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Pair of SONIDO SFR-200 8 inch Fullrange Drivers

Company Sonido was founded in the year 1993. by Mr. Istvan Varga who worked in Budapest Electro-acoustic Factory (BEAG). The main activity is production of fullrange drivers. SFR 200 is the largest one from this production line. It is a little bit smaller than ordinary 8" driver. The frame is die-cast with very simple construction. There is no opening behind the spider - something unusual for a modern fullrange speaker.

SONIDO SFR-200 whizzer cone

The cone is paper, which has a rumors about, than has a special formula, adopted from the legendary Telefunken speakers. In the company's website I couldn't find such an information and I cannot find any visual similarity between the paper materials of SONIDO and old Telefunken. The membrane is light and with neutral sonic response. The whizzer has 47mm outer diameter and the phase plug is made of untreated beech wood.

SONIDO SFR-200 Roll Surround SONIDO SFR-200 Accordion Surround

SFR-200 has two versions with different shape of surround - single roll and "accordion" as they were shown in the pictures above. According to the manufacturer's datasheets, there is also a slight difference in parameters.

This is the manufacturer's datasheet of the old Link To SONIDO SFR-200 Manufacturer's Datasheet and new Link To SONIDO SFR-200 Manufacturer's Datasheet version of this model.

My Measurements

The measured unit was the older version with half-roll surround.

Driver Properties Thiele - Small Parameters
Chassis material Cast  aluminum alloy   Parameter Measured Datasheet
Membrane material  Paper   Fs 47.8Hz 49.4 Hz
Magnet System Ferrite Re 7.75 Ω 7.7 Ω
Surround Impregnated Cloth Qms 5.75 7.83
Voice Coil Diameter 32 mm Qes 0.27 0.29
Nominal Impedance 8 Ω Qts 0.26 0.28
Sensitivity 95 dB/W/m   Vas 61 ltr 50 ltr
Rated Power N/A   Le 0.24 mH 0.35 mH


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.

SONIDO SFR-200 SPL Responce at 1m on axis and 15 30 deg off axis SONIDO SFR-200 SPL Responce at 1m on 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

SONIDO SFR-200 Second, Third and Fourth Harmonic in 18 ltr sealed box SONIDO SFR-200 Second, Third and Fourth Harmonic in the Universal Horn

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

SONIDO SFR-200 Burst decay Responce at 1m in 19 ltr sealed box SONIDO SFR-200 Burst decay Responce at 1m in the Universal Horn

Burst decay response, measured at 1m on axis

SONIDO SFR-200 impedance in free air and in 18 ltr seled box SONIDO SFR-200 impedance in Universal Horn

The impedance curves

 Measurement of the correcting networks for Fostex SONIDO SFR-200

The SPL graphics of the SFR-200 Show double peak with about 8dB above the smoothed curve. It can be corrected with RLC network, connected in series, which consists of resistor 4.7 Ω, inductance  0.39 mH and capacitor 2.2 µF in parallel.
The red curve is without the crossover. The blue one is with the crossover.

SONIDO SFR-200 Impedance with Crossover SONIDO SFR-200 Burst Decay with Crossover

Impedance and burst decay when the correcting network is applied.


If I must describe the sound of SONIDO SFR-200 with one word, this word is neutrality. The tonal balance is good even no network is added. The presence of vocals is just right. The overall performance is consistent and musical, but needs some more brightness. It can be corrected with a properly chosen amplifier. 

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