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Fixing the Microphone Distortion issue - need your input

FM Former Member
I think you've seen in other posts we recognize that some of you are having issues with microphone distortion on the VMS4. I'm going to run more tests to make sure that we resolve this issue properly. Your input is valuable here.

If you have experience microphone distortion issues please first:
1) For wireless mics, please use the lowest gain setting possible.
2) Please see if you can reduce the distortion by lowering gains on the VMS4 and then increasing the power amp gain.

If it is still not possible to eliminate the distortion, please check the following:

1) What is the mic brand & model number?
2) What is the cable setup? Type (XLR cable, 1/4" cable, XLR to 1/4" cable, etc.), cable length, and brand are helpful.
3) What are the VMS4 settings for mic gain, mic EQ, and master gain, and what does the VU meter read when you use the microphone and get distortion?
4) Roughly what is the sound setup? Is it a studio, stage, club where you get the distortion?
5) Does the distortion go away if you get farther from the microphone or talk at a lower volume? If it does, please identify the mic gain, mic EQ, master gain, and VU meter reading you get when the sound is as loud as it can get without distorting.

I know it's asking a lot, but the better you can answer the above questions, the quicker I can duplicate the issue and make sure it's resolved.

For the purposes of identifying the issue, please identify what happens without impedance transformers.

@hardwiredentertainment, @thewicked, @Corneloues I particularly look forward to your feedback.

Everyone else please feel free to contribute here but again please stick to the microphone distortion issue.
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FM Former Member
quote:
Originally posted by GroovinDJ:
I have a whole bunch of different mics I can try, if you're interested.

So far I've only used my SM58 and not experienced problems, but I don't mind testing with the others (inc wireless).


Yes I would be interested. Thanks for your offer. This is very helpful.

Elliot
FM Former Member
OK, I've had a play with six different mics.

Shure SM58 I already know sounds OK.

Next was a Realistic Highball, which is a SM58 clone, sold by Tandy (Radio Shack). That was slightly quieter than the SM58 but no problems.

Next was an old black mic with no branding on it, but looks similar to an SM58. This was the loudest so far, but still can be used without causing any uncontrollable distortion.

Next was an AKG C1000S condenser mic. This runs off a 9v battery when there's no phantom power. More sensitive than the dynamics of course, but still no cause for concern.

Next was another condenser, but a cheap one sold by Tandy in the 80s, with a hardwired jack plug. Again, works fine.

Finally I tried a cheap radio mic (Gemini). I can get the VMS4 input to distort like crazy if I turn up the output volume of the receiver, but at a sensible level it works fine.

I'm not going to bother testing with any more mics because it seems to me that as long as you're not shouting into it while it's half way down your throat, or using a radio mic with the output set too high, it all works fine.
FM Former Member
I used it with:
Senheiser E something will look when back. I also used with sm58 and experienced same problem

Was using xlr. Cable by canford audio and neutrik connectors. They are ex BBC so I am sure it's not the cable. I am beginning to think that some people have the issue and some don't depending on the batch you get?...
FM Former Member
Hello all,

Thanks for those trying to solve the microphone distortion.

Emarx, here are my answers:

First test:

1) Shure BETA 58
2) "XLR to 1/4" cable, 2 meters, Neutrick
3) Mic gain : mini, Mic EQ : middle, Master gain : middle, VU meter : green
4) Studio
5) No

Second test:

1) Shure PG58
>> same result...

Third test:

1) Shure SM58 wireless (PG4)
2) "XLR to 1/4" cable, 2 meters, Neutrick
And "1/4 to 1/4" cable, 2 meters, Neutrick
>> Same results...
Last edited by Former Member
FM Former Member
DJ Alvyn K, Oli: I find it hard to believe that you can't make the distortion go away by talking at a lower volume or moving away from the microphone. At what point does the distortion go away?

