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Little Labs LL2A

Compressor-Limiter By Hugh Robjohns
Published February 2021

Little Labs LL2A

Ever wondered what a ‘four‑quadrant analogue multiplier compressor’ might sound like? Neither had we — but it turns out to be something a bit special!

Californian manufacturers Little Labs have acquired a great reputation for their range of elegantly, and often unusually, designed products which address all manner of everyday studio requirements. The latest addition to their range is a deceptively simple compressor‑limiter called the LL2A. Before I move on I should state, for the benefit of those with dyslexic tendencies, that there is no direct relationship between this and the famous UREI Teletronix LA‑2A Levelling Amp! In fact, from a technology point of view, this Little Labs design is a wholly original product for which designer Jonathan Little has adopted an unusual approach and used some even more unusual technology, aided by the analogue modelling expertise of Anamod’s co‑founder Dave Amels — the ‘A’ in the product name is a reference to Amels’ contributions.


The LL2A unit is a half‑rack width, 1U‑high device, and an optional panel is available for those wishing to rack two units together. Fitting the rack panel is straightforward, and I was impressed to find the hex keys required to remove the knobs and front panel are provided with every LL2A. Mains power is provided by an external universal switch‑mode (line‑lump) power supply made by InPhase Engineering. This is built into a nice metal case and delivers ±16V DC from any mains supply between 100‑240 V AC. Unfortunately, the review model did not carry the CE marking necessary for sale in the UK and Europe, although I’m sure that was more of an administrative oversight on the review model than a real problem. The PSU output cable is terminated in a Vellman CUF4, four‑pin, screw‑locking power connector, as is used on many other Little Labs products.

The audio connections are straightforward, although there is a very unusual option which I’ll return to later. The electronically balanced input and output are both available on parallel‑wired XLR and TRS connectors, so either format can be used. For stereo operation with a second LL2A, the side‑chains of both units can be coupled by patching a standard unbalanced instrument cable with TS plugs into their Link sockets. The front panel controls have to be set the same on both compressors, of course, and whichever compressor calls for the most gain reduction wins.

Another TRS socket is labelled ‘Side‑Chain Insert’. This is actually a misnomer, as it’s a balanced side‑chain input which overrides the normal side‑chain signal path derived from the audio input. A balanced line‑level signal connected to this side‑chain input can be used to introduce gain‑reduction, or ‘ducking’. This is useful for allowing a bass guitar to be ducked by a kick drum, for example, or for guitars or reverb returns to be ducked to leave space for the vocals.

Alternatively, this side‑chain input can also be used to reduce the compressor’s sensitivity to bass frequencies. If the compressor’s main input signal is also routed into a high‑pass filter, the output from the filter can be injected back into the side‑chain socket, thereby reducing the compressor’s sensitivity to the low‑end of the mix. It’s a technique which is very helpful when performing bus compression, for example. This approach...

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Published February 2021