Drivers ListFocusWorks Audio DriversGUJ18V1

ManufactureFocusWorks Audio
Motor TypeUnderhung
Driver Size18 "
Driver Weight32 lbs
Coil Diameter4.5 "
Coil MaterialAL
Manufacture's Xmax30 mm

TS Parameters (Measured by

Fs19.8 Hz
Res4.9 Ω
Le 1khz2.95 mH
Sd0.117 m2
Vas292.2 liters
Mms423 grams
Cms153 μm/N
BL24.53 Tm
BL2/Res122.8 N2/W
L/R Time Constant0.6 milliseconds
SplSens89.07 dB


The GUJ18v1 18 inch bass driver and it’s brother the larger GUJ21v1 21 inch, are both from a startup company called Focusworks Audio. Both drivers are a lightweight, long throw designs suitable for larger sealed systems or perhaps very large EBS style vented systems. Some of the driver engineering expertise and assembly for these drivers are provided by Funk Audio, which explains some of the shared family traits.

The GUJ18v1 is built on the familiar 6 spoke style cast aluminum frame and includes a rubber wrap around gasket. The design of the GUJ18v1 is an underhung topology with an inner neo magnet slug. There is an aluminum pole sleeve covering the entire pole and gap area of the driver to lower and linearize inductive distortion. The motor also includes a large center pole vent and is also quite compact and relatively lightweight. The frame also has 6 under spider vents machined into it to provide venting above the gap. The voice coil is a very large 4.5” diameter 4 layer wind which is said to have a higher winding height than normal for an underhung topology. Xmax for this driver is said to be 30mm at 70% BL with Xmech at 40mm. The suspension for the driver consists of a large 10 inch diameter spider and a large half roll foam surround. The cone itself appears to be a heavy pressed paper with a carbon fiber front face. An inverted aluminum dust-cap completes the front of the driver. The driver is a dual voice coil design with a pair of spring loaded binding posts for each coil.

Testing of the GUJ18v1 produced a set of parameters that were in close agreement with the factory ones provided. The driver is essentially a nominal 6ohm driver with the coils in series or perhaps 8ohms. The BL^2/Re of the driver is a bit lower than usual at about 123 and the Fs came in at a low 19.8Hz partly due to a soft suspension. The Mms of the driver is about 420g which is middle of the road for a driver of this size with such a large geometric Xmax. All of this adds up to a driver with a low EBP product and a Qts of about 0.4. This driver does like a bit of air volume to work with for best results. Inductance seems to be well mannered and under control judging by the distortion results from testing this driver and the shape of the impedance rise after the driver resonance. Free air testing of the GUJ18v1 indicated it is quite clean and mechanically quiet up to 2” peak to peak and at about 2.75” peak to peak it starts to develop some chatter that indicates it is becoming increasingly non linear. It was pushed to about 3” peak to peak without issue other than high levels of distortion and air noise. Mechanically it seems well built and abuse tolerant. This particular driver also did quite well with large power inputs for an underhung design. Generally underhung designs have lower efficiency and less coil mass so they do not do as well with large power inputs. The GUJ drivers are an exception to that due to extensive cooling in the motors and relatively massive voice coils. Distortion on these drivers was quite low until the drivers were pushed to huge amounts of excursion. Both the 18” and 21” drivers give warning sounds of overload and distortion well before any mechanical damage can occur which is always good.

The GUJ drivers are expensive with MSRP of about $850 for the 18 and $900 for the 21 with street pricing TBD. These drivers are lightweight weighing less than 40lbs and offer a ton of displacement with low distortion. I can’t think of any other underhung drivers that will take the amount of long term power that these will so overall these are a bit of a different breed from most other drivers available. Focusworks Audio indicate that these should be available for sale to the public soon. 

FocusWorks Audio 18" GUJ18V1 Systems