Lewitt Audio Pure Tube

Lewitt’s vocal‑oriented Pure Tube promises valve tone without the noise.

From their headquarters in Vienna, Austria, Lewitt Audio have built up a formidable reputation for innovation in microphone design, culminating in last year’s flagship LCT 1040: a mic that offers an extensive selection of sonic options around the theme of blending between valve and FET signal paths (reviewed SOS March 2022). The impressive features of the 1040 come at a cost, however, and Lewitt have sensibly borrowed some of the R&D that went into that product to produce a more affordable option for engineers who require a valve mic of similar quality but who don’t need all the bells and whistles. The result is the Lewitt Pure Tube, a cardioid‑only valve capacitor microphone.

First Impressions

Lewitt offer the Pure Tube as part of two different bundles. The Essential Set comes with a minimal set of accessories, including a basic mic mount and an even more basic case for keeping the mic dust‑free. I was sent the Studio Set, which features a robust Peli‑style case housing the mic, the compact power supply and a very large shockmount, which also serves as a neat way of attaching the custom pop filter. I like this idea of offering both a minimal set and a more fully featured package, and it is perhaps a better option than cutting corners by supplying lower‑quality cases and mounts to all buyers regardless of whether they’re needed.

The mic itself looks very similar to the flagship 1040, with a simple, functional form factor that makes no attempt whatsoever to mimic any of the vintage designs we are so accustomed to. I often like to ask clients coming through my studio what they think of a review mic’s appearance and, for what it’s worth, I recall hearing the words ‘fancy’ and ‘modern’ more than once. I won’t dwell too much on aesthetics, but the design choice of having the valve visible — housed like a trophy in a miniature cabinet — serves no practical purpose and will perhaps spilt opinion. It can look nice in a moody low‑light recording session, thanks to a small LED that creates the impression of the valve glowing, but it could also be described as an unnecessary gimmick. Overall, though, I was very impressed with how solid everything looked and felt in use and this, combined with its impressive 10 year guarantee, means you should feel confident about the reliability of what will be a substantial purchase for many people.

Circuit Training

Lewitt are keen to point out that the “revolutionary” circuit design of the Pure Tube delivers unusually low self‑noise for a valve microphone. This is said to be due to the absence of any semiconductors or capacitors in the signal path, and the quoted self‑noise figure of just 7dB (A‑weighted) is very impressive indeed. By way of comparison, for example, the quoted self‑noise of the Neumann M147 is 12dBA, and most other current valve models are noisier still. In fact, only a handful of solid‑state mics actually better the Pure Tube’s self‑noise specification.

Although it’s not often a problem in my day‑to‑day recording work, where I’m tracking bands or material that has a dense backing, microphone self‑noise can become audible if you use heavy compression and like to layer up your vocals. The Pure Tube’s impressively low noise floor also opens up the option of using it in settings where a valve microphone might not otherwise be considered appropriate, such as sparse acoustic and classical recordings, or even voiceover sessions.

Features

The Pure Tube features a one‑inch, gold‑spluttered capacitor capsule that is clearly visible through the grille, with a lime‑green capsule surround that ties in with the look of the overall package. The all‑important valve is a 12AU7/ECC82. As the Pure Tube is a fixed‑cardioid mic and has no pad or filter settings, there are no user controls at all, and this is reflected in the compactness of the external power supply. If you’re contemplating buying the Studio Set, it’s worth mentioning that the included shockmount is pretty imposing! Its size shouldn’t cause any practical issues, but it won’t suit users who prefer a sleeker, more discreet look, and it would be hard to hide in photos or video. It seems beautifully engineered, however, and getting the mic set up and adjusted was refreshingly quick and intuitive. It also allows you to quickly attach the included pop filter so that it’s perfectly positioned for vocal recording.

In Use

My routine for reviewing mics at my studio is fairly well established by now: I make a point of trying out the mic ‘blind’ at first, in order to be as objective as I can, and will initially use the mic in a few ‘low risk’ settings such as drum room mics or as an extra vocal option, while I get a sense of what the mic is like. I’ll wait until I’ve developed a feeling for its capabilities and decided I can trust it before throwing it up as a main mic with a paying client.

My first use for the Pure Tube was on a cello recording session, where I positioned it as an alternative alongside a Neumann U87 at a distance of around three feet from the instrument. I was immediately impressed with the balanced, clean recording coming back through the speakers. It offered a subtly different tonal quality to the U87, with a softer midrange that pushed the sound of the bow meeting the strings a bit further back in the mix. Next up was a drum recording session, where the Pure Tube served as a mono room mic positioned about five feet in front of the kit. I’m not sure this is a role the designers had in mind for their mic, but I was happy with the slightly trashy mono room option it provided. Cymbals can be a good test of a mic, and the results here were bright but not overly harsh.

It had all the detail I was looking for, with a nicely balanced midrange...

After an equally impressive performance in front on an acoustic guitar, where it had all the detail I was looking for, with a nicely balanced midrange, I felt confident enough putting the Pure Tube up to track a male vocalist (recording a Christmas song in July!), and we were all impressed with how it allowed the singer to get very close to the mic, for an intimate feel, without the proximity effect becoming overbearing. This last point is one of the things I noticed consistently when using the Pure Tube in my studio: it always seemed to provide a compact bottom end, even when positioned close to a singer or instrument. This can be useful in many situations, but it didn’t perhaps strike me as the best option if I was looking to help fill out a thin‑sounding singer.

Summing Up

I managed to use the Pure Tube on a varied selection of vocalists over the review period, in styles including acoustic, indie rock, rap and full‑on metal. I could tell I was using a valve mic, but in a nicely understated way: harsher voices were softened slightly, and you could hear some subtle saturation on very loud singers. In fact, I found myself liking less how the Pure Tube handled very loud singers as, unlike my U47‑style mics at the studio, it seemed to become a little thin‑sounding, and generally it provided less obvious saturation and character than you might get from other valve options. The flip side to this, though, was that it always provided a good sense of clarity, and stayed true to what was in front of it.

Overall, the Lewitt Pure Tube is a great‑sounding microphone that seems to offer a nicely judged balance between the sound of a valve mic and ultra‑quiet, clean operation. At around the same price, there are also good alternatives based on the design of historic valve mics, but if you want a more modern design that offers a bit more versatility — and is very, very quiet! — the Pure Tube could be a great option for your studio.