Has Rode’s new USB‑capable NT1 made clipping a thing of the past?
Innovation in music technology can take many forms. Sometimes it means implementing features and creating products that have never been seen before. But it can also involve bringing existing developments to new markets, by finding ways to manufacture them more affordably. This latter kind of innovation has always been at the heart of Rode’s business model, but in recent years they’ve also scored some impressive design firsts. The NTR, for example, goes where no ribbon microphone has gone before, with its laser‑cut ribbon, insanely high build quality and extended frequency response.
The new NT1 5th Generation, arguably, innovates on both fronts.
One Up
Rode have had an NT1 in their line‑up for more than 25 years now. It’s always been a strong option for those seeking a no‑frills capacitor mic, and I’d hazard that it’s featured on more well‑known recordings than people are letting on! It’s a fixed‑cardioid, large‑diaphragm mic, and the no‑frills aspect of the design means you don’t get pad or filter switches. Unlike many fixed‑cardioid mics, its one‑inch capsule is truly single‑sided, rather than being a Braunmühl‑Weber design with the rear diaphragm disconnected. The current iteration of this capsule is called the HF6, and is unique to the NT1. In fact, this capsule is one aspect of the design that hasn’t changed in the new 5th Generation model. The cosmetics are also practically identical to those of the previous 4th Generation model, with a smart dual‑layer headbasket and functional matte black body.
So what has changed? Well, the key to the 5th Gen’s newfound powers is located in the base of the microphone. The conventional XLR connector from the 4th Gen model has been replaced by a new, patent‑pending socket that can accept either a female XLR or a USB Type‑C plug. When connected the old‑fashioned way, the NT1 5th Gen behaves much like its predecessors: it’s a conventional capacitor mic, which requires phantom power and delivers an analogue signal through your preamp of choice. And in this role, it has some eye‑catching specifications, most notably an incredibly low self‑noise of just 4dBA. But on that front, nothing much is new, because the 4th Gen already offered the same analogue performance. The focus of the next generation is digital.
All In One
Unlike many USB mics, the NT1 5th Gen is an input‑only device, and doesn’t have a headphone output of its own. Nor does it have a physical gain control. As we’ll see, this isn’t necessarily an issue, and for spur‑of‑the‑moment recordings where you don’t need to monitor anything, you could just plug in and go. For most use cases, though, you’ll want to install the Rode Connect utility. This allows you to aggregate multiple Rode USB devices and perform low‑latency cue mixing. It also reveals that there’s a lot more going on inside the NT1 than mere A‑D conversion.
Clicking on the NT1 icon within Rode Connect brings up an editing window that exposes multiple parameters, none of which is accessible from the mic itself or available when it’s used as an analogue source. First up is a gain control that runs from 0 to +60 dB in 1dB steps. Below this you’ll find radio buttons for a high‑pass filter which can be engaged at 75 or 150 Hz, but it doesn’t stop there.
Rode Connect is designed primarily for use with the RodeCaster Pro podcast production suite, hence the buttons for triggering sound effects!
During their massive growth over the last 30 years, Rode have absorbed other companies including Aphex, makers of the original Aural Exciter enhancer and Compellor compressor. Their designers’ know‑how has been put to good use in the NT1 5th Gen, and four icons to the right of the gain control engage simple ‘one‑button’ noise gate, compressor, Aural Exciter and Big Bottom processing. These are implemented digitally and have no controls other than the on/off button, but since they come after the gain control in the signal path, it is possible to manipulate the amount of compression that is applied by increasing or decreasing the gain.
The obvious limitation here is that if you increase the gain too far, you risk making the signal too hot to handle and causing clipping. Except you don’t — and that’s where the unique aspect of the NT1 5th Gen design comes in.
