JZ Microphones MU-1

JZ’s innovative MU‑1 gives you two microphones in one — and more besides.

Review mics that come my way often get lent to other engineers during the testing period. This helps ensure they get put in front of the widest possible variety of sources, and can provide a useful sanity check.

Back in 2021, I did exactly this with JZ Microphones’ BB29 capacitor mic. The engineer in question reported that he, like me, had found it to be on the bright side — but really liked the sound he got from putting up the BB29 next to a ribbon mic and blending the two together. My reaction was probably to smile and mentally file this under “ways to make recording unnecessarily complicated”, but it turns out my friend was ahead of the curve.

Grammy‑winning engineer and producer Marc Urselli is a passionate advocate of this technique (see box), and has a longstanding relationship with JZ Microphones. And he has now worked with JZ to create the MU‑1, described as “the first studio microphone to house a ribbon element and a large‑diaphragm condenser capsule side‑by‑side in a single, level‑matched and phase‑coherent body”.

Yin & Yang

Dual‑element mics are unusual, but not unknown. Before the invention of the cardioid capsule, one of the few ways of generating a unidirectional pickup pattern was to combine a ribbon motor, which is natively figure‑8, with an omnidirectional moving‑coil cartridge. This principle was used in the Western Electric / Altec 639 ‘birdcage’ mic and the STC 4033, and has recently been revived by Samar Audio, whose MF08 pairs a ribbon element and a small‑diaphragm capacitor capsule. Manufacturers such as AKG, Sony and Sanken have also experimented with dual‑capsule designs for other purposes such as extending the frequency response, minimising proximity effect and making the polar pattern more consistent.

The ribbon and capacitor elements in the MU‑1 are positioned as close together as possible, to try to make them coincident and avoid phase problems.However, there is no precedent I know of for the specific combination of a large‑diaphragm, cardioid capacitor mic capsule and a figure‑8 ribbon capsule. The logic behind JZ’s pairing is also novel. The primary goal is not to synthesize other polar patterns or permit capture of ultrasonic frequencies, but to allow the tonality of the on‑axis capture to be varied. The intention is that the signals from the two elements will be recorded separately and blended to taste after the fact; consequently, they have entirely separate signal paths and independent outputs.

Get The Drop

The capacitor capsule used in the MU‑1 is one of JZ’s Golden Drop designs, and is the same capsule employed in their Black Hole microphones. As JZ don’t make ribbon microphones, they’ve licensed the ribbon element from another Eastern European manufacturer. The two are positioned side‑by‑side within what is necessarily a rather wide headbasket. The shell as a whole is made of sturdy metal and is pretty heavy. Thankfully, given the size and weight of the MU‑1, JZ have developed a proprietary shockmount, which is included. The outputs from the two elements emerge on a single 5‑pin XLR socket. A splitter cable is supplied, but it’s very short, so you will always need two XLR cables of your own. Mic, mount and cable are all supplied in a smart wooden box, and build quality throughout seems flawless.

JZ describe the two outputs as being “level‑matched”. This is a moving target given the different properties of the capacitor and ribbon elements, but in order to bring the sensitivity of the ribbon component up to that of the capacitor side, JZ have implemented a phantom‑powered active circuit employing a custom toroidal transformer. By contrast, the capacitor circuit is transformerless. In practice, the levels of the signals derived from the two elements vary depending on the spectral content of the source and its placement relative to the mic. With close‑miked vocals, I typically found that the signal from the capacitor element was slightly hotter than that of the ribbon.

Sensibly, JZ provide separate specifications for the capacitor and ribbon elements within the MU‑1; real‑world performance will of course depend on how these are combined in use. The capacitor side boasts an impressively low self‑noise figure of 6.5dBA and a sensitivity of 21mV/Pa. For the ribbon side, JZ quote an Equivalent Input Noise figure of ‑130dBu for the active circuitry. Output impedance is given as 50Ω for the capacitor and 250Ω for the ribbon, while maximum SPL for 0.5% THD is 134.5 and 125 dB respectively. On paper, this might be an issue when recording very loud guitar amps, though you’re unlikely to notice THD creeping above 0.5% when a Marshall stack is blaring away.

