Infinity 310-A, 311-A Service manual

Reference Series

310a

311a

1 CHANNEL POWER AMPLIFIER

SERVICE MANUAL

Infinity Systems, Inc.

250 Crossways Park Dr.

Woodbury, New York 11797 Rev

2aa10/2005

Power Amplifier Reference 310a/311a

- CONTENTS -

SPECIFICATIONS ………………………………….……..1

FEATURES/TEST CONDITIONS……..…………………2

CONTROLS/CONNECTIONS………….……..…...…..…3

INSTALLATION………………….……...……..…...…...…5

BASIC TROUBLESHOOTING..…….…….………………7

TYPICAL SYSTEM WIRING..…….…….……………..…8

EXPLODED VIEW/PARTS LIST…….….….…………....9

MECHANICAL PARTS LIST……………..…………......10

AMPLIFIER BLOCK DIAGRAM…………………………11

P.C.B. DRAWINGS….…………………………………….12

ELECTRICAL PARTS LIST ……………………………. 15 REF 311a ELECTRICAL PARTS LIST ADDENDUM….…….….18

IC/TRANSISTOR PINOUTS..…………………………….19

REF 310a SCHEMATICS………..……….…….………..22

REF 311a SCHEMATICS………..……….……….……..24

PACKING…………………….…………………………....26

Referen ce 31 0a/ 31 1a S pe cifi ca ti on s

Output Power: 116W RMS x 1 channels @ 4 ohms; ≤1% THD + N

(14.4V supply) 312W RMS x 1 channels @ 4 ohms; ≤1% THD + N

Signal-to-noise ratio: 81dBA (reference 1W into 4 ohms)

Dynamic power: 347W @ 2 ohms

Effective damping factor: 6.398 @ 4 ohms

Frequency response: 17Hz – 302Hz (–3dB)

Maximum input signal: 6.0V

Maximum sensitivity: Reference 310a - 250mV

Reference 311a - 75mV

DC Offset <50mV (-50%)

Output regulation: .05dB @ 4 ohms

Idle Current 800mA

Input Impedance 22kΩ

Max Current Draw 24A @ 4 ohms

40A @ 2 ohms

Dimensions: 12 x 11 7/16 x 2 11/16” (L x W x D)

(305mm x 290mm x 68mm)

Fuse: 30A

Infinity continually strives to update and improve existing products, as well as create new ones. The specifications and details in this and related publications are therefore subject to change without notice.

Reference 310a/311a

The Reference amplifiers are capable of delivering high power levels, and require a reliable connection to the vehicle’s electrical system in order to perform optimally. See Figure 1 for connection location. Please adhere to the following instructions carefully.

GROUND CONNECTION

Connect the amplifier’s Ground (GND) terminal to a solid point on the vehicle’s metal chassis, as close to the amplifier as possible. Refer to the chart below to determine minimum wire-gauge size. Sand away any paint from this location; use a star-type-lock washer to secure the connection.

POWER CONNECTION

Connect a wire (see chart at right for appropriate gauge) directly to the vehicle’s positive battery terminal, and install an appropriate fuse holder within 18" of the battery terminal. Do not install the fuse at this time. Route the wire to the amplifier’s location, and connect it to the amplifier’s positive (+12V) terminal. Be sure to use appropriate grommets whenever routing wires through the firewall or other sheet metal. Failure to adequately protect the positive wire from potential damage may result in a vehicle fire. When you are done routing and connecting this wire to the battery and to the amplifier, you may install the fuse at the battery. The fuse value should be selected based on total amplifier-current draw; see chart at right.

REMOTE CONNECTION

Connect the amplifier’s Remote (REMOTE) terminal to the source unit’s Remote Turn-On lead using a minimum of 18-gauge wire. If your source unit does not have a remote turn-on connection, connect the amplifier’s (REMOTE) terminal to the vehicle’s accessory circuit.

SPEAKER CONNECTIONS

Refer to the application guides on the pages that follow. Speaker connections should be made using a minimum of 16-gauge wire.

NOTE: When using the low-level or high-level inputs, the AUX outputs can be used to pass a full-range line-level signal to another amplifier.

POWER CONNECTIONS

Power Amplifier

WIRE-GAUGE CHART

Amplifier Maximum Minimum Model Current Draw Wire Gauge AWG AWG 310a/311a 40A #8 AWG AWG AWG

These recommendations assume 7' – 10' wire runs. If your installation differs markedly, you will need to adjust the wire gauge accordingly.

Reference 310a/311a

Figure 1.Terminal-connection end plate.

Figure 4. Reference subwoofer amplifier with one woofer connection.

Power Amplifier

APPLICATIONS – 310a/311a

The Reference subwoofer amplifiers are single-channel amplifiers. There are two sets of terminals to make it easy to connect multiple woofers. Either set of (+/–) terminals may be used when connecting woofers.

To the right are two application diagrams to help plan your subwoofer system installation. Figures 3 and 4 show how to configure the Reference subwoofer amplifiers

1210a).

NOTE: For simplicity, Figures 3 and 4 do not show power, remote and input connections.

NOTE: Minimum speaker load is 2 ohms.

Figure 3. Reference subwoofer amplifier with two woofer connections.

