LF
Fullrange
4"
40NFR
Code: DR-4-008-16R-B2-C0001
Full-Range/4inch/Neo/GF/25W/16ohm
Key Features
- Full-range FREQUENCY RESPONSE
- Unique cone material
- For column systems, desktop high performance 2 way or one-way speakers, hi-fi applications
Quick Specs
Impedance
16 Ω
Program Power
50 W
Sensitivity
85.52 dB
Fs
115.00 Hz
Magnet
Neodymium
Voice Coil
19 mm
Design Notes
The 40NFR is a very high efficiency, (86dB 1watt / 1 meter) 4-inch full range speaker with linear frequency response characteristics and high power handling capability while generating low harmonic distortion artifacts. The 40NFR uses a unique exponential cone, made off very lightweight glass-carbon fiber woven fabric, along with a NBR single roll geometry surround. The combination provides remarkable strength, high efficiency and sustained output under extreme conditions.
Magnetic circuit design
REDCATT engineers have developed neodymium based magnetic circuit, capable of delivering the highest level of performance, providing a consistent, high integrity magnetic flux gap, low distortion characteristic. The magnetic circuit design is optimized to generate the minimum amount of flux modulation, providing exceptional stability. The compact size of the magnetic circuit ensures the speaker can fit in tight space of modern audio product designs.
Magnetic circuit design
REDCATT engineers have developed neodymium based magnetic circuit, capable of delivering the highest level of performance, providing a consistent, high integrity magnetic flux gap, low distortion characteristic. The magnetic circuit design is optimized to generate the minimum amount of flux modulation, providing exceptional stability. The compact size of the magnetic circuit ensures the speaker can fit in tight space of modern audio product designs.
Specifications
General Specs
Nominal Diameter
4"
Rated Impedance
16 Ohm
Magnet
Neodymium
Basket Material
Steel
Power Handling
AES Power
25 W
Continuous Power
50 W
Peak Power
100 W
Voice Coil
Diameter
19 mm
Winding Wire
CCAW
Former
Kapton
Winding Height
4.9 mm
T/S Parameters
Resonant Frequency (Fs)
115.00 Hz
Re
12.30 \u2126
Qes
1.300
Qms
6.20
Qts
1.100
Vas
1.50 liters
Sd
50.20 cm\u00B2
Mms
4.40 grams
Rms
0.51
Cms
0.4400
Bl
5.30 T\u00B7m
Le
0.200 mH
Sensitivity
85.52 dB
Design Details
Surround Material
NBR
Cone/Dome Material
Paper CF
Spider
Nomex
T-Plate
4 mm
Xmax (peak)
0.45 mm
Xmech
4.45 mm
Overall Diameter
103.50 mm
Bolt Circle Diameter
115.00 mm
Baffle Cutout Dia.
91.00 mm
Mounting Holes
4
Depth (flange to rear)
50.50 mm
Net Weight
0.20 kg
Ordering Codes
Product Code
DR-4-008-16R-B2-C0001
Downloads
Frequency Response & Impedance
2D Drawing
Technical Summary
The 40NFRX16-223 is a 4-inch full-range driver featuring a neodymium magnetic circuit
optimized for minimum flux modulation, a steel basket, woven glass-carbon fiber fabric
cone with exponential profile, NBR single-roll surround, Nomex spider, and a 19mm CCAW
voice coil wound on a Kapton former. The woven glass-carbon fiber cone combines high
stiffness with low mass, contributing to the low Mms of 4.4 g and supporting extended
high-frequency response. The neodymium circuit design targets minimum gap flux modulation,
reducing position-dependent inductance variation and even-order harmonic distortion across
the excursion range. Net weight is 0.20 kg - the lightest driver in the full-range family.
The 40NFRX16-223 is the sole 4-inch driver in the lineup, offered in 16 ohm nominal
impedance with the same form factor available in 4, 8, and 16 ohm versions per application.
Enclosure alignment:
- Free-air / open-back (only recommended installation):
f-3dB approx. 87 Hz; ~+1.8 dB peak at ~88 Hz (DSP-correctable)
High-pass filter at 70-90 Hz recommended in all installations
Sealed enclosures raise f-3dB above 87 Hz and are not recommended
In column array applications, the 103.5 mm driver OD limits coherent vertical directivity
to approximately 1.66 kHz - the lowest limit in the full-range family. A co-located tweeter
with crossover at 1.5-2.0 kHz is mandatory for full-range column array coverage. The 16 ohm
nominal impedance enables flexible array wiring: four drivers in parallel produce a 4 ohm
load on a standard amplifier channel, consistent with the 21NFRX16-393D wiring approach.
Excursion management is critical: Xmax = 0.45 mm limits bass equalization headroom;
a subsonic high-pass filter at 70-90 Hz and excursion limiter at 50 Hz are recommended
to prevent mechanical over-excursion during low-frequency program content.
