microphones

VMS4 is a very good controller... but I have the same opinion as Oli. The 2 microphone inputs are unusable and ADJ must correct the problem.

I tested the two inputs with a "so classic" BETA58, a PG58 and a wireless SM58 (PG4). In 3 cases, the sound is saturated (and unusable), even with minimum gain. "Use a high impedance mics cheap and nasty" is not an acceptable answer.

PLEASE FIX!!!

Yep. And what they call 'gain' is not gain! It is volume. The gain is set, hence when you turn the gain down all you get is quieter distorted sound.

I think this must be a batch problem, because mine isn't distorted when using the mic.

Hello All,

I have discussed this problem internally with American Audio and it's becoming clear to me that the issue is lack of headroom on the microphone preamp circuit in the VMS4. The distortion will only happen with higher output microphones.

Being the engineer on this project, I know the fix requires some form of gain reduction either on the pre-amp or on the mic signal going into the pre-amp. And we'll probably need to make some adjustments on the mic volume gain to make sure that there is the correct range for accomodating both low output (typically high impedance less expensive ones) and high output microphones (typically low impedance more expensive ones).

So note we are aware of this issue, but please be patient as I discuss with American Audio internally how to address this issue.

Thanks for open and honest response. As you are probably aware, we don't buy products to criticise them, so when there are issues we raise them to help better the product or raise these concerns with the manufacturer.

It's good to know that our feedback isn't falling on deaf ears! I wait with anticipation to know whether this issue can be resolved via a firmware patch as you have mentioned harware components in your post.

Cheers,

Roy

As I mentioned before, the issue is the hardware pre-amp circuit gain is too high. So unfortunately the fix isn't so simple as a firmware patch.

In this post, thewicked installed an impedance transformer which eliminated the distortion:
http://forums.americandj.com/e...27105965/m/603101696

Interestingly though he set it up for high impedance input so it put a gain reduction on the microphone which cleaned up the sound. But the part he used picked up extra hum.

Roy I get you. Thanks for your positive feedback. I'll keep on top of this and keep in touch with others at American Audio to resolve this issue.

Elliot

quote:

Originally posted by emarx:
The distortion will only happen with higher output microphones.

....which are the ones that it's been designed for (Hi Z)?

If that's the case, how do you explain that my mic channel sounds OK (to me) when using an SM58, but others are complaining that using an SM58 gives distortion?

Higher output and high impedance are two different things. The SM58 output is high compared to other similar low impedance microphones.

As I mentioned in the other post, I used a Sennheiser low impedance microphone on the VMS4 and had no issues on my end.

The VMS4 is designed to work with low, mid, and high impedance microphones. It is not specifically designed for one or the other. The issue is a headroom issue on the VMS4 mic preamp hardware circuit.

I'm pretty sure it comes down to the environment where the microphone is used. So someone may have no issues while others pushing the microphone with higher input will have distortion on the same microphone.

I find it unlikely this can be quickly fixed. I would hope that aa will send out a free adaptor to bring the gain down on microphones as I said, the 'gain' is not gain, it is volume. The gain is set. I wish they'd get on and fix asap, it needs sorting!

Adapators are one solution. Although as TheWicked said his adaptor caused a hum and you now have another 'thing' to plug in and carry with you when the VMS4 is supposed to reduce our overall 'footprint' of plugs, wires, etc.

I'll leave it for emarx to keep us informed rather than second guessing the outcome. I'm just glad people are listening ;-)

Cheers,

Roy

Here is a possible solution? I think this would probably cure it:
http://www.dv247.com/microphon...hase-inverter--74319

Hey all,

Please follow through on this post. Thanks:

http://forums.americandj.com/e...27105965/m/538107707

@hardwiredentertainment yes I believe this would cure the issue. Thanks for your feedback.

quote:

Originally posted by hardwiredentertainment:
Here is a possible solution? I think this would probably cure it:
http://www.dv247.com/microphon...hase-inverter--74319

It probably would, and with an extra £60 expense. For a problem I have never had before with ANY mixer.

Roy

quote:

Originally posted by Corneloues:

quote:

Originally posted by hardwiredentertainment:
Here is a possible solution? I think this would probably cure it:
http://www.dv247.com/microphon...hase-inverter--74319

It probably would, and with an extra £60 expense. For a problem I have never had before with ANY mixer.

Roy

amen to that!

OK guys you've made your point already. Further complaints won't make this fix happen any faster because I already have instructions from the top to fix this.

Cool - so do we have any idea what the fix is or when it will be implemented?

