Overview:
The SB Acoustics SB26STAC-C000-4 is a 4Ω coated textile dome tweeter using a 1” voice coil together with copper cap pole piece. The 100mm aluminium faceplate enhances the sturdy build quality and looks.
Key features:
- Cast aluminium faceplate
- Copper cap for reduced voice coil inductance and minimum phase shift
- Non-reflective rear chamber with optimized damping for improved dynamics
- Flow optimized vented pole piece for optimum coupling to rear chamber
- Fine weave soft fabric dome for smooth frequency response
- Saturation controlled motor system for low distortion
- CCAW voice coil for low moving mass
- Long life silver lead wires
- Low resonance frequency
SB Acoustics Spec sheet: SB26STAC-C000-4
T/S Parameters:
Very good consistency between the two tweeter samples and they match very close to the manufacturer’s specification.
Impedance:
(click on picture to zoom)
Sample 1 = Green
Sample 2 = Blue
Almost identical impedance curves between the tweeter samples.
Frequency:
Frequency measurement conditions:
The tweeter is measured mounted on a baffle with the following conditions:
Baffle size (WxH): 24×35cm with 18mm round-over.
Driver position: Mounted on center-line with driver unit center 8cm from the top of the baffle.
Mic position: 1m distance, on tweeter-axis.
Smoothing: 1/24 octave smoothing applied.
(click on picture to zoom)
Left: Frequency response on-axis (Blue=sample1, Red=sample2).
Right: Frequency response 15deg off-axis (Blue=sample1, Red=sample2).
Almost identical frequency response up to about 15kHz where the two driver samples starts to deviate somewhat in level.
0deg = Blue
15deg = Red
22.5deg = Green
30deg = Blue
45deg = Red
60deg = Green
The tweeter has a very nice off-axis frequency response.
Distortion:
Measurement setup:
- Tweeter near-field measurement at 10cm
- Frequency Range Tweeter: 500-10000Hz
- Baffle size WxH: 24×35cm
The distortion measurements are done in near-field and the amplifier output level was adjusted for each driver so that the fundamental is 90dB and 95dB at 1m. This setting simulates medium-high and high listening levels.
(click on picture to zoom)
90dB @ 1m
Left = Sample 1
Right = Sample 2
(click on picture to zoom)
95dB @ 1m
Left = Sample 1
Right = Sample 2
Considering the price of this tweeter there isn’t much to complain about its distortion profile. Low odd-order distortion even at higher levels and somewhat elevated second-order distortion, which gradually raises below 2.5kHz.
This tweeter should be able to work nicely crossed-over at 2-2.5kHz or higher.