle
like the one I'm going to use for the next
ATS 4-way speaker? A quick
cardboard mock-up, approx. 13 x 20 cm, and some midrange cardboard
panel below display the red response above compared to the large flat
panel (green). Not bad at all! I took the measurement to my simulation
software and it looks easy. And no equalising step needed. Looking
forward to implementing this tweeter in my next construction.
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