Window Shopping
Every device designed to capture or process audio has a dynamic range: the ratio between the greatest amplitude that can be represented within the system, and the noise floor of the system. The NT1 has an incredibly low noise floor and can accept sound pressure levels of up to 132dB SPL, so considered purely as an analogue device, it has a massive dynamic range. It would take a very, very loud acoustic event to cause the mic’s analogue circuitry to clip; and at the other end of the scale, you’d have to be recording something vanishingly quiet in a completely isolated acoustic environment before its noise floor became apparent.
Making a digital recording from the NT1 or any other mic involves passing the signal through several other devices: a mic preamp, an A‑D converter and a digital recorder such as a DAW program. Each of these has its own dynamic range, and we can think of them as a series of ‘windows’ through which the signal must pass. In a modern digital recording system, the dynamic range of each of these individual elements is much greater than that of any acoustic signal we’re likely to be capturing at the mic. However, in order for the signal to make it from the mic to the end of the chain unmolested, it has to pass through all of the windows in turn, and if these windows are out of alignment with each other, clipping or noise problems can result.
The classic situation in which this problem arises is when we’re overdubbing to a previously recorded source. Struggling to hear the input signal clearly over the playback, we turn the input gain up when we should be turning the playback down. In doing so, we push the dynamic windows of our mic preamp and our A‑D converter apart. Go too far, and peaks in the analogue signal become too hot for the converter to handle. This trap is entirely avoidable, though it has to be said that the ergonomic design of software mixers doesn’t always do enough to prevent us falling into it.
Range Finding
When connected over USB, the NT1 5th Gen internalises several of these windows. The signal isn’t just being captured by the capsule and delivered through the impedance converter. It’s also being preamplified by Rode’s ‘Revolution’ preamp circuitry and converted to digital. So, on paper, there is potential for exactly the same trap to open up. If you push the preamp gain too high in order to hear yourself better, you risk overloading the digital stages and causing clipping. And that’s exactly what happens if you select the NT1 as a 24‑bit source within your DAW. Set the gain too high, and the recorded signal will be clipped. However, if you’ve been monitoring it via Rode Connect, the chances are you won’t have heard any ugliness during the recording. What’s going on?
The signal delivered by the NT1 to Rode Connect is effectively impossible to clip, because the NT1 5th Gen doesn’t just have one A‑D converter: it has two in parallel, and together these have a dynamic range that exceeds that of the mic and its internal preamp combined.
The answer is that the signal delivered by the NT1 to Rode Connect is effectively impossible to clip, because the NT1 5th Gen doesn’t just have one A‑D converter: it has two in parallel, and together these have a dynamic range that exceeds that of the mic and its internal preamp combined. To abuse the window analogy further, it’s as though Rode have placed a second window directly above the first. One of the A‑D converters is aligned such that it’s impossible to make the analogue circuitry in the NT1 generate a signal hot enough to clip it, even at maximum gain; the other is aligned such that its noise floor is lower than that of the NT1’s capsule and electronics at minimum gain. Adding the gain range of the preamp to the dynamic range of the mic itself suggests that this dual converter would need to have a total dynamic range of nearly 200dB to completely eliminate clipping. That is way more than can be represented in a 24‑bit fixed‑point signal, and so the native digital output of the NT1 is a 32‑bit floating‑point signal. This is what Rode Connect works with.
As was previously mentioned, this means that clipping is never audible within Rode Connect. And if your DAW supports 32‑bit floating‑point signals (not all do), the same applies here. Your recordings may show waveforms that look clipped, but by applying clip gain or normalising, you can always restore a sensible level with adequate headroom.
Stay Connected
I tested the NT1 with two 32‑bit capable DAWs — Reaper and Pro Tools — and provided you remember to set up the session for 32‑bit files, ‘unclippable’ recording works exactly as expected. In Reaper, you can use the Item Properties to adjust the volume of, or normalise, recorded clips. In Pro Tools, you can do the same using Clip Gain. In both cases it’s completely non‑destructive, and no matter how hot the gain setting, it’s always possible to recover a non‑clipped version of the recording (although in Pro Tools, the recording will continue to look clipped even after you apply Recalculate Waveform Overviews from the Clips window). The only fly in the ointment is that the NT1 is limited to 48kHz sample rates and multiples thereof, and can’t be used at 44.1 or 88.2 kHz. So if, for instance, you’re a remote session singer or voice artist and need to overdub to existing sessions, you may need to retain the ability to record analogue.
