POWER AMPLIFIER

Owners Manual

POWER AMPLIFIER XS SERIES

SIGNAL CLIP

PROTECTION

CLIP SIGNAL

Introduction
Thank you for purchasing a Yamaha XS350, XS250 series power amplifier. This series of audio amps was developed from Yamaha's wealth of experience in building PA equipment and its tradition of careful attention to every detail of circuit design. These amps feature high power and superb quality together with superior reliability and stability, guaranteeing the highest possible audio performance. Main features of the XS350, XS250 series The unit is equipped with two types of inputs: balanced XLR and barrier strip, and two types of outputs: barrier strip and binding post. This combination of inputs and outputs affords flexible capabilities and accommodates a wide range of applications. Three operating modes are provided: STEREO mode in which CHANNEL A and B operate independently, PARALLEL mode in which a mono source is output by two amp systems, and BRIDGE mode in which the unit operates as a single high-power amplifier. A high pass/low pass switchable filter is provided for each channel. The high pass filter features a continuous controller that allows you to change cut-off frequencies between 25 Hz and 150 Hz. A SIGNAL indicator and CLIP indicator is provided for each channel. The PROTECTION indicator shows the status of protective circuitry such as power-on/off protection, output muting, and the DC detection circuit. Variable-speed low-noise fan(s) ensures high reliability even under demanding conditions. This owner's manual covers the two models XS350, XS250. In order to take full advantage of your power amp and enjoy long and trouble-free operation, please read this owner's manual carefully before use.
WARNING: THIS APPARATUS MUST BE EARTHED

IMPORTANT

THE WIRES IN THIS MAINS LEAD ARE COLOURED IN ACCORDANCE WITH THE FOLLOWING CODE: GREEN-AND-YELLOW : BLUE : BROWN : EARTH NEUTRAL LIVE
As the colours of the wires in the mains lead of this apparatus may not correspond with the coloured markings identifying the terminals in your plug, proceed as follows: The wire which is coloured GREEN and YELLOW must be connected to the terminal in the plug which is marked by the letter E or by the safety earth symbol or coloured GREEN and YELLOW. The wire which is coloured BLUE must be connected to the terminal which is marked with the letter N or coloured BLACK. The wire which is coloured BROWN must be connected to the terminal which is marked with the letter L or coloured RED. * This applies only to products distributed by YAMAHA KEMBLE MUSIC (U.K.) LTD.

Precautions

Connect this units power cord only to an AC outlet of the type stated in this Owners Manual or as marked on the unit. Failure to do so is a fire and electrical shock hazard. Do not allow water to enter this unit or allow the unit to become wet. Fire or electrical shock may result. Do not place heavy objects, including this unit, on top of the power cord. A damaged power cord is a fire and electrical shock hazard. In particular, be careful not to place heavy objects on a power cord covered by a carpet. Do not scratch, bend, twist, pull, or heat the power cord. A damaged power cord is a fire and electrical shock hazard. Do not remove the units cover. You could receive an electrical shock. If you think internal inspection, maintenance, or repair is necessary, contact your dealer. Do not modify the unit. Doing so is a fire and electrical shock hazard. If the power cord is damaged (i.e., cut or a bare wire is exposed), ask your dealer for a replacement. Using the unit with a damaged power cord is a fire and electrical shock hazard. If you notice any abnormality, such as smoke, odor, or noise, or if a foreign object or liquid gets inside the unit, turn it off immediately. Remove the power cord from the AC outlet. Consult your dealer for repair. Using the unit in this condition is a fire and electrical shock hazard. Should this unit be dropped or the cabinet be damaged, turn the power switch off, remove the power plug from the AC outlet, and contact your dealer. If you continue using the unit without heeding this instruction, fire or electrical shock may result. Hold the power cord plug when disconnecting it from an AC outlet. Never pull the cord. A damaged power cord is a potential fire and electrical shock hazard. Do not touch the power plug with wet hands. Doing so is a potential electrical shock hazard. This unit has ventilation holes at the front, rear and sides to prevent the internal temperature rising too high. Do not block them. Blocked ventilation holes are a fire hazard. Allow enough free space around the unit for normal ventilation. This should be: 10 cm at the sides, 30 cm behind, and 20 cm above. These distances should also be adopted when rackmounting the unit. For normal ventilation during use, remove the rear of the rack or open a ventilation hole. If the airflow is not adequate, the unit will heat up inside and may cause a fire. To mount several of these units in an EIA-compliant rack, refer to the rack mounting instructions on page 11. Use only speaker cables when connecting speakers to amplifier outputs. Using other types of cables is a fire hazard. Do not use this amplifier for any purpose other than driving loudspeakers. XLR-type connectors are wired as follows: pin 1: ground, pin 2: hot (+), and pin 3: cold (). Using a mobile telephone near this unit may induce noise. If noise occurs, use the telephone away from the unit. Clean the contacts of the phone plug before connecting it to the SPEAKERS jack of this unit. Dirty contacts may generate heat.

