Drivers ListSundown Audio DriversZv3 18D1

ManufactureSundown Audio
Motor TypeOverhung
Driver Size18 "
Driver Weight60 lbs
Coil Diameter3 "
Coil MaterialAL
Manufacture's Xmax30 mm

TS Parameters (Measured by

Fs30.3 Hz
Res1.7 Ω
Le 1khz2.15 mH
Sd0.1195 m2
Vas119.5 liters
Mms458.4 grams
Cms60 μm/N
BL17.8 Tm
BL2/Res186.4 N2/W
L/R Time Constant1.26 milliseconds
SplSens90.37 dB


This Sundown driver is a big heavy duty 18" that weighs in at right about 60lbs. Packaging as delivered was good with a double box and the driver surrounded by expanding foam with the actual driver protected by a plastic bag. Sundown is primarily a car audio related brand that lists the Zv3 series as geared towards a combination of low distortion and high output at reasonable cost. This driver in particular is an 18" version with dual 1 ohm voice coils. This driver sells for $480 shipped and is an impressively well built and massive one.

The build quality is very good and the parts used are as well. The frame is the familiar 6 spoke 18" frame finished in a matte black paint. The motor is a large chunk of steel and ferrite having double stacked slugs protected by a rubber boot embossed with the Sundown logo, a large deeply bumped back plate with a flared 1" pole vent and 6 what look to be 1/4" diameter under gap vents. The chromed top plate is large as well, around 1" thick maybe more. There is also spacer plate which sports the sundown logo between the top plate and frame which provides extra mechanical clearance between the triple joint of the bottom spider and the motor and also provides room for a couple of large under spider vents.

Sundown lists the voice coil as a beefy 3" OD, 8 layer aluminum flat wind on a black aluminum former. This particular driver is a dual 1 ohm unit. Judging from the driver behavior observed this is also a long wind resulting in a fairly large amount of coil mass and high geometric xmax. Additionally Sundown also lists the Zv3 series as employing a pair of demodulation rings in the motor which is always a good sign for a motor with this much voice coil mass and steel. The cone itself appears to be a stiff heavy paper variety which is coated for weather resistance and possibly impregnated with another material. The surround is a foam high roll type which allows the driver to maintain a little extra SD as compared with a more common large half roll surround which also has the added measure of being sewn into the cone.

The rest of the suspension consists of a quadruple spider pack of about 9" diameter on a spacer . The voice coil leads are extra heavy gauge and additionally run in pairs of 2 for each terminal. They are sewn into the top spider. The terminals are heavy duty push spring that look like they could accept 4ga if need be. Overall the build quality and robustness of the driver is impressive.

After a bit of suspension break in using a high power 16Hz sine wave in free air the impedance and parameters were measured. Most of them came in very close to Sundown's factory specs. RE was dead on at 1.7 ohms with the voice coil's in series. I did not find an SD spec to compare with but a measurement which includes 1/3rd of the surround came out to 1150cm. The motor force came in the same as Sundown's spec of 17.8 but the moving mass came in slightly lower at about 460g so the resultant sensitivity is a little higher and the Q a little lower.

Despite the huge motor and voice coil the BL^2/RE is not as high as might be expected from looking at it. The inductance came in a bit higher at 1khz than the factory spec and is rather high despite the dual demodulation rings in the motor. This is unsurprising with the sheer amount of coil mass and steel involved in this driver motor. Judging from the close mic in a sealed enclosure and the impedance curves measured the Zv3 will have some top end roll off related to the inductance which will limit top end sensitivity some. Hopefully the driver can be tested in a quasi anechoic manner in a sealed enclosure in order to determine what the response shape is more accurately and how much inductance will play a roll in the response shape.

Sundown did not list an xmax or xmech spec that could be seen either but judging from the Zv3 18's very quiet and clean excursion during free air testing with sine waves an xmax spec of 30mm seems appropriate. The xmech is probably in excess of 40mm as the driver was driven to about 3" peak to peak or a little more during free air testing --This driver is capable of a lot of stroke.

Sundown Audio 18" Zv3 18D1 Systems