I have a T8s with the following problem: footage attached shows T8s with strong noise floor output when no input is present. The hiss only appears when pan is full left, when full right there's no sound.

What should I do in order to fix this? I've just updated the T8s with latest firmware, non result.

 

I have also discovered another T4s unit has the same issue, but when I pan right I have this noise and with pan left there's nothing.

Attachments

Videos (1)
VIDEO-2019-06-11-16-09-44
Original Post

Hi FGe,

Thanks for the video.

I'd like to replicate what you are experiencing.

Please tell us:

  • What is the setting of the Master Volume?
  • What are you on when you experience this?
  • What is the trim setting when you experience this?
  • Is the noise still there when you connect an input source (e.g., microphone or instrument)?
  • What are the settings on the individual channel volumes?
  • What is connected to the Master Outputs(s) of the T8S?
    • Which outputs are you using?
    • What type of cables are you using?
      • XLR?
      •  1/4 inch (6.3 mm) Tip-Ring-Sleeve? 
  • What is the setting of the input trim of the device connected to the Master Outputs of the T8S?



Thanks,

ST

Hello there,

in order to demonstrate the effect I turned the knobs fully clockwise, therefore max. gain. Demo was made on an L1-II+B2 setup, one channel used. XLR cables, no input. Didn't try with input.

The customer has complained about this kind of noise onto his recording, don't know which volume settings.

 

Thank you!

Hi FGe,

Thanks for the added information.

I've been able to replicate the noise you hear in the video, but I don't think this is a flaw with the T8S, T4S, or the L1. Let me explain.

In live sound systems (and recording systems), one of the primary considerations is the signal to noise ratio. That is: what we want to hear compared to we don't want to hear.

Every system has some self-noise, but for practical purposes we deem that noise to be tolerable if it doesn't intrude on our ability to hear and enjoy the music.

FGe posted:

Hello there,

in order to demonstrate the effect I turned the knobs fully clockwise, therefore max. gain.

You have amplified any self-noise to the maximum possible

Demo was made on an L1-II+B2 setup, one channel used. XLR cables, no input. Didn't try with input.

with no signal.

In summary, you have created this situation:  No signal/all noise.

This is not something you would do in a live performance setting. If you had connected a microphone and sung at performance volume,

  • You would have to turn down the input trim to avoid clipping
  • You would probably turn the Channel volume, and Master volume controls to about 12:00 o'clock
  • You should have set the L1 Model II Analog Input trim to about 9:00-10:00 o'clock

If you did all of these things, you should be able to get very close to the maximum usable volume from the system AND very little noise.

At this point, if you need more volume, you can turn up the Master Volume and should be able to maintain a good signal to noise ratio. That is, the signal will be loud enough that the noise is inaudible.

In loud situations where you have gaps in the signal (no one is singing), you can use the Comp/Gate - Noise Gate to shut down a channel when there's no signal.



The customer has complained about this kind of noise onto his recording, don't know which volume settings.

Thank you!

To figure out if there is a problem, we'd need to know the exact signal chain from end-to-end. 

If you have excessive noise in a signal chain, the first thing to do is increase the signal at the source (e.g., sing louder and closer to the microphone, or turn up the instrument). Then adjust the gain at the trim, channel, master volume until you have a strong enough signal to suit your application. If everything is set correctly, there should be minimal noise. 

FGe posted:

I have a T8s with the following problem: footage attached shows T8s with strong noise floor output when no input is present.

We've dealt with the noise floor above.



The hiss only appears when pan is full left, when full right there's no sound.

What you are experiencing with the pan control is normal. If you have only one L1 (or any powered loudspeaker) connected to the mixer?

  • When you pan hard to the side where the loudspeaker is connected, you will hear sound
  • When you pan straight up, you will hear sound (but not quite as loud as when you pan hard as above
  • When you pan hard to the other side, you will hear no sound from the loudspeaker


This is normal.

What should I do in order to fix this? I've just updated the T8s with latest firmware, non result.

I have also discovered another T4s unit has the same issue, but when I pan right I have this noise and with pan left there's nothing.

  • A: It sounds like the T4S was connected via the ToneMatch cable. If you connect only one L1, the ToneMatch cable connection is the RIGHT channel.
  • B: And it sounds like you connected the T8S to the Left output. 

If A and B are correct, that would explain what is happening the pan control.

Please consider inviting "the customer" to join this conversation.

Thanks,

ST

Yes, probably connected units onto different channels: T4s on the 'power' channel, didn't keep evidence which channel connected on T8s.

I'm aware of what I've done, this was only to demonstrate the effect. For recordings, imagine you have channels playing very low or not playing from time to time, where signal is absent. In this case, signal/noise becomes very low.

i'll try to get user into this topic, thank you so far!

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