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McDSP Classic Pack

Pro Tools Plug-ins
Published January 2007
By Mike Thornton

McDSP's compression and EQ designs offer a huge amount of control with the potential for accurate emulation of vintage devices. Throw in a tape-modelling suite and a powerful multi-band compressor, and you have the Classic Pack.

Colin McDowell founded McDSP in 1998, and the company are now based in Silicon Valley in California. Before setting up McDSP, Colin was a key signal processing engineer at Digidesign and his work included conceiving, designing and prototyping the Digidesign Multishell for the Pro Tools Mix system. He was also part of the team that created the Dolby E algorithm for Dolby Labs. Another key member of the McDSP team is Diana Lee, who is an adjunct faculty member of Santa Clara University's Graduate School of Engineering's Applied Mathematics department.

McDSP Classic Pack

McDSP were in the business of modelling and emulating vintage hardware long before it became the trendy thing to do. Now they have to compete with a wide range of modelling and emulation software plug-ins from the big boys like Waves, Eventide and Digidesign themselves. So how do their products compare?

Packing Them In

McDSP's Classic Pack bundle brings together four of their 'classic' software packages: Analogue Channel, Compressor Bank, Filter Bank and the MC2000 multi-band compressor plug-in. It's available in two versions, for HD and native Pro Tools systems, and is, in many respects, a 'bundle of bundles': as you will see, Colin and his team have a tendency to create products which are actually made up of a number of different plug-ins, so be prepared for even longer plug-in lists!

The McDSP user interface gives you a choice of sliders (left) or knobs (below). The McDSP user interface gives you a choice of sliders (left) or knobs (below).

For me, the first excellent piece of design from Colin and the team is that you can choose to have most of your McDSP plug-ins in either slider or, if you must, knob versions. The first time Pro Tools loads a McDSP plug-in, you are offered the choice of which style of interface you would like, and you also get the opportunity to tick a 'Don't Ask Again' box, so that you won't be asked this every time. If you do subsequently change your mind, at the point when you choose a McDSP plug-in, hold down the 'U' and 'I' keys on your keyboard as you select your plug-in and the User Interface dialogue box will come up again. Note that this choice can be different for each group of plug-ins, and doesn't change any instances of the group of plug-ins already created, so if you want to, you can choose to have your filters in knob mode and your compressors in slider mode.

You can also choose whether to have a Frequency or Gain grid on the graphical displays of any of the plug-ins, by holding down the Ctrl key and clicking on the graphical display, though I would have preferred that the grid be on by default, as it makes the display so much easier to interpret.

In The Bank

Filter Bank is a collection of 10 EQ plug-ins that each contain a combination of low and high-pass filters, low- and high-frequency shelving EQ, and parametric EQ modules, as follows:McDSP Classic Pack

  • E2: low shelf, high shelf.
  • E4: low shelf, high shelf, parametric, high-pass filter.
  • E6: low shelf, high shelf, two parametric EQs, high-pass filter, low-pass filter.
  • P2: two parametric EQs.
  • P4: four parametric EQs.
  • P6: six parametric EQs.
  • F1: low-pass filter.
  • F2: low-pass filter, high-pass filter.
  • F3: high-pass filter.
  • B1: band-pass or band-stop filter.

Let's take a closer look at E6 (see top screen overleaf), since this has examples of all the individual elements except the B1 band-pass/stop filter, which we'll look at separately. The low and high shelving EQ modules have the expected range of controls, such as Gain (cut and boost) and Frequency, but then the 'LCD' display section hides three additional pop-up controls that are accessed by clicking on the arrows under each section title. Slope sets the slope of the shelf, and the other two are controls you don't normally see on any EQ module, called Peak and Dip. These shape what happens at the top and bottom of the Slope section of the EQ curve, and enable you to have a peak 'overshoot' at the corner frequency or a soft transition. The variation of these two parameters gives Filter Bank a wide range of 'characters'.

The parametric section is the most straightforward, with Gain, Frequency and Q controls. On the P-series plug-ins, you have a choice of four different Q modes: Normal, Notch, Gain-dependent, and 5x, for when you need 'surgical' EQ settings.

