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Old 07-11-2019, 05:38 PM   #19
Peterk312
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I believe I did this test accurately, without using a master track for reference, to show the monitors are out of phase with each other. Here's my procedure:

1. Removed the COM port serial cables from PC to monitor and between monitors so that no Windows application was being fed to the monitors. Checked input levels and matched with a 1 kHz test tone. Checked all EQ bands were at 0 db gain. Checked both monitors were on preset 1 (flat setting).

2. Setup an AM 52 condenser mic (just happens to be an Alesis mic) 8 inches away from the front of the speaker, diaphragm centered between the drivers.



3. In Reaper, set up panned L/R pairs of tracks each with the JS Tone Generator plugin. Each pair was set for 100Hz, 1kHz, 2.5kHz, and 6kHz.

4. Recorded two test conditions:

Test 1 - Both speaker cables normal polarity (+tip/-ring/sleeve, TRS jacks)

Test 2 - One speaker cable on one side reverse polarity (-tip/+ring/sleeve)

Note: Test condition 2 was my current fix given I suspect the monitors are out of phase with each other. If I'm right, then Test 1 should indicate out of phase wave forms in Reaper.

Procedure: I started with the Right monitor, which was the speaker that has the sticker that says "Positive Phase." I simply played the test tone first then hit record for each Right Side track. I believe doing it this way allowed me to maintain time alignment for the tones between the two monitors. When done with Right monitor, I moved the microphone to the same position at the Left monitor and repeated the recording.

Results Test 1

Here's the wave forms captured in Reaper with speaker cables having normal polarity:


100 Hz



1 kHz



2.5 kHz



6 kHz

--in every case above, the wave forms are out of phase with each other.

Results Test 2

Remember, before recording the output of the monitors I had to reverse polarity on one of the speaker cables, which is a fix for monitors that are out of phase with each other. Test tones:


100 Hz



1 kHz



2.5 kHz



6 kHz

In test condition 2, because these monitors are out of phase with each other I compensated by reversing polarity on one of the speaker cables. The wave forms indicate the speakers are now in phase with each other.

Unless I did not do a valid test above, I think there's no doubt at this point that the monitors are out of phase with each other.

Last edited by Peterk312; 07-11-2019 at 05:43 PM.
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