In 2016 ScanSpeak company (https://www.scan-speak.dk) updated its Revelator series by the new model 18M/4631T00 which it positions as midrange driver. This driver is a successor of legendary Revelator series midwoofer 18W/4531G00 which was born in 1997.
Both the drivers have:
- sliced cone of paper with special damping material filling the slices. Due to this technology the control over break-up modes is greatly improved, which gives an extended and more even frequency response
- acoustically transparent cast basket made of light alloy
- patented ferrite magnet SD-1 motor
- progressive spider
The differences between the models:
- 18M/4631T00 have voice coil former of titan but 18W/4531G00 of glassfiber does
- 18M/4631T00 have coated foam surround but 18W/4531G00 of SBR rubber does
- voice coil length of 18M/4631T00 is 11 mm against 18 mm which 18W/4531G00 does have
- 18M/4631T00 has more stiffer spider
The beforementioned design differences resulted in the following differences in technical parameters:
- due the shorter voice coil 18M/4631T00 has ±3 mm linear excursion but 18W/4531G00 does have ±6.5mm
- due the shorter voice coil 18M/4631T00 has 0.16mH inductance but 18W/4531G00 does have 0.27mH
- sensitivity of 18M/4631T00 is 92dB/2.83 Volt vs 8 dB/2.83 Volt of 18W/4531G00
- the 18M/4631T00 moving mass is 14.3g vs 16.9g of 18W/4531G00
- 18M/4631T00 resonance frequency is 65Hz vs 34Hz of 18W/4531G00
- VAS of 18M/4631T00 is 14 liters vs 45.6 liters of 18W/4531G00
Our measurements conformed that as a result of the changes introduced by ScanSpeak in the base construction an excellent midrange driver was born which have very low nonlinear distortion, very flat response and good sensitivity.
Our measurements were carry out after a very very good broken-in procedure but inspite this the measured 18M/4631T00 resonance frequency (Fs=76.7Hz) couldn't reach the datasheet value - 65Hz.