McDSP Classic PackThe low- and high-pass filters also have the expected controls, with Frequency and Slope being set by radio-style buttons. The E-series filters offer 6dB/octave or 12dB/octave slopes and the F-series offer up to 24dB/octave, as well as a Peak control.

The B1 band-pass or band-stop filter (above), by contrast, is a specialised module with a 'super' notch filter configuration, designed mainly as a hum filter, with a Q range that McDSP claim can be as tight as one semitone! The band-pass mode can be used to band-limit the signal going through it, or to help to identify what you would like to remove in the band-stop mode, as it is a lot easier to find problem frequencies by first boosting them to home in on the problem. I was disappointed that there was no gain control to govern the depth of the notch, and that there was no graphical display on this section. With plug-ins, you only start to realise the benefit of graphical displays when they aren't available to you!

How does Filter Bank sound? Well, the simple answer is that it does the job. I had no trouble in getting any of the Filter Bank plug-ins to do what I wanted them to do, and the Peak and Dip controls enable you to produce EQ curves with 'character', and give the potential to model a wide range of classic hardware EQ units. There are presets inspired by EQs such as the Neve 1084, Avalon 2055, GML 8200, Manley and Pultec designs, and it is lovely to have a range of EQ plug-ins that recreates great EQ curves of the past. I am a particular fan of the British presets inspired by the old Neve hardware modules that I am old enough to have used for real! My main reservation is that some of the control ranges are rather restrictive. In particular, the high-frequency shelving frequency only goes down to 5kHz and the high-pass filter only goes up to 3kHz.

McDSP Classic Pack

One, Two, Three, Four...

Compressor Bank takes the design philosophy from Filter Bank and applies it to the world of compression, to create a group of different compressor plug-ins. As with Filter Bank, you can select slider or knob modes, and in addition you can choose to view the graphical display or not.

McDSP Classic Pack

CB1 (see right) is the most basic of the compressors in this suite of plug-ins. At first glance it looks pretty straightforward, with Threshold, Comp (Ratio), Attack, Release and Output (gain make-up) controls. The Attack and Release section has three options: Type 1 is a conventional manual mode, Type 2 retains manual control but adds a two-stage release section with different release times, and Auto makes the attack and release programme-dependent. As in Filter Bank, though, the 'LCD' display contains two extra 'character' controls. The first is Knee, which enables you to control the shape of the transition at the threshold point, from a 'dog-leg' shape, through the conventional 'definite corner' to a soft-knee with a gently curved transition. The other control in this section is labelled Bite. This stands for 'Bi-directional Intelligent Transient Enhancement' and, surprise surprise, it gives the compressor more 'bite' by allowing more transients to pass through it. These two controls are the key to Compressor Bank 's ability to model a wide range of analogue compressors. Finally, there are the usual (in Pro Tools!) External Key and side-chain monitor options.

McDSP Classic Pack

The Compressor Bank plug-ins' Knee control allows you to vary the compression characteristics from 'dog-leg' super-hard (top) to soft (bottom). The Compressor Bank plug-ins' Knee control allows you to vary the compression characteristics from 'dog-leg' super-hard (top) to soft (bottom). CB2 adds a Pre Filter section to a CB1. This section can be configured as a low-pass, high-pass or band-pass filter, or as a band-stop device. This filter can be placed only in the side-chain path, or it can be used to process both the main signal and the side-chain. CB3 (overleaf) adds another EQ stage, this time on the output of the compressor. This EQ can be either Static, applying a fixed amount of EQ to the output, or Dynamic, where the EQ is controlled by the side-chain from the compressor stage. This enables Compressor Bank to become a de-esser, as well as to handle other 'intelligent' dynamics duties.

CB3 adds pre- and post-compressor equalisers to the CB1 compression algorithm.CB3 adds pre- and post-compressor equalisers to the CB1 compression algorithm.Finally, CB4 (immediately below) is exclusively set up as a modelling plug-in, with presets inspired by classic compressors and limiters such as the Teletronix LA2A, Urei 1176LN, Fairchild 670, Manley Variable-Mu, Neve 2254 and 33609 and the Dbx 165. McDSP stress that these presets are 'inspired by' rather than being exact models of these classic compressors, but the manual goes into great detail to show how close they have managed to get the compression curves to those of the original analogue units.

