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Lindell Audio WL-3 R

500-series Channel Strip
Published April 2018
By Hugh Robjohns

Lindell Audio WL‑3 R

How did the 500-series’ first discrete, transformer-balanced full channel strip fare in our tests?

Tobias Lindell’s products are always interesting, as they’re designed essentially to meet his own needs as a producer and engineer; as his marketing states, they are “designed by engineers for engineers”. Called the WL‑3 R, his latest offering is actually a revamped version of the original WL‑3 500-series channel strip launched a few years ago, and which Lindell claimed to be the first 500-series channel-strip module — by which he means a single unit combining preamp, EQ and dynamics processing.

Whereas that original model was a single-width module, the new version is designed to occupy a double-width slot and it looks very classy and elegant, with an attractive, 8mm-thick, burgundy-red anodised aluminium front panel. It also features eight custom-made knurled solid-aluminium knobs and a short-throw fader with metal knob, and all the rotary potentiometers have a 41-notch detented action. The audio signal path is book-ended with Carnhill input and output transformers, too.

A joint venture between Tobias Lindell and Paul Wolff (probably best known for his past design connections with API), the WL‑3 R channel strip combines a mic preamp, a three-band equaliser with separate high-pass filter, a compressor, and an output fader — but this undersells the versatility of what is on offer here. Disappointingly, the review unit didn’t come with a manual and neither could I find one online — but thankfully the basic operation seems fairly straight forward, and at least some background details are available on the company’s web site.

Mic Preamp

Following the input transformer, the mic preamp features a continuously variable gain control, marked with a range from +6 to +60 dB. The short-throw (60mm) fader below it can add a further 10dB of gain at the output stage if required. In the middle of the panel near the bottom are five small, grey buttons, all with status LEDs, and the lowest three select +48V phantom power, Line input mode (which inserts a 20dB pad), and Polarity Reverse. A further button to the left of these three activates a second-order (12dB/oct) 80Hz High-pass Filter which remains available regardless of whether the main EQ section is enabled or not.

Testing the WL‑3 R on the bench with my Audio Precision test system showed the actual gain range to be +7 to +57 dB in mic mode, with the output fader at its unity mark. Pushing the fader all the way up produced an overall maximum gain (with the EQ and Dynamics sections bypassed) of 67dB. As is so often the case with variable gain controls, the lower end of the range increments the gain very slowly, building towards a mad rush as the control nears the clockwise extreme.

To deliver a nominal +4dBu signal at the output, the maximum mic input level is -3dBu, which might be a little low for some close-mic applications, and the minimum is -53dBu. However, the 20dB pad introduced when the Line mode is selected raises the minimum and maximum input levels to -33 and +17 dBu, respectively (all with the output fader at its unity mark). I used an NTI Minirator MR-PRO to check the input impedance, which measured 5kΩ in mic mode, although that dropped to just 1.4kΩ in Line mode, which is surprisingly low. While this shouldn’t be a problem with most line-level equipment, some might complain, and I certainly wouldn’t advise splitting the output of a device to feed the WL‑3 R in parallel with something else. The unit passed my test to check whether it can provide the maximum phantom power current without issue.

Looking at the frequency response on the AP system, the low-frequency -3dB limit is 25Hz with a second-order (12dB/oct) roll-off, rising to 100Hz when the high-pass filter is switched in. With the output transformer unterminated (the AP provides a 200kΩ load by default) I measured a very gently rising response above 30kHz, but when connected in a normal audio chain with a typical destination impedance (10-50 kΩ) the response will be flat to well beyond 30kHz.

Checking the distortion figures, I measured a THD+N of 0.01 percent at minimum gain, rising to 0.12 percent at maximum gain (both when delivering +4dBu at the output, EQ and Compressor bypassed). The equivalent input noise (EIN) figure is around -125dBu (150Ω source, 20-20kHz bandwidth), which is respectable if somewhat shy of the state of the art.

