AML ez1081 Mic Pre - DIY Audio Kit

5 DIY audio kits to improve your recording

The birth of DIY Audio

DIY audio has been around for a long time. The earliest recording studios didn’t have the possibilities we have today. If a studio engineer wanted a piece of gear for a specific function they had to build it. They couldn’t just nip out to Studiospares!

Names such as EMI, Decca and Trident are synonymous with music labels. Yet they also built their own mixing consoles and the circuits they developed are still used to this day.

In the 1990s, technology such as the ADAT and hard-disk recorder meant that the home studio finally became a reality. Before then, the only real possibility to get into a studio was to already have a record deal in place.

Even then though, certain pieces of studio equipment were out of the budget of most small studios. Pieces like the Fairchild compressor, Pultec equaliser, Neve 1073 preamp, and Neumann U47.


Home-studio DIY Audio Kits

We are now in a golden age of affordable music technology.

Today there are many great DIY options available to the home recordist. Many classic pieces of recording gear are now available; either in kit form or within a small budget.

Warm Audio, Stam Audio and Klark Technik amongst others, now sell affordable clones of many pieces of gear. The Urei 1176, API 312, Pultec EQ and LA-2A are the most-often cloned pieces of hardware, yet it doesn’t stop there. You can also pick up cheaper versions of U87, U47, U67, and C12-style microphones.

I have built many pieces of studio gear in search of the tones I heard on records from the 1970s and 80s and I would like to talk about my top 5 choices for the small studio that won’t break the bank.


1. AML ez1081

Threecircles Recording Studio - AML ez1081

Audio Maintenance Limited make a selection of DIY audio kits. All kits draw inspiration from Classic British hardware. You can buy the ez1073 mic preamp and EQ, ez1081 & ez1073 preamp and ez2254 compressor. They also offer a Pultec EQ.

I have built the ez1073 preamp and equaliser which I documented in a previous blog post. I then went on to build 6 ez1081 mic preamps for the API 500-series and these get a lot of use at Threecircles.

These are my go-to preamps for drum recording. They have a full-bodied sound but yet still keep transients punchy and detailed. They are a Class AB design rather than the Class A found in the ez1073.

For around £200 in kit form, these are a seriously good buy. No other manufacturers that I know of are offering the 1081-inspired design. Many people now offer 1073-style preamps but I really dig what these units do.

The ez1081 is great fun to build and was very straightforward. All components are in individual bags not to mention that the resistors even come pre-cut!


2. CAPI BT50

Threecircles Recording Studio - CAPI BT50 EQ

Classic Audio Products Inc. are the brainchild of Jeff Steiger and ship from the USA. All the DIY audio products available draw inspiration from classic American consoles from the 1970s.

There are several preamp designs on offer such as the VP26 and VP28 which get a lot of love in recording circles. They also offer a couple of EQ choices such as the BT50. This takes its name from the API 550 which inspired it and offers a similar set of features. These are selectable top, middle and low bands as well as low and high-pass filters.

These sell for around the £400 mark which then gets confused as you have to factor in import duties. They pack some serious punch though, and have remained glued to mix mix-buss since I built them.

The build process is very easy, with excellent documentation throughout. There is also forum support via GroupDIY.


3. Serpent Audio SA-3A

Threecircles Recording Studio - Serpent Audio SA-3A

This is a clone of a stereo Urei LA-3A compressor. The kit I have actually bears the name “Shadow Audio” before the company changed names. The kits, faceplates, and PCBs are still available from time to time from their website. I documented the build of this kit in a previous blog post.

This build definitely had more of a DIY feel to it. Unlike kits from AML and CAPI, which come with everything you need, this build needs parts from elsewhere.

Several parts such as the T4 optical attenuators are only available from a handful of places. This is also true for the input and output transformers.

The whole unit cost somewhere in the order of £650 – not bad considering there are two independent units! This also happens to be a serious workhorse compressor and it gets used lots on vocals and guitars.


4. DIY-Racked DR609

Threecircles Recording Studio - DIY-Racked DR-609

This unit is a clone of a famous British stereo compressor from the 1970s. The unit has both limiters and compressors and can function as two separate mono units or stereo. This function means that it is a revered compressor on the mix-bus and that’s where mine gets the most use.

This is another DIY audio kit shop that leaves you slightly to your own devices. The basic packages on offer usually include the faceplate, chassis, and PSU. You must buy all the other components elsewhere.

This was a more frustrating build as there were several errors on the BOM (Bill of Materials) provided. This meant that I had to re-order several small components which meant more postage costs!

There were also supposed to be calibration instructions provided. These are still not available at the time of writing. Indeed, I actually ended up getting help from a guy in Germany who was building one at the same time!

This unit also is the most expensive on the list – coming in at around £1000 for the whole build. For that money, though you get a serious tone injection. In fact, this one piece of gear has become my studio favourite and you’d need to prise it out of my cold, dead hands!


5. C12/251 Microphone

Threecircles Recording Studio - Apex 460

I have several self-built microphones in the studio but this one deserves special mention. It is slightly misplaced on this list, however as it requires you to buy a “donor” microphone.

The mic in question is the Alctron HST-11a which goes under several other aliases. It was bought in bulk and re-badged by many manufacturers including Apex & Telefunken. It can be found for around £200 on eBay.

Once you have the suitable donor, you can buy a kit to convert it into a much superior specimen. Kits are available from Micparts and include a new capsule and better parts. In fact, the modification has proven so popular that they now even offer a full kit.

This mod was a breeze – I even went so far as to source a better headbasket for the mic and this mic is now a regular go-to for vocal duties.


Honourable Mentions

It is slightly remiss of me not to mention Hairball Audio which got me into the DIY audio world in the first place. I have built 3 of their 1176 compressors which I also documented in blog posts. These compressors get used all the time and definitely warrant the title of “studio workhorse”. The only reason these weren’t included in the list above is that I could technically get by without them. Recording wouldn’t be nearly as much fun, but the other units are more versatile for me.

There are many other sources for DIY Audio kits that I haven’t yet explored but get some love online. These include Sound Skulptor, Don Classics and Total Audio Control that are worth checking out.

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