Using a Compressor after a Reverb vs using a Pre-delay on the Reverb

[Mark1971]

Hi!

So, I've used both of these methods to delay a reverb from effecting a lead vocal. It's not

a new concept at all. But I always wondered what the difference is between using a comp

and using a pre-delay knob on the reverb itself. They both delay the reverb from hitting the

vocal but is there an actual sonic difference? I feel like when I use the compressor method

I can dial in the effect for a more natural sound; whereas the pre-delay is just waiting to release

to whatever delay time you chose.

 

Any thoughts?

[Holger Lagerfeldt]

The two methods are not similar, in the sense that the compressor does not delay anything. In fact the two things are not really comparable.

You should always set your pre-delay to the right sound or feel, even if you use a compressor on the reverb. They're not mutually exclusive either.

The compressor can reduce the level of the reverb dynamically, and it can do so with a slow or fast attack speed.

However, neither a fast nor a slow attack speed apply any delay. If you want to learn more about compression, including attack and release speed, then you can watch my video here: 

 

If your aim is to separate the reverb a bit from the lead vocal then an alternative compression option could be to use external side-chain compression.

When you compress the reverb by adding a compressor after the reverb (on the reverb aux), the compressor reacts to the output level of the reverb. In terms of threshold this means that the compressor will activate once the input level (which listens to the output level of the reverb) exceeds the compressor's threshold.

This type of compression has no relation to timing or the level of the lead vocal, apart from the fact that the lead vocal is causing the reverb to activate in the first place. However, this can work quite well in many cases.

Using externally side-chained compression on the reverb will duck the reverb relative to the timing and level of the lead vocal itself rather than the reverb output. This allows you to hear the vocal even more clearly or perceive it as more dry, while still allowing the tails of the reverb to pop out.

It's often done with delay effects (echo) as well, in fact this method is most commonly used with delays.

To enable external side-chain compression in Logic's compressor, switch from internal to external side-chain input in the upper right corner of the plug-in. Choose your lead vocal as the audio input.

Experiment with extreme settings to understand how ducking reacts to the lead vocal input signal.

You may also want to equalize or multiband compress the reverb subtly, especially in the low mids. This can help clear up any mud between the vocal and the reverb.

As an alternative to EQ: play around with the decay times per frequency band in the reverb. This allows you to e.g. reduce the decay time in the lows or low mids and keep them slightly longer in the highs. Unlike a static EQ cut, this will keep the warmth and fullness, but reduce mud.

Finally, it's common to de-ess the input of the vocal reverb to avoid sibilant explosions. This also allows you to have more high end in the reverb, if you so desire. Simply insert a de-esser in the first slot on the reverb aux and set it up correctly to reduce sibilance, even to the point of lisping. This doesn't affect the lead vocal or the output of the reverb per se, only in the input.

Edited October 3, 2023 by lagerfeldt

[Mark1971]

Okay, so (if I'm understanding this correctly) the pre-delay on a reverb is holding off the delay until whatever time you set it too; then it releases it. So, it's more like intermittent wipers on a car...lol. The other method of using a compressor on an aux (sidechained to lead vocal) will provide a ducking effect but still let some reverb through.

[des99]

The reverb pre-delay delays the reverb tail component of the reverb, distancing and separating it from the dry signal, and the early-reflections.

Compressors don't delay the reverb, they just (in this context) turn the level of the reverb down when there is  signal present (at the sidechain).

[David Nahmani]

16 hours ago, Mark1971 said:

so (if I'm understanding this correctly) the pre-delay on a reverb is holding off the delay until whatever time you set it too; then it releases it.

It's delaying the entire reverb tail. If you think about a real life situation, if you're in a large concert hall, an instrument is close to the back walls and you're far away, there won't be much delay between the direct sound and the first reflections, so that's a really small pre-delay. If the sound source is close to you and away from the reflective walls then there'll be a long pre-delay as you'll get the direct sound much earlier than the first reflections. 

[Holger Lagerfeldt]

Usually pre-delay does not delay the early reflections (ER) in a reverb unit. ERs will stay in place regardless of the pre-delay setting.

The pre-delay setting in a reverb usually only delay the reverb (tail).

Simplified: ERs are the very closest reflections, such as the floor where the source is, and any other very close boundaries. The reverb (tail) is what gets bounced around.

Not all reverbs let you control ER and the tail separately or they may not have actual ER in their algorithm at all.

ERs can sound like a super-short bathroomy effect. The tail is the longer, potentially lush tapering off effect.

This means that timing-wise you can keep ERs directly on top of i.e. your snare or vocal to add thickness or a natural roomy blend, while still delaying the tail using pre-delay.

Edited October 12, 2023 by lagerfeldt

[Mark1971]

Ahh, okay. That's making more sense to me. The pre-delay is effecting the tails not the early reflections. For some reason I got it in my head that that the pre-day effected the early reflections and the tails.

[David Nahmani]

On 10/12/2023 at 3:34 PM, lagerfeldt said:

Usually pre-delay does not delay the early reflections (ER) in a reverb unit. ERs will stay in place regardless of the pre-delay setting.

That's the opposite of what I've always experienced? In my experience, pre-delay delays the early reflections, which can be used to simulate the sensation of a large room. 

I suppose it may behave differently on different reverb units? 

[des99]

48 minutes ago, David Nahmani said:

That's the opposite of what I've always experienced?

It depends on how the reverb has been implemented. For example, here's some blurb about this from the LiquidSonics Tai Chi reverb manual, which has an option for either behaviour:

Different reverbs treat reflection pre-delays differently. Some lock the reflections relative to the reverb (so pre-delay also affects reflection timing too) and some lock reflections relative to the dry signal. Different situations can call for a different strategy, these can be accommodated here.

So basically - "it depends". 🙂

Edited October 19, 2023 by des99

[David Nahmani]

3 minutes ago, des99 said:

So basically - "it depends". 🙂

Great. Thanks @des99!! 🙂