Guys, the keys to a good mix? Can anyone explain frequencies to me?

[kev]

Hi guys, My mixes arnt going really how i would like most of the time in terms of clarity. When i listen to Andy's work, everything is so clean and clear, and i would like to get as close to this (just like everyone else) with my current gear setup. I think my main issue is sorting out all the different instrument frequencies, as all i tend to do is stick everything together in a mix with NO frequency adjustment at all, as i dont really know what i am doing. I do a bit of panning at the moment, but im not too hot at that either. I know as much as kick, snare and bass guitar going centre mix, toms and cymbals being spread from L50 to R50 and guitar tracks on the outside. This is reffering to a pop mix tho

I guess what im looking for here is some advice on how to split a mix up with all the typical metal band instrument features in terms of panning and mainly frequency adjustment. Even a pointer to a site which could help me develop better technqiue would be ace.

I realise this is going to come far from overnight, but here's a cyber pint if you can contribute at all!

Kev

 

[chadsxe]

My oh my....

There is no answer to this question....people have to realize that no one can answer this question without hearing the material in contexts.......it really takes practice and training of the ear.....overtime you will start to be able to hear what is going on in commercial mixes.....my best advice to you is to sit down with an album you are in love with and listen.....I mean really listen.....list to the guitar....not the mix of the guitar and bass....listen to the bass....no the mix of the bass and the kick....listen to the vocals....and were they fall on the mid freq range....you have to really develop an ear and start separating this stuff in your head.......there is a reason why Andy is who he is and why we are all hear......because he has developed a great ear.....sure he has the great equipment to use but like the saying goes "you can't polish a turd"......if I were to stick you in his studio with all the same advantages you might be able to pull off something decent but not great.......it really does take practice.....practice with your ears....practice with your gear....practice with your listen environment.....let me guess your mixing on some computer speakers....I am sorry but this is just not going to work......believe me MONITERS MAKE A DIFFRENCE...a huge difference....god I can go on and on....

"The most important part of a record starts before you even hit record"

 

[006]

Well, there are some things we can help him with. Frequencies, not so much, but help with seperation, yes.

For metal, the drums have to have a certain sound, they cannot sound natural like on rock or pop music. Why? Because of the distorted guitars. If there weren't distorted guitars in metal then the kick drum would not need a click to it. The toms would not have to have all that slap. And the snare drum could sound more natural and boxy. But because we use distortion on our guitars in metal music, the drums have to accomodate.

That said, the guitar is a MID instrument. It has been since the first time anyone ever made one, and will always be- a MID instrument. You must keep this in mind. The major area of great guitar tones comes from the mids. I have explained this before but here we go again:

Drums have the highs and the low taken care of.
The bass guitar has the lows and low mids taken care of.

So where else is there for the guitar tracks to be? In the middle. Yes, guitars have highs and lows just like everything else, but the mids are what make the difference. You cannot compete with the high end that a drum set's cymbals can pump out. You just can't. So you need to let them take care of their business. The low end from a drum set cannot be faught with either, as the drum set is suppose to be felt, and it works. When you make the guitars have those low frequencies like the drums, they get muddy. The bass guitar comes into play here.

The bass guitar is going to handle the extreme low-end of the spectrum. It is felt as well as heard. It pumps out low frequencies (40Hz, etc.) like nobody's business. The thing is, thats so low that you honestly do not *hear* that part, but you *feel* it. You can't hear 20Hz. You feel it. So do the speakers. When you are adding lows like that to the guitars, it's just making them muddy.

As far as guitars are concerned, you need to roll off 80Hz and below, and typically 12kHz and above, this varies though depending on the application (guitar used, amp used, cabinet used, mic used, type of music, etc.). 80Hz and below because the kick drum, toms, and bass guitar need this space. 12kHz and above (variable) because the high end of the kick drum, snare drum, toms, and the ever loving cymbals/hi-hats need this space.

Most of the time, the toms on a recording for metal music have very little mids. They have to have a slap and a certain low-end to them. Taking the mids out welcomes this sound. Also true for the kick drum. You take the mids out of a kick drum it is literally automatically easier heard over metal guitars. You add the click (high-end) and keep the low-end tight and puncy, and you have yourself a metal kick drum that cuts through those guitars. The snare drum is suppose to have a "pop" to it, very tight. Taking some mids out, but it varies on the snare drum and the player, helps with this, as well as smashing it with a compressor. Cymbals and hi-hats can be rolled off at like 800Hz sometimes, this makes them soft sounding, especially the china crashes...those have a lot of lows that just irritate everything in the mix. Hi-hats typically have a bit more low-end than the overheads...it's just how you do it. Or at least how I do it anyway.

