Really struggling with compressor - limiter
 

Hi Guys

I've posted before seeking advice on setting up a compressor in a small video studio and even with your kind responses and advice sought on help guides elsewhere, I'm struggling to get the desired output.

We film video interviews, usually a presenter and guest, sometimes 2 guests - but it's all speech based.

We have this Behringer Compressor - I know it's far from the best available, but sadly its the best the budget could stretch too!

Basically, I jsut want to stop it peaking - which I thought the limiter would help with - but I'm not sure if I'm not pressing the right combination of buttons - but it just never seems to kick in so when there's a laughter or a loud moment, we get regular audio peaks which sound very rough!

I also hoped it would help in bringing some uniform to the audio in that it boosts so it doesn't fall too low or reduce so it doesn't peak - a happy medium - as at the moment during recordings we can end up with some real low points and then high points.

I'm really not lazy! I've tried for months to get it working effectively, is anyone able to help out in a little more detail about what buttons should be pressed, and what knobs turned?!

Would be extremly grateful for any help & advice.

Daniel

Re: Really struggling with compressor - limiter
 

Crank the 'Ratio' up to 10:1 (or higher or to infinity if needed) and adjust the 'Threshold' so it engages just on the peaks. Set the 'Attack' around 5-15ms and play with the 'Release' to make it the least noticeable, or try 'auto' release if it has it.
The thing is to get the comp/limiter to do what you want w/o hearing it working... unless you want an effect.
You will probably want to leave the Exp/Gate off or to a minimum.

Re: Really struggling with compressor - limiter
 

Try this instead of a brick wall limiter.....

Send tone through your desk at 0vu (compressor in bypass) check the entire system to VTRs, recorders etc.
Then lower the level to -3 on the meter (now switch IN the compressor) and adjust ratio to about 4:1 - 6:1 then adjust the threshold so the first LED comes on [this give you the activation point] then raise your tone back to the original setting and then adjust the output of the compressor to give the 0vu again to maintain unity gain in the system.

This set up gives a medium / light compression over the peaks of the audio and make it easy for your operator to keep levels under control. If the talk show was quite heated with lots of shouting or sports commentary then you might like to increase the ratio level to 10:1 but it is rare you would need to go that hard.

Re: Really struggling with compressor - limiter
 

How do you connect it in your chain?

Anyway, my advice would be to ditch that noisy piece of crap and compress in post but if you absolutely want to use it, first tell us how it is connected in the first place.

Re: Really struggling with compressor - limiter
 

Hi Guys

Thanks for the replies so far.

Sorry I should have said what the workflow was, audio comes from a Yamaha MC124C mixer, into an audio delay box then into the compressor with the output of this going through an audio distributor.

From what I've read, the compressor I think should be going into channel inserts in the mixer? But wouldn't we then need another unit to cope with the 3rd mic.

Plus I wanted it to control the overall output volume and not just those microphones which have a channel insert.

Re: Really struggling with compressor - limiter
 

Also, the mixer itself does have a built in compressor - just one knob going from 0 to 10 - can't say I notice much difference when I adjust this.

COMP Control
Adjusts the amount of compression applied to the channel.
As the knob is turned to the right the compression ratio
increases while the output gain is automatically adjusted
accordingly. The result is smoother, more even dynamics
because louder signals are attenuated while the overall level
is boosted.
Avoid setting the compression too high, as the the
higher average output level that results may lead to
feedback.

Re: Really struggling with compressor - limiter
 

Put it in the master output rather than the indervidual channels, this will then be active for everything that goes through it.

Re: Really struggling with compressor - limiter
 

Why a delay?

Ty Ford

Re: Really struggling with compressor - limiter
 

Indeed, mention of the delay creates far more questions about your workflow than it answers.

Perhaps the built-in compression in the mixer doesn't seem to do much because you haven't got the channel gain adjusted properly? How much do you know about gain staging and setting levels at all points in the signal chain?

How much time have you spent (outside production hours) experimenting with the equipment and familiarizing yourself with all the features and controls?