EQ & Dynamics

A set of EQ response curves showing the high (blue) and low (red) shelves in their default settings, along with the sweep-mid (green) at the control extremes and centre. Somewhat unusually, the maximum boost/cut for the mid-section is 3dB greater in the middle of its range.A set of EQ response curves showing the high (blue) and low (red) shelves in their default settings, along with the sweep-mid (green) at the control extremes and centre. Somewhat unusually, the maximum boost/cut for the mid-section is 3dB greater in the middle of its range.The equaliser section, on the left side of the front panel, has its own EQ On button (with status LED), and features ±10dB gain controls for the high and low shelves and the sweep-mid band. The LF shelf is set at the factory to peak around 100Hz and the HF shelf around 5kHz, but jumper links on the circuit card offer alternative settings of 200Hz and 10kHz, respectively. Although the web site specs claim the centre frequency of the sweep mid-section can be tuned from 900Hz to 5kHz, the front-panel markings suggest the intended range is actually 250Hz to 5kHz — and the unit I had for testing measured close to that, at 290Hz to 5kHz (as shown in the Audio Precision plot).

Arranged in the centre of the panel are three more rotary controls which all relate to the VCA compressor. The top knob is labelled Compression and this is effectively a Threshold control, scaled simply from 0 (Less) to 10 (More). Below that is a Make-Up Gain control, scaled in the same way and providing up to 15dB of additional gain. The third control, which I was expecting to be a release time, turned out to be a wet/dry mix facility for quick-and-easy parallel compression.

Lindell Audio WL‑3 RAnother pair of buttons (both with status LEDs) insert the dynamics section into the signal path and link the side-chain with that of an adjacent unit (if present) for stereo working. Stereo-linking is a standard feature in most mono compressors, but for anyone unfamiliar the idea, this facility makes sure that the gain-reducing elements in both channels apply the same amount of gain reduction at all times, regardless of which channel exceeds the threshold the most. Without stereo-linking the stereo image would pull to one side or the other as each channels’ compression circuits imposed different amounts of gain reduction — and that’s not the kind of auto-pan effect most people want!

Interestingly, more jumper links on the circuit boards allow the user to select either a feed-forward or feedback topology, as well as fast or slow Attack times. The feed-back/feed-forward options give two distinct sound characteristics, with the feed-back mode reminiscent of older classic compressors like the UA1176, for example, while the feed-forward mode is more like a modern VCA compressor. It’s a shame that Lindell couldn’t find space on the front panel for a button to select these modes, but at least the unit can be user-configured before installation in the rack.

The compressor’s release time is entirely programme dependent (ie. an auto-release system), and I found it to be pretty fast and ‘pumpy’ on most sources. This choice is perhaps explained by Tobias Lindell’s enthusiasm for parallel compression — this reactive character works very well when used in that configuration. Apparently, the VCA circuitry also features an ‘Equal Energy Detector’ (EED) in the side-chain, which is intended to give the compressor a relatively smooth personality. It turns out the EED circuit is essentially a ‘tilt’ filter, which increases the compressor’s sensitivity to high frequencies and reduces it to low frequencies, thereby providing more compression for treble signals while not reacting too heavily to bass instruments.

A set of transfer curves showing how the threshold is adjusted with the Compression control. The ratio steepens progressively as the input level increases, and at high compression settings considerable make-up gain is added automatically too.A set of transfer curves showing how the threshold is adjusted with the Compression control. The ratio steepens progressively as the input level increases, and at high compression settings considerable make-up gain is added automatically too.I plotted a set of transfer curves to show how the compressor behaves with different settings. There is no physical ratio control, but from these plots it’s clear that the ratio builds progressively as the input level rises above the threshold, starting with a soft-knee and gradually stiffening towards limiting. As the compression knob is turned up (more compression) the shape of the compression curve remains the same, but the threshold is effectively reduced so that the limiting level is lowered, resulting in more (and harder) compression.

Interestingly, though, by the time the compression knob is at the 12 o’clock position this VCA compressor starts automatically to introduce some make-up gain, lifting low-level elements at the same time as squashing the high-level sounds. At the extreme clockwise position, I measured around 22dB of gain added to the low-level elements, and the effective threshold level reduces from +5dBu at minimal compression settings to -35dBu at maximum. Again, this works extremely well in the parallel compression mode. The separate make-up gain control works conventionally, with up to 15dB of extra gain available, although I suspect this won’t be needed as often as in a more conventional compressor.

Squeezed in between the dynamics and mic preamp/output sections are two six-LED bar-graph meters. The top one shows the signal level (before the output fader) and is scaled from -18 to +18 dBu. However, with the fader at its unity mark, the bottom LED actually lights fully with an output level of -25dBu, the penultimate (yellow) LED lights at +18dBu, and the top red one at +24dBu when the unit is within 1dB of clipping.

