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Peavey GPS Series


PDFGPS Series Manual (pdf)


Rear Panel

AC Power

The following section will describe the AC power features of your GPS Series amplifier. AC power is a critical element in power amplification. Please read this section carefully, paying special attention to any warning signs.

NOTE: Always make connections to your GPS Series amplifier while the unit is turned off.

1. Removable AC Power Cord (Located on the rear of the unit)
This receptacle is for the IEC line cord (included), which provides AC power to the unit. Connect the line cord to this connector and to a properly grounded AC supply. Damage to the equipment may occur if an improper line voltage is used. (See voltage marking on unit.) Never remove or cut the ground pin of the line cord plug. This unit is supplied with a properly rated line cord. When lost or damaged, replace this cord with one of the proper ratings.

2. AC Power Switch (Located on the front of the unit)
A two-position power switch is on the right side of the front panel. With the top portion of the switch pushed to the "IN" position the amplifier is "ON". Press the bottom portion of the switch to the "IN" position to turn the unit "OFF".

3. Power LED (Located on the front of the unit)
The Power LEDs illuminate to indicate the amplifier is turned on.

Mode Selection

The Ins and Outs of Mode Selection
Once you have provided proper AC power to the amplifier, you may now connect to the inputs and outputs. Remember to do this while the power to the unit is turned off (Power LED is not lit). The rear panel of your GPS Series amplifier provides a central location for all input and output connections. Regardless of the GPS model, all input connections are located at the bottom-center portion of the rear panel and all output connections are located at the top-center portion. In addition, your amplifier can operate in either stereo or bridged (mono) mode. All GPS Series amplifiers have DDT compression. However, only GPS models 900 and 1500 have a switch to defeat this feature. This section will describe these areas of your GPS Series amplifier in detail.

4. Mode Switch
This switch determines which mode your amplifier will operate in. Before connecting your input signal and speaker cables to the amp, you must determine how you want the amp to function. Two modes of operation are offered on your amplifier, stereo or bridged (seperate).

When using the term "stereo" it is referring to two channels, not necessarily left and right. Therefore, in "stereo" mode there are essentially two power amps regardless of input type. You may use a stereo input, one stereo input to each channel of the GPS, or you may send two mono inputs to the GPS in the same manner. A good example of two separate inputs would be the use of one channel for mono mains and one channel for mono monitor signals. In order to select the "stereo" mode of operation you must place the Mode Switch in the "out" position. In this mode, Channel A Output is supplied by the Channel A Input. Channel B Output is supplied by Channel B Input.

Bridged or Mono:
In the "bridge" mode the two channels of the amplifier combine to form a single mono channel. The benefit of using your amplifier in this mode is that the power is doubled. To use the GPS Series amp in "bridge" mode, place the Mode Switch to the "in" position where the switch remains down. The amp is now a mono amplifier and only requires a single input. Plug your input signal into Channel A only for "bridge" mode operation. Channel B input must not have anything connected.

Note for GPS 900 and 1500:
When these models are switched to "bridge" mode, the Power LED (3) for Channel B will no longer illuminate.


5. Channel A Combination Input

- GPS 900 and 1500
These GPS Series amplifiers offer both XLR electronic balanced and phone jack quasi-balanced inputs for each channel using Neutrik’s "combo" connector to save panel space.

The female XLR inputs are connected to dual OP AMP circuitry which offers very low noise and extremely high common mode rejection ratio to minimize outside interference!

The female 1/4" phone jack input in the center of the "combo" connectors are also connected to a unique "quasi-balanced" input circuitry. When used, these 1/4" jacks are not "chassis grounded" but connected to ground through a relatively low impedance circuit which is part of a "ground loop" elimination circuit associated with the input. This will normally allow "hum free" operation when relatively short 1/4" cable patches are made to this input by various outputs from other equipment that share the same rack with this amp. This "quasi-balanced" circuit is "automatic", and is virtually invisible in normal usage. It cannot be defeated. Use only a two-conductor (TS) phone plug when connecting to the 1/4" input of this connector.

- GPS 2600, 3400 and 3500
These GPS Series amplifiers offer both XLR electronic balanced and phone jack balanced/unbalanced inputs for each channel using Neutrik's new "combo" connector to save panel space.

