50th Anniversary Edition
Issue 61

ADK 3 Zigma Z-MOD Custom Shop Valve Microphones


September 19, 2014


ADK wears its colour on its sleeve with the Z-Mod series of valve condensers, but it’s what’s inside that counts.

Review: Mark Davie

Everyone needs a bit more colour in their lives. And ADK is trying to scratch that particular itch. Its custom shop 3 Zigma Z-Mod series of microphones takes its standard Chinese-made multi-pattern valve condenser and pimps it up with some tasty tonal variations and metallic powder-coat colours.

The starting point is ADK’s TT multi-pattern tube condenser, which has a vaguely AKG C12-ish/Telefunken ELAM251-ish body. It has a dual-layer grille head basket, and a straight body that easily screws apart so you can take a look inside or swap out tubes.

The Z-Mods upgrade the cosmetics with chrome head baskets, and powder-coated bodies in a range of appealing colours. And in a show of quality control, all the Z-Mod mics screwed apart and fit together more confidently than the standard TT.

The lineup comprises five microphones that get their names from various classic microphones — there’s the Z-12, Z-47, Z-49, Z-67 and Z-251. No prizes for guessing where those numbers came from.

They all use the same basic body, PCB layout, and custom power supply. Overall, the quality of components has gone up a few notches over the standard TT — bigger capacitors and resistors, better transformers and tubes. Between the Z-Mod mics, there are a few resistor value changes, and different transformers — you get a Lundahl LL1530 in the Z-49 and Z-67, a Jensen in the Z-251 and Sowters in the Z-12 and Z-47.

All the mics come with a selection of JJ and Mullard tubes to play around with in the 12AX7/ECC83 family, a step up in gain from the Chinese-made 12AT7 in the TT. The tube type is the same across all mics, so you can swap out tube flavours even if you have different models — even though the Neumann U67 uses an EF86 pentode wired in as a triode, and the ELAM251 used a 6072/12AY7, which has much lower gain than a 12AX7. It seems circuit designer, JP Gerrard, is making his work easier by keeping the PCBs uniform, but it also means these aren’t dedicated copies — a good or bad thing depending on how influenced your ears are.


The main difference in each mic is the capsule, designed by a mysterious Australian aerospace engineer, though ADK has managed to keep their identity buried. He or she is like the Stig of audio. Or perhaps ADK thought no one would bother looking for the engineer Down Under.

While the capsules might not always physically resemble their vintage counterparts, sometimes that’s for good reason. For instance, rather than cloning the U67 capsule — requiring ADK to implement a new PCB layout with an equalisation circuit like the original mic — the capsule is designed to mimic not only the response of the capsule but the frequency response changes of the U67 circuitry. It’s an all-in-one 67.

The normal TT is no slouch of a microphone. It’s Chinese-made, and comes stock with a Chinese made 12AT7, as opposed to the higher gain 12AX7. It comes with essentially the same accessories, bar the souped up custom power supply and higher quality cables. It’s a nice-sounding mic, with a bit of a boost around 2.5kHz that sounds a bit throaty and pushes sources forward. But the limitations of the capsule and electronics have been revealed by the specifications quoted on the Z-Mod series, showing the upgraded components are at least having an effect on performance. The ADK Area 51 TT has an EIN spec of 20dBA, the Z-MOD mics are 16dBA and below, and the Z-Mod mics handle a few more dB of SPL. They’re still relatively sensitive though, and while they are useful for recording most sources, you’ll want to have pads on hand for anything loud.


I was able to spend some quality time with four of the Z-Mod series, only missing out on a date with the Z-12. With no frequency plots on hand, it was a fun game to really stretch the ears and listen for the subtle differences. Depending on the source, these could be quite subtle, but after a lot of listening, I felt I was able to grasp the character of each mic and what it would do for me.

After doing all that, I was pointed to the capsule plots online by Adam Boon from Professional Audio Services. And it was intriguing to see if what I was hearing was in the charts.

The main noticeable difference between all the Z-Mod microphones and the TT was in the high end. All of them had more air up there.

The Z-251 had generally better reproduction down low that rounded out most sounds and gave them a sense of fullness. I felt that it had a little more pronounced low mid around 180-200Hz on some sources, but it was really just the low end extension I was hearing. Interestingly, the Z-251 also has the most boost in the high frequencies, whereas most of the other capsules start rolling off above 15kHz. But to be honest, I wasn’t hearing much of a difference on most of the sources I was recording.

My sensation when comparing the Z-67, was that it had more top end across the board, with a slight general lift centred around 4kHz. It was nice to see this confirmed on the frequency plot, my ears doth not deceive me. It was interesting to see how wide a boost it had though, from about 2-6.5kHz. And the overall feeling of hearing more top end probably also had a bit to do with the gentle roll off starting at about 200Hz as well.

The Z-47 was probably the most neutral of the lot. I kept coming back to this one on male vocals, it just seemed to be the one that captured the sweetest upper mid range.

The Z-49 sounded like it had a bit of a bump around 1kHz, which gives a nice round harmonic, washy aggression to things like cymbals without being overstated. Really, it just made the mic sound nice and full in the areas where you want it to push.

If you had to twist my arm, I would say the Z-251 would probably be my favourite. In the way we often describe tube gear as harmonically rich and warm, the Z-251 most lives up to that ideal. It adds more full round bottom end on all sources without ever losing clarity. It also balanced out the top end boost, giving it more of a foundation. The rest is just a matter of flavour and where you want a source to cut through. If you just want more top end — or really, less bottom — go for the Z-67. I found this was the best fit on acoustic dreadnaught-shaped guitars, the gentle rolloff was perfect for the low end, where the Z-251 was too full. A more neutral top end? Unpack the Z-47. If you want more harmonic bite, have a look at the 49, especially on percussion, I liked what it did to the high end.


For a standard Chinese mic body, it seems to be pretty sound. There wasn’t any really noticeable basket resonances, given the variety of high frequency responses I was hearing from the different capsules and electronics.

The suspension mount works pretty well. It’s a simple design that feels robust, although the locking angle adjuster could do with a refresh, as the mic’s weight pushes the boundaries of its grip and you have to really crank it.

The packaging is also neat, the whole kit packs away nicely in a metal case, and the microphones have an extra layer of protection courtesy of a velvet-lined wooden box. The power supplies are nice, with nine polar pattern selections from omni, through cardioid to figure-eight. The rejection in figure-eight was very good, and the back side often seemed to have a slightly duller tonality to it, which might come in handy. The cardioid setting is not super wide, but you’ve got plenty of scope to spread it wider or thin it down with the polar pattern selection.

The only thing letting down the level of finish is the stick-on label for the serial and model numbers. It cheapens the whole look, and if it peels off, you’ll have to remember which flavour it is by the powdercoat colour.


These mics are really worth checking out if you’re in the market for a multi-pattern tube condenser. If you’re worried about the quality of Chinese-made condensers and were hoping to steer clear, opening one of these up should waylay any concerns — they’re full of quality components, and are well put together. Plus, the capsules and tubes are fitted and tested in the good ol’ US of A. They also come with a five-year warranty.

The differences between the mics is sometimes subtle, when you first put them up they all sound really great on a lot of sources, but with a bit of listening you can start to appreciate each for the character they bring. And while they’re not component for component remakes, these will stand up alongside any other tube mic you’ve got, and spec-wise, they’ll likely clean up any vintage comparisons.


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50th Anniversary Edition
Issue 61