Loudspeakers is a well-established U.S. speaker manufacturer--they've been in business
since 1976. They make high value, stereo and home theatre speaker systems that utilize top
quality components, and offer performance that equals or exceeds that of rivals costing
far more. The current product line includes three powered subwoofers that share the same
cabinet dimensions (a tiny cubical box about 15-inches on a side) and appearance. All
three use 12-inch polycone drivers and efficient, powerful switching amplifiers. The
Digital SubTM 150 and the Digital SubTM 250 are straight forward,
air suspension designs with electronic equalization. The
Digital SubTM 350 is a
compound (Isobarik) design with two drivers, one behind the other.
PINNACLE® submitted the
150 and 350 models for this review.
The Digital SubTM 150 comes in a premium black
vinyl cabinet just large enough to house its 12-inch driver. Its dimensions are 15 x 14.25
x 15 inches. The removable black, cloth-covered grille has a gold
PINNACLE® badge at the
bottom center, and covers nearly the entire surface of the front of the cabinet. Solid
brass, cone-shaped feet are furnished to improve bass definition by minimizing cabinet
movement in reaction to cone movement. They work. The appearance is simple and not
particularly striking, but this subwoofer is so small you will hardly notice it in the
room anyway. The back panel has no protruding heat sinks as this product uses a switching
power supply. There are blade-type (sometimes called push-to-connect) speaker-level inputs
and outputs, line-level inputs, a phase switch, a volume control, and a control to vary
the low-pass frequency from 75-180 Hz.
The Digital SubTM 150 uses a 12-inch
polypropylene cone driver with a 1 1/2-inch dual-layer voice coil, a foam surround, and a
20-ounce magnet. This driver is mounted in a second-order, sealed enclosure and driven by
a 150 watt amplifier with a switching power supply and discrete MOSFET output devices. A
switching power supply is efficient, offering high power with low heat at minimum cost. An
anti-clipping circuit, active second-order low-pass and passive first-order speaker-level
high-pass filters are included. The low-pass filter is variable over the range of 75-180
Hz but there are no calibration markings between these minimum and maximum frequencies, so
you have to measure as I did, or guess to achieve the desired crossover frequency.
The little PINNACLE® 150 has surprisingly linear response,
producing 100 dB at 50 Hz, a peak undistorted output of 103 dB at 40 Hz, and dropping only
slightly to 101 dB at 35 Hz. Output at lower frequencies remained virtually flat giving
100 dB at 30 Hz and 99 dB at 25 Hz before rolling off sharply. This subwoofer will play
louder than this but can be easily driven into doubling, a form of harmonic distortion
usually caused by the voice coil leaving the gap. Is this a problem? Well, that depends.
Doubling raises the intended frequency an octave and distorts the waveform, which is
hardly noticeable on sound effects if the peak is brief. For music this type of distortion
is objectionable, but 103 dB at 40 Hz is pretty loud for music and lower levels are
reproduced cleanly. As long as the volume remains below the level where distortion becomes
audible, bass is tight and well defined, pitch definition is very good, and rhythm and
pace are easy to follow. This is excellent performance for the price when reproducing
music. Punch and slam on sound effects is pretty good but can overload the subwoofer if
level's are too high.
The PINNACLE® Digital SubTM 150 costs only $595
and offers excellent performance for a product in this price category. It can be
overdriven on loud effects, so using two would be advisable in larger rooms, but I think
everybody should have at least two subwoofers anyway. One of these will be enough for
smaller rooms (or lower levels), offering very good performance for music or film sound.
At its modest asking price, this subwoofer is a real bargain.
The step-up product in the line is the Digital SubTM
250 (not reviewed). It utilizes a more robust 12-inch polycone driver with a 2-inch voice
coil, rubber surround, and a 40-ounce magnet. The internal amplifier is a more powerful
Class D switching device that produces 250 watts RMS continuous power. The cabinet looks
the same as the 150 model, but the higher quality internal components should offer
improved performance. The price of the Digital SubTM 250 is $850-still a very
Richard Hardesty / Widescreen
Review Volume 6, Number 4, Issue 26