LF
Mid-Woofer
8"
81XR
Code: 81XRX8-424A
Woofer/XR Woofer/8inch/Neo/Paper/200W/8ohm
Key Features
- Nonparallel voice and low frequency reproduction quality
- Patented magnetic circuit and air venting design
- Extremely low harmonic distortion
Quick Specs
Impedance
8 Ω
Program Power
400 W
Sensitivity
93.00 dB
Fs
73.00 Hz
Magnet
Neodymium
Voice Coil
63.5 mm
Design Notes
The 81XR was designed to be simply the best driver for 2-way and multi-way systems on the market, yet this driver will also shine in sub-woofer applications. The combination of our XR patented technology with static shorting coil brings an nonparallel opportunity to the audio designers. The common request for 2-way speakers is “more of everything”. Designers wishes for more bass, more mids. Well, there you have it! But not only that. We bring this with clarity in the mid-frequencies and undistorted bass. Our designers were able to achieve THD below 0.5% from 20Hz up to 2.5kHz. There isn’t another driver like this on the market.
Motor Design
The magnetic design incorporates large neodymium magnets placed along the voice coil winding, together with the 2nd and static coil placed on the pole piece. This has allowed us to push the cone excursion to 30mm peak to peak, while lowering the inductance. The shorting coil covers the complete main coil excursion. This is also an improvement compared to some previous designs on the market that utilizes static coil. Unique gap side venting ensures good air circulation, lowers air noise and greatly improves the reliability of this driver.
Motor Design
The magnetic design incorporates large neodymium magnets placed along the voice coil winding, together with the 2nd and static coil placed on the pole piece. This has allowed us to push the cone excursion to 30mm peak to peak, while lowering the inductance. The shorting coil covers the complete main coil excursion. This is also an improvement compared to some previous designs on the market that utilizes static coil. Unique gap side venting ensures good air circulation, lowers air noise and greatly improves the reliability of this driver.
Specifications
General Specs
Nominal Diameter
8"
Rated Impedance
8 Ohm
Magnet
Neodymium
Basket Material
Aluminum
Power Handling
AES Power
200 W
Continuous Power
400 W
Peak Power
800 W
Voice Coil
Diameter
63.5 mm
Former
Glass Fiber
Winding Height
18.3 mm
T/S Parameters
Resonant Frequency (Fs)
73.00 Hz
Re
5.50 \u2126
Qes
0.370
Qms
1.47
Qts
0.300
Vas
7.20 liters
Sd
201.00 cm\u00B2
Mms
38.00 grams
Rms
11.90
Cms
0.1300
Bl
16.00 T\u00B7m
Le
0.190 mH
Sensitivity
93.00 dB
Design Details
Surround Material
fabric
Cone/Dome Material
Paper GF
Spider
Nomex
T-Plate
31 mm
Xmax (peak)
6.35 mm
Xmech
25 mm
Overall Diameter
210.00 mm
Bolt Circle Diameter
195.00 mm
Baffle Cutout Dia.
186.88 mm
Mounting Holes
8
Depth (flange to rear)
128.30 mm
Net Weight
4.90 kg
Ordering Codes
Product Code
81XRX8-424A
Downloads
Frequency Response & Impedance
2D Drawing
Technical Summary
This design is particularly effective in single or multi-driver bass reflex systems used in professional two-way and multi-way PA systems, powered monitors, and compact bass-reflex enclosures, where extended bandwidth, controlled distortion across the full operating range, and versatile system integration are required.
