Compression on master bus or during mastering?

paulscape

Member
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3,525
When do you start 'gluing' your mix together? I've searched around a bit and it seems a lot of mixers will add master bus compression whilst mixing as well as during mastering. I do have a compressor on the master bus to use on different songs or to test what I'm doing but generally I glue everything during mastering stage so it works with overall final EQ, excitement and limiting.
 

dewey decibel

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10,323
I'm nowhere near as experienced as a lot of the guys on this forum but since you're asking more of a philosophical question (and I'm a couple beers in) I figured I'd give it a shot. When someone says, "glueing the mix together", what do they mean exactly? The way I look at it, back in the day everything was cut live in the same room, and even if there were close mics there was a lot of bleed and a lot of air. Each track/instrument sounded like they fit together because, well they did, and often things were run into a killer echo chamber and cut to tape (which has some natural compression), which further glues everything together naturally. In the modern day where everything is tracked separately, close mic'd and isolated (if even recorded at all as there's so many samples and software instruments on most recordings) we need to play around more to make it sound like all these tracks belong together, so it doesn't all sound like a random bunch of sounds.

In general people use compression as a utility to get better control of the transients (often when tracking but sometimes after the fact). For example if you're compressing on the way in you can run the signal hotter because it will even things out. The other reason people use it is because it can change the way things sound/feel, it's an instrument in of itself. Both approaches to compression can be used on just a single instrument, a sub buss, or the final stereo buss.

I think the first place most to start using compression to get that "glue" happening is on sub busses, most notably drum busses. It's really crazy how much you can change the way the entire drum track not just sounds but feels, depending upon the type of compression and the amount. And then you can play around with parallel compression and even side chaining to get certain things to push/pull differently. So this can be a mix of compression for both utility and aesthetics. Using compression in this way (along with EQ, reverb, etc) to really carve out a specific sonic space for each instrument group is what gets things to sound like they were all recorded live in the same room, even if they weren't. It can take a lot of time to do this properly.

To me, If you spend enough time on each track and sub buss you shouldn't need to compress at the stereo buss stage. That said, it can be a lot easier to simply slap on a compressor or other plugin to get it sound "right", and give it that glue. Really depends on how much time you have and your skill level. A lot of times when writing/recording a demo I'll just slap a compressor and reverb on the stereo buss to at least give me an idea of what it could sound like when I'm done.

Compression (more often limiting) in the mastering stage would be more of a utility, where the goal is to get everything as even and as loud as possible. It's not really about glue or changing the sound at all.

Those are just my opinions based on my minimal real world experience.
 
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I put a compressor on the two bus as soon as I start the mixing process, because I find that it will change the way I'm feeding the levels into it. In other words I can't just add it toward the end of my mix and expect everything to magically glue in place. I have to mix into it along the way or it doesn't work.

I agree that mastering is not really the time to change the tonality of what you have done, as the mix should have sounded exactly how you wanted it to sound. Mastering is the time to get competitive volume and, more importantly, a fresh set of ears to evaluate what you have done and address any flaws you may have missed because you're too close to the track.
 

Billinder33

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1,569
Generally, I don't use compression on mix busses... which is not to say that I never do it. Depends upon the track really. I've never been comfortable mixing into a compressor, so if I do add one, it's only at the end of the mix process.

In every mix, I do throw a clipper on the master buss at the end of the process to kill the occasional ISP/overage.
 

Amp_Addicted

Member
Messages
521
When I used to engineer, I would sometimes use parallel compression for stem mixes. Sometimes i would employ a mix buss compressor, but I also mixed down to 1/4" & 1/2" tape: why bother using buss compression when the tape was already doing that. I had access to a Smart C2(SSL Type), Manley Vari Mu & pair of Neve 33314a(the 33609 precursor). All three are classic buss compressors. The real key to using buss compression during mixdown is to turn it off every few passes while you're working on a mix. Most people overshoot compression, so it's super important to hear what the compressor is actually doing to your mix. I also had a habit of hiding the meters from my view. People often look more closely at the meters on the compressor than actually listen to what that compression is doing to the overall sound of the tracks.

Digital recording made people reach for compressors that was inherent when you tracked hot to analog tape. In that instance outboard compression added noise that you might not want. These days musical production has way too much compression at every stage of recording. It makes the resulting music sound flat. If you tracked with a bunch of heavy compression, mix buss compression can crush a mix to a lifeless state of audio existence when you just wanted a couple of the elements of a track to be crushed.

