Samson S-Zone 4 Zone Stereo Mixer Issues

[JoyK]

Hello,

I have been in the process of setting up a multi-zone setup. I was able to get a good deal on a Samson S-Zone (https://samsontech.com/products/mixers/rack-mixers/szone/), which has a lot of features that I liked/wanted. However, there seems to be a lot of buzzing noise produced by it. Here are some things I have played and tested around with it:

• Using grounded and not grounded outlets. It doesn't seem to make any difference and the noise stays the same.
• Different cables and different inputs/outputs. Same results. In fact, the mixer has a monitor on it, which when nothing is even plugged in (minus the power), the buzzing noise becomes apparent and louder once its volume control reaches around 40%+. It is even possible to hear the buzzing at lower volumes once you know it's there.
• I have looked inside at its guts and it's clean. As far as I know, it looks fine to my beginner eye.
• I have tried different power cables. No difference.
• I have tested and use a combination of either powered or amp + passive speakers. Both behave similarly to how much buzzing occurs. The powered speakers will create a loud "pop" sound if they're connected to the mixer and I turn it on.

If anyone has advice or require more information in order to give advice, please let me know and I'll do my best to respond.

Thank you.

 

[MaxwellsEq]

Buzzing and hum are always tricky to eliminate and they are frequently unique to a specific circumstance. Sometimes it's an earth-loop, sometimes induction (e.g. from LED lights etc.).

The link you included states SNR at 96dB, which should mean noise is mostly inaudible (although a Noise Figure would tell us more).

One thing you can't do is check noise with inputs unconnected. That 96dB figure would have been measured with the inputs all shorted. If you short all the inputs and use a non-earthed device such as headphones, to listen and you still hear a buzz, the device is probably faulty.

 

[Sokel]

The loud pop coming from the speakers is not a good health sign, I would at least measure its outputs for DC (as I would do with any unknown new gear, PRIOR of connecting them to anything else) .

The good deal you got had probably something to do with this.

 

[JoyK]

Buzzing and hum are always tricky to eliminate and they are frequently unique to a specific circumstance. Sometimes it's an earth-loop, sometimes induction (e.g. from LED lights etc.).

The link you included states SNR at 96dB, which should mean noise is mostly inaudible (although a Noise Figure would tell us more).

One thing you can't do is check noise with inputs unconnected. That 96dB figure would have been measured with the inputs all shorted. If you short all the inputs and use a non-earthed device such as headphones, to listen and you still hear a buzz, the device is probably faulty.

Thank you for your reply! Can you clarify what "short all the inputs" mean? I would like to test what you said, but I am unfamiliar with this terminology.

On the other hand, I went ahead and tested the monitor headphones input and played with it's volume control. Oddly enough, the buzzing starts out what appears to be mono. As I increase the volume it gradually becomes stereo. At max volume, it's panned and mostly heard all the way to the right. Not sure if this info is helpful, but I was amused by it.

 

[JoyK]

The loud pop coming from the speakers is not a good health sign, I would at least measure its outputs for DC (as I would do with any unknown new gear, PRIOR of connecting them to anything else) .

The good deal you got had probably something to do with this.

Thanks for your reply! I also assume the good deal is related, unfortunately.

I would like to test the outputs for DC. I did a brief search on how to test DC on a nine-pin euroblock output, but had trouble finding any info. Would you know or have any resources for me on how to do this?

 

[Krusty09]

Thanks for your reply! I also assume the good deal is related, unfortunately.

I would like to test the outputs for DC. I did a brief search on how to test DC on a nine-pin euroblock output, but had trouble finding any info. Would you know or have any resources for me on how to do this?

On the back you will see neg and positive for each output just measure to see if you have dc. I think under 100 mv is acceptable.

 

[JoyK]

On the back you will see neg and positive for each output just measure to see if you have dc. I think under 100 mv is acceptable.

Thank you for taking the time to help. Just to double check, I would test each left and right channel separately. For example, I would put the multimeter's red probe in L+ and black probe in L-. Then I can repeat for R+ and R-.

If that's the case, I already went ahead and put my multimeter's measurement to 200m to run some tests. The end results, for each output, they were all nearly 0mv. I am not exactly sure what this is telling me.

 

[Krusty09]

That seems correct. So probably no dc voltage .

 

[JoyK]

To clarify, is this not as intended? If you don't mind, can you or someone else give a quick explanation on what I should see and why?

If it's not as intended, are there any recommended solutions?

 

[Krusty09]

Try this now. Check your outlet. Chances are its zero but you have nothing to lose

Google Search

 

[Sokel]

Thanks for your reply! I also assume the good deal is related, unfortunately.

I would like to test the outputs for DC. I did a brief search on how to test DC on a nine-pin euroblock output, but had trouble finding any info. Would you know or have any resources for me on how to do this?

Negative probe to ground, steady.

Then check with positive probe, each of the L+ ,L- ,R+ , R- .
At line level voltages you would want to see less than 10mVDC or so.

 

[JoyK]

Negative probe to ground, steady.

Then check with positive probe, each of the L+ ,L- ,R+ , R- .
At line level voltages you would want to see less than 10mVDC or so.

I measured and tested based on your instructions. Testing every output, they were all 0mVDC. Is it strange to have it just be zero or should there at least be some voltage fluctuation or variety?

Try this now. Check your outlet. Chances are its zero but you have nothing to lose

Google Search

Thank you for the Google search. Are you suggesting to test my wall outlet? I am confused, because shouldn't it read somewhere around 120V instead of 0V? Sorry if I am misunderstanding you.

 

[Sokel]

should there at least be some voltage fluctuation or variety?

Not if they have output capacitors who block it.

Now, can you check the same way having the probes connected while you turn it off and on?
And check both DC and AC, I'm curious about that loud pop.

 

[JoyK]

Now, can you check the same way having the probes connected while you turn it off and on?
And check both DC and AC, I'm curious about that loud pop.

Sorry for the late reply. I went ahead and tested what you suggested. It seems that with each output tested, they all behave similarly. Once turned on, there is a big spike of voltage and then an exponential decrease back to 0mVDC. It is about the same when turning the mixer off. When turning it on, I have seen a spiked range between 110mVDC - 10mVDC.

If I tested it correctly, AC just stayed at zero.

Here is an imgur link to a video of what it looks like when I am measuring DC. I don't know why I didn't noticed, but when turning off the mixer, the monitor speaker gives a little "pop" sound too. You should be able to hear it around the 22 second mark.