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TL Audio Crimson C3021

Tube Compressor By Paul White
Published March 1997

Paul White studio tests the Crimson C3021 to see how favourably it compares with its Indigo counterpart.

TL Audio's Crimson range is basically a lower‑cost version of their Indigo range of hybrid tube processors, but using solid‑state circuitry in place of the tube sections. The Crimson C3021 reviewed here is a dual‑channel compressor limiter and, like its Indigo counterpart, it is fitted with both unbalanced jacks and balanced in/out XLRs. The pair of front‑panel instrument jacks (with switchable Hi/Lo sensitivity) has been retained for use with high‑impedance sources such as guitars. It is possible to use both the XLR and jack inputs simultaneously, but the lack of any independent means of controlling the various levels limits the usefulness of this feature. However, you never know when it might help you out of a tight spot.

As far as I can tell, the controls are exactly the same as those on the Indigo C2021, with switched fast and slow attack and release times in place of the more usual variable controls. This arrangement works surprisingly well, no doubt in part due to the programme‑dependent circuitry that automatically varies the time constants to suit the dynamics of the incoming material. Gain, threshold, ratio and makeup gain are fully variable via rotary controls, and a Stereo Link button links the channel side‑chains for stereo operation; in stereo link mode, channel A's controls affect both channels. Each channel has its own Bypass switch and the two bargraph meters to the right of the front panel may be switched to show either gain reduction or output level. Side‑chain access is provided by means of a TRS insert jack, and the integral mains PSU may be switched for 230V or 110V operation.

In Use

Though there is a difference in sound between the Crimson and Indigo versions of this compressor, the lack of tube stages isn't as serious as you might imagine — this is still a nice‑sounding, well‑behaved compressor. At one extreme you can add just a hint of gentle compression; or, by cranking up the ratio to maximum, you can apply true limiting. Having an input gain control as well as an output gain control means that you can bypass the compressor, then use the output level meter to help you optimise the input gain setting. After that, it's a matter of setting suitable ratio and threshold values, and selecting fast or slow attack and release times. In fact, setting up this compressor is so simple that it could do very well in the sound‑reinforcement market, where processors need to be very intuitive and straightforward.

As I pointed out earlier, I half‑expected to find the lack of fully adjustable attack and release times restricting in some way but, providing you don't want to do anything too far out of the ordinary, there's really no problem. The abundance of headroom and bandwidth lends the unit an expensive, transparent sound, and I was pleased to find that I could set up both 'invisible' level control compression and more obvious 'compression as an effect' settings. I would imagine that most people will buy a compressor like this to handle vocals, acoustic guitars, bass guitars, drums and so on, and in this capacity it gives no cause for complaint.


Though the Crimson C3012's feature set is fairly basic, this is still a surprisingly flexible and sweet‑sounding compressor. It lacks a little of the valve warmth of its Indigo counterpart, but still manages a rich sound with no tendency towards thinness. It can also be used to apply fairly heavy compression without stifling all the detail out of a sound.

Given the choice, I'd probably still pay the extra and go for the Indigo version, but at a saving of around £200 on the Indigo the Crimson competes well on price with some of the other serious non‑valve compressors, and it sounds a lot better than many of them. As a marketing move, introducing the Crimson range gives more private studio owners the ability to afford TL Audio products, and that can only be a good thing. Don't be put off too much by the 'tubeless' design, because there's a lot more to making a good‑sounding compressor than simply putting tubes in it. The high‑quality solid‑state circuit components and circuits used here are exactly the same as those found in the Indigo range and the result is a compressor that sounds very nice indeed. TL Audio have built their reputation on affordable tube‑hybrid processors, so it's a brave move to introduce a range with no valves inside at all. However, I think they've pulled it off here — and without doing their reputation any harm whatsoever. If you can afford an Indigo, great; but if you have to settle for a Crimson, I can guarantee that you won't feel like a second‑class citizen!


  • Distinctive design with clear graphics.
  • Affordable.
  • Classy, transparent sound.


  • Not quite as warm‑sounding as the Indigo version,


The Crimson range in general performs very well, and even without the valve coloration the sound is smooth and detailed.