What is a Mic Preamp?

A Microphone preamp is the little gizmo that turns up the mic signal before you record it. You never really needed to worry about them before because they were built into every mixing console. However, more and more studios are getting rid of their consoles and consequently the preamp has become markedly more important.

Preamps nowadays exist either in dedicated channel strips – possibly coupled with EQ and compression, or as standalone units. Studios are shrinking and as a result the 500 series racks from manufactures such as API have become increasingly popular. This attraction is undoubtedly due to the fact that you can squeeze lots of units into a fairly small space. There are a number of preamps already available for the 500 series and furthermore there are a lot of DIY options.

 

New Mic Preamps for the Recording Studio

I’ve just finished building some lovely new microphone preamps from AML (Audio Maintenance Limited). The kits are called the “ez1081 Mic Pre” and they obviously pay homage to a well-respected line of transformer-based preamps! The grey metalwork and red marconi gain switch is surely a bit of a giveaway as to the inspiration. So how does this new offering from AML fare?

The ez1081 mic pre units ship either pre-assembled or as a DIY kit and it’s the latter that I opted for.

Firstly I should point out that everything required to build the preamp is included in the bundle. This is great because there is no need to source hard-to-find pots, switches or other components. Compared with some of the other kits I’ve built this really is a one-stop shop. The metalwork is similarly of excellent quality and the PCB fits the chassis like a glove. The resistors even come pre-cut so as a result this really is an easy build for first-timers as well as seasoned DIY-ers.

I’ve built a kit from AML before: namely the ez1073 Mic Pre that I have documented in another blog post. AML build probably the best DIY kits available in the UK at the moment. Lastly, the documentation is very thorough and easy to follow but more significantly the gear sounds fantastic!

It took me almost 2 days from start to finish to build and calibrate 4 of these preamps. It is also worth noting that they fit perfectly in a standard API 500-series rack. I’m using the classic API 6B rackable lunchbox. The units sell for £179.95 + VAT per unit which is surprisingly reasonable and details of the units can be found on the AML website.

You can see a slideshow of images of the build process below:

The ez1081 Mic Pre on test…

The preamps built in to my Avid C|24 console are undeniably lacking in dynamic range and also transient response. As a result, I’m hoping that these new preamps will become my go-to choice for percussion. Therefore I decided to road-test them to see how well they handle a drum recording.

I setup my drum kit and miked it up using 4 mics. Firstly I used an Audix D6 on Kick – a common microphone in this application. Secondly I used a Beyer M201 on Snare – a nice contrast to the ubiquitous SM57. And finally I used a pair of Coles 4038s as overheads because they really shine in this role. The Mic signals were split through my ART S8 8-channel mic splitter, therefore I could compare preamps on the same performance. Tracks were then recorded via the ez1081 mic pres as well as the Apogee Mini MPs for comparison.

You can see a video of the process below:

So how do they sound?

In conclusion I really like the preamps – especially in their 300 Ohm setting. This seems to lend weight and punch to the tracks as well as an openness, while in contrast, the Apogees appear slightly anaemic in this regard. This effect was far less pronounced when switching the ez1081 units to their 1200 Ohm setting however. As a result it’s definitely going to be worth my while checking how this affects signals being run through them.

Above all though was that I could hear – especially on the kick drum – the beginnings of saturation. This is due to the two Carnhill transformers in the unit in contrast to the transformer-less design of the Apogees. This effect can be pushed even more by running the gain higher and padding the output. I was hearing some slight compression on the kick as well as some slight ducking after each hit. It is slightly annoying these preamps don’t come with an output attenuator like the ez1073, but despite this slight niggle I wouldn’t hesitate to recommend them.

To summarise though: at this price point it’s very difficult to fault these units. They have a recallable gain switch, high quality components and great build quality and despite the odd niggle they seem built to last.