Loyola Enterprises

A veteran and minority owned SDB Certified Business.


Electro-Voice PA Series


PDFPA Series Brochure (pdf)

PDFPA Series Manual (pdf)


Front Panel

Front Panel

Mains Switch

Mains Switch
Use the mains switch to switch the unit’s power on. A soft-start function prevents inrush current peaks on the mains, additionally preventing the mains line protection switch from activating during the amp’s power-on operation. Loudspeaker outputs are activated via relay switching with a delay of approx. 2 seconds, which effectively eliminates eventual power-on noise. During this delay period, the Protect LED lights to confirm correct operation of the protection circuitry.

Level Indication

Protect (PROT)
A lit Protect LED indicates that one of the integrated protections against thermal overload, short-circuit... has been activated. The audio channels’ protection circuits operate independent from each other. At the occurrence of failure or overload conditions the affected power amp channel is separated from the load connected via output relay, preventing the connected loudspeaker systems and the power amplifier itself from being damaged. Whatever caused the fault – e.g. a short-circuited speaker cable – needs to be remedied. In case of thermal overload you have to wait until the power amplifier automatically returns to normal operation.

The Limit indicator lights as soon as the integrated dynamic limiter is being activated and the power amp is driven at the clipping limit or generally at its maximum capacity. Short-term blinking is not a problem, because the internal limiter trims input levels of up to +21dBu down to a THD+N of approximately 1%. If, on the other hand, this LED lights constantly, reducing the volume is strongly recommended to prevent the connected loudspeaker systems from being damaged by probable overload.

Level Indication
The level indicators signify the power amplifier’s current modulation. The -30dB LED starts lighting at approx. 30dB below full modulation while the -10dB LED lights at approx. 10dB below full modulation. Shorted speaker cables or the activation of a protection circuit causes these indicators to go out.

The Power indicator lights when switching the power amplifier on. If the power on LED does not light please check to make sure the unit is plugged in or that the primary fuse is not blown. If the fuse is blown please contact an authorized service center.

Rear Panel

Audio Signal Inputs

Audio Signal Inputs
The electronically balanced inputs facilitate the connection of external signal sources (e.g. mixing consoles). When screwed to the power amp, the screwlock connectors provided with the unit prevent accidental disconnection. Choosing balanced cables (2 conductors for audio signals + separate shielding mesh) for LF-signal connection is generally recommended, even when the connected signal source does not provide balanced output signals. This is possible by jointly connecting "-" conductor and shield on the source side (also refer to LF-Connection Cords).

Level Controls

Level Controls
The Level Controls allow setting the according power amp channel’s overall amplification. To prevent distortion in mixing consoles connected to the amp, setting these controls to a value between -6dB and 0dB is generally recommended. A scale provides direct indication of the varying additional control attenuation applied to the fixed internal amplification.

Mode Switch
Mode Switch

Mode Switch
The Mode Switch allows selecting the power amp’s mode of operation. With the four-channel model it is possible to independently select channels A and B or C and D. The signle-channel model comes without mode switch.

DUAL: The power amp channels work independently from each other, each reproducing the audio signals fed to the corresponding input.

PARALLEL: Both channels reproduce the audio signal fed to input A (or C). However, using the level controls allows individually setting the channel volumes.

BDGD: Audio signals need to be fed to channel A (or C) when in Bridged Mode. Power amps A and B (or C and D) now work in push-pull operation delivering doubled output voltage. Please keep in mind to correctly connect the loudspeaker systems for Bridged Mode operation. (also refer to Loudspeaker Outputs)

High Pass Filter
High Pass Filter

High Pass Filter (HPF)
The Hi-Pass filter allows effective attenuation of low bass audio signals. You can choose from three cut-off frequency settings.

Power Amps with low impedance outputs
300Hz, 12dB/Oct., BW
50Hz, 12dB/Oct., BW

Power Amps with output transformer
300Hz, 12dB/Oct., BW
70Hz, 12dB/Oct., BW

As a basic priciple, all models with output transformer have a 50Hz Hi-Pass filter in the audio signal path to protect the transformer from being driven into saturation by high level low-frequency signals.

