GUI Sound FR-222B8 Neodymium
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
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.
Frequency response at 1m with 2.83 V input RED - on axis, BLUE - 15 º off axis, GREEN - 30 º off axis
The second, third and fourth harmonic curves measured at 2.83V input RMS.
Burst decay response, measured at 1m on axis
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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