BUS-COMP

The Warm Audio BUS-COMP is an all-analog, 2 channel, stereo VCA bus compressor based on classic circuitry that has provided silky smooth tone for decades. Stereo VCA bus compressors are masterful at controlling dynamics on many sources, but they have become widely known for their magic touch on stereo mixes.

The BUS-COMP will perform well on stereo mixes, drum mixes, drum overheads, acoustic guitars, keyboards, piano, orchestral instruments, voice-overs and an array of other sources. The BUS-COMP is primarily designed for stereo use, but it can be used just as successfully on individual mono sources. VCA bus compressors of this type have become widely loved for their ability to control dynamics effortlessly but also for the added tone and depth they provide to the audio signal that passes through them, even when no compression is applied.

A Look Inside

Re-creating legendary VCA bus compressor technology was the focus of the BUS-COMP’s design, however, adding options and improvements was just as important during its development. One feature is the BUS-COMP’s ability to have US-made CineMag transformers inserted into the signal path driven by fully discrete operational amplifiers. With a single push of a front panel switch, these custom transformers are inserted into the audio’s path providing increased depth, tone and vibe!

As with all of the products from Warm Audio, the BUS-COMP was designed with a price point in mind. With efficient, modern manufacturing techniques we are proud to bring this boutique quality, classic VCA bus compressor to the market at a quality-to-price ratio previously unseen. More studios than ever before will now have access to analog quality VCA bus compression. Our desire is for all musicians to be heard the way they want to be heard and we feel the BUS-COMP is the perfect tool to perfect any mix!

Features:

• All analog, 2 channel, stereo VCA bus compressor
• Based on legendary VCA bus compressor technology
• Selectable discrete opamp stage with CineMag USA transformers
• External side chain source select
• Selectable Hi-pass Filter: 30, 60, 105, 125, 185 Hz
• Compressor engage switch for easy A/B compress vs. no-compress comparison
• Performs well on stereo mixes, drum mixes, drum overheads, acoustic guitars, keyboards, piano, orchestral instruments, voice-overs and endless other sources
• Can be used on stereo as well as individual mono sources
• THAT 2180 VCA’s
• Optimally provides both XLR and TRS connectivity
• Noise: < -90dBu
• Headroom: > +29dBu, 20Hz – 20kHz
• Dynamic Range: > 120dB
• Frequency Response: 18Hz – 22kHz
• THD + Noise, 20Hz – 20kHz, +20dBu input: < .05%
• Input Impedance: 10k Ohms
• Output Impedance: 50 Ohms

Direct Boxes

Whether you play guitar, bass, keyboards or another stringed instrument, you’ll need a direct box that won’t diminish your instrument’s tone, like the Direct Box Active and Direct Box Passive from Warm Audio. Every aspect of these direct boxes are designed for maximum sonic integrity, from the custom-wound CineMag transformer to the rugged metal knob and switches. You can expect warm, rich tone even after long cable runs, and the extruded aluminium enclosure ensures a long life span. When you need to convert an instrument-level signal to mic-level, with sonic quality as your top priority, you’ll be well-served with the Direct Box Active and Direct Box Passive from Warm Audio.

Built around world-famous CineMag USA Transformer topology and engineering, like no other DI Boxes in the world. Constructed with top-tier discrete components housed in rugged aluminium chassis’ that include switches, knobs and connectors that are all designed to withstand heavy abuse on the road or in the studio.

The Direct Box Active & Passive by Warm Audio are stunningly transparent. It will not diminish your instrument’s original sound or tone in any way…other than making it sound better. 

Get the rare versatility of having an onboard variable pad which attenuates your input signal anywhere from -3dB to -30dB. This allows you to easily tame any instrument’s input source. 

Direct Box Active is best for instruments with passive pickups, especially acoustic instruments. The Direct Box Active can also operate in “passive” mode. Direct Box Passive is best for balancing the signal of instruments with active electronics, but still performs extremely well on passive pickups by producing a frequency range that exceeds the bandwidth of most passive DI boxes on the market.

Both of our Direct Boxes offer a Thru-put jack that is jumpered to the input jack. It is a convenience jack allowing you to send your instrument’s signal to a second place in addition to the live mixer or recording device. Direct Boxes can also take a recorded signal at line level and send it to another line input while simultaneously sending signal out of the XLR mic level output of the Direct Box.

