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GUI Sound FR-222B8 Neodymium

Pair of GUI Sound FR-222B8 Neodymium 8 inch Fullrange Drivers

I bought this interesting pair of fullrange drivers from e-bay without any information about the particular model. I believe they were manufactured by GUI (Guide) Sound OEM factory in China. The closest GUI Sound model is FR222B8-11F model. They look like Audio Nirvana Super 8 Neodymium, but with different shape of the front chassis .

This is the manufacturer's datasheet for FR222B8-11F Link To GUI Sound FR222B8-11F Manufacturer's Datasheet

My Measurements

Driver Properties Thiele - Small Parameters
Chassis material Vacuum-molded aluminum alloy   Parameter Measured Datasheet
Membrane material Paper   Fs 57.3 Hz 42.6 Hz
Magnet System Neodymium Re 7.0 Ω 6.8 Ω
Surround Impregnated Cloth Qms 2.50 4.42
Voice Coil Diameter 32 mm Qes 0.24 0.23
Nominal Impedance 8 Ω Qts 0.22 0.22
Sensitivity 96 dB/W/m   Vas 32  ltr 84 ltr
Rated Power 30W   Le 0.12 mH N/A

                                       

This driver is suitable for back-loaded horn applications.
That's why I included a measurements in so-called "Universal" Horn.
More details about this project can be found here.

GUI Sound FR-222B8 Neodymium responce at 1m on axis and 15 and 30 degrees of axis in 18 ltr sealed box GUI Sound FR-222B8 Neodymium responce at 1m on axis and 15 and 30 degrees of axis in the Universal Horn

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


GUI Sound FR-222B8 Neodymium Second, Third and Fourth Harmonic in 18 ltr sealed box GUI Sound FR-222B8 Neodymium Second, Third and Fourth Harmonic in the Universal Horn

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



GUI Sound FR-222B8 Neodymium Burst decay Responce at 1m in 19 ltr sealed box GUI Sound FR-222B8 Neodymium Burst decay Responce at 1m in the Universal Horn

Burst decay response, measured at 1m on axis


GUI Sound FR-222B8 Neodymium impedance in free air and in 18 ltr seled box GUI Sound FR-222B8 Neodymium impedance in Universal Horn

The impedance curves


Conclusion

This fullrange driver shows an excellent capability of power loading. Mounted in a proper backloaded horn It can perform big band or rock music without observable exertion. With some types of amplifiers it can show a slight tendency of aggression in the middle, but the overall performance is good enough not to use any correcting crossover networks. The best matching amplifiers are single-ended triode designs based on low internal resistance valves like 6AS7, 6П19П or 6C41C

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