Avid Matrix Mic Pre clicking

[its2loud]

Posting a question to any users of the Avid Matrix with the A/D card with mic pre option.

Is anyone experiencing clicks or pops when increasing or decreasing the mic pre gain? We have four units that all experience this issue when adjusting.
Wondering if this is intentional (not sure why) or a circuitry defect.

Thanks.

[LDS]

Originally Posted by its2loud

Posting a question to any users of the Avid Matrix with the A/D card with mic pre option.

Is anyone experience clicks or pops when increasing or decreasing the mic pre gain? We have four units that all experience this issue when adjusting.
Wondering if this is intentional (not sure why) or a circuitry defect.

Thanks.

I haven't used the Matrix, but clicking is pretty common in a lot of devices when increasing gain. I'm pretty sure the Avid Pre does the same thing, as do a whole slew of digital mixing desk preamps, etc. From my understanding it is the result of the digital gain control, which is incremental rather than continuously variable like in fully analogue circuits. The PGA2500 mic preamp chip is a prime example, where the clicks can be minimised by design but not necessarily removed entirely. It appears in a whooooole lot of audio interfaces being made today.

Even in higher end designs, to achieve high levels of matched digital gain control, relays are pretty commonly used. It wouldn't surprise me if the clicks and pops are just a byproduct of the design.

[EddieJones]

Yes, it's the relays. This is to achieve the best quality we can. (You shouldn't be adjusting the gain whilst recording)

Accurate Mic-pres with relay gain system
The MTRX mic pre’s have an outstanding performance with an equivalent input noise below -130 dB. A resistor-based gain step circuitry with relays ensures that no un-linear distortion is added to the sensitive microphone signal when amplified. Each 0.1 dB gain step is digitally compensated for an inter channel accuracy of 0.1 dB.

[its2loud]

Ha ha. Thanks Eddie. Not sure if that’s good news or bad news. So, I’m not supposed to adjust the gain on the fly when recording ADR and the actor goes from screaming to whispering in a scene? Is there no way to fix this gain structure so it doesn’t happen? Riding mic gain is normal part of record dialog for animation or ADR.

[EddieJones]

This is a standard design in high-end mic pres. It has 130db headroom...you could use the fader.

[its2loud]

Fader? I’m using the S6 fader to adjust gain now. Just trying to figure out the best way to minimize clicks. I get the circuitry and the relay factor.

Please clarify what you mean by “use the fader”.



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[EddieJones]

You would set the Mic gain so that the absolute Max signal hit 0db (or -1) digital. Then use the fader to ride gain for cues. With some compression/limiter if needed.

[EddieJones]

If there were obvious scenes where you knew there was going to be whispering etc then you would preset the Mic gain before the take.

[its2loud]

Are you referring to using an aux fader in ProTools? If so, I get that. That’s how we record now. But when you’re using compression on said aux feeding an audio track and want the incoming signal to have more gain to the aux, sometimes you need to adjust the pre gain. Just a matter of logistics. Not arguing semantics here. Just want to know if reducing the clicks is possible. I get the pre has tons of headroom. That’s great.

Every analog mic preamp in existence did not exhibit clicks and pops when increasing or decreasing gain. Not sure if that makes it acceptable for
A/D preamps to exhibit opposite behavior.

Appreciate your input.


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[its2loud]

Originally Posted by EddieJones

If there were obvious scenes where you knew there was going to be whispering etc then you would preset the Mic gain before the take.

That’s not always an applicable way things operate in the real world unfortunately.


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