Reference 310a/311a

Figure 13. Control end panel.

SETTING INPUT SENSITIVITY

1. Initially turn the INPUT LEVEL control(s) to minimum (counterclockwise).

2. Reconnect the (–) negative lead to the vehi-

cle’s battery. Apply power to the audio system and play a dynamic music track.

3. On the source unit, increase the volume

control to 3/4 volume. Slowly increase the INPUT LEVEL control(s) toward three o’clock until you hear slight distortion in the music. Then reduce the INPUT LEVEL slightly until distortion is no longer heard.

NOTE: After the source unit is on, blue LEDs (on the top panel) will light, indicating the amplifier is on. If not, check the wiring, especially the remote connection from the source unit. Also refer to “Troubleshooting” on the page 7.

INSTALLATION AND SETUP

REMOTE LEVEL CONTROL (OPTIONAL)

All three Reference subwoofer amplifiers and the 5760a amplifier have inputs for an optional remote level control (100rc). This will allow the subwoofer level to be adjusted from the listening position. Connect the optional remote level control using the RJ-11 jack on the side of the amplifier. Install the control module in the front of the vehicle within easy reach of the driver. Both the underside of the dash and the center console are suitable locations. Refer to the mounting instructions accompanying the 100rc.

NOTE: When using the low- or high-level inputs, the AUX outputs can be used to pass a full-range line-level signal to another amplifier.

Power Amplifier

Reference 310a/311a

AUX OUTPUT

Reference amplifiers are equipped with full-range outputs that can be used to connect additional amplifiers.

-9

-6

-3

-12 20 80

Freq. (Hz)

DBO HP FREQ Control

(adjusts cut-off

frequency)

HP FREQ

100Hz20Hz

-6

-12 20 80

Freq. (Hz)

DBO BOOST Control

(adjusts boost amount

at cut-off frequency)

BOOST

MAX MIN

Power Amplifier

INSTALLATION AND SETUP (CONT.)

SETTING DBO

The Dynamic Bass Optimizer (DBO) is used to enhance low-frequency reproduction in a vehicle. Conventional bass-boost circuits only increase bass at a fixed frequency, and cause the amplifier to consume considerable power. The DBO allows you to adjust the frequency (20Hz – 80Hz) as well as the boost level (up to 12dB; see Figure 14), allowing you to fine-tune the bass in your system to optimize performance.

For sealed enclosures, the DBO can be used to enhance the lower bass region of sealed enclosures.

For bigger/fuller bass, adjust the HP FREQ between 35Hz and 45Hz; adjust the BOOST control according to your preference.

For tighter-sounding bass, adjust the HP FREQ between 45Hz and 55Hz; adjust the BOOST control according to your preference.

For vented enclosures, the DBO should be used as a subsonic filter to reduce overexcursion of the woofers. Set the HP FREQ control 10Hz below the tuning frequency of the enclosure (e.g., 25Hz for a box tuning of 35Hz); adjust the BOOST control to taste. This will conserve amplifier power typically wasted on frequencies below the tuned frequency of the enclosure.

™

STATUS LEDs Clip: Indicates the amplifier is being overdriven,

and your speakers may be in danger. This should blink only on musical peaks, and not be on constantly.

Power: Indicates the amplifier is on. Protection: Refer to “Troubleshooting” for specific

indications.

Figure 15. LED status.

Reference 310a/311a

For infinite-baffle applications, set the HP FREQ to the speaker’s Fs value (reducing overexcursion of the woofer); adjust the Boost control to taste.

Figure 14. Frequency-response curves show typical DBO control ranges.

•

PROBLEM:

No audio (POWER LED is off).

CAUSE and SOLUTION: No voltage at BATT+ and/or REM terminals, or bad or no ground connection. Check voltages at amplifier terminals with VOM.

•

PROBLEM:

No audio (PROTECT LED flashes every 4 seconds).

CAUSE and SOLUTION: DC voltage on amplifier output. Amplifier may need service; see enclosed warranty card for service information.

•

PROBLEM:

No audio (PROTECT LED is on).

CAUSE and SOLUTION: Amplifier is overheated. Make sure amplifier cooling is not blocked at mounting location; verify that speaker-system impedance is within specified limits.

•

PROBLEM:

No audio (PROTECT and POWER LEDs flash).

CAUSE and SOLUTION: Voltage less than 9V on BATT+ connection. Check vehicle charging system.

•

PROBLEM:

No audio (PROTECT LED is on).

CAUSE and SOLUTION: Voltage greater than 16V or less than 8.5V on BATT+ connection. Check vehicle charging system.

•

PROBLEM:

Distorted audio.

CAUSE and SOLUTION: Input sensitivity is not set properly, or amplifier or source unit is defective. Check INPUT LEVEL setting, or check speaker wires for shorts or grounds.

•

PROBLEM:

Distorted audio (PROTECT LED flashes).

CAUSE and SOLUTION: Short circuit in speaker or wire. Remove speaker leads one at a time to locate shorted speaker or wire, then repair.

•

PROBLEM:

Music lacks “punch.”

CAUSE and SOLUTION: Speakers are not connected properly. Check speaker connections for proper polarity.

TROUBLESHOOTING

Power Amplifier

Reference 310a/311a

+ 18 hidden pages