A Look Inside

Every aspect of our Direct Boxes are designed for maximum sonic integrity, from custom-wound CineMag USA transformers, to their metal switches and connectors, to their gold-plated circuit traces. You can expect warm, rich tones coming from these small, yet extremely rugged Direct Boxes.

Direct Box Active Features:

• Custom-wound CineMag USA transformer.
• Converts instruments to mic-level signals without signal degradation.
• Ideal solution for plugging your instrument direct into any mic pre, mixer or recording device.
• Top-quality discrete components with gold-plated traces on circuit board. 
• Rugged aluminium chassis construction.
• Pad: Variable from -3dB to -30dB.Balanced Output: 600 ohms, mic level.
• Input Impedance: 1 Meg Ohms.THD: .01% from 20Hz to 50Hz. Less than .003% from 50Hz to 20kHz.Frequency Response: 10Hz to 90kHz +/- 0.5dB.
• Linear Performance: +/- 0.05dB 20Hz to 50kHz.
• Power: 48V Phantom or two 9V batteries. Can also be used passively.

Direct Box Passive Features:

• Custom-wound CineMag USA transformer.
• Converts instruments to mic-level signals without signal degradation.
• Ideal solution for plugging your instrument direct into any mic pre, mixer or recording device.
• Top-quality discrete components with gold-plated traces on circuit board. 
• Rugged aluminium chassis construction. 
• Pad: Variable from -3 to -30dB.
• Balanced Output: 600 ohms, mic level.
• Input Impedance: 1 Meg Ohms.
• THD: .01% from 20Hz to 100Hz. Less than .004% from 100Hz to 20kHz.
• Frequency Response: 20Hz to 70kHz +/- 0.5dB.

WARMING IT UP

Over the last couple of months of use, the Warm Audio 273-EQ has been faultless. The internal power supply doesn’t induce any noticeable noise, and makes it simple to rack. All the buttons have a nice deep travel, and all the dual concentric switch pots are from Blore Edwards, a UK manufacturer that makes Neve-specific switches and pots. The switches all felt good, but the pots were inconsistent. Even over a small sample size of six EQ knobs, some had a quality feel with decent resistance, others felt a little elastic, while one was very loose. They were not a match for the original knobs. Likewise, the click of the main switches felt more clingy and the reissue Marconi knobs don’t feel like the real thing. Still, they do a good job at their function, it’s just hard to imagine them holding the same level of quality in 50 years time when they start out inferior.

One cost-cutting measure common to clones is to label the chassis instead of the face of the button. It’s understandable, but is a little problematic on the 273-EQ. There are six buttons for each channel, in two rows of three. For some reason Warm printed the legending for the top row above the buttons, and the rest below the second row. If you stick it in a rack, you have to bend right over below the buttons to read the bottom set of labels. If they’d simply printed the labels above both rows of buttons, it would be far less of an issue.

JUST ONE TRANSFORMER

Insofar as similarities go, the Warm Audio 273-EQ has every single feature of the original.

The only major circuit difference is the inclusion of only one mic input transformer — not separate stages for mic and line, with separate transformers to match. Instead, the signal is simply padded by up to -20dB for line level inputs. It does alter the gain staging and switch labelling a bit. Traditionally, the line level section would travel from -20dB to +10dB. It then has an off switch, so you don’t get a thump when switching between the two sources. Likewise, there’s another off position above +50dB to stop another thump occurring when the third amplifier is switched into the path.

Like most clones, the Warm Audio saves a bit of dosh by ditching the separate line input stage and simply switching in a pad. In this case, a rotary pad that extends past the 0 setting on the switch.

I doubt most people looking at buying the 273 EQ are going to miss the separate stage. Especially considering everything else is there: A full 80dB of gain for mic inputs, high pass filter with four selectable frequencies, three band switchable EQ, and a phase flip.

FREQUENT FIXTURES

There are plenty of features you don’t get on a vintage 80 series 1073 module that you do on the Warm Audio 273-EQ.  On the 1073 EQ, the low band has switchable frequencies of 35, 60, 110 and 220Hz, while the mid band switches between 360 and 700Hz, and 1.6, 3.2, 4.8 and 7.2kHz. The high band is typically set at a fixed frequency of 12kHz. The Warm Audio EQ adds some extra choice up here, allowing you to switch between 10, 12 and 16kHz.