I put a compressor on the two bus as soon as I start the mixing process, because I find that it will change the way I'm feeding the levels into it. In other words I can't just add it toward the end of my mix and expect everything to magically glue in place. I have to mix into it along the way or it doesn't work.
This is a good approach. If you want to use buss compression, it's better start using it early in the mixdown process. If you're adding it at the end, then it's probably better to leave that to a mastering engineer.
 
Messages
1,317
When I used to engineer, I would sometimes use parallel compression for stem mixes. Sometimes i would employ a mix buss compressor, but I also mixed down to 1/4" & 1/2" tape: why bother using buss compression when the tape was already doing that. I had access to a Smart C2(SSL Type), Manley Vari Mu & pair of Neve 33314a(the 33609 precursor). All three are classic buss compressors. The real key to using buss compression during mixdown is to turn it off every few passes while you're working on a mix. Most people overshoot compression, so it's super important to hear what the compressor is actually doing to your mix. I also had a habit of hiding the meters from my view. People often look more closely at the meters on the compressor than actually listen to what that compression is doing to the overall sound of the tracks.

Digital recording made people reach for compressors that was inherent when you tracked hot to analog tape. In that instance outboard compression added noise that you might not want. These days musical production has way too much compression at every stage of recording. It makes the resulting music sound flat. If you tracked with a bunch of heavy compression, mix buss compression can crush a mix to a lifeless state of audio existence when you just wanted a couple of the elements of a track to be crushed.



This is a good approach. If you want to use buss compression, it's better start using it early in the mixdown process. If you're adding it at the end, then it's probably better to leave that to a mastering engineer.
The more I read about classic album productions from the early 90s and before, I’m surprised how many records were mixed with little to no mix bus compression. But it makes sense if the engineers were getting a similar effect from hitting the tape at certain levels.

I wonder how much the SSL with its onboard bus comp changed the practice too? Were many people strapping compressors across the mix bus before the SSL came out?
 

twoheadedboy

Member
Messages
11,404
When do you start 'gluing' your mix together? I've searched around a bit and it seems a lot of mixers will add master bus compression whilst mixing as well as during mastering. I do have a compressor on the master bus to use on different songs or to test what I'm doing but generally I glue everything during mastering stage so it works with overall final EQ, excitement and limiting.
I try to use as little buss compression as possible, because I don't like the sound of it. If you compress individual tracks as needed, you may find little need for buss compression.

I do not like to mix into a buss compressor, because I need to understand what is going on with the individual tracks when I'm mixing, and putting a compressor and EQ on the whole mix makes it harder to know what is going on with each track, which in turn makes it harder for me to find and solve problems. Usually, I will not EQ or compress the entire mix until I've got everything else where I want it. Usually I have to make a few adjustments once I add the buss compressor, but usually there isn't much to do.
 
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RevDrucifer

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100
That’s top-down mixing.

I keep a Waves SSLComp and L-2 limiter on my mix bus for everything. They aren’t doing a lot, just there to add a little glue and give me an idea of the final product as I work. At most, I’ll give them some juice when I‘m checking mixes in my truck or other stereo systems.
 

batsbrew

Member
Messages
5,301
When do you start 'gluing' your mix together? I
I've been mixing into a 2-bus compressor for about 10 years now.
i use the Waves SSL G-master bus compressor...
i set it very conservatively, 2:1 ratio, threshold for no more than about 2db max reduction...
auto release,
and attack based on the meter of the song, more or less, typically i set it for the longest setting (30 ms) to start, and tweak if need to.
 

proxy

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Messages
431
Both are valid. If I just want a little sheen/polish then I’d probably try to get the mix as close as possible without it, then apply a little as a finishing step. If I want a more colorful mix, I might mix into the comp. I do a hybrid.

I put some moderate compression on each of my four groups (vocals, rhythm section, hooks, pads), then parallel compression on the 2 bus, which gives it some oomph, but also lets it breathe.

I usually get a rough balance up without those comps, then turn on these comps and finish the mix through them.
 

batsbrew

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5,301
i'm speaking strictly mixing,
for mastering,
the use of compression is strictly by the song...

different mixers use different techniques to get where they want to go,
and that might be assuming aggressive compression at the mastering level,
in which case they may have drastic peaks throughout that they are keeping at the mix level KNOWING they will pull them down at mastering.

others, like me, want the master to sound just like the mix output,
except for overall level... in which case i have everything 'leveled' with mutli level compression at the final mixdown, and mastering is used just for overall spectral balancing.
 

eigentone

Silver Supporting Member
Messages
7,236
It's ultimately stylistic.

