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Supravox T215 RTF 64

Supravox T215 RTF 64 8 inch Fullrange Drivers

The abbreviation RTF in the name of this driver comes from la Radio Télévision Française. Supravox created this drive in mid sixties with revolutionary for its time membrane to fulfill the requirements of French studios like ORTF, RAI, RTL and EUROPE 1. Very soon T215 RTF 64 became one of the most popular fullrange drivers among the audiophiles.

Close view of Supravox T215 RTF 64 cone

The cone is made of long-fiber paper, with impregnated center sector for more rigidity. The surround is three-ribs "accordion" type without coating.

The whizzer cone is very thin and very stiff to a touch. From the picture can be seen that it is attached at the inner surface of the voice coil. The dust cap is common part of the whizzer.

The gasket is made of 6 mm thick fine white felt.

Magnet system of Supravox T215 RTF 64

The magnet system features AlNiCo (Ticonal) magnet which is covered with aluminum back cap.

On the die-casted aluminum alloy we can see a base for a matching transformer in case the loudspeaker is used in a 100 V line network. Because of this supplement the driver can be mounted at the back of the acoustic panels only.

Supravox T215 RTF 64 Datasheet

This is the manufacturer's brochure Link To Supravox T215 RTF 64 Manufacturer's Datasheet

My Measurements

Driver Properties Thiele - Small Parameters
Chassis material Aluminum Die Cast    Parameter Measured Datasheet
Membrane material Paper Fs 55.5 Hz 50 Hz
Magnet System AlNiCo Re 5.9 Ω N/A 
Surround  Paper Qms 4.8 N/A
Voice Coil Diameter 25 mm Qes 0.60 N/A
Nominal Impedance 8 Ω Qts 0.53 N/A
Sensitivity 95 dB/W/m   Vas 76 ltr N/A
Rated Power 30W Le 0.30 mH N/A

SPL Responce of Supravox T215 RTF 64 at 1m on axis and 15 30 deg off axis  SPL Responce of Supravox T215 RTF 64 at 1m on axis and 15 30 deg off axis 

On left - frequency response at 1m with 2.83 V input RED - on axis, BLUE - 15 º off axis, GREEN - 30 º off axis
On right - frequency response smoothed at 1/3 Oct at 0-90º of axis wit a step of 10º

Second, Third and Fourth Harmonic of Supravox T215 RTF 64  in 18 ltr sealed box

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

Burst decay Responce of Supravox T215 RTF 64 at 1m in the Universal Horn

Burst decay response, measured at 1m on axis

The impedance of Supravox T215 RTF 64 in 18 ltr seled box 

The impedance curves BLACK - in a free air, BLUE - in 18 ltr sealed volume


The first commercial construction for T215 RTF 64 is Supravox Picola 2 - a double aperiodic vent bookshelf speaker system.

Supravox Picola 2 Loudspeaker System

The audiophiles use this driver in various applications.
It is suitable for TQWT or open-baffle constructions, with or without low frequency support.
My favorite application is Baffles Compensés RJ which is a combination between a small front panel, with Helmholtz resonator box, adjusted at 250Hz attached. I recommend it to everyone who doesn't like the "box" sound. Here are the plans of this construction, as they were given in the Supravox web page: Link To Supravox T215 RTF 64 Manufacturer's Datasheet
In all the application the T215 RTF 64  shows its full-blooded sound signature. The performance of vocals is expressive and persuasive. The sound stage is wide and slightly forwarded. This speaker is very easy to drive and cooperates well with both push-pull and single ended tube amplifiers.

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