Have Michael Joly Engineering upgrade your MXL 990 with our professional in-house modification service.

"MJ" badge and "Michael Joly Engineering" branding strip
Michael Joly Engineering Modified Hulk 990 with signature single layer headbasket and 3 micron diaphragm MJE-K47 capsule
Your MJE 990 can go head-to-head with the industry standard U 87ai. Listen for yourself.

SOUND FILE: Male Vocal, U 87ai
SOUND FILE: Male Vocal, MJE Mod'd 990

SOUND FILE: Ac Gtr Fingerstyle, U 87ai
SOUND FILE: Ac Gtr Fingerstyle, MJE Mod'd 990

SOUND FILE: Ac Gtr Strummed, U 87ai
SOUND FILE: Ac Gtr Strummed, MJE Mod'd 990

SOUND FILE: Female Vocal, U 87ai
SOUND FILE: Female Vocal, MJE Mod'd 990

Great Sound. Great Value. Risk-Free.

Need an affordable U 87ai alternative? Start with a mic you already own - the MXL 990. Then have Michael Joly Engineering upgrade it with field-proven microphone mods. This is Michael Joly writing, the founder of OktavaMod. Read on and find out why a modification to your 990 mic is right for you.

Single Layer Headbasket Mod -

Like all Michael Joly Engineering microphone upgrades, the MJE-K47 mod suite for your MXL 990 starts with my signature single layer headbasket conversion. This new, angled headbasket increases open area to reduce internal reflections and coloration. You’ll hear clearer, less “boxy” and more detailed sound with more accurate transient response – hallmarks of the classic AKG C12 – a single layer headbasket design. And the angled design reduces internal standing wave coloration compared to the stock cylindrical shape (The angled Neumann M 49 headbasket with its greater open area was designed to deliver a more neutural sound than the cylindrical headbasket used on the earlier U 47).

MJE-K47 Capsule Upgrade -

Classic sound – plus, is within reach. The 3 micron MJE-K47 capsule was designed to track an actual Neumann K47 capsule through the important midrange then provide an extra touch of “air” at the very top end. You’ll hear the classic mid-focused vocal punch of the K47 design with just a bit of modern sheen on top.

When this frequency response extension is translated to the time domain it means faster and more accurate transient response as well. And faster, more accurate transient response means greater detail and resolution – without high frequency EQ boost. Finally, upgrading to the more sensitive MJE-K47 large diaphragm capsule (from the stock small diaphragm capsule installed in the MXL 990) will improve your mic's S/N ratio as well.


Michael Joly Engineering Hulk 990 with MJE-K47 Capsule (red) vs. U 87ai (black)
Note extended high frequency "air" provided by the 3 micron diaphragm MJE-K47 capsule

Premium Electronics Modification -

The circuit used in the 990 is a close approximation of a classic Schoeps transformerless design. But to save on production costs in the stock mics, inexpensive poor-sounding ceramic and under-sized capacitors are used in critical signal path locations. The MJE-K47 Mod Suite attacks these compromises by substituting components and topology pioneered in my field-proven Premium Electronics modification. These component upgrades improve bass response while reducing graininess and mid-to-high frequency distortion. MJE Hulk 990 = classic sound.

Easy to order the MJE K47 modifications for your MXL 990 -

Click "Add to Cart" to purchase the Michael Joly Engineering MJE-K47 Mod Suite for your MXL 990 mic - a low cost and risk-free way to experience classic K47 capsule type sound.

You'll get an immediate confirmation email of your order. By the close of the next business day you'll receive a personal email with your scheduled modification (generally 1 week from date of order) and return ship dates (next business day).


Hear the new MJE-384K capsule upgrade for the RODE NT5 vs the Schoeps CMC6 and Neumann KM 184