Mid Range Driver
  • New ergonomic, vented cast aluminium chassis offers improved thermal control
  • Improved motor plating providing a more resilient finish and resistance to corrosion
  • Mid range transducer suitable for either direct radiating or horn-loaded applications
  • Smooth frequency response for easy integration across vocal frequency band
Klippel Verifeid
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Download PDF Datasheet

The PD.121/2 excels in a variety of systems being perfectly suited to either direct radiating or horn loaded applications. Covering the critical vocal range in a single unit the PD.121/2 is particularly effective at faithfully reproducing the pattern of powerful low end male vocals.

The PD.121 perfectly compliments our 15”, 18”, 21” and 24” transducers as part of a three-way system.

General Specifications
Nominal Diameter12” / 300 mm
Voice Coil Diameter2.5” / 63 mm
Available Impedances4 / 8 / 16 Ohm
Power Rating 1 2 *300 W (A.E.S.)
Peak Power (6dB Crest Factor)*1200 W (A.E.S.)
Sensitivity (1W – 1m)*99 dB
Frequency Range100 Hz - 6 kHz
Recommended Enclosure Volume10 - 60 Litres
Resonance53.27 Hz
Voice Coil Winding Depth12 mm / 0.47”
Magnet Gap Depth9 mm / 0.35”
Flux Density1.5 Tesla
Magnet MaterialCeramic
Magnet Weight
Voice Coil MaterialCopper
Former MaterialGlass Fibre
Dust Dome MaterialPaper
Suspension MaterialFabric
Cone MaterialPaper
Surround MaterialFabric
Thiele Small Parameters
Fs53.27 Hz
Re5.93 Ω
Le (@1 kHz)0.42 mH
Le (@10 kHz)'-
Vas66.58 Litres
Mms65.37 g
Sd530.93 cm2
Cms168.33 μm/N
BL21.46 T/m
Xmax2.7 mm
Vd0.143 Litres
Ref. Efficiency5.10%
EBP231.60 Hz


Dimensions & Mounting
Overall Diameter331 mm
Widths Across Flats320 mm
Flange Height11 mm
Depth (Excl. Flange)112.23 mm
Magnet Diameter200 mm
Chassis Shoulder Diameter282 mm
Outer Bolt Circlex4 M6 on 318 mm PCD
Inner Bolt Circlex8 M6 on 293 mm PCD


Shipping Information
Nett Weight9.20 kg / 20.28 lb
Shipping Weight10.00 kg / 22.05 lb
* Power compression is the reduction of sensitivity at the specified power. Higher power ratings do not necessarily give a proportionate increase in SPL therefore the maximum SPL of the driver may significantly exceed that of other manufacturers with high power ratings.
** Distortion is measured at 10% of the rated power (AES Standard).

1. AES Standard (60 to 600 Hz). Program 600 Watts.
2. AES Recommended Practice.
3. Thiele - Small Parameters follow a 300 Watt preconditioning period verified by Klippel LSI measurement.
4. 2.83V. Half space response measured in a 975 Litre sealed enclosure.

Please note that frequency response measurements are supplied for comparison purposes only and are not a measure of the low frequency performance which may be achievable in a fully optimised system.
Frequency Response & Impedance
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