The female 1/4" phone jack input in the center of the "combo" connectors is also connected to a unique balanced/unbalanced input circuitry. When used, these 1/4" jacks can accept both unbalanced two-conductor (TS) and balanced three-conductor (TRS) inputs. Balanced operation is always recommended for optimum signal-to-noise. If unbalanced operation is required, always keep the input cable to a minimum length to avoid excessive noise.

6. Channel B Combination Input
This connector is identical to the Channel A Combination Input (5) except it is not used during "bridge" mode [See Mode Switch (4).]

7. Input Polarity
Located between the Channel A and Channel B Inputs is a recessed Input Polarity Switch (7) that allows the user to select the desired polarity (phase) of the XLR inputs. This switch is a push-push type and a small diameter "tool" is required to select the desired position. Set to the out (default) position, the polarity is pin #3 positive, pin #2 negative, and pin #1 ground. This is the polarity found on most Peavey power amplifiers. Although this is not the world "standard" (IEC) polarity, it was chosen by Peavey more than 20 years ago, and thus we offer this polarity to be consistent with products both past and present. If this amplifier is used with other competitive products which use the IEC standard polarity, then the "in" position of switch (7) should be selected yielding pin #2 positive, pin #3 negative, and pin #1 ground. As with any electronic gear, polarity (phasing) is important because the loudspeaker enclosures associated with this power amplifier must be in phase with any other loudspeaker enclosures associated with other power amps. If one loudspeaker system were to "push" while the other "pulls", a serious sound "cancellation" could result. Changing the setting of the polarity switch has the same effect as reversing the polarity of the loudspeaker connections at the output.

8. Thru
Each channel has a female phone jack (8) labeled "thru". This Thru jack offers very flexible patching capability. When the XLR input of the combination connectors (5 and 6) are used, this THRU jack is the output of the electronic balanced input circuitry, and as such can be used as a "line out" to connect to the other input jack on this amplifier or other amps in the same rack. Thus, one balanced mixer feed can be connected to the amp via the XLR connector and then further distributed (unbalanced) locally via the THRU jack. Alternatively, when the 1/4" phone jack input of the combination connectors (5 and 6) is used as the input, the THRU jack becomes a "bridged" input to it (similar to a Y-cord), again allowing this input signal to be patched to the other input jack on this amplifier or other amps in the system. Important: The THRU jack is not intended to be an "input", and inadvertent usage as such will result in excessive loading of the input source. Although not a catastrophic mistake, it will cause a significant reduction in "system gain" due to the loading, and will seriously limit overall system performance.


9. Speaker Output Connectors
Each GPS Series amplifier offers two separate output sections featuring parallel outputs. The type of output jack differs from model to model. Find the model and AC supply voltage of your unit to identify which description is applicable to your product.

Rear Panel

- GPS 900 or GPS 1500 120 VAC (Domestic) Models:
These two models feature 1/4" output jacks located on the top-center of the rear panel. There are two parallel 1/4" jacks per channel which are labeled either "CHANNEL A" or "CHANNEL B". In addition to the 1/4" output jacks, Binding Posts (10) are also provided for each channel.

Rear Panel

- All other GPS models:
These models offer dual Speakon® Quick Connectors. The Speakon® is a four-wire connector with the connections labeled as 1+, 1-, 2+ and 2-. The Speakon connectors found on your GPS Series amplifier are connected with pins 1+ and 2+ wired in parallel to the positive output. Pins 1- and 2- are wired in parallel to the negative output. This is typical for each channel.

10. Binding Post Output Connectors
Five-way binding post speaker outputs can be found on each channel regardless of model. For each channel, the outputs are in parallel, hence the speaker connection cables can be terminated with banana plugs or stripped wires for use in the binding post terminals as well as the output connectors (9). For sustained high power applications, the use of the binding post terminals is recommended; however, care must be exercised to assure the correct speaker polarity. The red binding posts are the signal outputs from each channel, and the black binding posts are chassis ground. The red binding post should be connected to the positive inputs of the associated loudspeakers. For "bridge" mode operation, only the red binding posts are used, and the associated loudspeaker load is connected between the two binding posts. The red binding post associated with Channel A should be considered the positive output for the system and thus should be connected to the positive input of the associated loudspeaker system.