The bass guitar and the guitars need to be seamless. The bass guitar needs to pick up where the regular guitar leaves off, and vice versa. They need to sound like *one* instrument. This is easier said than done. Most of the time it's difficult because the players are not tight. The tighter they are, the easier this is accomplished. The bass guiatr also has to fight with the kick drum and toms of a drum set because of the low-end.

The key really is finding out every peice of the picture's place. Everything needs it's room to breathe. The more everything is fighting with each other, the more muddled and horrible it will sound. You need to find everything's area in the spectrum, and make every peice work together to create the big picture.

I hope that helped in some way. This is coming from my experience and everyone that knows, knows that there is no *perfect* mix. Even if it's Andy's . What it comes down to is making it all work together. This is not a perfect science, and it's different according to a lot of variables, the room you are in, the musicians, the picks they use, the drumsticks the use the STRINGS they are using, the temperature in the room where the guitar cabinets are, leaving the amp on for warm-up 10 more minutes rather than 10 less minutes...the angle of a microphone, one more little dB of 2,000kHz...I mean...there's a lot of shit that makes a HUGE difference.

Check out Noise 101 for tips directly from Andy involving every peice of the band. Good luck.

~006

 

[Brett - K A L I S I A]

Another boring day 006 eh ? ;p

 

[chadsxe]

Another boring day 006 eh ? ;p

Hahaha....he seems to be having a lot of those these days....

 

[chadsxe]

On that note...

Generally the mark of a real noob or amateur and his mixing abilities is the low to low-mid range. More often then not people associate these big bottom ends with huge chugging guitar riffs strictly with the guitar. It is amazing how many people think that this 80 cycles and below felling you get from a well mixed album is from the guitars. Like I said before you really need to know what you’re going after before going after it. Try and find albums were guitars are soloed at different passages. Shoot try and find album were all instruments are soloed at different points. The point I am trying to make is what you hear is not always what you think it is.

On another note......

Don't really on the mixing phase to make things right. Especially with eq. The closer you are with tracking the better off you going to be in the end.

 

[Black neon bob]

006.. good job on the explanation!

Now, if i may ask this in this topic, how much would you all rate input over mixing abillities?

Input being anything that's recorded.. guitars, drums, bass, etc..

and mixing being, well.. making everything fit in together with plugins/hardware to make sounds shine..

Which one is more important?

 

[~BURNY~]

Input (including playing and assuming there's no sound replacement)=85% of the job

 

[Brett - K A L I S I A]

Which one is more important?

None. Or should I say both. , you get the idea

 

[Genius Gone Insane]

Kev,

One mistake I made early on was EQing when I should have been compressing. And +1 for what 006 said, even though that guy has way too much time on his hands.

 

[chadsxe]

006.. good job on the explanation!

Now, if i may ask this in this topic, how much would you all rate input over mixing abillities?

Input being anything that's recorded.. guitars, drums, bass, etc..

and mixing being, well.. making everything fit in together with plugins/hardware to make sounds shine..

Which one is more important?

Depending on the music I would say it is diffrent for styles and instruments.....

But none the less I still fell like it is 90 percent of the whole picture......Espically if we are factoring in playing ability.

As far as my instrument comment goes. Well think about it. With drums we have the every so bueatiful thing called sample replacment. We don't like something bam find something we like and replace it. Also timing can be adjusted and so forth. We also can get away with a lot of stuff as far as the bass is concerned. Guitar and vocals on the other hand are all about what happens before that Red button is pushed.

 

[Salvation 13]

Here's a pretty good tutorial to eq. Remember that these are just quidelines, though. http://www.computermusic.co.uk/tutorial/eq/1.asp

 

[006]

Yeah, lol, another mix day here. I type very fast too, so it's *that* long to me. And I like what Genious brought up, that he, early on, was trying to eq when compression would have done the trick. I too did this when I was first starting. But as time goes by and you learn by *experience* how to actually use compression, you see it's many uses. There are a lot of times that using band compression (such as the Waves C4 plug-in) instead of trying to actually cut out something works out much better. Like Andy's usage of it on guitars. Instead of literally cutting out the frequencies, he's compressing them, so they are still there, but they don't dominate as much anymore. If you cut that area instead of compressing it, then you might thin out the guitars too much and then you start fiddling with the other frequencies trying to bring back the life of it and you eventually end up with a mess. Compression, gating, limiting, and eq'ing really requires someone to bring an "A" game as far as knowing when to use what and how to use it. One can only develop the ear for the ques with experience.