Blended Families

As well as carrying out my own tests with the review mic, I naturally lent it to the same engineer who helped me test the BB29 half a decade ago. Between us we tried it on quite a few sources including drums, male and female vocals, amplifier cabinets and acoustic instruments. I quickly decided that he’d been right and I’d been wrong: the MU‑1 is much more than just a way to make recording more complicated! In fact, the whole point is that it opens up new tonal possibilities without making recording very much more complicated at all.

Used on its own, the capacitor capsule in the MU‑1 matches my memory of the JZ BB29, in that it displays quite a prominent presence lift and a correspondingly ‘tucked in’ lower midrange. That works very nicely for some sources, including my own voice, but by its nature it’s a little bit hit and miss. Normally, when my initial mic choice proves a miss, my instinctive reaction as an engineer is not to put up another mic next to it and crossfade between them; it’s simply to dig out another mic with a different character and try that instead. Assuming you have both outputs plugged in, the MU‑1 gives you both options without having to do anything at all.

In a typical on‑axis, close‑miking scenario, the output from the ribbon motor is as you’d expect much darker and smoother than that of the capacitor capsule. However, the combination of both has its own distinctive sound. It’s not really like swapping one of the MU‑1’s elements out for a darker capacitor mic or a brighter ribbon. With the capacitor element dominant in the blend, you retain that bite at the top end whilst filling out the lows in a characteristically ribbon‑y way, with tons of proximity effect and a slightly woolly warmth in the midrange. Flip the balance so that the ribbon mic dominates, and you can dial in just enough crispness to help the source cut through without things getting harsh.

And, of course, that’s only the start of it. Since you have two entirely separate signals to play with, you’re free to record and process them through different signal chains. Filter all the top off the ribbon signal and all of the low end from the capacitor capsule, and shove them through different compressors with different characteristics. Use the ribbon signal to feed a reverb, while the capacitor signal supplies the dry component of the vocal sound. And so on.

I encountered only one real limitation when playing around in this way. I can absolutely see why JZ have chosen to make the ribbon element active, to avoid a huge sensitivity difference compared to the capacitor element, but the review mic backed up my experience that active ribbons are more prone to noise problems than passive designs. My benchmark for low noise in an active ribbon mic is the Rode NT‑R, and I’d say the ribbon system within the MU‑1 I tested was a good 10dB less quiet. It was not so noisy as to be a nuisance in most contexts, but some harsh‑sounding hiss was apparent on quieter sources, or when I compressed things heavily. JZ told me that no noise problems had been reported with other examples, so perhaps I was just unlucky; certainly, the capacitor element was whisper‑quiet.

A problem I anticipated that did not materialise, meanwhile, was phase‑y weirdness with sources that move or are off‑axis. The two capsules are close enough together to be considered coincident for most intents and purposes; sound arriving at 90 degrees is picked up off‑axis by the capacitor capsule and rejected almost entirely by the figure‑8 ribbon, whilst sound incident from behind is mainly picked up by the ribbon alone, so has a much darker character. With the two capsules combined at an equal level, therefore, the MU‑1 doesn’t have a classically pure polar pattern, but in practice it’s fairly benign and doesn’t require singers to remain rooted to the spot.

The two elements in the MU‑1 are sufficiently different that if one doesn’t work well, the other very likely will.

Swiss Army Knife

When I first heard about the MU‑1, I’ll confess to a certain degree of scepticism. I wondered whether it might turn out to be a solution in search of a problem, or yet another excuse to avoid committing to a sound at source. It’s not. It is a genuinely useful studio tool that addresses real‑world needs. In the large majority of sessions that I do, there isn’t time to spend hours trying out different mics. The two elements in the MU‑1 are sufficiently different that if one doesn’t work well, the other very likely will; and more often than not, the sweet spot is to be found by combining them. What’s more, this combination has a character all of its own. The MU‑1 isn’t just two mics in one: it’s a whole spectrum.