P h a n t o m

Voice Coil. Reprinted by permission. Entire contents copyright ©2015 Segment, LLC. All rights reserved. For subscription information, go to www.audioxpress.com, call 800-269-6301, or e-mail voicecoil@pcspublink.com.
the dome (see Photo 2). Other features include a 20-mm
voice coil diameter, XMAX = 1.2-mm, 76-dB 1-W/1-m sensitivity, F0 = 170 Hz, QTS = 0.46, and a 170-Hz-to-20-kHz
operating range. The T1-1931S is the same driver designed
in its own 14-mm × 35-mm × 87-mm composite enclosure
with a built in 11-mm × 29-mm diaphragm wide surround
passive radiator. With the enclosure and PR, the system
Impedance vs Freq
ang
50
Ohm
40
30
20
Photo 2: Tang Band’s T1-1931S full-range passive radiator
system features a small enclosure.
10
9
8
7
6
5
4
The T1-1931S
3
2
1
10 Hz
20
50
100
200
500
1K
2K
5K
10K
20K
40K
Figure 9: Tang Band T1-1931S impedance plot
Map
24: TB T1-1931s imp
Notes
Voice Coil’s March 2013 issue featured a report on the
new Tang Band T1-1942S full-range passive radiator system, an enclosed version of Tang Band’s W1-1942S 1” fullrange dome device. This month I received the T1-1942S’s
“little brother,” the T1-1931S. Like the T1-1942S, the
T1-1931S is based on the 0.75” version of the W1-1942S,
the W1-1931S. These are all described as full-range systems, but the T versions use a small enclosure with a passive radiator to extend the low-frequency response.
As with the W1-1942S, the W1-1931S has a wide santoprene surround and a 0.75” diameter polypropylene dome
with a cloverleaf elastomeric damping material that overlays
SPL vs Freq
85
dBSPL
Data Measured: Mar 15, 2013 Fri 10:25 am
80
4.6.0.371
May/29/2007
Person:
Company:
Project:
File: VC Mar 13.lib
Mar 24, 2013
Sun 10:04 am
75
70
65
60
55
50
45
40
35
*MATT-XX Mic Attenuator 10, 20, 30 dB Handle higher SPLs
ACO Pacific, Inc.
Tel: 650-595-8588 Fax: 650-591-2891
www.acopacific.com sales@acopacific.com
26
VOICE COIL
25
300 Hz
500
1K
2K
5K
10K
20K
40K
Figure 10: Tang Band T1-1931S on-axis frequency response
Notes
Map
10: TB T1-1931s a 0
Data Measured: Mar 12, 2013 Tue 8:36 am
4.6.0.371
May/29/2007
Person:
Company:
Project:
File: VC Mar 13.lib
Mar 24, 2013
Sun 10:07 am
Figure 11: Tang Band T1-1931S factory on-axis frequency
response
SPL vs Freq
90
dBSPL
85
80
75
70
65
60
55
50
45
40
35
30
300 Hz
Map
P
r
e
c
i
s
i
o
n
Powered
500
1K
2K
5K
10K
20K
Figure 12: Tang Band T1-1931S on- and off-axis frequency response
10: TB T1-1931s a 0
11: 15
12: 30
13: 45
Notes
T
i
t
a
n
i
u
m
A
c
Measurement Mic System P
c
e
7052E
h
l
IEC61094-4 Compliant
e
Titanium Diaphragm
a
4 Hz to >25 kHz
r
<16 dBA >135 dBSPL*
o
n
m
4048 Preamp
t
e
Stainless Body
t
Phantom
o
e
<18Vdc to >56Vdc
m
r
s,
to
Superior
M
Long-term
I
i
Temp and Humidity
c
Stability
E
s
Operational <-20C >70C
Storage <-30C >85C
P
&
E
m
3-4 mA
o
r
7052PH/MK224PH IEPE1248 e
30
Data Measured: Mar 12, 2013 Tue 8:36 am
4.6.0.371
May/29/2007
Data Measured: Mar 12, 2013 Tue 8:38 am
Person:
Company:
Project:
File: VC Mar 13.lib
Mar 24, 2013
Sun 10:29 am
40K
Voice Coil. Reprinted by permission. Entire contents copyright ©2015 Segment, LLC. All rights reserved. For subscription information, go to www.audioxpress.com, call 800-269-6301, or e-mail voicecoil@pcspublink.com.