Contents

Controls and Functions.. 4 Front Panel... 4 Rear Panel... 5 Speaker Impedance.. 7 Caution for Speaker Connection. 9 Rack Mounting... 10 Mounting in an EIA standard rack. 10 Portable Rack Mounting. 11 Fixed Installation Mounting.. 11 General Specifications.. 12 Specifications... 12 Block Diagram.. 13 Dimensions... 13 Troubleshooting.. 14

Controls and Functions

s Front Panel

ON OFF

1 POWER switch and indicator
This is the main POWER switch. Press to power ON the amplifier. Press again to power OFF. The POWER indicator lights up when the amplifier is powered ON.

4 PROTECTION indicator

These LED indicators light up to indicate that the protection circuit is working. The speaker system is disconnected from the amplifier outputs and no sound is output from the speakers. The protection circuit is activated in the following situations: When the amplifier is powered on: The protection circuit is activated for approximately 3 seconds when the amplifier is powered on. After 3 seconds, the protection system is deactivated automatically, and the amplifier is ready to use. If a DC voltage is present at the amplifiers outputs: If the DC voltage problem is corrected, normal amplifier operation resumes. If overheating occurs: Turn off the power to the amplifier to cool down the unit and consult the Precautions section of this manual to improve the vent condition, if necessary. Turn the power on to the amplifier after it cools down.

2 SIGNAL indicators

These green LED indicators light up when the respective channels output signal exceeds 2 Vrms. This is equivalent to 1/2 W into 8, 1 W into 4.

3 CLIP indicators

These red LED indicators light up when the respective channels output signal distortion exceeds 1% (i.e. clipping). Output signal clipping is usually due to excessive input signal levels.

s Rear Panel

FILTER

CHANNEL B

Hz Hz 00 dB 0

CHANNEL A

dB 6 3
LOW CUT SUB WOOFER OFF LOW CUT SUB WOOFER OFF STEREO

PARALLEL

BRIDGE

SPEAKERS

B-2 CHANNEL A-2

CHANNEL

4-8/CHANNEL (STEREO) + +

4-8/CHANNEL (STEREO) + +

CHANNEL B CHANNEL A CHANNEL B
G CHANNEL A (BRIDGE) (PARALLEL) G
() (+) 8-16 (BRIDGE) () (+)

8-16 (BRIDGE)

(BRIDGE) (PARALLEL)
1 Frequency controls/Filter select switches (CHANNEL A, B) These knobs and sliding switches are used to select a filter type and control the cut-off frequencies respectively. You can select one of the following filter type:

LOW CUT SUB WOOFER OFF

2 Volume controls (CHANNEL A, B)
These knobs enable you to adjust the output level of Channels A and B in the range between dB and 0 dB. In BRIDGE mode, only the volume control for Channel A is available.
3 STEREO/BRIDGE/PARALLEL switch
This slide switch is used to set the amplifier operating mode: STEREO, BRIDGE or PARALLEL.

