The dry/wet mix control makes parallel compression easy — and with the superb transient control of this compressor, it can be really effective.
The debut compressor from ribbon‑mic legends AEA is a classy and versatile affair.
Founded in California in the mid‑1960s, Audio Engineering Associates are more familiarly known by their initials AEA, and best known for their range of high‑quality, handcrafted ribbon microphones and preamplifiers. Their involvement in this area dates back to 1976, when they took over the repair of RCA’s ribbon mic range. 1998 saw the release of the first AEA mic, the R44C, and 27 years on AEA still produce it — but their range has grown considerably since then, to include 10 ribbon mics, five mic preamps, and two phantom‑powered, active DI boxes. Now, the company have moved further along the signal chain, with the recent release of the AEA 1029, a stereo VCA compressor.
First Look
The AEA 1029 takes the form of a 1U half‑rackmount device, and shares the classic aesthetic of its preamp stablemates: a dark grey chassis and fascia; white lettering and scaling; a circular, retro‑styled red and silver company logo; and AEA’s signature tall, knurl‑tip silver knobs with black position indicators. Despite being small, the knobs’ combination of knurling and narrow diameter ensures that the controls feel nicely spaced, even to my large hands. Depressing the Compressor In button activates relays that switch the compressor out of a hard bypass. An associated green LED illuminates to indicate that the compressor circuitry is active.
The compression characteristics are set by a three‑position mode and timing toggle switch (Peak Fast / RMS / Peak Slow), and continuously variable rotary threshold and ratio controls. Up to 20dB of make‑up gain allows you to compensate for any loss of level due to compression, and a dry/wet control encourages you to explore parallel compression. Below/between the threshold and ratio controls, a red LED illuminates when the set threshold level is exceeded and gain reduction occurs.
Three horizontal LED ladders indicate the level of gain reduction (six segments, 1‑12 dB), and of the summed input and summed output signals (seven segments, ‑20dBu up to clipping). Finally, there’s a comparatively large red power on/off button, and a green power indicator LED. The 1029’s rear panel carries the 5‑pin XLR connector for the external switching power supply, and balanced XLR I/O connectors for each channel.
Lifting the lid of the AEA 1029 reveals a single, beautifully laid‑out circuit board that hosts all the componentry and each channel’s Fred Forssell‑designed discrete op‑amp. The majority of components, even on those op‑amps, are surface‑mount types, though a number of full‑size, electrolytic capacitors are employed in the audio circuits.
The stereo‑linked compressors feature THAT Corporation’s 4305 Analog Engine single‑chip dynamics processors, and the 4305 itself has two main parts, an RMS (Root Mean Square) level detector, and a Blackmer voltage‑controlled amplifier (VCA). Both the RMS detector and the VCA are pre‑trimmed during chip manufacture to deliver low distortion (typically 0.07% THD).
On the rear, as well as the balanced I/O on XLRs, there’s a 5‑pin socket for the external PSU.
Current Thinking
Since the 4305’s VCA acts on current, not voltage, the L‑R voltages of an incoming stereo signal are first converted to currents, which are then routed to the input of their respective channel’s 4305. In parallel, a summed tap of those currents is sent to the RMS detector of one 4305. This routing configures the 1029 as a feed‑forward, true‑stereo compressor. The RMS detector computes the RMS level of the input current signal by rectifying it, converting the result to a logarithmic voltage, and then applying that voltage to a log‑domain filter. That filter’s output is a DC voltage that’s proportional to the RMS level (in dB) of the input signal current. This voltage, modified by that single 4305’s side‑chain controls (mode/time constant, threshold, ratio and make‑up gain), is then sent to each channel’s 4305 VCA to control its output current level.
The idea of all that is that, since the VCA gain (in dB) is proportional to the control voltage, and the control voltage is proportional to the RMS level (in dB) of the input signal current, changes in the level of the VCA’s output signal current reflect the way in which we humans perceive loudness. The advantage is to create a more natural‑sounding gain control, with high levels of precision and stability over a wide dynamic range.
For the RMS mode, the control voltage is derived from the mean average of both the positive peaks and negative troughs of the incoming current’s amplitude. In Peak mode, on the other hand, the control voltage is derived only from the peaks. The 4305’s RMS detector can be easily reconfigured to act as a peak level detector by changing the values and number of certain capacitors around the chip. In the 1029, a DPDT (Double Pole/Double Throw) switch and an array of solid‑state opto‑relays is used to carry out the necessary changes to toggle between RMS and twin Peak modes.