Ratio vs Freq
SPL vs Freq
dBR
10
90
dBSPL
85
5
80
0
75
-5
70
-10
65
-15
60
55
-20
50
-25
45
-30
40
-35
35
500
1K
2K
5K
10K
20K
Figure 13: Tang Band T1-1931S normalized on- and
off-axis vertical frequency response
29: 45
Map
26: Normalized t1 0
27: 15
28: 30
30
300 Hz
40K
500
1K
2K
5K
10K
20K
40K
Figure 14: Tang Band T1-1931S two-sample SPL
comparison
10: TB T1-1931s a 0
15: sample 2
Notes
Notes
Map
-40
300 Hz
Data Measured: Mar 12, 2013 Tue 8:36 am
4.6.0.371
May/29/2007
105
Person:
Company:
Project:
File: VC Mar 13.lib
Mar 24, 2013
Sun 10:33 am
SPL vs Freq
4.6.0.371
May/29/2007
Data Measured: Mar 12, 2013 Tue 8:52 am
Person:
Company:
Project:
File: VC Mar 13.lib
Mar 24, 2013
Sun 10:46 am
dBSPL
100
95
90
85
80
75
70
65
60
55
50
45
20 Hz
30
40
50
60
70
80
90
100
200
300
400
500
Figure 15: Tang Band T1-1931S near-field response
Figure 16: Tang Band T1-1931S SoundMap CSD graph
Notes
Map
14: NF
Data Measured: Mar 12, 2013 Tue 8:46 am
4.6.0.371
May/29/2007
Person:
Company:
Project:
File: VC Mar 13.lib
Mar 24, 2013
Sun 10:45 am
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Voice Coil. Reprinted by permission. Entire contents copyright ©2015 Segment, LLC. All rights reserved. For subscription information, go to www.audioxpress.com, call 800-269-6301, or e-mail voicecoil@pcspublink.com.
range is extended from 170 to 105 Hz (105 Hz to 20 kHz).
Suggested applications include portable audio, soundbars,
and multimedia. Both devices use patented technology,
although exactly what is patented is not specified in either
product’s literature.
I commenced testing the Tang Band’s T1-1931S by
using the LinearX LMS analyzer to run a stepped sine
wave impedance plot. Figure 9 shows the LMS 300-point
Figure 17: Tang Band T1-1931S SoundMap STFT plot
Figure 18: Tang Band T1-1931S SoundCheck distortion plot
impedance sine wave sweep’s result. The 0.75” full-range
passive radiator system exhibits the typical vented-type
twin-peak impedance profile that has a 117-Hz tuning
frequency. Minimum impedance for this device is 3.9 Ω at
1.1 kHz with a measured RE = 3.74 Ω.
After completing the impedance measurements, I
mounted the small enclosure on a large baffle that measured about 8” × 12”, placed it on the measurement stand,
and measured the on- and off-axis frequency response at
2.83 V/1 m. Figure 10 shows the on-axis response. The
frequency response for the T1-1931S is smooth and is
±2.4 dB out close to 10 kHz. Obviously, this will be baffle
dependent, with a flatter response on a larger baffle (e.g.,
the factory response shown in Figure 11). Sensitivity is
rated at 76 dB, which is about right for this transducer.
Figure 12 shows the TB T1-1931S module’s on- and
off-axis response. As with the T1-1942S, off axis the device
is substantially better than most 0.75” domes. Figure 13
shows Figure 12’s normalized version. In terms of production consistency, the two-sample SPL comparison is shown
in Figure 14, indicating the two samples were well matched
within about 1 to 1.5 dB.
The last SPL measurement I performed was a near-field
type with the measurement microphone placed between the
dome and passive radiator (see Figure 15). F3 was about
83 Hz, hence Tang Band’s published 105-Hz-to-20-kHz operating range. Tang Band suggests using a high-pass filter at
100 Hz for the T1-1931S.
Next, I used the Listen SoundConnect analyzer and 0.25”
SCM microphone to measure the impulse response with the
tweeter recess mounted. Importing this data into the Listen
SoundMap software produced the CSD (waterfall) plot in
Figure 16. Figure 17 shows the STFT displayed as a surface
plot. Last, I used the SoundCheck noise generator and SLM
utilities to set the 1-m SPL to 94 dB (7.6 V), and the sweep
range to 200 Hz to 20 kHz. I measured the second- and
third-harmonic distortion at 10 cm (see Figure 18). I performed the measurement to show the relationship between
second- and third-harmonic distortion; however, correlation
to subjective preference based on THD is not well established.
For more information on this interesting new transducer, visit
www.tb-speaker.com. VC
Submit Samples to Test Bench
Test Bench is an open forum for OEM driver manufacturers in the industry. All OEMs are invited to
submit samples to Voice Coil for inclusion in the Test
Bench column.
Driver samples can include any sector of the
loudspeaker market, including transducers for home
audio, car audio, pro sound, multimedia, or musical
instrument applications. Contact Voice Coil Editor
Vance Dickason to discuss which drivers are being
submitted.
All samples must include any published data on
the product, patent information, or any special information to explain the functioning of the transducer.
Include details on the materials used to construct
28
VOICE COIL
the transducer (e.g., cone material, voice coil former
material, and voice coil wire type). For woofers and
midrange drivers, include the voice coil height, gap
height, RMS power handling, and physically measured Mmd (complete cone assembly, including the
cone, surround, spider, and voice coil with 50% of the
spider, surround, and lead wires removed). Samples
should be sent in pairs to:
Vance Dickason Consulting
333 South State Street, #152
Lake Oswego, OR 97034
(503-557-0427)
vdconsult@comcast.net