Meyer Sound UM-1P, UM-100P Verifying Polarity, Troubleshooting, Driver Polarity in the Same UM-P

Verifying Polarity

Incorrect driver polarity impairs system performance and may damage the drivers. All Meyer Sound loud- speakers are shipped with the drivers in correct align- ment.

If the driver or circuit wiring has been removed or disassembled it is essential to check the polarity between adjacent monitors and between drivers and between adjacent loudspeakers.

Driver Polarity in the Same UM-P

Use the following test procedure to verify polarity between drivers in the same loudspeaker:

1.Place a monitoring microphone 1 meter from the front of the loudspeaker at the midway point be- tween the high and low frequency drivers.

2.Connect a full range signal to the loudspeaker and note the frequency response.

The polarity is correct if the frequency response is smooth through the crossover region (800Hz to 1.5kHz). Can- cellation of 6dB or more in this region indicates polarity reversal.

Polarity in Adjacent Loudspeakers

Use the following test procedure to verify the polarity between two adjacent loudspeakers of the same type:

1.Position two loudspeakers adjacent to each other.

2.Place a measurement microphone 3ft. from the speakers and 3 to 4 feet above the UM-1Ps, on the axis between the speakers.

3.Connect a signal source to one speaker and note the frequency response and overall level.

4.Apply the same signal to the second speaker with the first speaker still connected.

The polarity is correct if the frequency response remains constant with a 5-6 dB SPL increase in amplitude. Broadband cancellation (decreased overall level) in- dicates polarity reversal.

!Since polarity reversal causes excessive driver ex- cursion at high source levels, use moderate levels when conducting these tests.

UM-P

Reference

3 Feet

UM-P

Under Test

Troubleshooting

This section suggests several possible solutions to some common problems encountered by UM-P users and is not intended to be a thorough troubleshooting guide. Qualified electronics technicians with access to a test bench can request the following documents from Meyer Sound: Troubleshooting Guide, The Low Frequency Driver Replacement Procedure, and The High Frequency Driver Replacement Procedure for the UM-1P/100P.

The On/Temp. LED does not illuminate, there is no audio, and the power supply fan is off.

1.Make sure the AC power cable is the correct type for the regional voltage and that it is securely connected to the AC inlet then unplug and recon- nect the AC cable.

2.Use an AC voltmeter to verify that the AC voltage is within the ranges 88–264V, 47–63 Hz.

3.Call Meyer Sound Technical Support.

The On/Temp. LED is illuminated but there is no sound.

1.Verify that the audio source (mixer, EQ, delay) is sending a valid signal.

2.Make sure the XLR cable is securely fastened to the XLR audio input connector.

3.Verify that the XLR cable is functioning by substi- tuting another cable or by using the cable in ques- tion in a working system.

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