Warm Audio WA76 Series

FET Compressors

Signal Processors > Compressors

By Matt Houghton

Warm Audio pay tribute to two different revisions of the classic FET compressor, and throw in some helpful modern features to boot.

Released in 1968, UREI’s 1176 could act faster than most compressors and quickly gained a reputation for both its sound and versatility. Over the years, various ‘revisions’ introduced changes, with Rev C notably lowering the preamp noise and achieving a more linear response from the FET. Revs D and E were broadly similar, and it’s these popular low‑noise versions on which Universal Audio base their current 1176LN. A number of other companies, though, have also created products based on these designs, including Warm Audio, who launched their affordable WA76 (which sounded decent but offered little by way of additional features) a decade ago.

To celebrate this anniversary, Warm have just launched four more feature‑rich versions: single and dual‑channel versions based on the Rev A and Rev D. Called the WA76‑A, WA76‑A2, WA76‑D and WA76‑D2, the letter in the suffix indicates the revision, while the ‘2’ denotes that it’s a dual‑channel model. Each is housed in a 2U rackmountable chassis, with a front plate that’s consistent with the ‘blue stripe’ or ‘blackface’ styling of the originals. I was sent a WA76‑D and WA76‑A2, so that I could assess the sound of both revisions, and the features of both the single and dual‑channel devices.

Controls & Features

The single‑channel WA76‑D has the controls and layout you’d expect of any 1176‑inspired processor, with large input and output pots turned by transparent‑skirted knobs, with smaller knobs to set the attack and release (clockwise for faster). A column of four buttons selects the ratio (2, 8, 12 or 20:1), and multiple buttons can be engaged, including for the famously hard‑hitting ‘all‑buttons‑in trick’. A large, backlit, moving‑coil meter is switched by another four‑button stack to display gain reduction or output level (with 0 aligned to your pick of +4dBu or +8dBu), or off. There’s also a recessed trim pot to calibrate the gain‑reduction meter.

Less‑familiar features include an input impedance switch (600Ω or 10kΩ). The 1176’s 600Ω was conceived for a time when impedance‑matching was the norm, but today most gear is designed with voltage‑matching in mind, and expects a higher impedance load. A hard‑bypass toggle passes the input straight to the output, but setting the attack to off (fully anti‑clockwise) bypasses the gain reduction, while still routing the signal through the device, making it a line amp that you can drive into saturation. Nice! A Mix knob dials in parallel compression, while a side‑chain high‑pass filter (30‑300 Hz) is set by an on/off switch and a pot.

On the rear, the analogue I/O are on both XLRs and quarter‑inch TRS jacks, and are joined by two quarter‑inch stereo‑link jacks; these allow up to 10 WA76s to respond to a shared side‑chain signal. A toggle on the front determines whether the compressor reacts to its own side‑chain or the shared one. Another neat feature is the side‑chain insert point: separate quarter‑inch send and return jacks mean you can insert, say, an EQ to sculpt the side‑chain, or use an external signal to trigger the gain reduction, such as when using a kick to duck a bass guitar.

Removing the top panel revealed the high‑quality construction I’ve come to expect from Warm Audio’s gear, and other than for the additional features, the circuit appeared, as claimed, to be faithful to the Rev D. Through‑hole components are used, so future repair and maintenance should be easy, and the custom Cinemag input and output transformers are reportedly made to the specifications of the Reichenbach ones in vintage 1176s.

Almost everything above also applies to the single‑channel WA76‑A: the layout of the two is identical, and other than their colour, the differences between the two are on the inside — as per the changes introduced in revisions C and D.

The single‑channel versions (top) take advantage of the additional internal and rear‑panel space to provide both side‑chain linking of up to 10 devices, and an insert point. The insert has a separate send and return, so you can use external processing on the internal side‑chain or use only the return for an external side‑chain.

Two Cool?

The two dual‑channel versions are likewise similar to each other, and I’m told that each channel’s circuitry and sound is the same as in their single‑channel siblings. Yet there are significant functional differences between the one‑ and two‑channel WA76s.

An obvious advantage to the WA76‑A2 and D2 is that they fit two channels into the same amount of rack space as one single‑channel model, while costing less than two of them. Most of the same front‑panel controls, both ‘traditional’ and ‘additional’, are there too, although the skirted input and output knobs are replaced with larger versions of the attack/release ones, and each channel’s meter is smaller (but plenty large enough!).

On these two, there’s no side‑chain insert or provision for side‑chain sharing. Instead, a front‑panel switch determines whether the compressor reacts to a left‑plus‑right summed control signal, to the left channel’s control signal only, or the loudest of the left‑ or right‑channel signals, so there’s still useful flexibility there.

Worth noting is that both channels share a single set of ratio buttons (the same goes for the meter mode). In terms of their muses, this puts these WA76‑x2 devices somewhere between the UREI 1178 and Universal Audio’s 2‑1176. The 1178 has separate input and output controls for each channel, but they share the attack, release, ratio and meter controls. The 2‑1176 has separate controls for each channel, so tweaking in stereo takes longer but you have greater flexibility when processing two mono signals.

Warm Audio’s implementations works very well for stereo, and you can use the left channel to process a mono signal. You can also use each channel to process a different mono signal, but only if you’re happy with the same ratio for both. That’s less restrictive in practice than it may seem: fine to treat two acoustic guitar or backing vocal parts, and 4:1 might work well on very different sources. But you can’t, say, use one channel to compress and the other to limit, so some might see an advantage in shelling out just a little more for two of the mono WA76s.

The higher input impedance option meant they played more nicely with the mixer’s inserts.

FET Accomplished?

Firing up a mix I know well, I used the review units on a range of sources, including vocals, electric and acoustic guitar, bass guitar, piano and drums. They both delivered precisely what I’d hoped they would in terms of sound and attitude. What’s more, when breaking a DAW mix out to my console, the higher input impedance option meant they played more nicely with the mixer’s inserts (which often seem to struggle with a 600Ω load). So that’s a very welcome addition.

As you’d expect, the WA76‑D sounds more elegant in terms of coloration and the gain reduction. Yet, it can go from smooth, gentle vocal or guitar control right up to the sort of grabby, assertive drum effects I associate with FET‑based compressors. If you’re contemplating a WA76 as your go‑to workhorse compressor, this is the flavour you want.

Just as billed, the WA76‑2A delivers a dirtier, grittier sound and an in‑your‑face attitude: very vintage, very vibey.

Just as billed, the WA76‑2A delivers a dirtier, grittier sound and an in‑your‑face attitude: very vintage, very vibey. There’s more noise and distortion, of course, but I’d wager that most of us who bring signals out of the box these days do so in search of character more than cleanliness, and these have it in spades. I could coax wonderfully explosive drum sounds from this thing, with a forward focus and urgency that I found tough to recreate with plug‑ins.

Other than the stereo version’s channels sharing one set of ratio buttons, I really can’t fault these compressors. And if greater control of two channels is important, two mono versions won’t cost a whole lot more, and would give you more features to boot. Recommended.