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  • Warm Audio WA-84 Small Diaphragm Condenser Microphone

    By Phil O'Keefe |


    Little microphone, big sound






    Large diaphragm condenser microphones - especially large diaphragm tube condenser microphones - tend to be the rock stars of the microphone world. In a typical mic locker or collection (whether we're talking about a major commercial studio or a small home recording setup), the most expensive and most prized mics are often large diaphragm models. But let me let you in on a little secret: the real condenser mic workhorses of many mic collections aren't the large, mega-expensive tube LDC's, but rather, the small diaphragm condenser mics. Every studio needs at least one good pair of SDC's (small diaphragm condensers); they tend to get used on a wide variety of sound sources, such as drum overheads and cymbal spot-mics, stereo group and ensemble recordings, acoustic guitars, percussion (especially hand-held percussion, cymbals, and small drums), guitar amps, acoustic piano, orchestral string instruments like violin, cello and contrabass, brass and reed instruments - in fact, there's little that you can't do with a good pair of SDCs. While vocals tend to be tracked with large diaphragm mics more often than with SDC's, it's not unheard-of for them to be used for that purpose too. 

    Small diaphragm condensers offer advantages over LDC's, including less-colored off-axis response, faster transient response, and easier placement in tight quarters. The main disadvantages are that they tend to have a little more self-noise than large diaphragm FET mics, and many of the modern SDC's tend to be fairly bright, with less robust low frequency response. One of the earliest SDC designs was the Neumann KM-84. The world's first phantom-powered microphone, it was released in 1966 and discontinued in 1992. Known for its small size (KM stands for "Kleine Mikrofon", which translates as "small microphone") as well as its flat frequency response, uniform cardioid polar pattern and relative lack of off-axis tonal coloration, it has long been one of the most popular SDC's, and it is the mic that other similar types of microphones inevitably get compared to. Unlike most of the modern SDC's (which use transformerless outputs), it utilized a transformer-balanced output, which was part of the reason for its larger and fuller sound. Many engineers prefer this model over the brighter sounding microphone that replaced it. When the vintage gear fans at Warm Audio decided to build a recreation of a classic discontinued small diaphragm condenser to add to their line of large diaphragm FET and tube condenser microphones, the KM-84 was the obvious choice to try to emulate. The result of their efforts is the WA-84 under review here.    






    What You Need To Know

    • The Warm Audio WA-84 is a small diaphragm, phantom powered cardioid condenser microphone based on the long-discontinued Neumann KM-84.


    • The WA-84 is available in two different colors, just like the original mics were - nickel and black. Additionally, the WA-84 is offered in both stereo sets and as a single microphone. I was sent a stereo pair of nickel WA-84s to test and evaluate for this review.


    • The Warm Audio WA-84 is a small pencil-style condenser mic that measures 131 mm long and 22 mm in diameter (5.16" x 0.87"), and weighs 122 grams / 4.3 ounces. This makes it basically the same diameter as a vintage '84, but around 20 mm longer.


    • The body of the WA-84 looks very similar to the vintage '84, right down to the very similarly sized and shaped vents behind the removable capsule.


    • The WA-84 has a -10 dB pad switch on the side of the body. The switch is slightly recessed to prevent accidental activation - you'll need a small screwdriver, toothpick, or the tip of a pen to move it. The pad comes immediately after the capsule but before the rest of the mic's electronics, which keeps the signal from the capsule from overloading the input of the onboard amplifier.



    • With the pad engaged the WA-84 can handle levels as high as 133 dB SPL @ 1 kHz, 0.5% THD, so it's quite capable of handling loud sound sources such as guitar amps and drums.


    • Like the mic that inspired it, the WA-84 uses fully-discrete, Class A, FET-based solid state electronics. Warm Audio uses a Fairchild BF245 JFET in the WA-84. The Warm Audio WA-84 requires 48V phantom power for operation.


    • As with their other microphones, Warm has chosen good-quality electronic parts for use throughout the WA-84, including polystyrene and Wima capacitors. This time, they're using a combination of 5% tolerance carbon and 1% tolerance metal film resistors.




    • Many modern small diaphragm condenser microphones use transformerless output circuitry, which makes the microphones easier to build (it's hard to fit a transformer inside such a small mic body) and cheaper too, but many engineers prefer the sound of the older transformer-based designs.


    • If you're going to use a transformer-balanced circuit in a microphone, the quality of the transformer you select is critical. Warm Audio didn't skimp here - they selected an American-built CineMag CM-5722W transformer for use in the WA-84. This high-quality nickel transformer is similar to the BV-107 that was used in the Neumann KM-84 and uses very fine and thin laminations, and has excellent inductance.


    • Warm Audio uses an Australian-built recreation of the 20 mm capsules used on the classic KM-84. Neumann's KK64 / KK84 capsules, as used on the KM-84 mics, have a unique slotted backplate design. While I was unable to take a WA-84 capsule apart to verify whether the capsule on the WA-84 uses the same exact configuration internally, Warm Audio tells me that it does use the same design as the mic that inspired it. An examination of the two capsules certainly seems to bear this out - they look practically identical both from the front and from the rear, with the exception of what appears to be a finer mesh screen material protecting the front of the capsule on the vintage '84.