Hello Everyone we are currently working in a solution for the Mic issue. The mic input is for a mic level signal alot of you are running wireless mic's. even if you are running them at MIC level with you gain on the receiver, the Gain and boosting the EQ may cause you to have distortion. if in fact you do have distortion when the VMS4 mic gain level is at the minimum this is a clear indicator that your input signal is overloading the circuit so bring down your signal. We will fix this to have more of a tolerance but if you have a wireless mic with a line level output it should have a mic setting as well in rare case it does not then this can be a scenario where you will need a signal pad -10 db for hot mics -30db for line level to mic input

quote:

Originally posted by Ihearyou(American Audio):
Hello Everyone we are currently working in a solution for the Mic issue. The mic input is for a mic level signal alot of you are running wireless mic's. even if you are running them at MIC level with you gain on the receiver, the Gain and boosting the EQ may cause you to have distortion. if in fact you do have distortion when the VMS4 mic gain level is at the minimum this is a clear indicator that your input signal is overloading the circuit so bring down your signal. We will fix this to have more of a tolerance but if you have a wireless mic with a line level output it should have a mic setting as well in rare case it does not then this can be a scenario where you will need a signal pad -10 db for hot mics -30db for line level to mic input

Many thanks for the update. Can you give us any information as to what you are working on as a fix and how long it will be until it is implemented?

Oli

quote:

Originally posted by hardwiredentertainment:

quote:

Originally posted by Ihearyou(American Audio):
Hello Everyone we are currently working in a solution for the Mic issue. The mic input is for a mic level signal alot of you are running wireless mic's. even if you are running them at MIC level with you gain on the receiver, the Gain and boosting the EQ may cause you to have distortion. if in fact you do have distortion when the VMS4 mic gain level is at the minimum this is a clear indicator that your input signal is overloading the circuit so bring down your signal. We will fix this to have more of a tolerance but if you have a wireless mic with a line level output it should have a mic setting as well in rare case it does not then this can be a scenario where you will need a signal pad -10 db for hot mics -30db for line level to mic input

Many thanks for the update. Can you give us any information as to what you are working on as a fix and how long it will be until it is implemented?

Oli

For the fix I'm working on adjusting the mic pre-amp gain to prevent distortion overload while not being so low that there is excessive noise in the circuit.

I'm getting a bunch of mics that have caused overload issues for testing soon and will keep everyone updated.

Hey Everyone,

If you are using a MIC with an impedance lower than 300 Ohms, you may need to use a low to high impedance adoptor. The mic inputs impedance is 600 ohms. I have personally tested a SM58 and did not have distortion. If you do have a problem with you inputs please dont post with out telling us what mic your using.

hardwiredentertainment says he used the same SM58 and got distortion in this post:
http://forums.americandj.com/e...27105965/m/538107707

@hardwiredentertainment: Is there any way you can do a video showing how you are using the microphone and getting distortion? This would be very helpful.

Yes can do. Am away in the USA at the moment but can do when I get back. I get back on Wednesday but go straight into musical rehearsals. Will do my best to get it done!

quote:

Originally posted by emarx:
hardwiredentertainment says he used the same SM58 and got distortion in this post:
http://forums.americandj.com/e...27105965/m/538107707

@hardwiredentertainment: Is there any way you can do a video showing how you are using the microphone and getting distortion? This would be very helpful.

Hi sorry - been a busy few days. I will try and do this week if i can before uni starts on Monday!

@hardwiredentertainment: Just some background on the VMS4 MIC circuit and what we're working on for a solution:

The current VMS4 circuit has 2 pre-amps which are each 20dB going to the DSP audio processor. So the total pre-amp gain is 40dB.

The solution I'm working on keeps the first 20dB pre-amp but replaces the second one with an amplifier with a -(infinity=off) to 20dB gain directly conrolled by the gain knob. So this change would have the same effect of eliminating distortion as using a 20dB external gain reducing adapter.

It is also possible to have the entire gain controlled by the front panel Gain knob, but then the noise would be much worse.

As a related note, we'll also fix the Master output so it can go much higher without distortion.

Are you happy with this solution or do you have any further comments or suggestions?

Nope that sounds like it would work!
The only question I have is how will it be implemented in my VMS4 as you are changing the hardware setup?
Rgds
Oli

quote:

Originally posted by hardwiredentertainment:
Nope that sounds like it would work!
The only question I have is how will it be implemented in my VMS4 as you are changing the hardware setup?
Rgds
Oli

+1

quote:

Originally posted by Mark Stewart (JSM):

quote:

Originally posted by hardwiredentertainment:
Nope that sounds like it would work!
The only question I have is how will it be implemented in my VMS4 as you are changing the hardware setup?
Rgds
Oli

+1

+2

quote:

Originally posted by weephillie:

quote:

Originally posted by Mark Stewart (JSM):

quote:

Originally posted by hardwiredentertainment:
Nope that sounds like it would work!
The only question I have is how will it be implemented in my VMS4 as you are changing the hardware setup?
Rgds
Oli

+1

+2

+3

+4

+5

+6 .. I had the same issue this past weekend at my first gig using both corded and cordless mics.

The board was awesome other that the mic issue!!

Hello all,

OK I got the message. I'll ask customer service to answer directly about resolving this issue for existing VMS4 users.

Elliot

cannot wait to hear the out come of this. I am guessing its going to have to be some sort of mass recall. Which will leave us all without the main part of are playout system

@Elliot
any update on this?

Hello Everyone,

We are working hard on a easy way to make your mics sound better and will have an announcement very soon. Thanks for your understanding.

many thanks - any idea of a time frame?