~006

 

[kev]

Jeez, just got back from a bit of a storming gig here tonite and my ears are still ringing an hour later... time to revisit that ear plug thread for sure. Its 2am too, but im pretty addicted to this great place! I have to say many thanks you guys, especially 006. Im surprised to get some good response to such a noob post. Im gonna re-read in the morning as there is a hell of a lot of good info here, but i think what has been discussed is certainly hitting the nail on the head. Its just that idea of sperating the instruments as much as possible so they each have their own distinctive place there in thr mix and can be heard with clarity. When using black album esque guitars in a mix, should the bass guitar do the work? I hear guitar sound can rely a heck of a lot on the mids, but scooping them out i guess can make it much harder to deal with as the guitar begins to occupy frequencies it ormally wouldnt???

I dont know if what i said made any sense, but hey what the hell

Thanks again,

Kev

P.s.

006 and Chad, do you guys have any recent recordings i could have a listen to?

 

[006]

When using black album esque guitars in a mix, should the bass guitar do the work?

Yes. The bass guitar should deliver that low end. If you notice, sometimes it is a little hard to pick the bass guitar out. This is partly due to them playing very tightly. But also because it was engineered (mixed) the way we've been discussing, where the bass guitar picks up where the guitars leave off and vice versa. It ends up being one instrument. However, the seperation is still there, since the bass guitar is straight up the middle, and the guitars are 100% L/R.

I hear the guitar sound can rely a heck of a lot on the mids, but scooping them out i guess can make it much harder to deal with as the guitar begins to occupy frequencies it ormally wouldnt???

Precisely. The guitars *are* the mids of a mix. So scooping it's fundamental area only makes it fight with the other things that are already in there positions.

Im surprised to get some good response to such a noob post.

Aw cmon kev, you've been here longer than I have. And this is not a noob question. Really, you are just starting out with your recording "career", everyone needs advice in the beginning, and even if they are seasoned pros, everyone needs tips, tricks, advice, and general words of the wise every once in a while.

~006

 

[006]

To add another note...

My boss is a better engineer than I am. I mean, he's got years of experience more than I have. But even still, there have been a few times when he's asked me a question about something, or he's been getting a hard time from something in a mix, and my experience has allowed me to help *him* out. Very often though, it's the other way around, hehe. But when those times comes when I can answer *his* questions or help *him* out with a mix, it feels really good. It gives me a sense of accomplishment every time, like I just scored the last second shot and won the game, lol. You too will, in time, get to that point where you are on here, or in a studio (hopefully ) and you can answer someone's questions, whether they are pros or amateurs.

~006

 

[kev]

Yes. The bass guitar should deliver that low end. If you notice, sometimes it is a little hard to pick the bass guitar out. This is partly due to them playing very tightly. But also because it was engineered (mixed) the way we've been discussing, where the bass guitar picks up where the guitars leave off and vice versa. It ends up being one instrument. However, the seperation is still there, since the bass guitar is straight up the middle, and the guitars are 100% L/R.



Precisely. The guitars *are* the mids of a mix. So scooping it's fundamental area only makes it fight with the other things that are already in there positions.

Aw cmon kev, you've been here longer than I have. And this is not a noob question. Really, you are just starting out with your recording "career", everyone needs advice in the beginning, and even if they are seasoned pros, everyone needs tips, tricks, advice, and general words of the wise every once in a while.

~006

Thanks a lot man. Later on tonite, im gonna have a go at a mix, and i'll see what happens. The reasons listed are hopefully gonna help me get rid of some of this mud.

 

[chadsxe]

Key....I know were you are and we all started there......I recalled when I was just starting out I would gather all the information I could and put it into one doc.....well I happen to find the doc and I am going to post a whole bunch of this shit for you to read....I am shure METALHEAD28 will recgonize this stuff...

WARNING: These are not my work......some of this stuff is legit and some sucks....but all of it will give someone who is just starting out a lot of help......if you need to know who wrote let me know and I will get you in contact with them....

 

[chadsxe]

MIXING

This is my little mix method:

1.) First thing listen to your recorded material and make some decisions. What needs to be up front? What needs to be in the background? What are the important parts of the mix? Have you recorded everything you need in a clear, high quality manner?

