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1000 W. Wilshire Blvd., Suite 362 

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 Oklahoma City, Oklahoma 73116 

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 Phone: 405.848.3108 

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 Fax: 405.848.3217 

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www.altecpro.com

 

 
 

 
 

 
 

 
 

 
 

 
 

 
 

 
 

 
 

 
 

 

  SLC308-8T 

Preassembled Ceiling Speaker System 

 

FEATURES – THE ALTEC LANSING DIFFERENCE 

 

High Efficiency – 97 dB SPL 

 

High Output – 109 dB Peak SPL (8 watt Tap) 

 

Preassembled Speaker System for Quick Installation 

 

Off-White Décor Snap-On One Piece Metal Grille 

 

5-Position Switch for Easy Transformer Tap Selection 

 

½ in. (13 mm) Conduit Connector 

 

Metal Tile Bridge Included 

 

GENERAL PRODUCT DESCRIPTION 

 
High labor costs are driving the development of a new generation 

of preassembled, quick-install ceiling speaker systems. Altec 
Lansing’s SLC308-8T builds on the company’s strength as one of 
the world’s leading supplier of premium 8 in. (203 mm) Duplex

®

 

ceiling speakers equipped with premium, low-insertion loss 
transformers. 
 

The SLC308-8T features Altec’s best selling CD308-8T component. 
The CD308 is an 8 in. (203 mm) Duplex

®

 component rated at 16W 

AES / 64W peak power handling. The 8 watt 70V/100V 
transformer has a broadband insertion loss of < 0.6 dB from 50 Hz 
to 15 kHz.   

 
Altec’s high efficiency Duplex

®

 design delivers maximum output 

with minimum amplifier power. At a broadband efficiency rating 
of 97 dB SPL (1W/1m), the SLC308-8T has rated peak output of 
109 dB SPL using the 8 watt transformer tap at a distance of one 
meter. Less efficient ceiling speaker systems require 30W to 60W 

transformer taps to generate similar output. The high efficiency 
design of the SLC308-8T allows the systems integrator to 
downsize the amplifier channel assigned to each zone of ceiling 
speakers by a factor of two-thirds or more. Using the SLC308-8T 
is the most profitable choice a sound contractor can make. 

 
The CD308-8T is installed in a round, metal, dampened 0.25 
cubic foot enclosure with metal strain relief strap. Three metal 
dogleg arms are screwed-down to secure the enclosure to the 
included metal tile bridge. An off-white one-piece metal décor 
grille snaps into the assembly. The SLC308-8T has a two-wire 

input connection (red & black), making it fool-proof for even the 
least experienced installers. The ½ in. (13 mm) connector easily 
mates to either metal or flex conduit. 

 
Installers particularly like Altec’s package. The mounting hole in 
the metal tile bridge serves as a hard template for cutting a 
perfect hole in the ceiling tile. A metal S-hook allows the 
installer to hang the enclosure from the ceiling grid of flex-
conduit while wiring up the SLC308-8T. 

 
In addition to industry-leading efficiency and output, the SLC308-
8T is among the most lightweight packages available to sound 
contractors. The low-profile design allows the SLC308-8T to fit 
into tight ceiling spaces. An optional ring (SLC-RING) is required 

for plaster or sheetrock ceilings. 
 

NOTE: SHIPPED IN PAIRS 

 

 

SPECIFICATIONS 

FREQUENCY RESPONSE 

1, 2

 

 

130 Hz – 20 kHz (

±

5 dB) 

USABLE LOW FREQUENCY LIMIT (-10 dB) 

1, 2

 

 110 

Hz 

SENSITIVITY

 

3

 

 

97 dB SPL 

POWER HANDLING

 

4

 

 

16 W AES (continuous); 64 W peak 

PEAK OUTPUT (1 m)

 

5

 

 

115 dB SPL; 109 dB SPL (8W transformer tap)

 

COVERAGE ANGLES 

6

 

 

90º (horizontal) by 90º (vertical)

  

DIRECTIVITY FACTOR, Q 

6

 

 11.91

 

DIRECTIVITY INDEX, DI 

6

 

 10.76 

dB 

TRANSDUCER COMPONENTS 

 

LF: 1 x 8-in. (203 mm), low frequency woofer 

 

HF: 1 x 3-in. (76 mm), high frequency tweeter 

IMPEDANCE 

7

 

 Nominal: 

8.0 

ohms 

 

Minimum: 

7.3 ohms at approximately 7.5 kHz 

CROSSOVER FREQUENCY 

 

Passive LF - HF: 3,000 Hz 

TRANSFORMER 

 

Premium 8 watt 70V/100V, switch selectable taps of 8W, 4W, 

 

2W, and 1W; rated at < 0.6 dB insertion loss, 50Hz – 15 kHz 

INPUT CONNECTIONS 

 

Only 2 wires, pre-stripped, for simple, quick installation 

FINISH 

 

Enclosure - Black Painted Steel with internal damping material 

 

Grille – Matte White Décor Round Metal Grille 

DIMENSIONS 

 Diameter: 

Can - 9.31 in. (236 mm); Baffle – 11.75 in. (298 mm) 

 

 

 

Grille – 12.75 in. (324 mm) 

 

Depth:  

Can – 7.85 in. (199 mm) 

 

Length/Width: 

Tile Bridge – 23.75 in. (603 mm) / 14 in. (356 mm) 

NET WEIGHT 

 

8.5 lbs. (3.86 kg), one speaker system with grille  

SHIPPING WEIGHT 

 

31.7 lbs. (14.38 kg), 

(includes 2 speaker systems with grilles and tile bridges)

 

 

CD308-8A – THEILE-SMALL PARAMETERS 

Free Air Resonance, ƒ

S

:  

92.2 

Hz 

Equivalent Volume Compliance, V

AS

: 0.84 

ft.

3

 (23.7 l) 

Total Q, Q

TS

  0.87 

Electrical Q, Q

ES

  1.05 

Mechanical Q, Q

MS

  5.26 

D.C. Resistance, R

E

  8.0 

ohms 

Peak Linear Displacement, X

max

0.05 in. (1.3 mm) 

Reference Efficiency, 

η

o

:  

2.13% 

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