BRIDGE STEREO PARALLEL

OFF. Turns the filter off. SUB WOOFER. Turns the low pass filter on. (The cut-off frequencies for the low pass filter are fixed.) This setting is suitable when using the unit as an amplifier for a subwoofer. LOW CUT. Turns the high pass (low cut) filter on. (The cut-off frequencies are variable.) If you select LOW CUT, you can use the frequency controls to adjust the cut-off frequencies in the range of 25 Hz to 150 Hz.
STEREO mode In this mode, channels A and B operate independently (as a conventional stereo amp). The CHANNEL A input signal will be output from the CHANNEL A output jacks, and the CHANNEL B input signal will be output from the CHANNEL B output jacks. BRIDGE mode In this mode, the CHANNEL A input signal will be output from the BRIDGE output jacks. In this case, use the rear panel CHANNEL A volume control to adjust the volume. PARALLEL mode In this mode, the CHANNEL A input signal will be output from the output jacks of both channels A and B. The CHANNEL B input jack is not used. The CHANNEL A and B volumes can be adjusted independently.
Note: In BRIDGE mode, only the frequency control and filter select switch for Channel A are available.

4 SPEAKERS terminals

Two types of speaker output terminals: Binding post (Channel A-1, B-1) and barrier strip (Channel A-2, B-2) are available. These parallel wirings are internally connected and output identical signals simultaneously. The output impedance varies depending on whether you use either or both types of SPEAKERS terminals. (Refer to Speaker Impedance on page 7 for more information.) The following figures show terminal polarity in STEREO, PARALLEL, and BRIDGE modes. STEREO, PARALLEL mode
B-2 CHANNEL A-2 B-1 CHANNEL A-1

6 GND terminals

This is the grounding screw terminal. If hum or noise occurs, ground (earth) the unit via this jack, or try connecting it to the chassis of the mixer or preamp, etc.
4-8/CHANNEL (STEREO) 4-8/CHANNEL (STEREO)

() () (+)

BRIDGE mode
In BRIDGE mode, the (-) jacks of CHANNELS A1, B-1 and A-2, B-2 are not used. The minimum impedance for the connected speaker system is specified in Speaker Impedance on page 7.
5 INPUT terminals (CHANNEL A, B)

Two types of balanced terminals for channels A and B are provided. Channel A input terminal is used in BRIDGE and PARALLEL mode. XLR-3-31 type connector They are wired pin 1ground, pin 2hot (+), and pin 3 cold (-).

Ground

Barrier strip Hot (+), Cold (-) and Ground (G).

s Speaker Impedance

In STEREO and PARALLEL modes, the minimum load (i.e., speaker) impedance is 4. In BRIDGE mode it is 8. Make sure that the impedance does not fall below this specified impedance.
Using the barrier strip and binding posts simultanuously

STEREO mode connections:

+ + + +

Set to STEREO

PARALLEL mode connections:

Set to PARALLEL

Each speaker min. 8

BRIDGE mode connections:

Set to BRIDGE

Speaker min. 16

Using the barrier strip or terminal posts

Using the barrier strip

Using the terminal posts

Not used

Each speaker min. 4

Speaker min. 8

Caution for Speaker Connection
1. Turn off the POWER switch. 2. Remove the cover attachment screws and remove the protective cover from the speaker terminals. Speaker fuse The output capacity of your amplifier is very high: 170 W+170 W (8), 250 W+250 W (4) in stereo and 500 W (8) in monaural on the XS250; 230 W+230 W (8), 350 W+350 W (4) in stereo and 700 W (8) in monaural on the XS350. Be sure to use a speaker system that has sufficient input capacity. If the input capacity of your speaker system is lower than the rated output of the power amplifier, you can protect your speakers by connecting a fuse serially between the speaker and amplifier as shown below.
3. For Barrier strip: After removing approx. 15 mm of insulation from the ends of the speaker cables, bind the bare ends of the speaker wires in the corresponding speaker terminals and tighten the terminals to securely clamp the wires. Refer to page 6 for speaker porality.

