A Complete 4-Part Series
Issue 71
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AwTAC Channel Amplifier 500 Series Microphone Preamp/Equaliser


August 22, 2014


AwTAC’s Channel Amplifier comes straight out of the Big Apple packing some big colour and big ideas into a 500 series box.

Review: Greg Walker

AwTAC is an audio brand I hadn’t come across before. It turns out that AwTAC stands for Awesome Transistor Amplifier Company based in the good ol’ US of A, with its 500 series modules coming out of New York City. AwTAC’s philosophy is a simple one of building by hand and tuning designs by ear. The other guiding principle at AwTAC HQ is to use transformers wherever possible… truckloads of the things. As their informative and colourful (they describe their products as ‘f**king awesome’) website illustrates, these guys are passionate about ’70s recording gear and have dedicated themselves to delivering on those kinds of classic sounds. It’s early days yet with a product line comprising just a compressor and preamp/EQ module, but already the companies’ philosophy seems to be bearing fruit, and its the latter ‘Channel Amplifier’ pre/EQ we’ll be looking at here.


Somewhat unusually for the 500 series format this preamp/EQ module is a two rack-space unit with preamp controls on the left hand side and equaliser facilities on the right. The faceplate is finished in a nifty semi-industrial slate grey and the build quality looks to be excellent, with the chunky steel housing being complemented by no-fuss grey knobs and steel switches as well as gold-plated connectors. Everything feels smooth and easy to operate with more finger space than the average 500 series unit. My only small gripe here is the lack of centre detents.

The mic pre features custom wound Sowter and Crimson Audio transformers, and Cinemag inductors in the circuit, as well as some extra features not found in many other designs. Firstly, below the standard phantom power (with a very bright LED indicator), low-end filter and phase reverse switches are two additional smaller switches. The first of these is a simple left/centre/right panning matrix that comes into its own when two or more Channel Amplifiers are set up together to form a mixer. The extra I/O offered by the double width format means the Channel Amplifier can be shoehorned into a mix bus role and multiple modules can be daisy chained together — there’s even the possibility of building yourself a complete multichannel AwTAC mixer in the 500 series format.

The second switch offers output transformer loading at 1200Ω, 600Ω, or removes the load resistance altogether in the middle position. Below these is a standard 1/4-inch socket to DI instruments, which automatically overrides the mic/line XLR input on the back of the unit. The gain structure is simply determined by input and attenuation controls.


Perhaps the most unusual characteristic of the Channel Amplifier is the fact that the higher input settings quickly bring about the onset of saturation and distortion artefacts, even with DI’d signals. It’s a cinch to get things hotted up through the AwTAC, and a joy to hear a circuit that’s been designed to be overdriven. The only place you need to be careful is when driving the input extra hard. The attenuating pot has a very quick taper at the lower end of its range, so matching levels can be tricky.

Running line level signals back through the Channel Amplifier can deliver anything from subtle tonal thickening to outright fuzz. In short, this thing is designed to be driven into the red. The harder you drive it the more the treble rises to prominence but this is no bad thing as the distortion is a very useable ‘transformer saturated’ one rather than a harsh buzz saw effect. I found the saturation and distortion effects delivered by the AwTAC to be extremely pleasing and quite addictive. On the right material it’s a real rock ’n’ roll powerhouse of a box and works beautifully on all sorts of sources including vocals and electric guitars. If things are getting a little too bright you might also consider turning to the neighbouring EQ controls.


The Channel Amplifier has three bands of EQ with some interesting frequency choices along the way. The high shelf starts at 6kHz, then up to 11kHz or 17kHz, while the low frequencies are 35Hz, 70Hz or 130Hz. The midrange has separate controls for cut/boost and frequency selection with the choice of notch or bell curves at the all-important 1kHz and 3kHz bands. The other curves are set at 300Hz, 500Hz, 600Hz, 800Hz, 5kHz and 8kHz. All bands are ±12dB with the high and low bands featuring Baxandall designs. There is also a curious forward/back switch which acts as a kind of presence control to allow things to sit forward or back in the mix depending on the instrument and where you want to place it in the mix. There’s no doubt these are well thought-out frequency bands and the sound of the EQ is musical, sweet up top and nice and chunky down low. A bypass switch at the bottom of the unit completes the controls and allows for easy A/Bing of the EQ’d signal.


You can probably tell by now that I’m a fan of the AwTAC Channel Amplifier. It’s got attitude to burn and I love the fact the preamp/EQ combination has so many different options with regard to flavouring source material and generating exciting harmonic colourings. I should also probably mention that it’s a very good clean preamp as well. I recorded various sources including acoustic guitar, drum overheads, lead and backing vocals, double bass and kick drum with the preamp set to moderate input levels and captured lovely detailed images of all these sources that sat really well in a mix context.

The preamp has a fairly forward character to it with the EQ bypassed but it is not overly bright or harsh sounding. I found the EQ particularly helpful in bringing out the punch and weight of the kick drum, the midrange and top end of a vocalist, and the detail of finger picked guitar parts. On the post-production side, I feel like I’m only just beginning to tap into what this module can do. I have run whole mixes through a stereo pair of the Channel Amplifiers and the results can be anything from gently sweetening to totally bombastic and floor shaking. On drum bus and vocal or guitar tracks this thing really does deliver sensational tonal and harmonic excitement and it’s hard to see this not becoming a somewhat iconic little saturation box over the next few years.

It’s been a mystery to me why more companies haven’t been pumping out distortion ‘colouring’ modules for the 500 series and it seems that AwTAC has finally risen to the challenge with a great, versatile, musical module that has a few extra tricks up its sleeve. I highly recommend the Channel Amplifier though it will take up a fair bit of your rack space. Oh and be warned… you’re gonna want two!


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A Complete 4-Part Series
Issue 71