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Philips AD 1256/M8

Pair of Philips 9710M/01 8 inch Fullrange Drivers

AD 1256/M8 is the largest fullrange loudspeaker, manufactured by Philips. It was introduced in 1969 as the successor to the AD 5200M.

Close view of Philips AD 1256/M8 cone

A close view of the cone shows a long-fiber paper. This is the version with the specific brown color of the Philips cones.  The surround is "accordion" type without coating.

There is another later version with black colored cone. Audiophiles who compared both versions rematk the superior sonic performance of the brown one.

There dist cap is made of acoustically transparent textile.

The gasket is made of cork.

Magnet system of Philips AD 1256/M8

The magnet system features AlNiCo magnet and a special shape center pole piece with a copper cap.

The voice coil is copper ant it is wounded on a paper former.

The unit was assembled with three bolts made of non-magnetic material. 

The chassis is attached to the magnet system by three screws on its side and can be easily removed.

Unfortunaly I couldn't find any manufacturer's datasheet for this driver.

My Measurements

Driver Properties Thiele - Small Parameters
Chassis material Stamped Aluminium   Parameter Measured Datasheet
Membrane material Paper Fs 48 Hz N/A
Magnet System AlNiCo Re 8.1 Ω N/A
Surround  Paper Qms 6.3 N/A
Voice Coil Diameter 35 mm Qes 0.63 N/A
Nominal Impedance 8 Ω Qts 0.58 N/A
Sensitivity 98 dB/W/m   Vas 96 ltr N/A
Rated Power 30W Le 0.16 mH N/A

Philips AD 1256/M8 SPL Responce at 1m on axis and 15 30 deg off axis 

Frequency response at 1m with 2.83 V input RED - on axis, BLUE - 15 º off axis, GREEN - 30 º off axis

Philips AD 1256/M8 Second, Third and Fourth Harmonic in 18 ltr sealed box

The second, third and fourth harmonic curves measured at 2.83V input RMS.

Philips AD 1256/M8 Burst decay Responce at 1m in the Universal Horn

Burst decay response, measured at 1m on axis

Philips AD 1256/M8 Impedance in 18 ltr seled box 

The impedance curve in 36 ltr sealed box

Philips AD 1256/M8 Matching Units in 18 ltr sealed box

This is the SPL graph at 1m of both tested units - one very close matched pair.


The best application of Philips AD 1256/M8 are open baffle constructions. A large transmission line is also possible.  The driver delivers consistent and well-focused sound. A supertweeter support is recommended.

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