Since the 4305’s VCAs output currents, a pair of discrete op‑amps then act as current‑to‑voltage converters, creating the signal voltages necessary to drive the electronically balanced L‑R outputs. Those op‑amps are designed by Fred Forssell, who has a 50‑year‑plus career designing, making and selling high‑performance audio equipment in the USA, and has played a key role in designing not just the 1029 but the entire range of AEA mic preamps. His proprietary low‑noise, low‑distortion op‑amps for the 1029 feature complementary NOS Toshiba PNP and NPN JFETs, and are designed to deliver current‑to‑voltage conversion of the highest quality and precision.
1029 In Use
Unusually for a compressor, in my experience at least, no signal is shown on the 1029’s input and output meters when it’s in bypass. In practical terms, this is no big deal, but it does require you to have the compressor active if troubleshooting or gain‑staging your signal chain. There’s no shortage of headroom, as the clip LEDs on the input and output meters come on at +22dBu, 4dBu before the actual clip points of +26dBu. Like me, then, you shouldn’t have any issues integrating the 1029 into your workflow.
The 1029 is impressively precise in the way it handles peaks and transients, particularly at lower frequencies.
As you might expect given the headroom, the frequency bandwidth specifications (dry: 10Hz‑200kHz +0/‑0.05 dB/wet: 10Hz‑200kHz +0/‑0.1 dB) and its signal‑to‑noise ratios of ‑97dBu (dry) and ‑91dBu (wet), the 1029 delivers a performance that is clean, open and transparent. Whilst the 1029 doesn’t offer the sonic character of, say, a vintage‑style valve or optical compressor, it has its own distinct qualities. In all three operating modes, the 1029 is impressively precise in the way it handles peaks and transients, particularly at lower frequencies. To my mind, the transparency and precision of this sonic performance may have something to do with the Forssell op‑amps that drive the outputs.
The continuously variable threshold (±20dB), ratio (1:1 to Limit) and up to 20dB of make‑up gain allow you to explore and exploit the 1029’s compression modes in detail. The Peak Fast mode (4ms attack, 17ms release) is adept at controlling the peak transients of drums and percussion. At higher ratios and thresholds, this mode can crush these sources into ideal candidates for wet/dry parallel compression. Peak Slow (4ms attack, 200ms release) could well become the perfect partner for a stereo‑miked double bass, but I also found it very effective on the spoken word.
For vocals, whether male or female, the 1029’s RMS mode (12ms attack, 50ms release) worked superbly, its strong and subtle overall control remaining transparent, smooth and virtually inaudible, until I started pushing past a ratio of 4:1. RMS mode also performed superbly on more complex stereo sources, with the sort of transients you’ll find in acoustic pianos, guitars, bowed instruments and even, dare I say it, my banjos. For my applications at least, a 1029 would probably spend the majority of its time in RMS mode.
Final Thoughts
At first, given the simplicity of its control layout and the fixed attack and release times of its various modes, I suspected that the 1029’s compression options might be a bit limiting (if you’ll pardon the pun). But first appearances can be deceptive,and my misgivings proved to be groundless. The time constants have been very carefully chosen for use in the real world, which implies much thought, consultation and experimentation in their selection. Once I’d become familiar with the extent of its capabilities, working with the 1029 on any particular source became a hugely enjoyable and intuitive exploration of the wide range of possibilities offered by the multitude of potential combinations of its mode/time constants, threshold levels, ratios and wet/dry mix levels.
After many years of multitracking, I’ve recently begun to return to my roots in old‑school analogue recording, using a stereo microphone and a stereo mic preamp direct to two‑track tape. The AEA 1029 has already proven itself an ideal travelling companion on this journey. If you’re looking for a high‑quality, true stereo compressor that offers excellent value for money and a superb level of performance, you really should give the AEA 1029 a try.
Pros
- Superb audio performance.
- Intuitive operation.
- Excellent value for money.
Cons
- Absolutely none!
Summary
A high‑quality, handcrafted, true‑stereo peak/RMS compressor that delivers a superb level of performance at an attractive price point.
Information
When you purchase via links on our site, SOS may earn an affiliate commission. More info...
