Some Compression questions

Hi all -

I know there are no cut and dried answers, but I was just wondering how to use those two things the best.

I did a little experimenting, Compression 101, last night.

I have a piano that I compressed using a Fairchild 670. It’s pretty soft at the beginning, pretty loud at the end. I kept the same compression throughout. I turned up the input so that at the loudest bits at the end, the VU meter in the Fairchild was just barely going into the red. Then I adjusted the compression (“Threshold” knob, if I remember correctly) so at the loudest bits at the end had about -6dB of GR. I didn’t ride that knob at all. Then I turned up the output so that the loudest bits were just barely in the red.

Question 1: Was that a reasonable way to go about compressing? I didn’t turn the compression way up at the beginning, because I wanted some dynamics.

I fed all that to an LA-2A, ratio of 20 - the idea was to use it as a limiter, just to take care of the peaks, so that I could have a hotter signal coming out of the previous stage (the Fairchild) without running my master bus too hot. I “gainstaged” the input and output using the LA-2A VU meters the same way as the Fairchild.

Question 2: When using a limiter like this, how much gain reduction does one usually expect to see, and how often should there actually be any gain reduction? Should I only see the GR VU meter move rarely, and only a few dB? Or …?

The final sound turned out OK to this newbie’s ears, but I just wanted to hear how you expert guys and gals might use the limiting amplifier in these circumstances.

Thanks much!

The question to question 1 would be, just what is the piano part playing along with? solo? some violins? or up to a heavy band? so it all depends.

Question 2:- personally I wouldn’t use a La2a as a limiter, although it may work in your circumstances. The attack and release parameters are not user definable and are in fact dependent on the amount of gain reduction and other things. Maybe the 1176 would be better

Thanks for your reply, Split!

Sorry, it’s accompanying solo voice. Not especially a soft ballad, but not a real hard or loud song either.

OK, thanks. Let’s say you were using the 1176 … the question is actually - with a well-compressed signal feeding it, what is the job description of the limiter … gain reduction just occasionally, and not much of it to speak of when it does, or more active than that?

I know I’m likely not using the right terminology :blush: , I hope I’m getting my ideas across somewhat …


Very hard to tell without hearing what is going on. But for Piano I would have thought 6dB of reduction on the louder bits (piano) would be a bit much, but then it depends on how the voice is sitting with the piano and how much if any compression the voice has (a good application for the La2a). Also if you can hear any compression being applied, then it’s too much, if not then it’s probably fine!

Limiting for loudness is also one of those things that has a vague answer, assuming a fast attack and fast release then, on your material, if you are getting minimal gain reduction then there’s not much limiting going on and the limiter will be acting more like a gain control. Its a question of how much dynamic you want? if you feel the overall dynamic is good then you should just increase the gain untill the peaks are near 0dB without limiting. If you feel the need to increase the loudness then you could use a limiter to start biting into the peaks untill the desired overall loudness is achieved. Again if you can hear it working then it’s too much.

The purist in me says don’t use any compression or limiting and let the dynamic of the performance rule. But that entirly relies on the skill and performance of the piano player and singer.

Thank you again Split, for a very helpful answer!

I’m using this more as an exercise in how to compress/limit … it’s just a rough demo of voice/piano. Your answer I think is giving me some nice insight into the process. Can I follow up with another question or two, Professor? :slight_smile:

^^ How do you determine whether “the peaks are near 0dB without limiting”? Listen for distortion, look at waveforms, use the “normalize” function, …? I did the latter (normalizing), but as I did, I was wondering if that was the right thing to do.

As the limiter just “starts biting into the peaks”, what would be the response of the gain reduction VU meter? Would it just start to become barely active, most of the time not moving because there are no peaks except rarely? I do hope one day to be able to tell this by listening only, but at least for now the VU meter is a handy tool for me.

Thanks again, Split!

Again difficult questions to answer with any degree of certainty.

Fast peaks may well not produce any action on a gain reduction meter, and if using a standard limiter the attack setting will have a major bearing on the response.

To say use your ears is an easy way out! but it really just takes time playing around with subtle to extreme settings to get a feel for what is happening.

Using the peak metering to have a look at the affect pre/post compression/limiting.

The uad card can also run a limiter designed for loudness, it’s a kind of look ahead brick wall thing that will catch even the fastest peaks.

When making a track louder it is normal to refer to a VU meter rather than a peak meter as this will show a better relationship with the overall volume/loudness.

Ok, thanks, Split. Back I go into the lab …

On this slow time musically for me, I have done a lot of experimentation with compression and limiting. I found that I get the best mix by using almost all my compression before the master bus. On the master, I use a multiband but all ranges are bypassed except the low-mids, which I squash a little more. It really helps bring the music out.

I also use compression on the individual tracks, attempting to get the best out of each track by getting each of the faders as close to nominal as possible (0db) without the master bus doing massive limiting. And my master bus is pretty much always set on 0db. It took ALOT of playing around to get close… and I still have a ways to go, but I’m seeing something for the first time that seems to be working for me.

I’m using this more as an exercise in how to compress/limit … it’s just a rough demo of voice/piano. Your answer I think is giving me some nice insight into the process. Can I follow up with another question or two, Professor? :slight_smile:

You can look at the meters in your track or whatever plugin you’re using. For that particular track. You set it so that the meter just hits 0db on the VAST majority of peaks.

If you can picture the track meters without limiting on them, the gain reduction meter would be inversely proportionate to them. Personally, I don’t use “full on” limiting, where there appears to be no movement of the track meter and its just buried at 0db… I’ll play with the track levels until I get limiting…err… about 70% of the time on choruses, and 50% of the time on verses (very loose estimate). This still provides a bit of dynamic range.

But it takes a ton of playing around. Seriously! I’ve had to shift > select all my tracks and pull them back more times than I can count so I’m not smashing the hell out of my songs. Once you get it, you’ll see that it’s a very delicate balance, but you’ll start to feel it when you’re close.