You are here

McDSP Chrome Tone

Amp Simulator & Effects (Pro Tools)
By Sam Inglis

McDSP Chrome Tone

If you want to trust your guitar sound to a plug-in rather than a real box of valves, there are already plenty of options — but McDSP's Chrome Tone is a litte out of the ordinary.

The idea behind 're-amping' is simple: rather than set a guitar sound in stone during tracking, the output from the electric guitar is recorded directly, allowing the choice of amplifier tone and effects chain to be put off until the mix stage. Guitarists and recording engineers have recognised the usefulness of this technique since the early '70s, but it was Line 6's Amp Farm plug-in for Pro Tools TDM systems that brought it into everyday use. Suddenly, you didn't need an array of vintage amps and cabs to make re-amping worthwhile; you just plugged your guitar into Pro Tools, chose a virtual amplifier and speaker from pop-up menus and twiddled the controls to your own satisfaction. What you heard was an amplified guitar sound; what went to disk was the dry DI'd tone. Amp Farm settings could then be fine-tuned — and, what's more, automated — at the mix stage, allowing you to match the guitar sound perfectly to the rest of your track.

Line 6 had this market pretty much to themselves for several years, but now there's competition. Users of other DSP systems have the reputedly excellent Nigel (for Universal Audio's UAD1) and the hotly awaited TC Thirty (for Powercore), while those with VST-compatible sequencers can enjoy the likes of Steinberg's Warp VST. Sonar is bundled with its own amp simulator, Izotope's Trash is a tempting PC Direct X offering, and Logic users can look forward to the forthcoming Guitar Amp. To my mind, however, the bar is currently set by IK Multimedia's Amplitube. It supports all the sequencers in common use, it offers excellent stomp-box effect emulations as well as its amp simulation, and most importantly, sounds great. The main disadvantage for Pro Tools TDM and HD/Accel users is that Amplitube is available only as an RTAS or HTDM plug-in. As a consequence, it tends to suffer from more latency than Amp Farm, and imposes a load on the host CPU rather than running on Digidesign's DSP cards.

And so we come to the subject of this review. Like Amp Farm, the plug-ins in McDSP's Chrome Tone suite run on Mix, HD or Accel DSP chips, with the benefits of negligible latency and zero load on the host CPU (though RTAS versions should also be available by the time you read this). Like Amplitube, they don't just model amp/speaker combos, but include delay-based effects, wah-wah and compression for greater flexibility. And unique to Chrome Tone are sophisticated envelope followers and LFOs which, as we'll see, take familiar guitar effects into new territory.

Rock & Roland

An interesting announcement from the recent Winter NAMM show was Roland's VS8F3 effects board for their VS-series multitrackers. Unlike most such products, this will support third-party plug-ins, and among the dozen or so announced at its launch is McDSP's Chrome Amp. From the screen shots available, this appears to be identical to the Amp element of the Chrome Tone suite. It's a shame that VS users won't get access to the wah and chorus too, but the VS multitrackers' mixer architecture probably wouldn't support their modulation features in any case. Chrome Amp for the VS8F3 is expected to retail for $195 in the USA.

Five Plug-ins For The Price Of One

I used the word 'suite' to describe Chrome Tone because its four main elements appear within Pro Tools as independent plug-ins, called Chrome Wah, Chrome Trem, Chrome Amp and Chrome Chorus, while the Chrome Stack plug-in combines all four of these elements. This arrangement helps to make the most of your DSP resources; a single Mix card DSP can only handle one mono Chrome Stack, for instance, but can cope with up to three Amps, six Choruses, seven Wahs, or 11 Trems, and they can be freely combined on the same DSP chip. The only fly in the ointment is that in the current version, presets for the individual plug-ins can't be loaded into Chrome Stack. This means that if you spend hours tweaking your Amp settings and then decide you want to add a little wah-wah and chorus, you'll either need to open additional plug-ins or recreate the Amp settings from scratch in the amp section of Chrome Stack. McDSP plan to improve this in a future version.

Chrome Tone runs under Mac OS 9 and OS X — there's currently no Windows support. It is authorised by iLok in the usual way, and I had no problems getting it working in my system. Each plug-in comes in the full range of mono, mono-to-stereo, stereo and multi-channel configurations, though the stereo and mono-to-stereo versions of the Chrome Stack plug-in require too much DSP to be loaded in a Mix system. There are no Audiosuite versions.