Oli: I checked with our production staff. The mic circuits on all production units are identical. It's extremely unlikely that the mic circuits are defective because the same exact distortion happens on both mic channels. Anyways if you could provide details like Alvyn K that would be really helpful.

Alvyn K: So you have mic gain = MINI. Could you be more specific? For example 7:00 is off, 9:00 is very low gain with the stripe pointing to the left, etc. Then for the LEDs in the green so at which dB level do they peak? This will give me an idea of how much signal you are getting out of the microphone.

For the wireless microphone, can't you just reduce the gain on the receiver?

Anyways, the Beta 58A looks like a good candidate for testing due to it's extremely high output compared to other microphones.
FM Former Member
I'm not able to give a fully qualified response at present as I'm replying on my mobile. This is just a quick message to say that I used the VMS4 yesterday for a karaoke show and barely survived the night due to the mic issue. Even customers were complaining about the distortion.

Obviously I can't ask singers to sing quietly...

Some observational though. People that held the microphone 'correctly' experienced the distortion. People who held the mic too far away or too low could hardly be heard and I had to keep adjusting the gain, but still distorted.

For myself, I held the radio mic as I always have done, spoke quieter and the distortion was still there just not noticeable.

Tried 3 wired mics. All distorted at any level!!!

I have a repeat event tonight. Because this is a paying gig with customers I am going to hook up my Xenyx mixer to run the mics through. I cannot afford another situation like last night.

I'm seeing the AA rep on Wednesday and will explain all to him there.

Cheers,

Roy
FM Former Member
@Corneloues: Haha I'm not asking singers to sing quietly I'm just trying to identify the issue. If there is still distortion when people sing/talk quietly this is a different issue. It sounds like what's happening is the MIDILOG channels are set as high as they can go without distortion, and when you try to get the mic sound even higher to balance the sound, the mic will sound distorted no matter what you do.

Please try lowering the gain on the MIDILOG channel EQ and increasing the gain on your output power amp. This way you'll have much more microphone headroom to work with.
FM Former Member
Thanks to you guys for your feedback. There are 2 solutions which came up in other threads:

One low cost solution tested and confirmed by thewicked:
http://www.maplin.co.uk/Module.aspx?ModuleNo=12151
This will definitely work when set for high impedance, but may have some hum.

A professional audio solution suggested by hardwiredentertainment:
http://www.dv247.com/microphon...hase-inverter--74319

In the meantime your feedback is helpful. Please keep it coming so we can fix the issue. Again the better you answer my questions the quicker we can get this resolved.
FM Former Member
quote:
Originally posted by emarx:
Alvyn K: So you have mic gain = MINI. Could you be more specific? For example 7:00 is off, 9:00 is very low gain with the stripe pointing to the left, etc. Then for the LEDs in the green so at which dB level do they peak? This will give me an idea of how much signal you are getting out of the microphone.


As mentioned before - the so called 'GAIN' is not gain, it is volume and the gain is set and unchangeable. Therefore it will distort at whatever volume level the 'gain' is set to. With regards to the solutions, I can't help but thinking that is should be AA who supply a free option since it is certainly a hardware problem?

Anyway, for now I am having to take another mixer which is just ANOTHER piece of kit to hump around. GRR
FM Former Member
quote:
Originally posted by emarx:
@hardwiredentertainment: I know you've made your point. Any way you can take another approach and answer my above questions? I am here to help.


Good Smiler I will try and answer the questions in the next day or two. Bit mental at the moment. What kind of solutions are there? Short of recalling all the units or issuing adaptors..

Cheers
Oli
FM Former Member
quote:
Originally posted by emarx:
Alvyn K: So you have mic gain = MINI. Could you be more specific? For example 7:00 is off, 9:00 is very low gain with the stripe pointing to the left, etc. Then for the LEDs in the green so at which dB level do they peak? This will give me an idea of how much signal you are getting out of the microphone.


emarx : I am away until mid-September without my VMS4. If necessary, I do it again some tests on my return.
FM Former Member
I have used a Audio-Technica ST95 MKII (first one I grabbed). It is a low Z mic. I used a 20' XLR cable for the mic.

