Hi guys,
I recently got two Beyma 10G-200 10" drivers on my table. I don't know where they were used before and how they were treated. Driver number 2 (Beyma 10G-200 NR2) has a small problem with the cone. It is separating on a ca. 5 cm section from the surround. I intend to repair the driver with the right glue, as soon as I receive it. In the meantime, I hope to evaluate the condition of the drivers with some measurements and got me a Focusrite 2i2 Audio Interface and build myself a cable so that I can measure the impedance of a driver.
Now I attached the measurements of the free air impedance of both drivers to compare them with the datasheet graph. This leads me to some questions I have. The resonance frequency in the datasheet is give at 45 Hz. My resonance peaks are found at 53 Hz and 56 Hz. What are the reasons for such a shift in frequency (other than the cone/surround issue of driver number 2)? Could it be the age of the drivers?
And with driver number 1 (Beyma 10G-200 NR1) there is a small bump at 1.7 kHz. What could be the source of that? A similar feature at this frequency is seen in the datasheet in the "VOICE COIL INDUCTANCE CURVE" and the "Re + Red(w) Curve".
Thank you very much for your input and suggestions.
I recently got two Beyma 10G-200 10" drivers on my table. I don't know where they were used before and how they were treated. Driver number 2 (Beyma 10G-200 NR2) has a small problem with the cone. It is separating on a ca. 5 cm section from the surround. I intend to repair the driver with the right glue, as soon as I receive it. In the meantime, I hope to evaluate the condition of the drivers with some measurements and got me a Focusrite 2i2 Audio Interface and build myself a cable so that I can measure the impedance of a driver.
Now I attached the measurements of the free air impedance of both drivers to compare them with the datasheet graph. This leads me to some questions I have. The resonance frequency in the datasheet is give at 45 Hz. My resonance peaks are found at 53 Hz and 56 Hz. What are the reasons for such a shift in frequency (other than the cone/surround issue of driver number 2)? Could it be the age of the drivers?
And with driver number 1 (Beyma 10G-200 NR1) there is a small bump at 1.7 kHz. What could be the source of that? A similar feature at this frequency is seen in the datasheet in the "VOICE COIL INDUCTANCE CURVE" and the "Re + Red(w) Curve".
Thank you very much for your input and suggestions.
