Logic has lots of different delay plugins, but one rather overlooked and misunderstood little plugin is our little friend, the Sample Delay. Put simply, the Sample Delay works by delaying its input by a set number of samples, specified by the sliders. You can delay the left and right channels independently, or you can link them together. You can also type in the box and enter your values manually instead of using the slider.
So, what's it for?
Well, it's really to compensate for the delay that certain plugins can exert on your audio pathway. In the days before plugin delay compensation, if you put a big beastie like the PSP Vintage Warmer on, say, your drum stem, you'd immediately hear that the drums were late, as the PSP takes a few milliseconds to process the signal. This is called plugin delay, and you could compensate for the tiny delays caused by plugins with the Sample Delay plugin.
You could also use it for compensating for delays caused by certain outboard processors, or for any ADC or DAC conversion that you do… but don't worry, we're not going to get into that here! I really want to talk about how to use the plugin creatively. But first, a tiny spot of maths. Logic works at 44.1kHz by default, which means 44100 samples per second. So, if you delay a signal in the Sample Delay plugin by 44 samples, we are delaying the signal by roughly one millisecond. So, this clearly isn't the same beast as a conventional delay plugin… it's the really tiny stuff we're dealing with here!
Milliseconds are massive
Milliseconds sound like tiny imperceptible units of time, don't they? Wrong. A millisecond is a huge amount of time. Considering that sound travels at 343 metres per second, it takes only 3 milliseconds for a sound to travel one meter. Our brains know this, and process this information constantly to tell us where sounds are coming from. In fact it's these tiny, fractional-millisecond delays between a sound hitting the right ear and left ear that the brain uses to work out where a sound is coming from. Don't let the fact that a millisecond is only one thousandth of a second long fool you – these are useful little things!
In terms of Logic's Sample Delay then, you might find it helpful to bear in mind that 120 samples relates to sound travelling one metre. If we say that the distance between two ears is 20 centimeters, this relates to approximately 24 samples. So we can use this to trick our brains into thinking a sound is panned when it's not. For instance, a sound that hits your right ear 24 samples before it hits your left ear can sound like it's coming from your right, all without the need for panning, which can often ruin the balance of a mix.
Making space
Another use for the sample delay plugin is in conjunction with reverbs. Delaying a reverb bus by 1200 samples will move the imaginary 'room' 10 metres away – great for separating out reverb from drums / strings to avoid a crowded mix and give a nice sense of space. (Actually, most good reverbs come with a pre-delay feature to make this easier, which is normally dialed in by the millisecond, so remember 1 metre = 3 milliseconds = 120 samples.)
If you want an alternative to reverb, then why not try delaying a dry bus by 1200 samples? This will simulate an artificial space 10 metres across, which you can blend into your sound for more 'body' without waving the reverb flag. Mathematically, this sound is a perfect reflecting sphere around the mic, so if you try this you may not like the results straight away. Experiment around with equalisation to make this sound useful, but watch out for phase interactions as these can affect mono compatibility – try removing some of the low end from your delayed bus to correct any phase issues (remember to use the Linear Phase EQ for this!).
Middle and sides
Another use for the Sample Delay plugin is to simulate a MS mic configuration. MS stands for middle and sides, and is a technique for miking a sound source (such as an acoustic guitar) to give it sense of space, without the mono compatibility problems that can arise when using other stereo mic configurations.
The technique involves using two microphones, one pointing directly at the sound (M for middle), and one figure-of-eight mic pointing 90ยบ off axis, picking up the 'room sound' on both sides of the direct mic (S for sides). This is then fed into an MS decoder (Logic's Direction Mixer, for instance) to translate the MS microphone signals into left and right channels, with a nice sense of stereo space and image. The advantage of this approach is that due to the clever MS decoding process, when you sum the mix down to mono, the S signal cancels out, and you're left with just the M channel, a perfect mono signal.
The good news is that you can cheat your way to your own MS sound without the need for two microphones. To do this you need to send some of your mono recorded signal to a stereo bus, which we will use for the S signal. Insert a Sample Delay plugin and a Gain plugin onto this bus. (It may help to insert a Linear Phase EQ also.) You then invert the phase of one of the channels (doesn't matter which) using the Gain plugin. Now make a decision about how big the live room was, and dial the appropriate figure in samples into your Sample Delay. (Remember 1 metre = 120 samples.) Make sure you have linked L and R channels in the Sample Delay. And – hey, presto! – you have your own S signal, all without buying any more microphones! Now, EQ to taste.
Important note: Only use the above MS configuration on dry, mono signals. After setting up the MS configuration in Logic, it's important to route both the signals from your M channel and S bus through to a new stereo bus, and do all processing (EQ, compression, etc) on this new bus. Any processing, especially time-based processing (such as reverb, delay or chorus) on your dry M or S signals will have a negative effect on the realism of your MS processing, and may cause all kinds of phasing problems that will negate the mono-compatibility advantages of this approach.
Delayed reaction
I hope you can make some use of the above processes, and if you do, you'll discover that the Sample Delay plugin is a powerful and overlooked tool in your creative arsenal. It can be used to give sounds their own space in your mix, to fill out a dull mono recording, and once you start playing around, you will find it has many other useful applications. In fact, you'll wonder how you ever did without it.