While the original only gave you buttons for phase flip and switching the EQ in and out of the circuit, the Warm Audio version also allows you to instantiate an insert, switch a DI into the circuit and change the turns ratio on the transformer, which adjusts the input impedance. This function is marked as Tone. With the switch out, microphones will see an impedance of 1200Ω, for a more natural open sound. Pressing in Tone changes that impedance to 300Ω, which can sound thicker and punchier with dynamic and ribbon mics. Condenser microphones could care less.

The DI is a great advantage. It makes the 273EQ a really well-rounded channel strip. Especially for those looking to make a leap in quality from the front end of their audio interface.

HOW DOES IT SOUND?

We set up both the Neve 1073s and the Warm 273-EQ in a side-by-side test, and asked talented singer-songwriter Angus Legg to come down and play a tune.

Preamp shootouts are always tough. Unlike converter tests, it’s incredibly hard to conduct them exactly. Split the signal and there’s always a tradeoff; transformers added, loss of level, or even frying an input with phantom power. Rather than trying to make it overly scientific, we like to test preamps by taking a song and layering a bunch of tracks up so the character of the gear starts to shine through.

We did this with Angus — recording his acoustic guitar and vocals, then layering a bunch of harmonies, shaker, and trying to play around the out-of-tune octaves of an upright piano to get a stereo track.

We had both channels of each preamp ready to go into the line inputs of an Antelope Audio interface. After each take, we’d simply swap the mic leads over and go again. The gain matching between both was pretty spot on with the Warm at full fader.

COMPARE THE PAIRS

With everything tracked, Preshan did a rough mix and copied the processing between the tracks. He then did the rounds with a couple of unnamed stereo tracks to see what we all liked better. Unlike a high-end converter comparison, where the devil is in the infinitesimal, largely indistinguishable detail. The differences were darn obvious. It simply came down to a matter of, which would I choose?

On first listen, one was very forward. It had a lot more presence to it, and just generally sounded more punchy. The other undoubtedly felt more glued together, but the acoustic had a boominess I felt was distracting

You can probably tell where this is going. After a couple of listens I went with the first one, which turned out to be the Warm Audio 273-EQ. Quelle horreur!

While I couldn’t get the acoustic boom out of my head, others were far more entranced by the glue of the Neve and picked that.

Comparisons are not without perils, and mixing one side first was probably an unfair play. There’s just no way to mix one and translate it to the other. EQ to compensate for a lack of body in one, would only accentuate the boominess in another recording.

Listening back to the original recordings, that acoustic boominess in the Neve mix translated to body that just wasn’t there in the Warm Audio tracks. In particular, when Angus occasionally plucked the lowest string on his guitar, it resonated satisfyingly deep and long in the Neve recording. On the Warm Audio recording, it didn’t have that resounding low end. The resonance of the low string matched the length of other strings, giving it a more compressed, controlled sound. In a mix, that can really help, but it also paints you into a bit more of a corner.

On the vocal side. It was hard to fault the solo vocal through the 273-EQ, which had more presence and air than the vintage Neve. It sounded pre-polished. However, when pushed, that presence could get a bit much and started to tax a little after layering three backing vocals. The Neve sounded more laid back on the solo vocal, and never felt overbearing when stacked.

RING TO IT

This is where the clone wars get interesting. Unlike the vintage Neve, the 273-EQ just sounds more modern. It was as if the harmonics were more obvious in the upper ranges than in the low end. Overall, it came across more modern mix ready, at the expense of extended low end and a darker tonality that can help to glue a track together.

Functionally, the 273-EQ far exceeds the vintage Neve. For one, you don’t have to carry it around in an 80 series rack. Everything you need for high quality stereo recording is in the one box.

If you’re desperate for the Warm Audio 273-EQ to be a dead ringer for a vintage Neve… well, it’s not. That’s not a bad thing. It’s just different; it’s a very capable, great-sounding preamp, that’s well-built, has a gorgeous EQ on it, the convenience of a built-in DI and 80dB of clean gain. All for a very keen price. If you’re looking for a different, Neve-ish sound to add to your arsenal, then this is a solid bet.

If you’re low on quality channel strips and were looking around for a classic design to kick off your setup, then this is a great place to start.