Power amplifier _ + Fuse

Speaker system + _
Use the following formula to determine the fuse capacity according to the speakers input capacity.

Po = I R I = Po/R

* Shown actual size.
For Five-way binding post: After removing approx. 15 mm of insulation from the ends of the speaker cables, pass the bare ends of the speaker wires through the holes in the corresponding speaker terminals and tighten the terminals to securely clamp the wires. Refer to page 6 for speaker porality.
P0 [W] : Speakers continuous input capacity (noise or RMS) R [] : Speakers nominal impedance I [A] : Required fuse capacity ex.) Speakers continuous input capacity : 100 W Speakers impedance : 8

I = 100/8

In this example, the required fuse capacity is calculated as 3.5 [A]. Speaker cable If you use a long speaker cable, use as thick a cable as possible to prevent deterioration of the damping factor or power loss inside the cable.

At this time make sure that the bare ends of the speaker cables do not extend from the terminals in such a way that they touch the chassis.
Wire should not touch the chassis.
4. Reattach the protective cover over the speaker terminals.

Rack Mounting

s Mounting in an EIA standard rack
If multiple high-power amp units are mounted in a rack with poor ventilation, the heat from the amps will cause the interior of the amp to become very hot, causing the performance of the amps to be impaired. In particular, when mounting in a rack whose back can not be left open, mount according to the following instructions. Rack: Leave a gap of 10 cm or more between the rear panel of the rack and the rear panel of the amplifier. Fan: Use a fan with 1.5 m3/min or more maximum wind and 5 mmH2O or more maximum static pressure. Mounting: Install the fan kit on the top slot or the top panel of the rack and install a blanking panel between two amps. Example of mounting The figure on the left below shows an example of a fan kit (panels and two fans) on the top slot of the rack. The fans are Minebia 3115PS-12T-B30 (with 0.9 m3/min maximum wind and 5 mmH2O maximum static pressure). The figure on the right below is a dimensional diagram of a panel on which two 3115PS-12T-B30 are installed.

Fan kit

71.50.1

XS350/XS250

71.50.1 248

Blanking panel

463 480

Unit: mm

s Portable Rack Mounting
This unit uses a forced cooling system in which air comes in through the front opening and goes out from the sides and rear. If you mount a single unit on a portable rack, be sure to maintain vent openings on the rear and sides.

(Side View)

LOW CUT

40Hz OFF 80Hz OFF

(Rear View)

Completely open

40Hz 80Hz dB dB 6 3

Air intake

Air exhaust

HIGH CUT

5kHz OFF 10kHz OFF

5kHz 10kHz

OUTPUT VOLTAGE

CHANNEL B CHANNEL A

CHANNEL A G
70V = 32/CHANNEL 100V = 64/CHANNEL

s Fixed Installation Mounting
Do not block the vent openings on the rear and sides when you use the power amplifier.