The 40NFRX16-223 is suited for column speaker systems requiring the deepest free-air bass
extension (87 Hz) from a full-range driver with 16 ohm parallel array wiring; 2-way
desktop, bookshelf, and surface-mount loudspeakers where the woven GF cone and neodymium
motor deliver low-distortion midrange and extended HF in an open-back or minimal-enclosure
format; hi-fi column and panel-mount designs crossed above 100 Hz to a woofer or subwoofer
with DSP correction of the 88 Hz resonance peak; and applications requiring the most
passive-crossover-friendly HF impedance characteristic in the full-range family (f_Le =
9,785 Hz), where Le-related HF droop is absent across the entire audio band.
optimized for minimum flux modulation, a steel basket, woven glass-carbon fiber fabric
cone with exponential profile, NBR single-roll surround, Nomex spider, and a 19mm CCAW
voice coil wound on a Kapton former. The woven glass-carbon fiber cone combines high
stiffness with low mass, contributing to the low Mms of 4.4 g and supporting extended
high-frequency response. The neodymium circuit design targets minimum gap flux modulation,
reducing position-dependent inductance variation and even-order harmonic distortion across
the excursion range. Net weight is 0.20 kg - the lightest driver in the full-range family.
The 40NFRX16-223 is the sole 4-inch driver in the lineup, offered in 16 ohm nominal
impedance with the same form factor available in 4, 8, and 16 ohm versions per application.
Enclosure alignment:
- Free-air / open-back (only recommended installation):
f-3dB approx. 87 Hz; ~+1.8 dB peak at ~88 Hz (DSP-correctable)
High-pass filter at 70-90 Hz recommended in all installations
Sealed enclosures raise f-3dB above 87 Hz and are not recommended
In column array applications, the 103.5 mm driver OD limits coherent vertical directivity
to approximately 1.66 kHz - the lowest limit in the full-range family. A co-located tweeter
with crossover at 1.5-2.0 kHz is mandatory for full-range column array coverage. The 16 ohm
nominal impedance enables flexible array wiring: four drivers in parallel produce a 4 ohm
load on a standard amplifier channel, consistent with the 21NFRX16-393D wiring approach.
Excursion management is critical: Xmax = 0.45 mm limits bass equalization headroom;
a subsonic high-pass filter at 70-90 Hz and excursion limiter at 50 Hz are recommended
to prevent mechanical over-excursion during low-frequency program content.
The 40NFRX16-223 is suited for column speaker systems requiring the deepest free-air bass
extension (87 Hz) from a full-range driver with 16 ohm parallel array wiring; 2-way
desktop, bookshelf, and surface-mount loudspeakers where the woven GF cone and neodymium
motor deliver low-distortion midrange and extended HF in an open-back or minimal-enclosure
format; hi-fi column and panel-mount designs crossed above 100 Hz to a woofer or subwoofer
with DSP correction of the 88 Hz resonance peak; and applications requiring the most
passive-crossover-friendly HF impedance characteristic in the full-range family (f_Le =
9,785 Hz), where Le-related HF droop is absent across the entire audio band.
Recommended enclosure volumes are simulated results. For best enclosure volumes and tuning, we recommend secondary simulation and careful evaluation. Several rounds of samples and fine-tuning may be required for optimal results.
Enclosure Recommendations
Free-air or open-back installation is the primary recommendation for this driver (Fs = 115 Hz, Qts = 1.1, Vas = 1.5 liters): any sealed cavity raises Qtc above 1.1 and increases the system resonance above 115 Hz, requiring DSP correction for flat response. Where a sealed rear cavity is necessary for structural or protection reasons, three reference alignments are available: - 1.5 liters (Qtc approx. 1.56): minimum practical volume; resonance approx. 183 Hz; full DSP required - 3.0 liters (Qtc approx. 1.25): moderate column bay volume; resonance approx. 146 Hz; DSP correction recommended above 100 Hz - 6.0 liters (Qtc approx. 1.13): largest practical volume; resonance approx. 122 Hz; closest to free-air character, DSP correction of 115 Hz resonance peak recommended
Frequently Asked Questions
- - Full-range FREQUENCY RESPONSE
- - Unique cone material
- - For column systems, desktop high performance 2 way or one-way speakers, hi-fi applications
Free-air or open-back installation is the primary recommendation for this driver (Fs = 115 Hz, Qts = 1.1, Vas = 1.5 liters): any sealed cavity raises Qtc above 1.1 and increases the system resonance above 115 Hz, requiring DSP correction for flat response. Where a sealed rear cavity is necessary for structural or protection reasons, three reference alignments are available: - 1.5 liters (Qtc approx. 1.56): minimum practical volume; resonance approx. 183 Hz; full DSP required - 3.0 liters (Qtc approx. 1.25): moderate column bay volume; resonance approx. 146 Hz; DSP correction recommended above 100 Hz - 6.0 liters (Qtc approx. 1.13): largest practical volume; resonance approx. 122 Hz; closest to free-air character, DSP correction of 115 Hz resonance peak recommended
Pa column midrange, small two-way monitors; weight-critical installs
AES Power: 25 W,
Continuous: 50 W,
Peak: 100 W.
Sensitivity: 85.52 dB (1W/1m).