IF YOUR RECORDED TRACKS AREN'T UP TO SNUFF GO BACK AND REDO THEM!

Nothing slows a mix down faster than tracks that have a lot of issues. If it's noisy, pops, bad performance or whatever you owe it to yourself to fix it before you mix it.

Unless you are getting paid by the hour you don't want to play the "fix it in the mix" game. Trust me, I've polished as many turds as a toilet at an overeaters anonymous seminar, and it is never fun. You will kick yourself and end up re-tracking it anyways, so why wait?

2.) Set levels manually for a rough mix in **MONO** (don't stereo pan yet). Don't touch any eq or compression at this point. KEEP IN MIND THAT YOU SHOULD MIX AROUND YOUR *VOCAL* LINE OR MELODY (if an instrumental song). At all times remember that songs are to sell a vocal performance and everything should be subordinate to it.

KEEP IN MIND MIXING IS EASIER IF YOU START WITH THE "CORE" ELEMENTS OF A SONG AND NAIL THOSE FIRST.

Thus, start with the main percussion (which may be all of it), the bassline, the main melodic instruments, vocals, background vocals, primary guitars--anything that is the strong parst of the song. Things like background noises, samples, special effects, random noises and the like should be *MUTED* and put on the backburner until after you complete this entire process.

The reasoning is that if your core material sounds great, you can fit the 'support' stuff *around* it and the song will still sound good. After all, it is bassackwards to have the greatest sounding pad that just rules if the vocals and drums are totally buried by it.

Thus--MIX FROM MOST IMPORTANT ELEMENTS TO LEAST. LESS IMPORTANT STUFF MUST WORK AROUND MORE IMPORTANT STUFF. THE VOCALS ARE ALWAYS THE MOST IMPORTANT ELEMENT.

3.) Once you've gotten a rough mix going on, listen to it again and note any deficiencies--is the low end tight? Is it muddy? Is something that is important not popping thru? Is something popping thru too much? Does a part go from too loud to too soft? How's the high end balance and clarity? Does the midrange sound cluttered?

4.) Now that you've mentally assembled your laundry list of mix complaints, it's time to do something about it.

5.) First clean up your low end. Run an EQ on all the tracks with nothing but a HIGH PASS FILTER on it. Stuff that should be part of your low end like kick drums, bass and so on get a HP filter around 35 or 40hz; stuff that shouldn't be cluttering your low end much like strings, sweepy pads should get a HP cutoff around 70 to 200hz. Vocals can be cut off around 150hz pretty safely. Guitar gets cut off around 70hz in general. Remember: you don't want excess garbage cluttering your low end--this is one of the main sources of audio mud.

IN GENERAL THE MORE BACKGROUND A TRACK IS THE MORE YOU SHOULD REMOVE ITS LOW END!

I've had pads start rolling off at 400hz before because all I really wanted was a little midrange color and some upper harmonics (so I boosted them around 11khz or so later on). Heck, on high hats I typically roll off starting at 500hz for that crisp, clean and transparent high hat sound.

6.) Now that things are looking clean on your low end re-examine your VOLUME issues, which means listening and start grabbing for the compressor.

7.) Stuff that still seems to pop in and out of the mix need compression--target these and compress them so that their volume stays put. (Read my compression tutorial for additional details.)

IN GENERAL I COMPRESS **EVERYTHING** IN MY MIXES AT LEAST A LITTLE BIT.

I am a big believer in fairly low compression ratios though. 2:1 on a lot of things. I always lightly compress analog synths because they are very erratic; if it's an analog synth doing a bassline I will squish it pretty good. In general VA, softsynths and digital synths need **LESS** compression than analogs, but let your ears and mix decide.

8.) Stuff that should be prominent rhythmically like kick and snare definately get some compression as well. Make them slam hard as hell.

9.) Get your low end instruments thumping be it bass guitar, synth or whatever. Make that low end steady, yet punchy. Try not to have more than 3 "low end" elements if you can.

10.) Now that you've gotten levels to be pretty consistent re-listen to the material critically and ask yourself--what needs more seperation, and what needs more integration?

11.) Now it's time to EQ. A lot of mixes sound tinny and thin because of overuse of EQ. If you've gotten your volume levels sounding great manually, and then used compression to make it even more tight, there shouldn't be a whole lot of EQ that you need to do.