On the upper track in this Reaper project, I’ve recorded myself speaking into the NT1 at maximum gain (first clip, above) and minimum gain (second clip, below). When these clips are normalised, there is no discernible difference between them, as shown on the lower screen. By contrast, the grey clip on the lower track was recorded with maximum gain at 24‑bit and remains irrevocably clipped even after I adjust its clip volume.
The experience of using the NT1 with Rode Connect on a recent MacBook was very slick, though I didn’t have access to other USB Rode gear, so can’t comment on how well the aggregation works. The preset Aphex processing sensibly errs on the side of subtlety, with the Aural Exciter adding a bit of sparkle to dull voices or acoustic guitars, and the Big Bottom doing just enough to give speech that Hollywood trailer effect. It’s perfect for podcasting, live streaming and voiceover recording, and the noise floor really is eerily low.
The NT1’s built‑in Aphex processing can be accessed only through Rode Connect.When it comes to music recording, the 3m USB cable and the option of aggregating further NT1s through Rode Connect mean it’s a more practical option than most USB mics, but for anything that involves multiple instruments or pairing with other types of mic, you’ll need to revert to old‑fashioned XLR connection. You won’t get the Aphex processing or high‑pass filter, and you’ll need a mic preamp, but the good news is that the NT1 is not only super‑quiet, but also sounds really good. It’s clean but not wholly characterless; compared with a Neumann U87, for example, you don’t quite get the same richness in the midrange, but there’s a gentle boost above 10kHz which adds an appealing and relatively subtle air to most sources.
If you disregard the NT1’s USB capabilities, its obvious competitors include the Austrian Audio OC16 and Sony C80. These are both excellent mics, and a competent engineer should be able to make good recordings with any of them. The NT1 doesn’t have the presence lift of the OC16, or the slightly dry sound of the Sony with its smaller capsule, but it too is a mic you can point at practically anything and expect good results. And not only is it the cheapest of the three, it’s the only one supplied with cables and a pop filter.
Not that I think music‑oriented purchasers should disregard the NT1’s USB capabilities. A USB mic might not have much of a role to play when recording a drum kit, but there are times where we can all use a simple but effective plug‑and‑play option for Zoom calls, impromptu overdubs, or to throw in the laptop bag in case inspiration strikes. This is a mic that punches a long way above its weight.
It’s All Here
The NT1 5th Gen comes in a smart cubic cardboard box which is absolutely stuffed with accessories. These include the matching SM6 shockmount with removable pop shield, a good‑quality mic cable, and a smart and tough 3m USB cable terminating in Type‑C connectors at both ends. The only thing obviously missing is any sort of case or storage box for the mic itself, but at this price, it’s hard to complain when you are getting absolutely everything you need to actually use the mic.
As ever with Rode, build quality is excellent for the price, and in fact the only minor niggle I have arises precisely because of the high quality of the USB cable. This has a toughened exterior which makes it relatively rigid and spring‑like, so the price you pay for durability is that bumps and scrapes are easily transferred to the mic.
Pros
- A very affordable studio‑quality mic that stands up against some much more expensive rivals.
- Incredibly low noise floor.
- Comprehensive accessories including shockmount, pop shield, USB and XLR cables.
- USB operation introduces optional Aphex processing and ‘unclippable’ 32‑bit floating‑point mode.
Cons
- No storage case or box included.
- USB operation doesn’t support 44.1kHz sample rate.
Summary
The NT1 5th Gen is an ideal starter mic for podcasters and home studio owners. You might want to add to it later on, but it’ll be a long, long time before you outgrow it.
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