Compressor on preacher lav

[buggyboy]

I've been using my compressor to good effect for several months now, but I'd like to run the theory by some more experienced sound guys.


So...

The pastor is on a lav, which means that he has at least 2 volume levels, with his head down reading a passage, and with his head up talking to the crowd. in addition to the normal changes.

The first control I can modify is the trim, and this is set according to the instructions using pfl so the mixer meter peaks at around 0db. so far so good.

However, with a compressor on the insert, the levels change. instead of trimming for 0 on the meter, I have to trim for the proper input on the compressor. I want to give the compressor a good healthy signal, but not overdrive it.

Then in the compressor, I set the threshold so that when the pastor is in "quiet mode" it leaves the signal alone. And when the pastor is in "loud mode" it activates (ratio about 4-5:1). (attack and release either auto or very fast, knee usually soft)

I'm a bit lost on the use of makeup gain. I want the low signal to pass through as if no compression was in use, while the loud signal is reduced to (near) the level of the low signal.

The only thing I can think of is that if I have to set the trim low enough to not overdrive the compressor, I tend to have a much lower level going back into the mixer. So the mixer meter shows my signal at about -30 or so. Should I use makeup gain to boost the signal up to the recommended voltage in the mixer?




I have input / output meters on the compressor, and I've been aiming at keeping the input signal from going past 0db (to avoid clipping in the compressor) and the output signal from going past 0db (to avoid clipping in the mixer). Did I miss something?



Bottom line:
What should I be aiming for on the meters (in/out on the comp, and the channel pfl meter on the mixer).



Also, recording via the line in on my computer, (reaper) I can't seem to get a perfectly flat recording...I always have some spikes. Why is that? I have an external compressor before the computer, and a compression plugin in the reaper recording chain. My method has been to use heavy ratio with a high threshold on the external unit, to knock down the highest peaks (to avoid clipping in the computer), and to use about 7:1 ratio with a lower threshold to even out the less violent variations in the plugin compressor.


thanks guys!

[waynehoskins]

The procedure remains largely the same. Set the head amp gain as you would otherwise, insert the compressor, and adjust its threshold until it is providing the desired amount of compression at the ratio you've selected. The level coming out will be less (by the gain reduction) than the level going in, so then you would apply makeup gain to return the signal to a desired operating level. The amount of makeup gain will usually be close to the amount of gain reduction under normal conditions.

I recently changed compressors on our lavs to a 266XL and spent quite a few minutes that first service working on the time constants. I picked a moderate ratio, about 4:1, with a moderate threshold such that most of the time it's operating. Fast-ish attack, but not percussive-fast, moderate release; my target was something on the order of 30/300, though these dials aren't marked.

Unless you squash the life out of it with fast attack, fast release, high ratio, you will still have relative peaks, dynamics, they just won't be as extreme as the source. The time constants determine everything. If the attack is too fast, it sounds lifeless; too slow and it reacts after the objectionable part of the peak. If the release is too fast, it's pumping all the time; too slow and his audio drops down for a time after a peak.

It almost sounds like your compressor is mismatched to the insert level. What console and compressor are you using?

[buggyboy]

Compressor is a behringer mdx 1600
mixer is a Mackie SR24-4

Your comment made me look up the manual for the compressor. I can't tell until the next time I'm near the unit, but there is a setting on the back for operating level...-10dbu or +4dbu... That may well be set wrong.

According to the mackie manual the insert nominal send and return level is 0dbu. Clipping begins at 22dbu (oh how I wish we could just use voltages, oy).

I would guess I should have the compressor set at +4 rather than -10.

Would the compressor being set at -10 explain what I'm seeing?



About the makeup gain, does it increase gain by a set amount, or does the amount of gain vary moment by moment based on the amount of attenuation caused by compression?


In a slightly different direction...

I've read just a bit about serial compression, and it sounds useful. It seems that compressor/limiters are designed to make use of this technique. The limiter killing the big peaks, while the smaller dynamics are dealt with by the compression section. This should be capable of outputting a very flat signal, right? which is exactly what I want in the record path.

Electrically which comes first? I would have thought the limiter would process the signal first, then the compressor. But the controls are arranged so the the limiter control is last. And based on the answer, which should be set first, the limiter or compressor?

If my goal is a flat (that is, very small peaks compared to the average level) output to the recording computer, what is the setup procedure?

Thanks again,
David

[waynehoskins]

Originally Posted by buggyboy

Compressor is a behringer mdx 1600
mixer is a Mackie SR24-4

Your comment made me look up the manual for the compressor. I can't tell until the next time I'm near the unit, but there is a setting on the back for operating level...-10dbu or +4dbu... That may well be set wrong.

According to the mackie manual the insert nominal send and return level is 0dbu. Clipping begins at 22dbu (oh how I wish we could just use voltages, oy).

