Located in Hannover Germany, BMS manufactures and designs compression drivers of high and mid-high frequency range for pro audio applications along with cones, horns, coaxials, and a planar wave device. BMS precision drivers are used in professional speakers, cinema sound systems, stage monitors, recording studio monitors, home theater, high end audiophile speakers, and test systems. BMS designs and manufactures OEM compression drivers for many well known, highly respected pro audio speaker manufacturers throughout the world. Chances are you have already heard BMS drivers.

Why do they sound better?

BMS has developed and patented a unique, domeless diaphragm with less mass than a traditional diaphragm, remarkably reducing diaphragm excursion and inertia. It has exceptional dynamic range and produces even the most complex musical signals with depth and definition. BMS drivers require much less energy than conventional diaphragms, allowing a much higher SPL, less dynamic compression, an increase in transient response, and lower harmonic distortion than traditional designs. With reduced excursion and excellent transient response, BMS drivers react extremely quickly to peak level signals and have high crest factors. The result is an increase in dynamic headroom and precise definition. An additional BMS benefit is a system that is more "single point source", especially when using the dual motor, mid/high 2" exit drivers. Because of the increased sensitivity and lower distortion, much lower crossover points can be used. With more of the frequency spectrum coming from a single point, the quality of sound is more focused and less smeared. The BMS neodymium drivers offer a more defined sound than the ceramic drivers. This is a function of higher flux density and less flux variation.

Assistance Audio & BMS

Assistance Audio is the North American distributor for BMS, with customers throughout the United States, Canada, and Mexico. We can drop ship large quantities anywhere using international airports. We are dedicated to bringing BMS to the masses.


Why don't they cost more?

1) BMS drivers are made with an innovative design. The diaphragms are small and are made with polyester, not special (expensive) metals. By improving some basic flaws in driver design, instead of trying to make a better full diaphragm dome, BMS improves the performance and reduces the cost of manufacturing. The neodymium drivers cost more and offer a more defined sound than the ceramic magnets.
2)Purchasing power. Not only do we have great purchasing power with the manufacturer, we also do our own customs clearance and handling which saves our customers a good deal of money.

Why don't they cost less?

One of BMS's guiding principals is; the best value, not the cheapest product. BMS has become a pioneer in manufacturing techniques in order to get the quality of diaphragm they (and their customers) want. Recently BMS licensed the patent to a major US speaker company that has been manufacturing drivers for decades in an effort to save money on shipping and import duty. Try as they might, this company could not replicate the BMS diaphragm. Now they manufacture the magnet assembly and import the diaphragms from the BMS factory in Germany. If you need the cheapest driver possible, buy a knock off from the east. If you want a great sounding driver at the best value, BMS is for you.

The Bottom Line

We liked BMS so much that we became the largest direct purchaser and end user of BMS products in the USA. Sadly, too many products in the audio industry are sold by hype and name recognition. BMS is a product that actually delivers as it is described. BMS is used in many speaker boxes as OEM products. Our mission is to also bring what we feel are the best drivers in the world to the small, independent user.

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Hearing is Believing.

Model 4524 4538 4540ND 4544 4550 4552ND 4510
Throat Diameter 1" 1" 1" 1" 1" 1" 1"x4"
Nominal Impedance 8 Ω 8 or 16 Ω 8 or 16 Ω 8 or 16 Ω 8 or 16 Ω 8 or 16 Ω 8 or 16 Ω
Frequency Range (Hz) 1.2kHz-30kHz 1.2kHz-30kHz 1.2kHz-30kHz 500Hz-20kHz 500Hz-20kHz 500Hz-20kHz 500Hz-20kHz
Recommended Crossover 1.9 kHz 1.9 kHz 1.9 kHz 1.2 kHz 800 Hz 1 kHz 1 kHz
Sensitivity on horn 1w/1m 113 dB (90x75) 114 dB (90x75) 114 dB (90x75) 114 dB (90x75) 113 dB (90x75) 113 dB (90x75) 115 dB (120x10)
Power Capacity (AES) 25W 60W 60W 80W 80W 80W 80W
Peak Power 200W 300W 300W 450W 450W 450W 450W
Magnet Material Ceramic Ceramic Neodymium Ceramic Ceramic Neodymium Neodymium
Flux Density (Tesla) 1.6 1.9 2.2 1.9 2 2.2 2.2
Voice Coil Diameter 1" 1.5" 1.5" 1.75" 1.75" 1.75" 1.75"
Overall Diameter 60mm 96mm 72mm 110mm 123mm 85mm 106mm
Depth 35mm 40mm 45mm 47mm 52mm 36mm 118mm
Net Weight .665kg .98kg .53kg 1.53kg 2.25kg .83kg 1.3kg
Mounting 2 bolt/5mm 2 bolt/5mm threaded 2 bolt/6mm 2 bolt/6mm 2 bolt/5mm screw holes
Model 4554 4555 4591 4590/4590P 4592ND 4594ND 4595ND
Throat Diameter 1.4" 1.5" 2" 2" 2" 1.4" 1.5"
Nominal Impedance 8 or 16 Ω 8 or 16 Ω 8 or 16 Ω 8 or 16 Ω 8 or 16 Ω 8 or 16 Ω 8 or 16 Ω
Frequency Range (Hz) 500Hz-20kHz 500Hz-20kHz 200Hz-9kHz 200Hz-22kHz 200Hz-22kHz 200Hz-22kHz 200Hz-22kHz
Recommended Crossover 1kHz 1kHz 300Hz 300Hz 300Hz 300Hz 300Hz
Sensitivity on horn 1w/1m 113dB (90x75) 113dB (90x75) 118dB (40x20) 118dB (40x20) 118dB (40x20) 118dB (40x20) 118dB (40x20)
Power Capacity (AES) 80W 80W 150W 80/150W 80/150W 80/150W 80/150W
Peak Power 450W 450W 1kW<500Hz 450W/1kW<500Hz 450W/1kW<500Hz 450W/1kW<500Hz 450W/1kW<500Hz
Magnet Material Ceramic Ceramic Ceramic Ceramic Neodymium Neodymium Neodymium
Flux Density (Tesla) 2.0 2.0 1.9 1.9 2.0/1.95 2.0/1.95 2.0/1.95
Voice Coil Diameter 1.75" 1.75" 3.5" 3.5" / 1.75" 3.5" / 1.75" 3.5" / 1.75" 3.5"/1.75"
Overall Diameter 123mm 123mm 182mm 182mm 132mm 132mm 132mm
Depth 52mm 52mm 90mm 129mm 113mm 94mm 94mm
Net Weight 2.25kg 2.25kg 6kg 9kg 2.8kg 2.63kg 2.63kg
Mounting 4 bolt/6mm 4 bolt/6mm 4 bolt/6mm 4 bolt/6mm 4 bolt/6mm 4 bolt/6mm 4 bolt/6mm