More than 10 cm

Specifications

s General Specifications

XS250 Power Output Level (Rated Power) 20 Hz~20 kHz THD+N= 0.1% 1 kHz THD+N= 0.1% 1 kHz, 20 ms, no clip Power Bandwidth Total Harmonic Distortion (THD + N) 20 Hz~20 kHz, Half Power Frequency Response Intermodulation distortion (IMD) 60 Hz:7 kHz, 4:1, Half Power Channel Separation Residual Noise SN Ratio Damping Factor Slew Rate 8 full swing Voltage Gain (Vol. max.) Input Impedance Controls Front Panel Rear Panel 8, f= 1 kHz STEREO BRIDGE 8/STEREO 4/STEREO 8/BRIDGE 8/STEREO 4/STEREO 8/BRIDGE 2/STEREO Half Power 4~8/STEREO 8/BRIDGE 8, Po= 1 W 4~8/STEREO 8/BRIDGE 170 W + 170 W 250 W + 250 W 500 W 185 W + 185 W 280 W + 280 W 560 W 400 W + 400 W 10 Hz~40 kHz (THD+N= 0.1%) 0.05% +0.5, 1 dB 0.05% 65 dB, 20 Hz~20 kHz 70 dB 75 dB 100 dB V/s 40 V/s +1.7 dB 32.1 dB +3.1 dB 32.1 dB 10 Hz~50 kHz XSW + 230 W 350 W + 350 W 700 W 250 W + 250 W 400 W + 400 W 800 W 600 W + 600 W
Half Power, RL= 8, Vol. max., input 600 shunt 12.7 kHz LPF IHF-A network

Vol. min.

Sensitivity (Vol. max.) Rated Power into 8
30 k/Balanced, 15 k/Unbalanced POWER switch (ON/OFF) Volume (31 position)x 2 Mode switch (STEREO/BRIDGE/PARALLEL) Filter switch (OFF/SUBWOOFER/LOW CUT)x 2 (12 dB/oct.) Freq. control (25 Hz~125 Hz)x 2 Barrier strip terminal XLR-3-31 type/ch Barrier strip terminal 5-way binding posts Green x 2 (Red) x 2 (Red) x 2 (Green) POWER switch ON muting, DC detection, Temp. detection (heatsink temp 90C) RL 1 Low/~50C, Variable/50~70C, High/70C~ US & Canada Europe Other Idling 1/8 output power, 4 Maximum output, V, 60 Hz 230 V, 50 Hz 240 V, 50 Hz 450 W/600 VA 45 W 400 W 1000 W 480 x 132 x 319 mm 18 kg 20 kg 600 W/800 VA 45 W 550 W 1400 W

Connectors

Input Output

Indicators

POWER PROTECTION CLIP SIGNAL
Protection Circuits PC limiter Fan Speed Power Requirements

Power Consumption

Dimensions (W x H x D) Weight
0 dB=0.775 Vrms, Half Power=1/2 Power Output Level (Rated Power) Specifications subject to change without notice.

s Block Diagram

SIGNAL A-1 + + + CHANNEL B-1
INPUT CHANNEL A (BRIDGE) (PARALLEL) CHANNEL A (BRIDGE) (PARALLEL) INPUT + CHANNEL B G + G
LPF CHANNEL A PROTECTION LOW CUT SUB WOOFER OFF INV HPF

Protector

A-2 + CHANNEL B + + CLIP SIGNAL CHANNEL B-2

INPUT CHANNEL B

LPF BA
PARALLEL BRIDGE STEREO MODE

s Dimensions

Troubleshooting
The following table lists the main causes of abnormal operation and the corrective measures required, as well as the protective circuit operation in each case.

Indicator

Probable Cause There is a short at a speaker terminal, amplifier terminal, or wire.

Remedy

Protection Circuit
Locate and correst the cause of the short. The PC limiter circuit operates to protect the power transistors.
CLIP indicator lights. The amplifier load is excessive. Use a speaker system with an impedance of at least 4 (stereo) or 8 (bridge). Check the amplifier ventilation conditions and take appropriate measures to improve airflow around the amplifier.
The heat sink temperature has exceeded 90C. PROTECTION indicator lights. A DC voltage of 2 V or greater was generated in the power amplifiers output circuit.
The thermal protection circuit operates to protect the power transistors.
Consult your dealer or nearest Yamaha service center.
The relay operates to protect the speaker system.

YAMAHA CORPORATION

V352950 RIP 16 NP Printed in Taiwan Pro Audio Division, #18/3 P.O. Box 3, Hamamatsu, 430-8651, Japan