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MA5000VZ


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#1 kevvywevvywoo

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Posted 03 April 2012 - 06:59 AM

Hello, I have an MA5000VZ here and at full output we get a 7Vrms difference in the output comparing ch1 to ch2. Ch2 is lower.

The difference is noticeable either with mode switch on 'parallel mono' or with stereo mode and ch1/2 from the same mono source.

I have tried to adjust the parallel balance pot, this has an effect but the best it will achieve is 5Vrms difference.

The error amps of ch1 / 2 are giving out 2.8v and 2.5v but the inputs of both are the same; suggesting the fault is downstream of the error amp.
The channels both achieve max output volts but at slightly different input levels. There is no distortion, clipping is symmetrical and at the same point; the VZ circuitry is working, ODEP voltages are perfect, static & dynamic balance is spot-on.  Output offset is 0.2mV on Ch2 and 6mV on Ch1.  I've swapped the output modules, the fault remains with ch1 higher than ch2.

Is there any advice anyone can give?

Thanks,

kevin

#2 dakos

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Posted 03 April 2012 - 09:25 AM

QUOTE(kevvywevvywoo @ Apr 3 2012, 06:59 AM) View Post
Hello, I have an MA5000VZ here and at full output we get a 7Vrms difference in the output comparing ch1 to ch2. Ch2 is lower.

The difference is noticeable either with mode switch on 'parallel mono' or with stereo mode and ch1/2 from the same mono source.

I have tried to adjust the parallel balance pot, this has an effect but the best it will achieve is 5Vrms difference.

The error amps of ch1 / 2 are giving out 2.8v and 2.5v but the inputs of both are the same; suggesting the fault is downstream of the error amp.
The channels both achieve max output volts but at slightly different input levels. There is no distortion, clipping is symmetrical and at the same point; the VZ circuitry is working, ODEP voltages are perfect, static & dynamic balance is spot-on.  Output offset is 0.2mV on Ch2 and 6mV on Ch1.  I've swapped the output modules, the fault remains with ch1 higher than ch2.

Is there any advice anyone can give?

Thanks,

kevin

Dear Kevin,
I'm not sure how the amp is supposed to handle this job and at first glance it did sound like a problem but the rated voltage gain of this amp is within a +/-0.5dB tollerance, if you take the maximum output voltage of this amp, 118.65V RMS, then 7Vrms difference is still within the limitations.
Hope it helps