The second bar-graph meter shows gain-reduction and is scaled from 2 to 20 dB but it works in a rather unusual way. On dynamic music sources it does as you’d expect, bouncing up and down to reflect the amount of gain-reduction being applied. However, it doesn’t register static amounts of gain reduction at all, such as when testing with sine tones, which is rather odd!

The signal path is book-ended by two chunky transformers, and the internal circuitry also contains jumpers to tweak some settings to the user’s taste.The signal path is book-ended by two chunky transformers, and the internal circuitry also contains jumpers to tweak some settings to the user’s taste.A short-throw output fader sits almost at the end of the signal path, with a Carnhill transformer feeding the result to the outside world. The fader is scaled with +10dB at the top and minus infinity at the bottom, and is really handy for riding levels while tracking. The Audio Precision test set confirmed the 10dB of gain in hand above the unity mark, while the maximum attenuation at the bottom of its travel measured -77dB. Unfortunately, though, I found that if moved by pressing on the lower edge, the fader cap can tilt and foul against the bottom fader mounting bolt (which sits proud of the surface). If this happens, the fader attenuation is restricted to just -28dB, and this caught me out a couple of times when trying to fade a track out. It’s a shame, as there’s no technical reason for the fader mounting bolts to sit proud at all, given the thickness of the aluminium front panel.

In Use

Of course, I didn’t just measure the performance of the WL‑3, but also put it to use. The preamp offered plenty of gain (up to almost 70dB with the output fader pushed up, and nearly 85dB with the compressor’s make-up gain dialled in too!), and although it isn’t the quietest I’ve used, it will be perfectly acceptable for most purposes. The elevated input impedance of 5kΩ makes it a good partner for ribbon and moving-coil dynamic mics too. The EQ is versatile and sweet-sounding, and while I preferred to set the HF shelf to peak at 10kHz rather than the default 5kHz — this added ‘air’ without over-emphasising bright sources — it’s nice that the user can choose the options that suit their own line of work. Unfortunately, the small grey paint-filled spots on the control knobs aren’t great at revealing the control settings, especially when viewed in low lighting or at an angle, and the 41-detent action means there’s no clear centre-detent for zeroing the controls quickly by feel either (perhaps black paint dots would help?). And while I’m at it, I accidentally pressed the Link button once or twice when seeking the Line button because the two terms look so similar at a quick glance; perhaps the latter could be labelled ‘Pad’ instead (although my apparently failing eyesight might still confuse it with the Pol button!).

Inevitably, everyone has different expectations and requirements of compressors and I have to confess that I was initially a little underwhelmed with the facility in the WL‑3 R. However, I’d been using it as a normal series-style compressor, and I soon learned that — like others in the Lindell range — this one has been designed very much to be used in parallel-compression mode, using the built-in wet/dry mix knob. Employed in that context, I found it to be both punchy and effective, and I grew to like it a lot.

Conclusion

Complete channel strips for the 500-series are few and far between (see the Alternatives box) and I’m amazed that nobody else appears to have used the ‘doublewide’ format to create a comprehensive, discrete channel strip such as this, so full credit must go to Lindell for spotting that opportunity and working with Paul Wolff to create the WL‑3 R. The result is a genuinely useful and high-quality product, with a decent mic preamp, a nice-sounding EQ, and an interestingly versatile compressor, and the output fader is a nice touch too.

There are a few quirks to consider, though. The way the gain reduction meter doesn’t show static GR levels, for instance, and the very low input impedance in line mode. I’m also surprised that an owner’s manual isn’t available yet, given the number of internal user-configurable jumpers and the fundamental way in which they can change the unit’s operation.

Overall, this is a lot of technology to pack into in a 500-series module. The price doesn’t quite put the WL‑3 in impulse-purchase territory, but it’s competitive for what’s on offer. It’s less expensive than the discrete rackmount offerings from most of the big-name competition and broadly on a par with rackmount preamp/EQ/compressor channel strips like the DAV Electronics BG5 MkII and the SPL Channel One MkII. It’s cleverly thought out, looks and feels classy, works well and sounds great — Lindell deserve to do well with it.  

Alternatives

There are several 500-series units featuring both preamp and EQ but lacking the compressor, and a handful with both preamp and compressor but no EQ, so it wouldn’t be difficult to assemble a channel strip comprising two single-width modules — but there’d be no fader, of course. There are certainly very few other full channel strips in this format. Aphex’s Project 500 appears to have been discontinued, and while JHS Pedals’ Pulp N Peel ticks all the functionality boxes, it’s a rather different proposition.

Published April 2018