JBL MTC-CBT-70T Bolt On Transformer Module Owner’s Manual

: June 3, 2024
: JBL

Table of Contents

Key Features
Applications
Specifications
Dimensions
Wiring Diagram
Support
References
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JBL MTC-CBT-70T Bolt On Transformer Module Owner’s Manual

Key Features

Adapts the CBT 70J-1 (and 70JE-1) for Use on Distributed Speaker Lines
120W, 60W, 30W for 70V or 100V (plus 15W for 70V)
Bolts onto Back of CBT 70J-1 or 70JE-1 Speaker
Gland Nuts Provide Water Tight Seal

Applications

MTC-CBT-70T is a bolt-on transformer module to adapt CBT 70J-1 and CBT 70JE-1 (and CBT 70J-1/JE-1 arrays) for use on distributed loudspeaker lines. It allows long cable runs and multiple speakers to be driven from a single distributed system amplifier channel.

Transformer taps include 120W, 60W, and 30W for 70V and 100V distributed lines, plus 15W for 70V only.

Connections are made via customer-supplied cable to screwdown terminals inside the enclosure. Two gland nuts are provided – one for the cable into the enclosure from the amplifier and one for the cable from the enclosed terminal strip to the input terminal of the loudspeaker. The gland nuts form a water- tight seal when used with round jacketed cable with outside diameter between 4.0 mm (0.16 in) and 9.0 mm (0.36 in).

The tap selection is made via the terminal connection of the cable from the power amplifier to the appropriate terminals on the internal terminal strip.

Mounting holes are provided that fit via two 6 mm screws to any of the two side-by-side insert points on the back of the CBT 70J-1 or CBT 70JE-1 cabinet.

Note that MTC-CBT-70T extends 86 mm (3.4 in) from the back of the CBT cabinet.

Available in black or white (-WH).

Specifications

Transformer Taps: 120W, 60W, 30W (and 15W at 70V only)
Connection: CE-compliant barrier strip terminals. Terminals accept up to 8 mm outside 4 mm inside open-lug (#6 or #8) plus bare wire up to 2.5 mm2 (12 AWG).

TERMINALS:

Terminal 1 = Common (black wire from transformer)
Terminal 2 = 120W @ 70V, N/C @ 100V (orange wire from transformer)
Terminal 3 = 60W @ 70V, 120W@100V (purple wire from transformer)
Terminal 4 = 30W @ 70V, 60W @ 100V (blue wire from transformer)
Terminal 5 = 15W @ 70V, 30W @ 100V (white wire from transformer)
Terminal 6 = N/C (no wire from transformer)
Terminal 7 = + Output to loudspeaker + terminal (yellow wire from
transformer)
Terminal 8 = – Output to loudspeaker – terminal (green wire from transformer)
Maximum Insertion Loss = Less than 1 dB at any tap.

Gland Nuts: Two total. One gland nut by the transformer selection terminals for cable from amplifier and one gland nut by the transformer secondary terminals (green and yellow wires) for output to speaker terminals. It is recommended to orient gland nuts toward bottom of enclosure.Watertight seal requires round jacketed cable with outside diameter between 4.0 mm(0.16 in) and 9.0 mm (0.36 in).
Mounting to Speaker Cabinet: Two holes in the back of the enclosure 70 mm (2.75 in) apart. Insert included 6 mm screw from inside MTC-CBT-70T enclosure, using 1 flat washer and 1 lock washer, into the
side-by-side M6 insert points on the back of the CBT70J-1 or
CBT70JE-1 cabinet.
Enclosure Material: Fiberglass filled ABS.
Environmental Capability: IP-55 rated, per IEC529. UV, moisture and salt-spray resistant.
Agency Rating: Transformer UL registered per UL1876, Isolating Signal and Feedback Transformers for Use in Electronic Equipment.
Dimensions (H x W x D): 157 x 114 x 86 mm (6.2 x 4.5 x 3.4 in) including gland nuts. 128 mm (5.0 in) enclosure height for enclosure only.
Net Weight: 1.13 kgs (2.5 lbs)
Shipping Weight: 1.36 kgs (3.0 lbs)
Included Accessories: Two 6 mm (x 15mm length x 1.0 thread pitch) bolts, flat washers & lock washers

JBL continually engages in research related to product improvement. Some materials, production methods and design refinements are introduced into existing products without notice as a routine expression of that philosophy. For this reason, any current JBL product may differ in some respect from its published description, but will always equal or exceed the original design specifications unless otherwise stated.