WARNING: Regardless of what connections are used, the minimum parallel speaker load should always be limited to 2 Ohms per channel or 4 Ohms "bridge" mode for any application (4 Ohms per channel/8 Ohms bridge for GPS 3500). Operation at loads of 4 Ohms per channel of 8 Ohms "bridge" mode is more desirable for sustained operation applications due to the fact that the amplifier will run much cooler at this loading. Operation above 4 Ohms per channel and even open circuit conditions can always be considered safe.

11. DDT Defeat
This switch is used to defeat the DDT compression used to protect against signal clipping. Only the GPS 900 and 1500 models offer this feature. It is recommended to leave the DDT compression enabled at all times to protect your speakers from damaging square waves. The DDT function is disabled when the switch is pressed to the "in" position. The DDT LEDs (12) will illuminate when DDT compression is occuring in that particular channel.

Front Panel Controls/Indicators

The following section describes the controls and indicators found on the front panel of your GPS Series amplifier. The Power Switch and LED are explained in a previous section, AC Power.

Front Panel

12. DDT LEDs
The DDT LEDs will illuminate when signal compression is occurring in that channel. If you have a GPS 900 or 1500 and you have the DDT compression defeated, these LED will indicate the channel is clipping.

13. Signal LEDs
Each channel has a Signal LED, which comes on when the amplifier channel output exceeds 1 Volt.

14. Input Gain
Each channel has an Input Gain control used to adjust the gain of the input signal. Maximum power amplifier input gain (minimum sensitivity) is achieved at the full clockwise setting (30 dB or 40x). This setting yields maximum mixer/system headroom. A setting of less than full clockwise will yield lower system noise at the expense of headroom.

15. Fan Grill (located on front and rear panel)
Two continuously variable-speed DC fans supply cool air to the amplifier.

- GPS 900 and 1500
The fans operate at a quiet, low speed when the unit is turned on. The speed of the fans increase as the amplifier heatsinks require cooling.

- GPS 2600, 3400 and 3500
The fans do not operate when the unit is first turned on. The operation and speed of the fans are temperature dependent and change as the amplifier heatsinks require cooling.

DO NOT BLOCK THIS EXHAUST PORT! During the operation of your GPS Series amplifier, it will require fresh air intake in order for the tunnel cooling to function properly. Blocking this air exhaust port or the air intake ports on the rear could result in thermal shutdown of your amplifier.

Operation Notes

AC Mains Circuit Size Requirements
Power requirements for the GPS Series amplifiers are rated at "typical" music conditions. The maximum power current draw rating is limited by the amplifier’s circuit breaker. Consult the specification sheet for the current that each amplifier will demand. AC mains voltage must be the same as that indicated on the back of the amplifier. Damage caused by connecting the amplifier to improper AC voltage is not covered by any warranty.

Line Cord
For your safety, a removable 3-wire line (mains) cable with proper grounding facilities has been incorporated. It is not advisable to remove the ground contact under any circumstances. If it is necessary to use the equipment without proper grounding facilities, suitable grounding adapters should be used. Less noise and greatly reduced shock hazard exists when the unit is operated with the proper grounded receptacles.

NOTE: Always turn off the amplifier before making audio connections. As an extra precaution, have the input attenuator turned down during power-up.

Cooling Requirements (GPS 900 and 1500)
These GPS Series amplifiers use a forced-air cooling system to maintain a low, even operating temperature. Cooling air is drawn by synchronized, variable-speed fans mounted on the back panel, and exhausts through slots on the front panel. The fans will remain at low speed until internal operating temperature rises above 45°C. Make sure that there is enough space around the back of the amplifier to allow air to enter. The normal operating temperature is 55°C. This is a very cool temperature when compared to most amplifier standards. What this means to you is a noticeable increase in product life. On the GPS 900 and 1500 models, the fans will turn on simultaneously when temperature activated.

Cooling Requirements (All models except GPS 900 and 1500)
These GPS Series amplifiers use a forced-air cooling system to maintain a low, even operating temperature. Cooling air is drawn by continuously variable speed fans mounted on the back panel, and exhausts through slots on the front panel. The fan will remain inactive until internal operating temperature rises above 45°C. Make sure that there is enough space around the back of the amplifier to allow air to enter. The normal operating temperature is 55°C. This is a very cool temperature when compared to most amplifier standards. What this means to you is a noticeable increase in product life.