12.) First thing--listen to the mix and try to identify weak sounding areas that sound BAD. Is there a little fizz to the guitars? Kick drum a little muffly sounding? High hats sound clangy? Prepare another mental list....

13.) Now use *subtractive EQ'ing* to locate and eliminate these discrepancies. Use the narrowest and smallest cuts you can get away with to bury the offending freq's in the *mix* (not solo'd by itself--always, always look at things in the context of the mix). When you have eliminated these frequencies (and there will probably be a few, perhaps none if you're lucky, sometimes on poorly recorded stuff there will be some in almost everything) we can move on.

14.) Now that the shit frequencies have been zapped listen to the song again and listen to see if the seperation/integration issues have been taken care of. Sometimes you can get lucky and a few problems will work themselves out; if not, the overall quality should have gone up a few notches.

15.) Now it's time to EQ for *SEPERATION*. Listen to the mix and figure out what elements are fighting for space in the low freqs, low-mids, midrange and high frequencies. Choose the one that you want to be more dominant in that frequency band--now go back and slightly cut that track in that band, while (sometimes) applying a slight boost (we're talking 1-2db's) to the dominant track. Keep doing this until you've gotten them all. Re-listen to the track.

16.) Now you want to integrate some of the elements so they work together more. An example is bass and kick drum. But how do you integrate AND seperate these sounds? Easy--give them boosts that are close on the lower end of the spectrum on or near the same frequency (for example: kick drum at 80hz with a boost, bass synth at 100hz with a boost); next move up into the midrange and boost one element someplace and the other one someplace else (such as boosting kick at 4khz and bass synth at 2khz). Play around with these techniques until you have things really cooking.

17.) Now listen to the WHOLE mix. Focus on the different frequency bands, paying special attention to the high end. Does the bass sound tight and clear--with the bass and kick working together yet with distinction? Does the voice mix well in the midrange with the other instruments? Is the high end crisp and clear, but not domineering and tinny? Can you hear the "air" and upper harmonics of the instruments in the over 10khz range?

18.) Now use EQ positively to *add* any of these missing characteristics... such as boosting some cymbals at 12khz, or a string synth at 9khz or wherever there is a bit of a pocket that needs filling, or place for something to shine a bit more without queering the mix.

BE CAREFUL WITH SUB 1khz BOOSTING. Too much boosting in this area can mess you up... too much cutting will give you a thin sound. This is a difficult area to master. When in doubt, leave it alone for the most part.

19.) Now, at long last, STEREO PAN your tracks. Try not to weight any one side more than the other. Keep low frequency or primary instruments centered, or close to center. Bass and kick should always be centered... and snare as well. Give a nice panorama of sound but don't get carried away. Panning over 50% is often too much. Panning less than 30% is what I do most of the time except in specific circumstances like mic'd drum overheads (due to stereo bleeding) which I'll put at 60-75% or so.

20.) Correct any deficiencies that may have arisen from the stereo panning. 80% of the time if you've done the steps pretty good you won't have any correcting to do. The song will suddenly have "mixed" itself when you stereo pan everything.

21.) Now go back and fit the less important elements into the mix. DON'T TOUCH THE CORE ELEMENTS--make the less important ones fit around them with compression and eq.

22.) When you're done, put the mix down for a day or two and go back and listen. Correct anything you don't dig. Compare it to CD's you like and see if it measures up. Make sure it's not too bright of a mix, make sure there is good low end, make sure it doesn't sound muddy, make sure the midrange is well defined, punchy and clear.

Most of all--have fun. There is no right or wrong way to mix YOUR songs.

 

[chadsxe]

COMPRESSION

I'm "reprinting" this so it is easier to find. By popular request I typed up a quick and dirty tutorial on better use of compression.

Here's the big secret of compression:

You should *barely* hear it working except as increasing your overall volume within the parameters you need. The average person may not even hear it working much. THAT is how the pro's set 75% of their compression, the other 25% is super squish city reserved for things like submixing drums in stereo and mixing it back in at low levels to beef stuff up.

Jim's rules for compression:

First let's define what a compressor does--which is to affect the amplitude of a signal by selectively reducing it. Compressors tend to have the following controls:

Compression ratio: this determines how 'hard' the compressor is supressing the signal. Usually described as a ratio such as 2:1, 4:1 and so forth. What this means is, after you cross the threshold setting, how many db's you have to go over to effect 1db of volume change. Thus a 4:1 ratio means that once you go over the threshold for every 4db over you will only get 1 db of amplitude change.