Enclosure Recommendations
ENCLOSURE RECOMMENDATIONS: 81XRX8-424A
Driver: 81XRX8-424A (81XR) — 8" Mid-Woofer
Key T/S: Fs=73.0Hz, Qts=0.3, Vas=7.2L, Sens=93.0dB
Power: AES 200W / Cont 400W / Peak 800W
Xmax=6.35mm, Sd=201.0cm², Bl=16.0T·m
RECOMMENDED ENCLOSURE TYPE: Bass Reflex (Vented)
PORT RECOMMENDATION: Round port (65mm diameter) — adequate for compact enclosures with lower air volume velocity
a) High SPL
Net Volume: 8 liters
Tuning (Fb): 75 Hz
Est. -3dB: 69 Hz
HP Filter: 67 Hz (24dB/oct recommended)
Round Port: 65mm dia × 201mm long
Slot Port: 150mm W × 40mm H × 384mm L
Port Velocity: 18.2 m/s
Notes: Strong mid-bass impact, reduced cone excursion, maximum output
b) Balanced Response
Net Volume: 8 liters
Tuning (Fb): 68 Hz
Est. -3dB: 58 Hz
HP Filter: 58 Hz (24dB/oct recommended)
Round Port: 65mm dia × 230mm long
Slot Port: 150mm W × 40mm H × 436mm L
Port Velocity: 16.4 m/s
Notes: General-purpose PA/subwoofer, even response, good transient behavior
c) Extended Low Frequency
Net Volume: 10 liters
Tuning (Fb): 59 Hz
Est. -3dB: 50 Hz
HP Filter: 47 Hz (24dB/oct recommended)
Round Port: 65mm dia × 262mm long
Slot Port: 150mm W × 40mm H × 493mm L
Port Velocity: 14.3 m/s
Notes: Deep bass extension, requires proper system protection below tuning
--- Summary ---
The 81XRX8-424A is a 8-inch mid-woofer driver designed for professional 2-way and multi-way systems with 93.0 dB sensitivity (1W/1m). The motor and suspension are optimized to maintain consistent performance at high drive levels, with controlled excursion and reduced thermal compression during long-term operation.
In bass reflex enclosures, the driver performs best in net internal volumes of 8 to 10 liters, tuned between 59 and 75 Hz. This alignment provides a balanced combination of low-frequency extension, cone control around resonance, and efficient port loading. Lower tuning improves deep bass extension but increases excursion below tuning, requiring appropriate high-pass filtering. Higher tuning increases sensitivity and output in the upper bass region while improving mechanical control.
The driver is intended for use with moderate amplification (approx. 200 W AES / 400 W continuous) and DSP control. A high-pass filter in the range of 47–67 Hz is recommended depending on enclosure tuning, along with proper limiting to manage thermal and mechanical stress. Typical operating bandwidth is 50–2500 Hz, covering bass through upper-mid frequencies for direct integration with a compression driver or tweeter in a two-way or multi-way system.
Frequently Asked Questions
- - Nonparallel voice and low frequency reproduction quality
- - Patented magnetic circuit and air venting design
- - Extremely low harmonic distortion
ENCLOSURE RECOMMENDATIONS: 81XRX8-424A
Driver: 81XRX8-424A (81XR) — 8" Mid-Woofer
Key T/S: Fs=73.0Hz, Qts=0.3, Vas=7.2L, Sens=93.0dB
Power: AES 200W / Cont 400W / Peak 800W
Xmax=6.35mm, Sd=201.0cm², Bl=16.0T·m
RECOMMENDED ENCLOSURE TYPE: Bass Reflex (Vented)
PORT RECOMMENDATION: Round port (65mm diameter) — adequate for compact enclosures with lower air volume velocity
a) High SPL
Net Volume: 8 liters
Tuning (Fb): 75 Hz
Est. -3dB: 69 Hz
HP Filter: 67 Hz (24dB/oct recommended)
Round Port: 65mm dia × 201mm long
Slot Port: 150mm W × 40mm H × 384mm L
Port Velocity: 18.2 m/s
Notes: Strong mid-bass impact, reduced cone excursion, maximum output
b) Balanced Response
Net Volume: 8 liters
Tuning (Fb): 68 Hz
Est. -3dB: 58 Hz
HP Filter: 58 Hz (24dB/oct recommended)
Round Port: 65mm dia × 230mm long
Slot Port: 150mm W × 40mm H × 436mm L
Port Velocity: 16.4 m/s
Notes: General-purpose PA/subwoofer, even response, good transient behavior
c) Extended Low Frequency
Net Volume: 10 liters
Tuning (Fb): 59 Hz
Est. -3dB: 50 Hz
HP Filter: 47 Hz (24dB/oct recommended)
Round Port: 65mm dia × 262mm long
Slot Port: 150mm W × 40mm H × 493mm L
Port Velocity: 14.3 m/s
Notes: Deep bass extension, requires proper system protection below tuning
--- Summary ---
The 81XRX8-424A is a 8-inch mid-woofer driver designed for professional 2-way and multi-way systems with 93.0 dB sensitivity (...
This design is particularly effective in single or multi-driver bass reflex systems used in professional two-way and multi-way PA systems, powered monitors, and compact bass-reflex enclosures, where extended bandwidth, controlled distortion across the full operating range, and versatile system integration are required.
AES Power: 200 W,
Continuous: 400 W,
Peak: 800 W.
Sensitivity: 93.00 dB (1W/1m).