If you want that squashed-in-your-face compressed sound or if you really like the character a smoother compressor adds, go for it. It's a bit like the guy with the always on boost on his pedal board. If you want a really compressed master, I think it generally works best to use compression at many stages (tracks, busses, masters) rather than a compressor/limiter at the end.

I used to use compression and limiting during mixing, but I have transitioned over to really favor more dynamics and a more natural sound. So, "No comp/limiter on the master for me" when doing a mix (of my own stuff.) That means "Gluing the Mix" starts when tracking and getting sounds. Of course, there are multiple ways to work. Try them and find what works for you.
 

jmoose

Member
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4,642
I wonder how much the SSL with its onboard bus comp changed the practice too? Were many people strapping compressors across the mix bus before the SSL came out?
Compression across the mix was happening decades before the first SSL console was even a thought... go back to the 1940s and early days of electrical recording.

The very first compressors were things like modified RCA and Gates broadcast limiters. Stuff like the RCA BA6A... bit later it was Altec 436. What year was the Fairchild 670 introduced? Late 50s?

Mix compression/limiting has been used and abused since the days of Elvis, even before the Beatles but its all over their albums too.

In the 50's and 60's everyone wanted their song to be the loudest single on the jukebox. How to accomplish that?!!

When and how much to apply? Well, I guess to some degree it depends on your confidence or lack of it.
 
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I like committing if at all possible. I like to compress very lightly on the way in. According to the genre one can apply simple parallel compression on a buss. Or you can compress each instrument and then use buss compression as well.

I usually have two software comps on the 2bus with 1db of gain reduction on both. Using two sounds better than one in my opinion.

At times I like to use a peak limiter on the snare and the overheads to control peaks. This allows for more clean level for the 2bus. That is where Glue sits for me. It levels out peaks which makes everything sound tighter.

Also you can use compression for groove. Fast attack pushes things forward (in front of the groove) or a slow attack (behind the groove).
 
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Compression across the mix was happening decades before the first SSL console was even a thought... go back to the 1940s and early days of electrical recording.

The very first compressors were things like modified RCA and Gates broadcast limiters. Stuff like the RCA BA6A... bit later it was Altec 436. What year was the Fairchild 670 introduced? Late 50s?

Mix compression/limiting has been used and abused since the days of Elvis, even before the Beatles but its all over their albums too.

In the 50's and 60's everyone wanted their song to be the loudest single on the jukebox. How to accomplish that?!!

When and how much to apply? Well, I guess to some degree it depends on your confidence or lack of it.
That's interesting. I've heard about the Beatles abusing the Fairchild quite a bit but wasn't sure if they were using it on individual busses or the master bus.

I've tried to do some digging on Rudy Van Gelder and it sounds like he may bought and modified a lot of broadcast gear early on, but he was so secretive it's hard to get any hard info. Based on the sound of the Blue Note records in the 50's I wouldn't be surprised if there was a fair amount of mix bus compression happening there.

Have you read any good books on the early years of audio engineering? It would be interesting to dig deeper.
 

jmoose

Member
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4,642
That's interesting. I've heard about the Beatles abusing the Fairchild quite a bit but wasn't sure if they were using it on individual busses or the master bus.

I've tried to do some digging on Rudy Van Gelder and it sounds like he may bought and modified a lot of broadcast gear early on, but he was so secretive it's hard to get any hard info. Based on the sound of the Blue Note records in the 50's I wouldn't be surprised if there was a fair amount of mix bus compression happening there.

Have you read any good books on the early years of audio engineering? It would be interesting to dig deeper.
Yeah, I've gone through a few books and done some research... but honestly a lot has come from simply making records for two decades. You don't do something creative for a living and not learn along the way. Being able to talk and work with old guys has been more valuable then any book.

Beatles vs Fairchild...

Maybe obviously those old consoles were very simple. Nothing like what we've had for the last couple decades with buses & sends galore. There was no parallel compression or anything of the sort. Very simple and direct signal paths.

There's one other (well a couple) compressor of note in the history of buss compression and the Beatles... mentioned above, the Altec 436 was one of the first commercially available boxes in the 50s. Lots of people bought 'em and modified them including Abbey Road.

Here's a good overview... https://www.musictech.net/reviews/altec-436/

Anywhoo. Point being that bus compression didn't start with SSL in 1980. Ya gotta go back another couple decades and there are a LOT of other old compression boxes out there people were using to make albums.
 

rumbletone

Silver Supporting Member
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6,664
I almost always have mix bus compression (other than for classical/acoustic), but it’s almost always very little. I leave the heavy lifting - to the extent warranted - for mastering.
 




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