All voice coils copper clad aluminum. Two layers inside and outside the VC except 4538 and 4540ND one layer.
All voice coil formers Kapton, diaphragm material Polyester.


A passive (6.5khz) crossover is available for the coaxial drivers. Note the screws for mounting directly to holes on the back of the 4590. Crossovers are $25ea and work with the coaxial versions of the 4590 4594, 4595 & 4592.

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BMS Horns

BMS also manufactures horns. We typically have all models in stock. Any BMS horn is available as part of our speaker kits.

Model Price Dispersion Low Frequency Cut Off Size
BMS 2193 $47.00     8.5" x 4.5" x 2.75"
BMS 2119 $62.00 90 x 40 1000 Hz 11.8" x 6.7" x 4.5"
BMS 2230 $104.00 90 x 55 700 Hz 12.8" x 9.1" x 4.6"
BMS 2250 $135.00 50 x 55 700 Hz 11" x 9" x 11.1"
BMS 2236 $165.00 60 x 40 400 Hz 19" x 13.8" x 10.4"

BMS Diaphragms

Replacement diaphragms are available for any BMS drivers, or BMS manufactured diaphragms

Driver Diaphragm Model Cost   Driver Diaphragm Model Cost
BMS 4538 M4538 (8 or 16) $65.00   BMS 4554 M4554 (8 or 16) $82.50
BMS 4540 M4540 (8 or 16) $72.50   BMS 4555 M4555 (8 or 16) $82.50
BMS 4544 M4544 (8 or 16) $70.00   BMS 4590(h) MH4590 (8 or 16) $61.00
BMS 4548 M4548 (8 or 16) $81.25   BMS 4590(m) M4590 (8 or 16) $115.00
BMS 4549 M4549 (8 or 16) $75.00   BMS 4592(h) MH4592 (8 or 16) $81.25
BMS 4550 M4550 (8 or 16) $81.25   BMS 4592(m) M4592 (8 or 16) $212.50
BMS 4552 M4552 (8 or 16) $90.00   BMS 4510 M4510 (8 or 16) $90.00

How To Order

Contact us to order, demo, or for more information.
801.486.2655 office
801.898.6023 mobile

We don't just sell them, we use them

Assistance Audio first learned about BMS at NAMM in 2000. We liked what we heard and bought some. Initially, we began simply replacing JBL 2450s in some of our front of house speakers. The difference was astounding. The speakers with BMS were much more efficient, clearer, and cleaner. The BMS are so efficient we were not using the HF amps very much at all. To make better use of our power, we lowered the crossover point, which was very foreign to us as a lifetime 10” midrange company. We were used to using cones to cover as much spectrum as possible, both for speaker protection and sound quality. BMS reversed our thinking. The BMS were much clearer in the 700-1200 range than the 10”, and were missing the “gack” or overring that the JBL compression drivers have. The BMS breathed new life in our whole system. Soon we went about replacing all the old drivers and selling them on eBay. We began utilizing DDS horns to fully realize the BMS potential. Our new systems are designed around the BMS and DDS. To improve our buying power, we became the largest non-OEM user of BMS in North America in 2001.

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