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Filters & signal processors · User manual

GP-LPSUB user manual

Subwoofer Signal Generator

Thank you for choosing the GP-LPSUB subwoofer signal generator. We appreciate your confidence in us for such an important purchase, and we built it to give you command over the sound your system produces.

Rev A · October 20266 chapters

View the GP-LPSUB
GP-LPSUB Subwoofer Signal Generator, front panel

Specifications

As engraved on the unit.

G Pulse Linear · Audio SolutionsModel GP-LPSUBRev A
Pass-through
DC – 100 kHz
Sub output
−1 dB to 35 / 65 Hz
Sub at 200 Hz
−38 dB
THD
Below 0.2 %
Input impedance
47 kΩ, RF filtered
Output impedance
100 Ω RCA · 50 Ω XLR
Hum and noise
Unmeasurable
Sub gain
0 to +6 dB
Maximum output
10 V RMS
Power
100–240 V AC
Dimensions
5 × 2 × 1.5 in
Weight
1 lb

The subwoofer output is DC blocked and −1 dB from 1 Hz to 35 or 65 Hz, referenced to 0 dB. The XLR output drives 600 Ω lines and has a shield ground-lift switch. Maximum output into a 2 kΩ load; distortion measured with an HP 334A analyzer.

Before you start

Connect first.
Power last.

Three things, in this order, every time you change your system.

Read before switching on

  1. Make every connection before you switch on this unit and the rest of your system.
  2. Never change connections while the system is on. Doing so can damage your equipment.
  3. Always start with the main system volume turned fully counterclockwise, to off. Mishaps happen, so take care.

Connections

Where it goes in your system.

PreamplifierA line output after volume and tone
GP-LPSUB front panel
GP-LPSUBLine pass-through on the front · sub outputs on the back
SubwooferRCA or balanced XLR

Pass-through

Left IN to left OUT, and right IN to right OUT, on the front panel, DC-coupled straight through.

Feed it after the volume

Use a line output that follows your preamplifier's volume and tone controls, so the sub level tracks your main volume once it is set.

Sub outputs

RCA or balanced XLR, on the back panel, to your subwoofer amplifier or powered subwoofer. Power it from the three-prong grounded cord.

Set-up

Set the controls.

Before you listen, set everything like this.

  • Subwoofer gain

    Fully counterclockwise before you switch on.

    Set to: off

  • Power

    Switch it up. The green LED lights.

    Set to: on

Then

  1. Switch on the main system and all amplifiers, with every volume control at minimum.
  2. Listen to your normal stereo first and make sure everything sounds right.
  3. If the GP-LPSUB sits in your preamplifier's external loop, set the preamplifier's loop control to external.

Operation

Setting the subwoofer level

The GP-LPSUB uses a steep filter to create the deep bass many stereo speakers cannot reproduce. Your subwoofer's own specification decides how much, and how well, that low end fills your room.

Start with the sub level fully counterclockwise. Choose your source and set your listening level on the main speakers, then slowly turn the sub level clockwise until the bass sounds right to you.

A little goes a long way. Stop before the room turns boomy: you want just enough to give the room the punch you would hear at a concert.

Take careIf you hear hum, you may have a ground loop. Turn the main volume to minimum, move the ground-lift switch up, then try again.

MaintenanceCare

  • Cleaning. Use a damp cloth only, never glass cleaners or alcohol-based products.

  • Surge protection. Put a surge protector on the power line, against a nearby lightning strike or a line-level overload.

Questions about your GP-LPSUB?

Talk it through with us.

Tell us what is in your system and what you want it to do. We answer set-up questions before and after you buy.

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