Sound-wise, McDSP have done it again, by producing a range of plug-ins that are so flexible in their configuration that they can be set to 'model' a wide range of classic compressors. My favourite has to be the Neve 2254. I owned a pair of these until quite recently, when the offer of loads of money was too great to refuse and I sold them! As soon as I dialled in the 'British' presets, that sound came flooding back. At the other end of the spectrum is the Dbx 'over easy' sound with the soft knee, which very quickly reminded me how good soft-knee compressors can be. It took me a while to get a good de-esser from CB3 until I fully grasped how the dynamic EQ section works with the compressor — I didn't find the way the Pre Filter works particularly intuitive — but once I understood the signal flow I quickly got to grips with using it.

Tips & Tricks

Even if you don't plan to buy any of their plug-ins, it's well worth taking a look at McDSP's web site for some great tips on EQ, compression and other processing:

Past Imperfect

I have to say that the name Analogue Channel confused me, as it implies that tis plug-in is a channel strip, which it isn't. It comes in two parts: AC1 (at the bottom of this page) is an analogue amplifier emulator and AC2 (overleaf) is an analogue tape emulation plug-in. McDSP have designed the AC1 plug-in to emulate how an analogue amplifier would perform, by preventing signals from hitting digital headroom and distorting digitally. Instead, it's designed to "gently roll off the dynamic range at a user-set level — preventing digital clipping and smoothing out signal transients". It can be used as a fail-safe for preventing unwanted clipping or as a creative tool for 'smoothing' or 'warming up' digital tracks to provide 'analogue character'.

McDSP Classic PackIn effect, it works like a kind of dynamics processor and shares a lot of those conventional controls, although there is no Threshold control. You need to remember that AC1 is always 'on': the process doesn't depend on the input signal going above a certain level, like conventional compression does. Rather, it moves the 'analogue' amplifier from its linear mode of operation, where the input follows the output, to its non-linear region of operation. The Input and Output controls set the levels through the plug-in; you then use the Drive control to limit or 'saturate' the input. Settings below 0dB reduce the amount of compression/saturation in the output, whereas Drive values above 0dB increase the effect. The Compressor control acts like a ratio control but at extreme settings has a very interesting shape. Whereas in a real analogue amplifier, attack and release times would be preset, McDSP have enabled you to adjust them to give a greater range of processing possibilities. Finally, there is an Auto button which, if selected, maintains a constant output signal level for given Input and Drive control settings.

I guess the AC2 plug-in owes its existence to the commonly held idea that certain types of sounds are 'better' when recorded to analogue tape. This is all to do with the fact that analogue tape recording is not a perfectly linear process, especially at the extremes of operation, such as when you approach the maximum recording level. Unlike digital systems, which handle the signal linearly until the headroom is exceeded, and thereafter distort in an ugly fashion, tape tends to distort gently in a way that is often used to 'enhance' the sound. I am of an age where I cut my teeth lining up analogue tape machines like Revox A77s and B77s, and Studer B62s and B67s, to name but a few, and the object of the exercise was always to line the tape machine up to be as linear as possible — so to find a plug-in which has been designed to put back the very flaws that I spent so much time avoiding is, to me, quite bizarre!

McDSP Classic PackThis plug-in can emulate both the tape machine and the tape itself, and as with AC1, you can see the effects the various changes are having on the signal. After the usual input level and phase controls, the first section emulates a problem we had with tape-head design where there would be a 'bump' in the low-frequency response. The other control in this section is Roll Off, which is, in effect, a high-pass filter. The switch underneath enables you to choose between settings modelled after different types of tape machines; for example, 'Swiss' is McDSP's way of saying Studer, while 'Japan-O' is an Otari, but again McDSP are careful to state that these are 'inspired by' rather than exact emulations of these and other classic tape machines.

Next we move on to the tape section. Bias is a high-frequency signal which is added to the audio to enable the recording process to be much more linear; there is a trade-off between noise, distortion and frequency response, and here it is being used as an effect. The various switches enable you to set the 'tape speed', measured in inches per second, then the Modern and Vintage buttons relate to the formulation of the 'tape' and the IEC switches relate to the equalisation curves used to record the signal on to tape: to get a better high-frequency noise performance, the high frequencies were boosted on record and a corresponding EQ shape was used in the playback side, so that the chain as a whole was 'flat'. The graphic display section shows what the combination of all these settings is doing to the frequency response of the plug-in, and the meters display the input, output and gain reduction levels.