Loudspeaker Outputs
The speaker output jacks are suitable for connecting speaker cables with a maximum diameter of 2.5mm². The provided screwlock connectors can be screwed to the power amp to prevent inadvertent disconnection. Power amps offer low impedance outputs and/or floating outputs (ISOLATED OUTPUTS) with nominal voltages of 50V, 70V and 100V, depending on the amp model.

The symbol of a FLASH at the loudspeaker connectors indicates that these outputs may carry high voltages which, when getting in contact with, can cause serious harm. Establishing connections at these outputs is only permissible for persons who have been instructed on how to do so. Otherwise use prefabricated cables only.


PA2450L & PA4150L
Loudspeaker systems connected to channels A and B (or C and D) have to be connected according to the polarity indicated. Please, make sure to mind the minimal impedance of 4 ohms per channel. For bridged operation, the load has to be connected according to the BRIDGED-label and the Mode switch needs to be set to "Bridged". Please, make sure to keep in mind that in Bridged Mode the minimal impedance is 8 ohms and that the input audio signal has to be fed to channel A (or C).

PA1250T, PA2250T & PA2400T
Integrated audio output transformers convert the power amp’s nominal output voltage to 50V, 70V and 100V. The amplifier models PA2250T and PA2400T present all voltages simultaneously at the floating outputs so that the power amp channels can be used in any combination of possible output voltages. Mixed operation of low-impedance speaker systems and floating loudspeaker lines on a single power amp channel is possible as well.
The use of loudspeaker systems with 100V or 70V matching transformers to reduce the effects of cable loss is recommended when the distance between power amp and speaker systems exceeds 165 feet. In addition, this also facilitates distributing the output power among loudspeakers.
As many loudspeaker systems as possible can be connected, as long as the speaker network’s overall power consumption does not exceed the power amp’s rated output power while at the same time not falling below the nominal load impedance of the power amp outputs.

Configuration example: PA2400T with 100V speaker systems connected.
Maximum working loads with 25W/100V and 6W/100V loudspeaker systems.


Mains Fuse
Under normal circumstance, the mains fuse blows only in the event of failure. When replacing the fuse, make sure to use a fuse of the same type with identical amperage, voltage and blow characteristics. If the mains fuse blows repeatedly, please contact an authorized service center.

Mains Socket

Mains Socket
Please, make sure to check whether the voltage selector is set to the correct mains voltage that matches the local mains supply at the installation site. An appropriate mains cord is included in the package.

This appliance has no user serviceable parts inside. Leave servicing to a qualified professional.

Voltage Selector

Voltage Selector
Sliding selector switch for switching between mains voltages 115V - 230V. Prior to switching the mains voltage, make sure to replace the mains fuse with an appropriate model. Please refer to the label on the rear of the enclosure indicating the correct values for different mains voltages.

LF-connection cords
Choosing balanced cables (two conductors for audio signals plus separate shielding mesh) is recommended for LF-signal connection. Although connecting unbalanced cables to the power amplifier inputs is possible as well, using balanced cables is always preferable.
A great number of today’s audio appliances provide balanced outputs carried out via XLR-type connectors. With balanced cabling, the shield interconnects all metal enclosure parts and therefore efficiently eliminates the introduction of external interference – mostly noise and hum.

Wiring examples

Cable to connect signal source with balanced XLR outputs.

Cable to connect signal source with unbalanced outputs.

Mains Operation & Resulting Temperature

Mains Operation
The following tables provide a useful aid in determining power supply and cabling requirements. Column "1/8 max. output power into 4 ohms" states the values to be used for normal operation. These results were measured with the power amplifier being operated at maximum output and a Pink Noise signal according to EN60065 applied at the input, which approximately represents the strain of an audio signal driving the power amp at maximum modulation.

