Adventures In Audio
Demonstrating the Waves J37 analog tape emulation plug-in and comparison with a real tape recorder

David Mellor

David Mellor is CEO and Course Director of Audio Masterclass. David has designed courses in audio education and training since 1986 and is the publisher and principal writer of Adventures In Audio.

Sunday July 12, 2015

It is strongly recommended that you should listen to this video on loudspeakers or headphones of studio monitoring quality.

Transcript of the video sound track...

I'm going to take a look at the Waves J37 tape emulation plug-in. I'm going to try it on a variety of signal sources, and also compare it with a real tape recorder.

First I'm going to experiment with a simple sine wave and play around with the controls. You will be able to see and hear what the controls can do to the sine wave. I'll start with the bypass control, and then get a bit more adventurous. One thing you might notice is that tape produces harmonics that are odd, whole-number multiples of the input frequency. Even-order harmonics, as you would find in a single-ended Class A amplifier are not present. This, in a way, gives tape its characteristic sound.

[Sine-wave demonstration]

Now I'll play around with the wow-and-flutter controls. Obviously in the heyday of the J37 the object was to have as little wow and as little flutter as possible. But now we can use it as an effect. Let's see what it can do to a sine wave. Sometimes the effects can be extreme.

[Sine-wave demonstration of wow and flutter]

There are some characteristics of analog tape recorders that I don't feel that I am hearing here. One is scrape flutter. Scrape flutter is caused literally by the tape scraping against the heads and guides of the machine. Scrape flutter causes harmonics which are not related in any simple way to the fundamental frequencies, and it makes a mass of them, a whole cloud of harmonics, and I don't feel that I am hearing them, and I certainly can't see them on the spectrogram. The second feature of analog tape recorders is modulation noise. This is noise that comes and goes with the level of the signal. I can demonstrate that neither of these are emulated in the J37 plug-in by using a low-frequency sine wave input signal. With a real tape recorder, you would hear this cloud of harmonics around the sine wave, but here it comes out very clean. And also, whether or not noise is introduced with the noise level control, it doesn't alter with the level of the signal. Take a listen to this...

[Investigation of scrape flutter and modulation noise]

Sine wave tests can be instructive because they show you what to listen out for. But here's a real-life signal. Here's a vocal recording, which we made using a Neumann U87 microphone through an Avalon M5 preamplifier. First we'll hear the clean digital recording.

Female vocal

[Original female vocal recording]

Now let's try it through the J37 plug-in. The settings have been chosen to produce quite a strong effect. So in the louder sections you should clearly hear the additional warmth that's produced. A little speed variation has been introduced as well.

[Female vocal processed through J37]

It's certainly a richer sound, but exactly what are we hearing? I've made a little test where I've taken the J37 version, and I've mixed that with an inverted version of the original digital signal. It doesn't cancel completely, but it allows us to hear more of what the J37 is doing. This isn't a sound that you would use in a real-life project perhaps, but it lets us hear a little bit more about how the plug-in is working.

[Female vocal, mix of processed version and inverted original]

Bass guitar

Let's move on to a recording of bass guitar. What I'll do in this example is switch the plug-in in and out repeatedly. You'll hear it change because there's a little click. Perhaps Waves has modeled a DC offset in the original J37. One interesting thing that you might notice is that the processed signal subjectively sounds louder and stronger, but in fact the peak level in this test is a little bit lower. That tells us something about what tape can do for a signal.

[Bass guitar comparison]


One of the classic applications of analog tape is for drums. If we think about the original era of the J37, during the 1960s, then typically the drums might have been recorded by just one mic. So here we have exactly that kind of recording. The setup is a single Neumann U47 directly in front of the kit. We'll hear it digitally recorded, then processed through the Waves J37 plug-in.

[Single-mic drums clean]

[Single-mic drums through J37]

As a more modern alternative, we have the conventional method of miking each drum separately, and the hihat, and two overheads, which results in an 8-mic setup for a five drum kit. We've recorded it digitally, and also processed it through the J37 plug-in. This time however, what we've done is process each track independently. So each track, each microphone, has its own separate instance of the J37 plug-in.

[8-mic drum recording]

[Multiple instances of the J37 plug-in]

Background vocals

Using multiple instances of the J37 plug-in is actually something that Waves recommends. Here we have a recording of background vocals where there are six tracks, and each is processed independently through the J37 plug-in. First we'll hear the original recording, then we'll hear the processed version. You might hear a little noise in the original version, but we'll have to accept that as part of the overall texture.

[Unprocessed background vocals]

[Background vocals processed through the J37 plug-in]

Comparison with a real tape recorder

What I'd like to do now is compare the Waves J37 plug-in with a real analog tape recorder, in this case the Revox PR99. I've recorded a sine wave and, as you will see and hear, on playback from tape, the result is quite messy. I have to say that there is a richness of texture here that the Waves J37 plug-in doesn't quite manage to imitate.

[Sine wave recorded on a real tape recorder]

Here I have a stereo recording of drums, which we will hear first in its original digital form, then through the Revox PR99, then through the Waves J37, and then through a different tape emulation plug-in. You will certainly hear differences in texture, and there are differences in the warmth and the richness of the sound. One interesting feature is that all of these recordings are normalized to the same peak level, but you will hear that some, subjectively, sound significantly louder than others.

So there we have it - a quick demonstration of the Waves J37 tape emulation plug-in. Thank you for listening.

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