NOTE: If the amplifier is rack-mounted, do not use doors or covers on the front or back while the unit is in operation. Whatever type of rack you are using, make sure that heated air can escape freely, and that there is no resistance to the intake of cool air through the back grill. Intake and exhaust air must flow without resistance.

Input Connections
The input connector accepts balanced and unbalanced audio signals. For use with an unbalanced source, tie the inverting (-) input to ground by installing a jumper to the signal ground connection. If the inverting input is left floating, a 6 dB loss in gain will result.

Signal Mode Configuration
GPS Series amplifiers are configured for two-channel (stereo) or bridged mode operation at the input connectors and via Mode Switch. To send the same signal to both channels, connect the input signal to Channel A via the input connector. Run a jumper from the Thru jack of Channel A to the input of Channel B. Both channels then share Channel A’s input signal, but will operate independently. Speakers are connected as in two-channel (stereo) mode.

Bridged mode converts the amplifier into a single-channel unit with a power rating equal to the sum of both channels’ power ratings, and at a load rating of twice that of the single-channel rating. In bridged mode, the channels operate at opposite polarity of each other so that one channel "pushes" and the other "pulls" equally. Signal is connected to the Channel A Input connector. The speakers are connected only to the designated "+" output terminals. Never ground either side of the speaker cable when the amplifier is in bridged mode, as both sides are "hot". For GPS Series amplifiers, the minimum nominal load impedance in bridged mode is 4 Ohms (8 Ohms for GPS 3500); this is equivalent of driving both channels at 2 Ohms (4 Ohms for GPS 3500).

NOTE: Regardless of operating mode, NEVER connect amplifier outputs together!

Speaker Output Connections
Speakers are connected using the output connectors on the rear of your amplifier. Make sure the amplifier is turned off before you change any output connections. Also, make sure that the load impedance is not lower than that rated for the amplifier.

Protection Features
The GPS Series incorporates protection features derived from Peavey’s extensive experience with reliability. The amplifiers are ruggedly built from high quality components and feature comprehensive protection circuits to protect your amplifier those "real world" occurrences.

At the amplifier’s full power, or clipping point, the channel gain will automatically be reduced, guarding the loudspeakers against damaging high power and continuous square waves that would otherwise be produced. This is indicated by illumination of the DDT LED. Operation is virtually transparent in use and full signal bandwidth is maintained. However, if you have a GPS 900 or 1500 and choose to defeat the DDT compression function, this will not apply and clipping may occur.

Load Fault Correction™
LFC™ (Load Fault Correction™) is an innovative circuit that will instantaneously reduce channel gain to allow the amplifier to operate at a safe level into an abnormal load. Moderate activation of LFC is inaudible in normal use. In addition, if extreme low impedance or a short circuit is encountered during high signal level conditions, the amplifier’s output relay will open.

Initialization Protection™ (IP™)
IP™ operates every time the amplifier is turned on, or after a protect condition. During turn-on, the amplifier goes into protect mode and leaves the speaker load disconnected until the amplifier determines that the operating status is normal. The IP™ circuit attenuates the signal during the initial turn-on or protect operation. After relay release, channel gain gradually increases to the attenuator setting to avoid unnecessary stress on the loudspeakers.

Thermal Protection
If the heatsink temperature or power transformer reaches an abnormally high temperature, the amplifier will protect itself by disconnecting the speaker load until the amplifier returns to a normal temperature. During this time, the Power LEDs will not illuminate for that particular channel, and the cooling fan(s) will operate at maximum speed.

Short Circuit
If an output is shorted, the LFC™, speaker relay and thermal circuits will automatically protect the amplifier. The LFC™ circuit senses the short circuit as an abnormal load condition and reduces the channel gain to a safe level for the load. In extreme or severe conditions, the speaker relays will disconnect the load and initiate a power-on start-up sequence.

DC Voltage Protection
If an amplifier channel detects DC voltage or subsonic signals at its output terminals, the speaker relay will immediately open to prevent loudspeaker damage.

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