Temperatures inside of the power amplifier
The power drawn from the mains network is converted into acoustic output to feed the connected loudspeaker systems plus heat. The difference between drawn power and dispensed power is referred to as leakage power or dissipation (Pd). The amount of heat resulting from power dissipation might remain inside of a rack-shelf and needs to be diverted using appropriate measures. The following table is meant as auxiliary means for calculating temperatures inside of a rack-shelf system/cabinet and the vetilation efforts necessary. The column "Pd" lists the leakage power in relation to different operational states. The column "BTU/hr" shows the dispensed heat amount per hour.

PA2450LUmains [V]Imains [A]Pmains [W]Pout [W]Pd [W]*BTU/hr†
Max. output power into 8Ω¹2305.49232x3003231102
Max. output power into 4Ω¹2308.816052x4806452201
1/3 max. output power into 4Ω¹2305.69532x1606332160
1/8 max. output power into 4Ω¹2303.75982x604781631
1/8 max. output power into 4Ω²2303.25302x604101399
1/8 max. output power into 4Ω²³2533.66292x734841651
Normal Mode (-10dB) into 4Ω¹2303.25502x484541549
Rated output power (0dB) into 4Ω¹2308.114822x4505821986
Alert-Mode (-3dB) into 4Ω¹2306.110652x2256152098

Max. output power into 8Ω¹2303.96534x100253863
Max. output power into 4Ω¹2306.311264x1604861658
1/3 max. output power into 4Ω¹2304.06654x534521541
1/8 max. output power into 4Ω¹2302.74284x203481187
1/8 max. output power into 4Ω²2302.43854x203051041
1/8 max. output power into 4Ω²³2532.64504x243531205
Normal Mode (-10dB) into 4Ω¹2302.43854x163211095
Rated output power (0dB) into 4Ω¹2306.110804x1504901638
Alert-Mode (-3dB) into 4Ω¹2304.67904x754901672

PA2400T - 100V outputUmains [V]Imains [A]Pmains [W]Pout [W]Pd [W]*BTU/hr†
Max. output power into 25Ω¹2308.916432x4307832672
1/3 max. output power into 25Ω¹2305.59522x1436652270
1/8 max. output power into 25Ω¹2303.76022x544951687
1/8 max. output power into 25Ω²2303.35452x544381493
1/8 max. output power into 25Ω²³2533.76462x655161760
Normal Mode (-10dB) into 25Ω¹2303.35402x434541549
Rated output power (0dB) into 25Ω¹2308.515502x4007502559
Alert-Mode (-3dB) into 25Ω¹2306.311192x2007192453

Max. output power into 40Ω¹2305.59602x2704201433
1/3 max. output power into 40Ω¹2303.55712x903911334
1/8 max. output power into 40Ω¹2302.33652x342981015
1/8 max. output power into 40Ω²2302.13302x34263896
1/8 max. output power into 40Ω²³2532.33852x413031035
Normal Mode (-10dB) into 40Ω¹2302.13282x27274935
Rated output power (0dB) into 40Ω¹2305.49292x2504291464
Alert-Mode (-3dB) into 40Ω¹2304.06682x1254181426

Max. output power into 40Ω¹2302.84871x270217740
1/3 max. output power into 40Ω¹2301.82891x90199679
1/8 max. output power into 40Ω¹2301.21821x34148506
1/8 max. output power into 40Ω²2301.11701x34136465
1/8 max. output power into 40Ω²³2531.21971x41156533
Normal Mode (-10dB) into 40Ω¹2301.11641x27137467
Rated output power (0dB) into 40Ω¹2302.74711x250221754
Alert-Mode (-3dB) into 40Ω¹2302.03391x125214730

¹ Sine wave 1kHz
² Pink noise acc. to EN60065
³ 10% mains over voltage
* Pd = Power dissipation
† 1BTU = 1055.06J = 1055.06Ws

The following factors allow direct proprtional calculation of the mains current (Imains) for different mains supply voltages: 100V = 2.3; 120V = 1.9; 220V = 1.05; 240V = 0.96

For power amp models with integrated transformers, the listed values for the 100V outputs are equally applicable for the 70V, 50V and for the low-impedance outputs as long as the connected load is equivalent as well.

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