The signal routing for the Chrome Stack (top) and Chrome Amp plug-ins. The signal routing for the Chrome Stack (top) and Chrome Amp plug-ins. The routing of the separate elements in the Chrome Stack plug-in is fixed, and can be viewed by clicking in the bottom left-hand corner. Input signals follow a logical path, beginning with conditioning that takes the form of a high-pass filter with adjustable cutoff, and a fairly conventional noise gate. (Both of these are also included in the separate Amp plug-in, but not in the others.) Then come the Wah and Tremolo sections, each of which has its own editing page, these being pretty much identical to that of the corresponding Wah or Trem plug-in. Both are most impressive, thanks to their comprehensive modulation options — see box overleaf for details.

The meat of Chrome Tone 's amp modelling is contained in the Compression and Distortion components. The compressor takes care of standard stomp-box dynamics duties, but is also used to replicate some of the behaviour of the amp itself. You choose the compression ratio from a pop-up list (2:1, 4:1 and 8:1 are the options); there's a standard Threshold control, while a single Response control sets both the attack and release time. The make-up gain parameter is labelled Sustain, and has its own Release control. Despite the name, the latter actually determines the rate at which the gain boost kicks in, and according to the manual is designed to recreate "a gain-slew effect common to many amplifiers when operated at high volume levels". It's easier to use than it is to describe, and the results are pretty authentic, with a long Release value on a high Sustain setting generating that classic Santana-style effect where long notes get louder as they sustain.

Whereas Amp Farm 's amp and speaker models are all based on specific, named originals, Chrome Tone 's Distortion models are much more generic. The models aren't divided into valve or solid-state, and their names don't even offer vague hints such as 'Brit Class A' or 'American Clean'; the six choices are 'Dist 1' through 'Dist 5', and 'Dist+BP'. The first five offer progressively heavier flavours of distortion, while Dist+BP combines distortion with a manually operated band-pass filter — the dedicated Wah section and plug-in offer much more comprehensive filtering options, but this allows you to get a basic wah-wah effect in the Amp plug-in rather than load in the greedier Stack.

Whichever distortion model you choose, the same four controls are available. You can adjust the colour of the distortion by selecting a Frequency between 200Hz and 2kHz to emphasise, and a Drive amount by which that frequency area should be boosted. There's also an overall distortion Amount control and an output Level trim. It's all easy enough to use and very flexible, though the absence of named models and familiar amplifier parameters means that editing a Chrome Amp or Stack patch is quite different from tweaking a real amp. If you have a particular sound in mind, you can't just dial up the appropriate amp and cab models as you can in Amp Farm; you'll have to work out appropriate Distortion and Compression settings yourself.

A Mighty Wah

McDSP Chrome Tone If Chrome Tone 's wah effect was a piece of hardware, it would be the most overspecified wah pedal in the known universe. The principle is the same as it always has been — a resonant filter is swept up or down as you play — but the range of filtering and control options on offer is staggering. The filter itself offers low-pass and high-pass as well as the more conventional band-pass modes, each available with 12, 24 and 36 dB/octave slopes. And that's not all: there's also an Experimental filter mode, plus a range of Phasor modes. These appear to be all-pass filters that cause a phase shift in the signal rather than changing its frequency content, and come into their own when the Wah plug-in is used in stereo. The filter also boasts cutoff Frequency, resonance (Q) and Range controls. The latter isn't mentioned in the manual at all, but seems to govern the overall extent to which the various modulation sources control the cutoff frequency.

Even without these modulation sources, Chrome Wah would do most of what you and I expect from a wah pedal, using automation or mouse movements to sweep the Frequency control. However, it's the sophistication of the envelope follower and Auto section that makes this effect truly remarkable.

To take the latter first, it offers an adjustable mix of two LFOs, the second of which can run at the same rate as the first, or two, three or four times faster. Each offers a choice of sine, square, triangle and saw up and down waveforms, and can run at the speed chosen by the Rate control or be sync'ed to MIDI Beat Clock, with a Groove slider varying the feel of the resulting rhythm. A Depth control determines how much the LFOs modulate the filter frequency, while the Spread control sets the phase difference between the LFO signal sent to the left and right channels when modulating a stereo signal.

The Auto section alone can be used to generate everything from choppy rhythmic filtering to subtle stereo phasing and thickening effects, but the envelope follower adds a whole new dimension. It features conventional Threshold, Attack and Decay controls, while a Depth control running from -100 to +100 determines how it affects the cutoff frequency. So far, so conventional, but two additional features lift it out of the everyday. The first is that the envelope follower can be triggered not only by the signal being processed or by a side-chain input, but by incoming MIDI note, velocity or controller data, with higher note numbers or velocity values providing sharper triggers. The second is that as well as modulating the filter frequency directly, the envelope follower can be used to modulate the Shape, Rate and Depth controls for the LFO. Finally, when you're using it in stereo, the output from the envelope follower can be inverted for one of the channels.