I would guess I should have the compressor set at +4 rather than -10.

Would the compressor being set at -10 explain what I'm seeing?

That would definitely explain it. -10 is consumer level, while +4 is pro level. If it's at -10, you have to attenuate a lot going into it, and then the level coming out is crazy low.

Originally Posted by buggyboy

About the makeup gain, does it increase gain by a set amount, or does the amount of gain vary moment by moment based on the amount of attenuation caused by compression?

It's a fixed amount. Most of the time I use about 6 dB of makeup gain, because that's what it usually takes to bring the compressed signal back to unity on the console.

Originally Posted by buggyboy

In a slightly different direction...

I've read just a bit about serial compression, and it sounds useful. It seems that compressor/limiters are designed to make use of this technique. The limiter killing the big peaks, while the smaller dynamics are dealt with by the compression section. This should be capable of outputting a very flat signal, right? which is exactly what I want in the record path.

Electrically which comes first? I would have thought the limiter would process the signal first, then the compressor. But the controls are arranged so the the limiter control is last. And based on the answer, which should be set first, the limiter or compressor?

I think the peakstop limiter is last. It's a safety net more than anything, to catch very fast pops. I think the only one I've heard is the limiter in Behringer's Multicom (which I presume would be similar to the circuit in the Autocom you have), and it's not nice when it operates. Take that back, I've heard the limiter on Presonus's Studiolive once too. It's not nice either. I don't think any of them are. They're a "catch the signal before it goes over this threshold, no matter how it sounds" circuit, a last resort. I'd be tempted to leave it out unless there were lots of pops that were faster than the compressor attack time.

Originally Posted by buggyboy

If my goal is a flat (that is, very small peaks compared to the average level) output to the recording computer, what is the setup procedure?

To do that, you'd probably need to gave gain reduction virtually the whole time. Low threshold, moderate ratio, fast times. You might need to engage the downward expander during silence to prevent feedback.

Let me suggest another configuration, one that probably sounds more natural than a very flat signal:
Low Contour (compressor sidechain high-pass) in
Interact Knee (soft knee/Overeasy) in
Auto Time out
Threshold -10 dB
Ratio 4:1
Attack 20-30 ms
Release 200-300 ms
Output (makeup gain) 3-6 dB

You may or may not need the downward expander or de-esser. If you do need the expander, set the Release (longer release time) switch in and the Gate switch out.

You might try the auto times as well, see how that fares. Auto times usually are at least half decent for speech and vocals.

[pdc]

If you are inserting that compressor into a Mackie, you should be using -10dB.

Use your ears. The numbers on the plate of the front panel are off. WAY off in some cases.

I would not use a limiter on a lav. I would use some light compression, no greater than 4:1 and ride the fader from there. You also have a tone difference, not just a volume difference when the pastor speaks into the mic. I would look for a used multiband compressor that allows for compression of specific frequency bands, use read up on sidechaining and use an EQ to compress those bands in the lows/low-mids.

[buggyboy]

That would definitely explain it. -10 is consumer level, while +4 is pro level. If it's at -10, you have to attenuate a lot going into it, and then the level coming out is crazy low.

I will look tomorrow night, but that describes my symptoms. I'm hopeful that's the issue.

For makeup gain, I'm guessing the setting procedure would be comparing the mixer meter with the compressor in about out of the chain, aiming for the same average level. Or is there another way?

I'll leave out the limiter in light of your experiences. thanks for the input.

The root reason I've been trying to send a flat signal to the recording computer is so I can normalize the entire file to increase the volume level when the file is played in a cd player.

Perhaps there is a better way to achieve a standard volume level in the final audio file. I'd like the file I burn to the cd to play back at a level neither too low nor too high. any thoughts?

I've noted your suggested settings and I'll give them a test as soon as I can.

@pdc: thanks for the reply... What makes you say that -10dbu is the right setting?

I have thought of multi-band compression, and it sounds promising. But I'm still learning how to use one channel for now.


Thanks again for the help
Ciao!

[buggyboy]

Quick update:

The switch on the compressor was set to -10dbu. I did a test with it in the +4 setting and I think it works better.

I had been starting to detect, just at the edge of hearing, a little distortion from time to time, and this may have been the culprit.

Now the levels with the compressor out and in are nearly the same. So I think this solved my issue.

My lav output (shure 839, phantom powered) is still low, but it is the nearly same with or without compression now, so I'm happy.

Gracias!

[buggyboy]

Update after a full sermon last week.

I got really good sound with the settings below.

expander: -30 - -35
threshold: ~0
ratio: ~6:1
attack: 0.3 msec
release: ~.200 sec
makeup: 5

Always more to do, but little by little, it's working.
thanks again.