Threshold: this sets the decibel level that the compressor starts to work. Signal underneath the threshold will be unaffected--signal above it will be hit by the compression amount determined by the ratio. Needless to say, setting the threshold above the peaks of the signal will NOT do jack shit to the signal. You gotta set it in the path of the signal, so to speak. This is always expressed in negative db, thus a -24 threshold will compress any audio above -24db, and leave everything below it alone. (*Note, soft knee compressors start to work a bit before the threshold!)

Attack time: how long, in milliseconds, it takes for the compressor to kick in. This keeps your transient peaks unaffected and is the trick for getting a "punchy" kick or snare (the front end crack will be uncompressed and thus louder than the following signal).

Release time: once the signal falls below the threshold how long, in milliseconds, it takes for the compressor to 'let go' of the signal. For vocals and other similar instruments you want this to be fairly long like 200-250ms. For drums 75-125ms is great.

Special note on soft-knee compressors: some compressors have a soft knee function. What this does is start compressing the signal lightly as it approaches the threshold, and as you get closer to the threshold it will compress harder and harder until you reach the threshold and the full compression ratio will be utilized. This provides for fairly transparent compression and is great on vocals. Personally it sucks for drums unless you are squishing a stereo submix of drums.

Another note on stereo compressors: you should *always* link stereo sides of compressors when processing stereo signals. Once a side reaches the threshold BOTH sides get the compression. Failure to do this can lead to, for example, drums that leap in volume on one side but not the other... very assy unless that's what you really wanted. (Why god, why???)

Moving right along.....

Here are some guidelines off the top of my head:

2:1 ratio--overheads, distorted guitar, soft vocals, most synths
3:1 ratio--clamping down on overheads, acoustic guitar, most singers
4:1 ratio--bass, snare, kick drums, toms, crap singers
8:1 ratio--bad bassists, screaming vocalists, squishing the life out of stuff
12:1 ratio--out of control peaks or when you want to sound like limiting but still keep some life to it

Compression ratio and threshold are intertwined, so set both accordingly!

If you need dynamic range--LOWERthe ratio
If you need more regularity in levels--RAISE the ratio
If you just need to shave off some peaks--RAISE the threshold
If you want to affect a lot of the signal--LOWER the threshold

Here's the tricky parts that require hard decisions:

If you want more smooth sounds--LOWER attack time (under 6ms)
If you want more punch--RAISE attack time (between 7-50ms)
If you need "more" compression--LOWER attack time more
If you need "less" compression--RAISE attack time

If you need 'invisible/natural' compression--RAISE release time
If you need 'audible/percussive' compression--LOWER release time

Now pull out yer ears:

If it pumps and breaths--RAISE release time (unless you want that)
If the compression seems to disappear--LOWER release time

Finally the number one rule for compression:

ALWAYS match relative volume levels (by ear) before and after compression using makeup gain--meaning that they should be peaking about the same. If you record using my "-15 to -12dbfs with peaks no greater than -6dbfs" rule this is easy; if you tend to record sloppy and "hot" you may need compression to keep you out of the red. Don't do this to yourself.

The idea for this is that LOUDER often equates to sounding better to us, fooling us into setting duff and mookish compression settings. When dialing in compression make sure that the before and after levels are identical so you can hear the compression and not the jump in volume.

Here are some guidelines on setting makeup gain:

The lower the threshold the more makeup gain you need.
The higher the threshold the less makeup gain you need.
The higher the ratio the more makeup gain you need.
The lower the ratio the less makeup gain you need.

Further modified by:

The faster the attack the more makeup gain you can get away with.
The slower the attack time the less makeup gain you can use.
The faster the release time the less makeup gain you can use.
The slower the release time the more makeup gain you can use.

You can also calculate the amount of makeup gain you need by looking at the signals peak levels or RMS--figure this out, and then:

COMPRESSION THRESHOLD = T
SIGNAL DB PEAK = P
COMPRESSION RATIO = R

(T-P)/R = A

P-A = MAKEUP GAIN

Thus if your threshold was -24db and your signal is peaking at -12db the amount of gain being compressed is 12db total; i.e. (T-P). Divide this amount, 12db, by the ratio of 4:1--making A = 3db reduction of peaks.

Then take the signal db peak and subtract the peak reduction--in this case -12db and subtract 3db... meaning you require 9db of makeup gain to approximate the original signal level.