The MIDI input and side-chaining options mean you can create complex filter patterns simply by routing a MIDI or audio track to Chrome Wah, and the ability to modulate the LFO with the envelope follower opens up some unique possibilities. Modulating LFO Rate in this way, for instance, can produce notes that bubble away increasingly fast as they decay.

Exactly the same envelope follower and LFO are available in the Chrome Trem and Chrome Chorus plug-ins, and the relevant sections of Chrome Stack; and here, too, they open up novel possibilities, such as tremolo that slowly builds on sustained notes, or decays into rhythmic chopping.

A Chorus Of Approval

Having been mangled by the Distortion, your guitar signal proceeds through a basic three-band EQ and into the Chorus generator. This also has its own editing page, mirroring the controls of the stand-alone Chrome Chorus plug-in, and is rather undersold by its name, since it handles delay and flanging as well as chorus effects (the delay option is available only in the Stack version).

The Chorus section features comprehensive envelope-following and modulation features identical to those of the Wah and Tremolo (see box, below). Here, they're applied to a straightforward modulated delay line with Delay, Feedback, Mix and modulation Range controls; and once again, they hugely increase the scope of what would otherwise be a fairly basic effect. I didn't manage to extract anything as rich as you can get from Eventide's Instant Flanger, but it's easy to create funky rhythmic effects or escape the repetitive sound of a simple LFO-based chorus or flanger.

Your sound emerges from the Chorus via a Reverb generator, with a single level control, and a Cabinet simulator. The reverb, to my mind, is a weak spot. It's apparently designed to provide "a combination of spring and 'room tone' reverberations", which seems like an odd aim to start with. If you're the kind of guitarist who likes to buff your crystalline tones to a high gloss with digital ambience, you're not going to want any dirty, clangy spring sounds creeping in; and if you're Dick Dale or Stacy Sutherland, you won't want your spring reverb diluted with room simulation. Personally, I'd rather stick with a decent spring emulation and leave the addition of any room ambience until later. As it is, Chrome Tone 's reverb sounds ugly, but not in a good way. The fixed decay time is too short, it breaks up nastily on high settings, and the overall effect is boxy and unpleasant. In a plug-in which models other effects such as wah-wah in such depth, the lack of control and flexibility here is disappointing.

Four Cabinet models, labelled 'A' to 'D', are available. Again, no reference is made to any real speakers or enclosures from which they're derived, but they cover the expected range from small to large. Each is available in close and distant-miked variants, and a direct mode allows you to bypass the cabinet emulation if desired.

Chrome Verdict

Chrome Tone doesn't provide the same sort of 'instant fix' as Amp Farm. You can't simply call up a virtual AC30 or Bassman with one click, and the factory presets don't do a particularly good job of showing what it's capable of; nor are all the controls properly explained in the PDF manual. The more you experiment, however, the more Chrome Tone 's strengths become apparent. With a little effort, it will run the range of classic guitar tones, from sparkly clean sounds through crunchy rhythm tones and singing leads to the outer extremities of shredding. I'd have no hesitation in using it for any of these, though my mind, there are better choices for guitar sounds towards the clean end of the spectrum. IK's Amplitube still nails the warmth and character of a just-breaking-up valve amp like no other plug-in, and I'd look there first for most country or blues tones.

By contrast, I found myself gravitating to Chrome Tone when I wanted something a little out of the ordinary. It excels at the heavily treated guitar tones favoured by bands like Garbage, Wire or Devo; and the modulation options provided by the envelope follower and LFO open up new territory for well-worn filter- and delay-based effects. It's also very handy for treating instruments other than guitars, especially since you can use the wah, chorus and tremolo separately. By not basing Chrome Tone around a list of well-known amplifier models and familiar controls, McDSP force the user to treat it as an original effect in its own right, rather than a substitute for a collection of vintage hardware. And as such, it has a lot to recommend it.

Test Spec

Chrome Tone v1.0.1.
Apple 300MHz G3 Mac with 256MB RAM, running Mac OS 9.2.
Digidesign Mix system with Pro Tools v5.1.3.


  • Very flexible and controllable.
  • Comprehensive modulation options bring new life to effects such as wah and tremolo.
  • Uses DSP resources well.
  • Capable of producing some very individual treated tones as well as conventional guitar sounds.


  • Nasty reverb.
  • Editing is not as immediate as with other amp modellers, and the controls don't reflect those found on a real amp.
  • Chrome Stack plug-in only available in mono on Mix systems.
  • Presets from individual plug-ins can't be loaded into Chrome Stack.
  • Documentation and factory presets don't always do it justice.


With Chrome Tone, McDSP have gone for depth and flexibility rather than instant gratification. The result is a product that takes some getting to know, but provides unique possibilities.


£433.58 including VAT.

Unity Audio +44 (0)1440 785843.

+44 (0)1440 785845.

Published April 2004