What is a glue compressor

A glue compressor is a compressor used for a certain job, not a specific type of compressor.

It’s used to glue together certain elements or groups in a mix. You could have three or four tracks with backing vocals on them, put them in a group and have a single compressor on the group output. This would be the job of a glue compressor.

SSL (Solid State Logic)

Over the years certain bits of music technology have become renowned for their “sound”. You may have heard of SSL.

Their name became synonymous with high-end mixing desks. Anyone who was anyone wanted to mix on an SSL desk because of “that” sound. These sought-after SSL desks had quite a few things built into them. One of them was compressors for the master buses. This made it easy to compress track groups.

This is probably where the phrase glue compressor came from. The compressor was the SSL G Master Bus Compressor.

The SSL compressor ratio wasn’t fully variable like it is with many compressors. It could only switch between 3 compression ratios. These were 2, 4 and 10. Other than that there’s not a lot noteworthy when it comes to controls, which just goes to show that it’s the sound, not the amount of control you get over it that matters.

As I’ve mentioned with other equipment and plug-ins in the past, it’s no use just having loads of controls if the sound is not that good to start with!

There have been quite a few plug-in emulations of it. The Waves Creative Access was one of the first.

Ableton glue compressor

The Ableton glue compressor is their take on the SSL bus compressor. It was introduced in Ableton version 9.

One of the first things you notice about the Ableton glue compressor is that they’ve simulated an analogue meter. I come from an age when these were the most common way to meter analogue signals! The attack and release controls are labelled with the same range that the original SSL compressor had. The attack goes from .1ms to 30ms and the release from .1s to 1.2s, with an auto setting at the end of the scale.

Native Instruments solid bus compressor

It probably won’t come as any surprise to find out that Native Instruments have a glue compressor, the “Solid Bus Compressor.”

They also have the “Solid EQ” and “Solid Dynamics” if you want to recreate that Solid State Logic sound.

The NI version of the glue compressor gives you more control over the ratio. You may know the SSL only gave you 3 switchable ratios of 2, 4 and 10. Ni gives you an additional 1.5, 2 and 5. The release also goes a bit longer with up to 1.6 seconds as opposed to 1.2 on the original.

The labelling under the controls changes from, for instance, “threshold” to the actual value in dB’s while you change it. Again I think this is more useful.

Where do you record vocals? Can you record vocals in a car?

Propellerhead’s Reason and Record

If you are familiar with Propellerhead’s Reason, you’ll find the master compressor to be very much like the SSL master bus one.

It has the familiar controls so you can get going with it if you are familiar with the SSL-based emulations (or lucky enough to have used a real SSL!) Incidentally, there is another product from Propellerheads called “Record” in which the mixing console resembles an SSL desk along with the other SSL processing.

I know of several people who export their tracks to run them through Record. This is something I’ll test in the future when I get time.

How do you use a glue compressor?

If you are unfamiliar with what a compressor does and how it works check out my article on beginners guide to effects processing to get a basic idea and then come back here.

To use it like the original SSL compressor you first group a section of your mix together that you want to glue. For instance the backing vocals. Then put the glue compressor on the group output.

The Ableton glue compressor has the threshold and makeup controls labelled in dBs which for me makes them easier to use than the original SSL which had -15 to +15 labels. Start with the ratio of 4 and the attack and release controls set midway. Set the range to 70.0 dB, the dry/wet to 100% and the threshold and makeup both to 0 dB.

The meter indicates the amount of compression. When you play the track the needle shouldn’t move as there is no compression happening. As you lower the threshold the meter should start to move and you’ll hear the effect of the compression. Lowering the range control will also alter the amount of compression, which you will also see on the meter.

The compressor lets sound through but squeezes” the signal peaks depending on how it is up. You can use the “makeup” control to make up the level.

Interestingly the Ableton glue compressors’ wet/dry control can be used for parallel compressing without having to do any other routing. Normally without this control, a compressor would compress the whole input which is like having the wet/dry to 100% wet. As you turn down this control to less than 100% you are starting to let some of the original signal through, hence parallel compression.

Final thoughts

The effect of a glue compressor is to glue the individual tracks together it does this by processing the tracks together, so the effect of the compressor is given to all of the sounds in the group.

Similar to if you grouped a few tracks together and then put them through the same EQ or processor. Don’t forget that you aren’t limited to just using the bus compressor on a bus.

For more information on using effects, read my guide.

Many people used the original SSL G Master Bus Compressor on single tracks and on the whole mix, so don’t be afraid to experiment. The SSL was and still is a much sought-after sound and using the glue compressor helps to create that sound especially if you add the “NI EQ” and “Dynamics” to the processed tracks.

I don’t think that the glue compressor has to be the SSL one. It’s more of a case that the group of sounds, such as backing vocals become “glued” because they are grouped together and go through the same compressor. However, you’ll have to decide for yourself self it its also because of the typical sound and properties that the SSL compressor exhibits. There are quite a few simulations of the SSL compressor.

Undoubtedly, my favourite is the Native Instruments Solid Bus Compressor, which is very similar to the SSL. As you can see, you aren’t short of options if you want to test out for yourself if it’s the SSL that makes the sound.