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LA Audio Classic Channel

Single-channel Preamp/Compressor/EQ By Paul White
Published November 1996

LA Audio have taken the best bits from their mic preamps, compressors and equalisers to create a dedicated, single channel mic/line processor. Paul White patches it in.

The idea of a single‑channel, 'does everything' preamp and processor makes a lot of sense: for high‑quality recording, you can process a mic or line input and feed it directly into your multitrack, bypassing your mixer altogether. You could even take a line signal off tape and process it for a bit of extra sweetening. In the September 1995 issue of SOS, we reviewed the Joe Meek Voice Channel, which provides just these kinds of facilities, and now we have an LA Audio unit of a similar kind to look at.

The rather elegant Classic Channel starts out with a transformer‑balanced mic preamp, then follows it up with a 4‑band equaliser configured as high, low and two sweep mids. This is a sweetening equaliser, and as such seems rather more subtle than some 'channel' EQs, which I've often found to be quite heavy handed. The Classic's compressor is based on the original Classic Compressor circuit (reviewed in Recording Musician August 1992) and is designed around an FET gain element, to produce a very tube‑like character. Having used a Classic Compressor before, I find it suits vocals and acoustic guitars particularly well, but it sounds pretty good on just about anything. The user has full control over compression threshold, attack, release and ratio, as well as output gain, and to add to the flexibility of this unit, a switchable, fixed‑frequency de‑essing filter is built in, to tame unruly vocal 's' sounds. Finally, the output stage is also transformer balanced, which not only delivers a warm sound, but also neatly eliminates ground loop problems.

A Closer Look

The mic amp offers a variable 20dB to 60dB of gain, and is fitted with a 20dB pad, phase reverse, and switchable phantom power, just as you'd expect from the front end of a serious mixing channel strip. An insert point is available directly after the EQ section for adding more processing, if needed, and if you're using a line‑level input, a front‑panel button switches to the Line jack input.

The EQ section comprises a variable‑frequency high‑pass filter, and a switchable 12kHz low‑pass filter preceding the 4‑band section. Though the high and low filters in the 4‑band section don't have variable frequencies, they can be switched to operate at 12kHz or 6kHz, and 120Hz or 80Hz respectively. Both mid‑range EQ sections have fixed 'Q' but variable frequency and gain settings, and a +/‑15dB range is available on all sections. Separate bypass switches, fitted with status LEDs, are provided for the 4‑band EQ and the high‑pass/low‑pass filter section.

Directly below the EQ section is the compressor, which has a variable 'knee' characteristic; it has a soft‑knee character for unobtrusive compression at low ratio settings, and a harder knee at high ratio settings. Fully variable control over threshold, attack and release is provided, but unusually, the ratio control is switchable in six steps from 1.5:1 to 20:1, rather than being completely variable. Again, the bypass button has its own status LED, and a separate button introduces a fixed sibilance filter into the side‑chain for de‑essing. Side‑chain access is provided on the rear panel, as is a Link input and Master/Slave switch, which allows two Classic Channels to be linked for stereo operation. A separate knob controls the output gain of the unit, with moving coil meters being used to monitor the output level and the amount of gain reduction taking place.

In Use

The Classic is completely silent during power‑up, as the power supply controls a relay which mutes output until the circuitry has stabilised. When the unit is connected, and up and running, it's simply a matter of adjusting the mic or line input gain to get a healthy level without lighting the input clip LED, and then setting the EQ and compressor controls. Because piling on a lot of EQ gain could cause clipping at the compressor input, a further clip LED is provided in the compressor section.

I found that the Classic's equaliser has a broad, warm character, and though there's plenty of cut or boost range, it seems to have been designed to have a very 'rounded' musical feel, rather than focus and precision — probably a result of the Qs chosen for the mid‑band controls. The high‑ and low‑pass filters are also very effective, especially when used in combination with the main EQ.

In common with the Classic Compressor, the compressor section on this unit has to be set up quite carefully. Initially, you can end up with quite audible output pumping, but a little experimentation produces an appropriate setting quite easily, and the overkill pumping sound can be used to great effect on rock vocals. As you'd imagine, the higher the ratio setting, the more obvious you can make the compression. As I think I said about the Classic Compressor, this isn't a box you buy for benign gain control anyway — you buy it because you want to hear the compression! Providing you don't over‑compress, the processed sounds remains bright and lively, though you do have to choose sensible attack and release times.

The de‑esser setting suffers from the usual single‑band de‑esser problem — as soon as a sibilant sound comes along, the gain of the whole signal takes a dip, but if you set it up so that it doesn't intrude too harshly, it works well enough. Not having a variable de‑essing frequency doesn't seem to cause too much of a problem, but you really need to be careful not to overdo the settings, otherwise the compressor will pump like mad. Then again, you might like the sound of a madly‑pumping compressor, especially if you're trying to recreate a 1967 Who sound!


I think LA Audio have pitched this product about right. Using transformer circuitry certainly helps get the desired 'classic' sound, and it also means that the input stage of the mic preamp is very quiet. The EQ has a nice warmth to it, the compressor has plenty of attitude, and the styling is a nice combination of clean‑cut modern lines, over‑sized knobs, and illuminated moving coil meters.

With awareness of good sound quality continuing to increase, using processors like this one to pipe vocals directly to the input of a multitrack recorder certainly helps, and if you're working with digital tape or a hard‑disk system, you'll probably appreciate the tonal warmth that FETs and transformers inject into the proceedings. I like very much what LA Audio are doing with their range, both in terms of styling, and in the facilities they're including, and from what I've seen of this newest family member, it deserves to do well.

Attack & Release

If you're not sure what to do with the Attack and Release controls on a compressor, set them to their centre positions and don't twiddle them again until you've set up the compressor's threshold for the desired amount of gain reduction. As a rule, longer attacks allow more of the natural transient of the signal through, and longer release times reduce the amount of audible 'pumping'.


  • Transformers and FETs contribute to a warm, vintage sound, but with the low‑noise performance of a modern design.
  • Easy to operate.
  • Smart styling.


  • De‑esser can turn violent in inexperienced hands.


A convenient and well‑designed processor that combines a pleasing tonal warmth with effective compression and EQ. Ideal for high‑quality vocal or instrumental recording as long as you only need a single channel.