Small mixer/wireless issue/advice

jds10011

Member
Maybe slightly unusual situation -- looking for solutions. We have a small room set up with two Shure BLX handheld mics. We have a Yamaha MG12XU mixer, an upgrade from an older MG124CX that began failing. We previously had older analog Shure ULX (not ULXD) handheld mics, which were far better. With the BLX handhelds and the MG12XU mixer, it is pretty frequent that a terrible buzzing-type clipping sound occurs when someone suddenly speaks too loudly. We have tried to lower the gain and engage the built-in compressor, but because the compressor seems to be "after" the preamp in the board, it doesn't help. Because the signal is mic level, we can't put an outboard compressor between the receiver and the input on the mixer. We did try the RDL EZ-MCP1 units, but this seems to lead to a really unfortunate gain structure and therefore doesn't really help either.

The choices seem to be (1) get a mixer with a better preamp and/or better compressor or in general better-behaved, (2) get better wireless handhelds, or (3) get some sort of gizmo/problem-solver item we haven't considered yet.

If the best option is a better mixer, we would want a recommendation something similar in size (at least 4 XLR mic inputs, at least two stereo input channels) with actual channel faders (not knobs). We're a little reluctant to get better handhelds as they are sometimes mistreated. It is also possible that something is failing in this mixer, though it is fairly new and the problem seems to affect multiple channels. (If something "great" is discontinued, feel free to mention it anyway and we'll check the used market.)

Suggestions/thoughts appreciated. Thanks!
 
The console has clip/peak lights. The wireless should also have clip/peak indicators. If neither of those devices are at issues it sounds like..... Your PA could also have a blown tweeter or woofer that is buzzing at loud/specifc frequencies.
 
The console has clip/peak lights. The wireless should also have clip/peak indicators. If neither of those devices are at issues it sounds like..... Your PA could also have a blown tweeter or woofer that is buzzing at loud/specifc frequencies.
Yes, the 'peak' light illuminates on the channel at the mixer. Most likely, here, I'm looking for a recommendation for a "better" small mixer that will behave in these circumstances, with the features above.
 
More than likely, the mixer is just fine. When the peak light flashes on the mixer channel, that means you need to turn down the gain trim on that channel. Peak flashing means input overload or clipping. Turn off the compression before adjusting anything else. If the L&R meters of the mixer have to be hot to get the desired output from the speakers, then reduce the mixer level and increase the gain in the equipment following the mixer, such as a power amp. This is called system gain structure. All of the components need to be working in their nominal range, from the wireless mic system to the power amp or active speaker.
 
Time to troubleshoot:
Hook up a wired sm58 and go nuts on it. Do the exact same thing that causes the wireless to buzz. Can you recreate the same buzz? If yes it's the mixer. If not, it's the mic.
 
Time to troubleshoot:
Hook up a wired sm58 and go nuts on it. Do the exact same thing that causes the wireless to buzz. Can you recreate the same buzz? If yes it's the mixer. If not, it's the mic.
Yes, it is easier to do with a crummier mic, but I certainly can make it happen with a wired 58. My assessment is that the mixer just doesn't handle this very well (put the gain at a reasonable level for speaking volume, then the person unexpectedly is too loud for a moment -- e.g. shushing a noisy audience member). I'm wondering about mixers that would handle this better (perhaps a built-in compressor that comes before the preamp somehow).
 
@jds10011 where is the gain set on the amps? I agree with @FMEng this sounds like it could be just a gain structure issue. Try turning your amps up then back the gain down on the mic channel.
It is certainly possible. There is an older DSP set up and I would need to convince the XP laptop with the serial port to work again to really answer the question, and perhaps I can get better results by making changes there. I can tell you that when I've tested with a digital mixer in the same setup, I've never had this issue (and not needed to alter anything in the DSP) -- we bring one in for larger events, but hooked up to the same input on the DSP with no settings changed.
 
It is certainly possible. There is an older DSP set up and I would need to convince the XP laptop with the serial port to work again to really answer the question, and perhaps I can get better results by making changes there. I can tell you that when I've tested with a digital mixer in the same setup, I've never had this issue (and not needed to alter anything in the DSP) -- we bring one in for larger events, but hooked up to the same input on the DSP with no settings changed.
Where are the physical knobs on the amp set?

Can you borrow another mixer from somebody? It would be great to swap mixers and try it again.
 

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