Re: Really struggling with compressor - limiter
 

The use of delay on the O/P of an audio desk is quite common these days. It is to match the audio to the video, most digital video switching desks have 2-4 frames delay in them.
If there is a camera on mini link for a production that also will need it own delay unit to match the signal, Delay for audio can be a complex issue with huge problems if you don't get it right.
Its impossible to fix in post..... If its going out live

Re: Really struggling with compressor - limiter
 

Hi Guys

Like Brian says, the delay is just caused by the vision mixer we use - so we have to use a delay box to bring the audio in line with the video.

I've become quite familiar with the features and controls of the desks and compressor, to be honest my field is video - but on this job we have to do everything really, so no sound supervisor! So I've been trying to learn and research as much as I can.

With adjusting the channel gain properly - would I be totally off the mark in trying have all the faders in line at 0 and using the gain to bring the level on par with each other?

Daniel

Re: Really struggling with compressor - limiter
 

Here is a real life situation of complex audio video delay.....

RF camera to video desk [3 frames] delay > to > Video desk [2 frames] delay > to > big screen [2 frames] delay..... So from the camera lens to screen [7 frames] delay, so the audio is now 7 frames (more than 1/4 second) IN FRONT of the picture, easy you say just delay the audio 7 frames?

BUT.....

You now have an inexperienced young girl singing the national anthem to a backing track off CD at an indoor sporting event which is being shot in close up from that RF camera..... Now you've got big problems as people can't sing hearing themselves back 1/4 sec in delay. The only thing that could be done is supply her with VERY LOUD in ear monitor monitor system (without delay) and make sure she doesn't look at the video screen at ANY cost, AND also feeding the broadcast truck with a NO delay mix

Trust me getting your head around the problem and with the appropriate calculations to convert frames to m/s and get it up and working on a Yamaha LS9 with the correct feeds going to the right places took more than a couple of minutes.

The digital age has brought some wonderful things both audio and video ....... BUT

Re: Really struggling with compressor - limiter
 

Hi Guys

:( ... thanks again for your replies and advice but had a real hard time of it today as we were filming. I tried some of the settings posted on here but experienced some of the most horrendous screeching when levels peaked.

Here are the exact settings I've got on the compressor at the minute, there's so many buttons - most not pushed on as I'm not sure if there relevant to what I'm doing, but I did try most of them in various configurations plus experimented with the attack and release but to no real change in output.

EXPANDER / GATE
Trigger - Off
Gate - Off
Release - Off

COMPRESSOR / LIMITER
Threshold - around -30db
SC Mon - Off
SC Ext - Off
Ratio - around 10db
LD Contour - Off
Attack - 5 to 10msec
Interact Knee - Off
Auto - tried both on and off
Release - tried various
Tube - Off
Enhancer - Off
Output - 0db
I/O Meter - Off
In/Out - Off

DE-ESSER
Level -
Male - Off
In/Out - Off

PEAK LIMITER
Level - 0db

I had all the mic levels setup nicely and everything is fine most of the time, but it's when there is a laughter or roar and the levels peak on the mixer.

What I really don't get is the Peak Limiter - at the end of the day I just want to cap all the audio to stop it re I've tried adjusting this knob but when ever it does light up as being active, I never notice any difference in the output.

Is my problem that the audio is peaking and distorting before it leaves the audio mixer to go into the compressor, by which time its too late to repair the damage?

Re: Really struggling with compressor - limiter
 

What do you mean by "screeching"? Are you doing sound reinforcement through loudspeakers to an audience or something? Is this acoustic feedback? Or is it some other sort of circuit instability? Perhaps your equipment is damaged or otherwise not functioning as designed..

This may seem like a dumb question, but if the compressor never seems to do anything, are you sure it is connected properly? Do you not see any indication of a signal on the compressor display LEDs? You really need to spend some "rehearsal" time with the equipment before the "heat of battle". We are assuming that you have the user manual and you have gone through it and understood it (or else you would have asked clarifying questions here).

Re: Really struggling with compressor - limiter
 

Hi Richard

Sorry - me saying it isn't doing anything - I mean output wise, it doesn't seem to improve it - the unit is definetly working as it lights up all over the show!

By screeching, it's just the audio peaking / clipping.

When we hit the highest peaks, the level meter on the desk maxes out into the red for clipping - what I'm starting to think is that tha audio is distorting before it's leaving the desk, and I doubt the compressor is going to polish that up is it?!

Hence wondering, if its recommended to use the compressor on the channel insert.