these are the two drivers i list as options in my design here:
and they are direct competitors. they’re both 1.75" annual diaphragm 1" exit compression drivers, both have similar frequency response, efficiency and power handling and they cost the same. they’re both also from companies known for their HF drivers.
but they are very different as you can see just by looking at them. here is BMS:
both are well designed in that the diaphragm is well protected during replacement procedure by the plastic part that ties the outside and inside of the annular diaphragm together and covers it form one side reducing the odds of damaging the diaphragm from mis-handling …
however on the BMS the assembly forms the rear of the driver which means it can be directly removed and replaced without detaching the driver from the horn ! this is the genius of BMS - the heavy part of the driver ( the motor ) bolts directly to the horn, and the diaphragm assembly, phase plug and rear cover are all a single piece of plastic so replacing the rear cover replaces the diaphragm ! PURE GENIUS !
for the Faital to you have to remove the driver from the horn then remove the front part of the driver and only then you have access to the diaphragm assembly.
not only that but the entire front part of the driver which is cast aluminum on the Faital is not present on the BMS which means BMS completely eliminates the size, cost and weight associated with that part ! again this is PURE GENIUS.
essentially the Faital has an extra large, heavy and expensive part ( the front of the driver that bolts to the horn ) that does nothing except triples the complexity of replacing the diaphragm compared to the BMS.
this is why BMS is the standard - small, light, easy to repair.
you see to achieve this brilliant trick of packaging and mechanical design BMS has to send the sound wave BACKWARDS then use 45 degree high frequency mirrors to reflect it by 90 degrees TWICE - first to send the wave from the ring diaphragm to the center of the driver and then to send it forward through the opening in the torus of the motor and into the horn …
these mirrors are integrated into the phase plug that is also the back cover that is also the diaphragm assembly - it’s all a single plastic injection - it costs and weighs nothing - that is not the issue …
the issue is that it makes the acoustical path from the diaphragm to the horn throat LONGER
in BMS the acoustical path is CIRCUITOUS whereas in Faital it is a DIRECT STRAIGHT LINE.
and we know that in compression drivers slow expansion rate of the horn is associated with higher distortion …
essentially whereas in regular drivers the primary driver of distortion is motor and the secondary driver is suspension in compression drivers the primary driver of distortion is COMPRESSION OF AIR ITSELF.
the slower the expansion rate of the horn the higher the compression and distortion.
modern systems use faster expansion sacrificing some efficiency to achieve more constant directivity and lower distortion …
the Faital is a newer design than BMS and seems to have a faster expansion / lower compression based on the fact that they both have same diaphragm size and throat size but the acoustical distance from diaphragm to throat seems shorter on the Faital …
so in theory Faital should have lower distortion … however BMS actually lists distortion measurements in their specs while Faital does not …
i should also mention Faital uses a newer diaphragm material - the milky white ketone polymer - versus the clear plastic diaphragm of BMS …
supposedly the ketone polymer is more like a hybrid between a hard and soft material - you know sort of like a silk dome or a phenolic dome is a composite material - basically it represents more modern and advanced material science.
the goal of diaphragm material is to have high stiffness and high damping at the same time but usually those are mutually exclusive. so for example titanium has good stiffness but poor damping and most plastics have good damping but low stiffness. however Ketone Polymer may just have the right mix.
so Faital is definitely not garbage, and in fact may very well sound better than BMS.
so which should you get ?
if your application is PA - get the BMS. they are small, light, easy to fix and have been around a long time.
if your application is Audiophile - buy both, and buy some horns too, and listen / measure various combinations until you find one you like best then return the others.
in any case both of these drivers are better than traditional dome drivers which represent an outdated approach to compression driver design. all modern designs are annular ring.
