Lowell 4A30-T870 Specifications

Spec No. 1287 | Rev. 02.01.16 | pg. 1/1

Heard Everywhere Since 1947

Model No.

4A30-T870

Premium 4" 30W Coaxial Driver with Transformer

Premium 4" 30W coaxial driver with mounted transformer
provides smooth musical sound and wide dispersion for very
high quality paging and background music.

Construction & Features

• 30W coaxial 4" (EIA 5") driver has the capacity to deliver
a wide angle of sound distribution at 2kHz with uniform re­sponse and clear audibility to ensure complete coverage
with minimum units. Includes 10 oz. magnet, 1" copper
voice coil, and polypropylene cone with half-roll rubber
surround for long cone travel and good edge damping.
Post-mounted liquid-cooled tweeter is a 1" diameter bal­anced drive dome with first order high-pass filter. Includes
stamped 20-ga. steel frame with black enamel paint and
zinc plated backplate.

• Factory-wired 70V transformer with 1, 2, 4, 8W taps.

A&E Specifications

The 4" (EIA 5") coaxial driver with mounted transformer shall
be Lowell Model No. 4A30-T870, which shall have a high fre­quency transducer (tweeter with 1" dia. balanced drive
dome) and low frequency transducer (4" dia. polypropylene
cone). A built-in electrical crossover network shall be em­ployed for proper frequency divisions. Crossover frequency
shall be at 5kHz with a first order high-pass filter. Power han­dling shall be rated at 30 watts (EIA 426B). The low fre­quency voice coil shall have 1" dia. and operate in a
magnetic field derived from a ferrite (ceramic) magnet with
nominal weight of 10 oz. The high frequency voice coil shall
have a 0.53" dia. and operate in a magnetic field derived
from a Neodymium magnet with nominal weight of 0.06 oz.
Voice coil impedance shall be 8 ohms. The assembly shall

Driver + Transformer Specifications

Driver + Xfmr. Driver Type & Driver Transformer Assembly Assembly Dispersion Assembly Assembly Max
No's. Power Rating Magnet Weight Taps Frequency Response @2000Hz Octave Sensitivity Mtg. Depth* SPL **

4A30 + TLM-870 coaxial 8ohm 10 oz. (woofer) 1, 2, 4, 8W 70Hz-20kHz (+6dB) 135 degrees conical 88.0dB 3.80" 97.0dB

30W 0.06 oz. (tweeter) @70V 50Hz-20kHz (+8.8dB) (-6dB) Avg SPL

* Minimum depth required for assembly to be rear-mounted to grille in an enclosure. Transformer is factory-mounted to basket with special bracket.

** Calculated value 1M @ maximum transformer tap (8W).

Additional technical information is available on the specification sheet for Driver No. 4A30.

have a round, structurally reinforced, stamped 20-gauge
steel frame for precise mechanical alignment. Overall dia.
shall be 5" with four round and four obround holes equally
spaced on a 4.688" dia. mounting bolt circle. External
metal parts shall be finished in black enamel paint or zinc
plating. The transformer shall have 70V primary voltage
and selectable power taps at 1, 2, 4 and 8W. The assem­bly shall be capable of producing a uniform audible fre­quency response over the range 70Hz-20kHz (+6dB);
50Hz-20kHz (+8.8dB) with dispersion angle of 135 de­grees @2000Hz octave (-6dB). Average sensitivity shall
measure 88.0dB (SPL at 1W/1M). Assembly mounting
depth shall not exceed 3.80". Assembly weight 2.7 lbs.

Lowell makes every effort to provide accurate information while reserving the right to change specifications and/or improve manufacturing methods without notification.
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