    • The WA-84's sensitivity is rated at -39 dB (11mV / Pa @ 1 kHz), and it has a equivalent noise rating of 16 dBA (IEC 651) - all of which is very similar to a vintage '84. The signal to noise ratio is 78 dBA, and the dynamic range is 107 dBA (IEC 651). Frequency response is listed as 20 Hz to 20 kHz, with no +/- tolerance listed, although based on the frequency response plot, it would appear to be roughly +/- 3 dB.



    • The WA-84 has a 200 Ohm output impedance, with a rated load impedance of equal to or greater than 1 k Ohm. The output jack is a gold plated 3-pin XLR.


    • Regardless of whether you opt for a single mic or a stereo pair, the WA-84's come well-appointed with a nice set of accessories, including a molded, foam-lined storage case, mic clip(s), shockmount(s), foam windscreen(s) and even extra shockmount elastic bands.



    • The shock mounts are color-coordinated with the microphones - if you order the nickel colored WA-84's, you'll get nickel colored shockmounts, and if you order black WA-84's, the shockmounts will match the bodies. A small thing, but it does show the attention to detail that Warm Audio puts into their products.


    • The WA-84 is covered by Warm Audio's one year limited warranty. 





    • Currently Warm Audio doesn't offer any other capsules for the WA-84 besides the included cardioid capsule. I suspect that many users won't care since cardioid is the most popular polar pattern for most recording tasks, but those of us who sometimes need the flexibility of alternate polar patterns would love to see Warm Audio offer optional omni and hypercardioid capsules.


    • While the capsules use the same basic design and are identical in size, with the same type of capsule mounting and connection pin configurations, the Warm Audio WA-84 is not compatible with Neumann's KM series capsules; the threads on the WA-84 are 1 mm larger, so the capsules are not interchangeable. This means it isn't possible to use Neumann KM series capsules with the WA-84 mic body and electronics, or vice versa. On a positive note, the threading for the WA-84 capsule appears to be of a higher quality than what you'd typically find on most Chinese-built small diaphragm condenser microphones; many of which I would have concerns about how well they'd hold up if I needed to swap capsules on them regularly.


    • The midrange, while quite good, isn't as detailed or seductively smooth as it is on a good vintage KM-84.




    Like all of the other products from Warm Audio that I've tried to date, the WA-84 represents a terrific value, and provides a suitable low-cost alternative for engineers and musicians who want the sound of classic gear but who otherwise might not be able to afford the stratospheric prices that such gear often sells for - when you can find it on the used market.

    The frequency response of the WA-84 is relatively flat, giving you a more accurate representation of the sound source than you get from many of the affordable small diaphragm condensers currently on the market. This is in no small part due to Warm Audio's decision to go with a transformer-balanced circuit, and their use of a high quality BV-107-style CineMag transformer. The quality of the capsule also comes into play here, and the Australian-built capsule that Warm Audio uses in the WA-84 is very similar to the original KK 64 style capsule, although I was disappointed to learn that they're not interchangeable. Let's hope that Warm Audio decides to release optional capsules with other polar patterns besides cardioid.

    I really like the sound of the Warm Audio WA-84. While I don't think the midrange sounds quite as detailed as the mic the WA-84 was inspired by, the sound quality is otherwise very reminiscent of the vintage classic it is based on, which means it's very good overall, with a honest yet slightly larger than life character, excellent low and low midrange response, and sweet sounding high frequencies that are clear, smooth and detailed without even a touch of harshness or brittleness. The lack of off-axis coloration is also quite impressive. Sounds that are coming from the sides and rear are attenuated evenly across most of the audible frequency range, so off-axis sounds don't suffer from a huge tonal shift like they do with many other mics. This is an extremely beneficial characteristic for stereo recordings, making the WA-84 an excellent mic for such purposes, whether we're talking about recording a classical piano recital or using them as stereo drum overhead mics on a rock session. 

    The WA-84 is very versatile, and you'll find them well-suited to a wide range of recording tasks. Short of close-miked vocals (where I found the WA-84 to be very susceptible to wind blasts and plosives - I'd recommend multiple pop filters if you want to use it for that), I liked, to flat-out loved the way they sounded on just about everything I tried them on. And best of all, they're available new, and at a price that just about any serious recording enthusiast can afford. Looks like Warm Audio has another winner on their hands - they have once again provided the recording community with a serious, high-quality tool at a very reasonable price - well done folks!    -HC-


    Want to discuss the Warm Audio WA-84 or have questions or comments about this review? Then head over to this thread in the Studio Trenches forum right here on Harmony Central and join the discussion!




    Warm Audio WA-84 Small Diaphragm Condenser Microphone (single mic: $399.00 MSRP, stereo pair: $749.00  MSRP)

    Warm Audio's product web page     


    You can purchase the Warm Audio WA-84 from:

    Stereo Pair:


    Full Compass     

    Guitar Center     

    B&H Photo Video    

    Musician's Friend     


    Single Mic:


    Full Compass     

    Guitar Center     

    B&H Photo Video     

    Musician's Friend     


















    Phil O'Keefe is a multi-instrumentalist, recording engineer / producer and the Senior Editor of Harmony Central. He has engineered, produced and performed on countless recording sessions in a diverse range of styles, with artists such as Alien Ant Farm, Jules Day, Voodoo Glow Skulls, John McGill, Michael Knott and Alexa's Wish. He is a former featured monthly columnist for EQ magazine, and his articles and product reviews have also appeared in Keyboard, Electronic Musician and Guitar Player magazines.  

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