McDSP Classic PackI find it really strange to reach for a plug-in that's designed to undo all the work I used to do to make analogue tape machines perform at their optimum. That said, you can use these plug-ins to process sounds like no other plug-in can. They change frequency response and add non-linearity (otherwise called distortion) in complex and interrelated ways. AC1 can emulate a range of vintage Class-A amplifiers and AC2 can emulate most of the classic analogue tape machines. As to their sound, all I need is a tape hiss control and I'd be back in the early '80s working with less-than-perfect tape machines!

In use, the effect that the AC1 plug-in adds is subtle, but McDSP don't claim that it is any more than that. I had more success with low-frequency sounds such as kick and bass with AC2. There was a definite thickening of the sound, but I personally struggle with the idea of a plug-in that sets out to 'distort' a sound I have worked hard to record cleanly! However, I am sure that this will not be a problem for most users, not least as there are now a growing number of generations of recording engineers and producers who have never used an analogue tape machine in anger. Certainly, as I train people in using Pro Tools I am coming across more and more people who have never even edited quarter-inch tape! One man's distortion is another man's desired sound, and if you actually want to recreate the imperfections of analogue recording, Analogue Channel will be a very useful tool.

Band Leader

The MC2000 multi-band compressor, by contrast, is a plug-in I can understand. It is basically four CB1 s configured as a multi-band processor (see screen below). The interface is very clear, with colour-coding for each band in both the frequency display and the dynamic display, so you can see exactly what is going on. The compressor sections are very similar to those of CB1, except that McDSP have made greater use of the LCD display to fit control over four parameters within a small space of screen real-estate. You can also choose not only whether to link or unlink the bands, but also which band should act as Master. Individual band Solo buttons let you listen to what is happening in each band by itself.

McDSP Classic PackThe mere thought of having four Neve 2254s set up as a multi-band processor made me very impatient to get this plug-in across some audio! The good news is that the MC2000 delivers. I thought I would try it on some individual sounds before using it on a mix, so I put it to work on a solo vocal track that has a huge dynamic swing in it — the vocal equivalent of a 'whisper to a roar' — and needed de-essing into the bargain. So out went the compressor and the de-esser and in went MC2000. I set the top band to deal with the sibilance, which I was very quickly able to bring under control, and then split the other three channels over the rest of the vocal range; there was no point in having a band tied up handling the low bass, as there isn't any, really, in a female vocal. One of the challenges of this particular track was that as the singer reached the peak of the song, the tone of her voice changed and tended to sound tighter and less round. MC2000 was able to help with this: by carefully choosing the crossover frequencies, I was able to get it to pull back the frequency band that was making the vocal sound tight. So I got compression, dynamic EQ and de-essing, all in one insert point.

Flushed with success from the vocal, I dropped another instance of MC2000 on the master fader to see how it would handle the whole mix. The simple answer was 'very well'. I was able to make major improvements in the sound very quickly, and very intuitively, too. My only criticism is that the frequency response display doesn't update to take into account the band gain. It would be nice for the band curve to go up above the zero line when you use some gain on that band. This could be something for the next version, maybe?


Reviewing these plug-ins has made me look again at how the basics of our trade, like EQ and dynamics, actually work, and how to get the best from them. If you want simple processors with the minimum of controls to adjust, these plug-ins probably aren't for you. But if you want to be able to control and vary all the different elements of each process, McDSP's compressors and EQs are very worthy contenders for your interest. What's more, you can download 14-day free demos of them from their web site at — You'll need to give your name, email address and iLok user ID so they can put demo licence assets into your iLok account.

The Filter Bank and Compressor Bank plug-ins are very useful, with loads of different options in each one, and Analogue Channel is great for those wanting to recreate that analogue tape sound. However, for me, MC2000 is the best of the bundle by a long way. The good news is that McDSP are bringing out a limiter version called ML4000 which will offer both single-band and four-band mastering limiters in the same plug-in, and I can't wait to get my hands on them. There is no doubt that Colin McDowell is delivering his aim of producing plug-ins "designed to emulate vintage and modern pro-audio equipment". 

Published January 2007

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