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TL Audio Crimson 3013

Parametric Equaliser By Paul White
Published August 1997

Paul White raises the tone of his studio by plugging in TL Audio's latest Crimson series parametric EQ.

TL Audio's Crimson range of products has now grown to include seven different units, all using the same basic circuitry as the Indigo tube series, but with solid‑state gain stages replacing the valves. While the valves add a certain character to the sound, the fundamental designs stand up perfectly well in their all solid‑state form, and save the end user a significant amount of money into the bargain. The 3013 reviewed here is a dual‑channel parametric equaliser in a 2U package but, unlike the 3012 (which we looked at in February 1997's SOS), it has four bands of fully parametric equalisation on each channel, plus a pair of very useful high‑ and low‑pass variable‑frequency shelving filters. To extend the flexibility of the unit further, a pair of balanced mic preamps is included, complete with switchable phantom power, and there's also an insert point between the mic amp and the equaliser for connecting additional signal processing.

Like the other Crimson models, the 3013 is powered via the mains, not an adaptor, and both balanced XLR and unbalanced jack audio connectors are provided on the rear panel. There's also an unbalanced auxiliary jack input for each channel, conveniently located on the front panel, and this may be switched to accept line or high‑Z instrument‑ or mic‑level signals. The impedance is high enough to use directly with passive electric guitars or basses. Stereo linking is available via a push‑button switch to the right of the front panel, allowing both channels to be controlled simultaneously from the lower channel controls.


A continuously variable front‑panel gain control (affecting all inputs) provides between 10 and 60dB of gain for the mic input, though there's no mic level metering other than the clip LED on the unit's Master output section. Mic or line operation is selected via a button adjacent to the jack input, and each channel has a 48V phantom power button with a red warning LED.

There are continually variable LF and HF frequencies for the 12dB/octave shelving filters covering the ranges 30Hz‑1kHz and 1‑25kHz, and each of these has its own bypass button with an amber status LED. Such controls are immensely useful for trimming away unwanted high or low frequencies without affecting the frequency range you do want too significantly, and are a welcome inclusion in any serious equaliser.

This equaliser lets you add air and detail to the top end and as much depth and punch as you need to the low end, but it manages this without 'smearing' the sound in the way that lesser equalisers so often do.

The parametric EQ comprises four sections which are identical in all respects except the frequency ranges they cover. Bands 1 and 2 have a range from 30Hz‑3kHz; bands 3 and 4 are fully variable from 1‑20kHz. All have a ±15dB gain range, and the filter's Q can be varied from 0.‑5, which is more than adequate for most practical purposes. Each section has its own bypass button with a green LED to show when it's on, and the gain controls are centre‑detented. The master section includes an overall channel EQ bypass button, again with status LED, and a Master level control. A red peak LED warns of clipping at the equaliser output, before the master gain control.


Over the past few months, I've tried out quite a few TL Audio products, from both the Indigo and the Crimson ranges, so I wasn't the least bit surprised when this particular model turned out to be a strong performer. You get the same high‑quality mic amps as are found in the other units, and though these don't have the same qualities as some top‑end esoteric mic preamps, they are noticeably better than most of those that come built into mid‑priced mixing consoles. I particularly appreciated the shelving filters, which are wonderful for taming flabby bass, or for taking the rough edge off guitar tracks, but of course the main thrust of this particular unit is the 4‑band parametric equaliser.

Equalisers vary enormously in quality, and I rarely find desk EQ satisfactory except on really top‑end consoles. Used on a stereo mix, this equaliser lets you add air and detail to the top end and as much depth and punch as you need to the low end, but it manages this without 'smearing' the sound in the way that lesser equalisers so often do. It isn't as transparent as the high‑end Focusrite gear, but on the other hand some users will probably say it has more character. If you have a peak to deal with, set up a high Q and apply cut — the 3013 has the capability to deal with such problems quite easily. Using a broad Q setting results in a musical, well‑behaved equalisation that can help shape voices or polish mixes without changing the fundamental timbre of the sound being processed.

While two bands of parametric EQ are usually fine for overall timbral shaping, it's useful to have the two extra bands for notching out peaks or for focusing on something like a hi‑hat to help lift it out of the mix. Admittedly, the tube magic isn't there, but then again, in some ways I think of tube coloration as an effect, so it makes more sense to keep it separate and in a more controllable form.


Not only is the 3013 an extremely flexible and well‑designed parametric equaliser, but the provision of such a versatile front end means that it can also be used as a direct‑to‑tape mic channel or as the ultimate guitar/bass DI box. Mechanically and cosmetically the unit inspires confidence, and the controls are set out clearly and logically, making it easy to navigate. All the relevant buttons have bright status LEDs and unbalanced jack connections are present for the majority of people with unbalanced desk insert points — yet fully professional, transformerless balanced connections are also included, along with insert points. These insert points are far from a luxury, as patching in a compressor between the EQ and mic pre turns this box into a powerful voice channel. And, of course, there are two channels, so you get two of everything, including stereo linking. Given the price, this is a powerful and very versatile box that does far more than just provide EQ.


  • Good build quality and cosmetic design.
  • High‑quality EQ with additional shelving filters.


  • Mic metering would be nice.


Like the other Crimson units, the 3013 delivers an excellent combination of value, performance and flexibility at a significantly lower cost than the tube version.