RCAs off the masters to a RCA to 1/4" to XLR adapter in to some small 10' active speakers.(what a rig, I know)

The sound was not awesome but I could tweek it enough to sound good. I will repost when I get a chance to run my other mics, vocal proccessor, wireless mics and differant audio set ups with it. So far so good. I will be very critical of the mic sound as I am a vocalist and a KJ as well so I need my mics to sound great.

So far I am enjoying the VMS4.
FM Former Member
@hardwiredentertainment, et al:

As I suggested above:

Please try lowering the gain on the MIDILOG channel EQs and increasing the gain on your output power amp. This way you'll have much more microphone headroom to work with.

Why do I suggest this? Because I think this happens in many cases:

You set up the sound system so the main channels sound just right. Problem is especially if you're doing Karaoke you probably want more sound out of your mics. But since the main channels are already near their limit the only way to get mic sound is to push them into the distortion range.

With what I suggested, as long as the microphone pre-amp isn't distorting, you will get no distortion and have plenty of sound as well as headroom to increase the mic gain if needed. The reason why I ask the above questions is this will make it clear if the distortion is from the mic preamp or from too much gain from the VMS4 mic gain, mic EQ, or Master. If the distortion is from the mic preamp, it won't go away with gain reduction. If the distortion is from too much VMS4 mic gain, mic EQ, or master, it will go away with gain reduction.

So hopefully this answers your question? I can't speak on behalf of how ADJ customer service will handle customer issues, but I'll do my best to help identify the issue and come up with solutions.
FM Former Member
Hi
I found I was getting the problem even when there was no audio being played. And The volume on the masters was just approaching 0db. The speakers were set normally. The eq on mics was flat and the gain on the mic input was at 9 o'clock. I was receiving distortion when talking even a tiny bit louder than normal speaking voice
FM Former Member
quote:
Originally posted by hardwiredentertainment:
Hi
I found I was getting the problem even when there was no audio being played. And The volume on the masters was just approaching 0db. The speakers were set normally. The eq on mics was flat and the gain on the mic input was at 9 o'clock. I was receiving distortion when talking even a tiny bit louder than normal speaking voice


Oli this is really helpful. Thanks. The MIC input gain is so low the distortion has to be coming from the mic pre-amp on your setup. Just to confirm, this is happening on the SM58 wired mic you are using, right?
FM Former Member
quote:
Please try lowering the gain on the MIDILOG channel EQ and increasing the gain on your output power amp. This way you'll have much more microphone headroom to work with.


Okay, I hear what you are saying. But I'm confused now about how the VMS4 should be configured.

I have the faders set at 100%. The Gain is at approx 50%. The master volume sits at roughly 55%. With these settings the unit peaks at +4 occasionally +7.

Even with these settings I can only turn the mic's up to 10-15% before they are a) too loud and b) distort.

If I lower the midilog gain and increase the master out volume I will have less play in the mic volume - less that 10% so I can't see how this will help!

Anyway, I tried my alternate setup for Friday evenings gig as follows:

VMS4 in to master input of the Behringer MX-882 splitter/mixer
Skytec Radio mics and wired mic in to a Xenyx 1204 mixer which went in to Ch5/6 of the MX-882 (simply because of the balanced 1/4" connection required from the Xenyx).

In this config I had no mic issues at all. I had planty of spare volume and gain on the Xenyx and the gain was set at 0 on the MX-882 and the VU's were nowhere near peaking on those channels.

The difference was major. The mics not only didn't distort, but they were crystal clear with very little EQ required.

When I am with Simon next week I'll set up identically and record the output.

I am really hoping this is an "early batch issue" as apart from the mic (and the master output levels) I am in love with this mixer. The integration with VDJ and the feel of the control and jogs for mixing are perfect.

Cheers,

Roy

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