MXL 990 condenser microphone capacitor upgrade MOD, body repaint, with sample audio

MXL 990 condenser microphone capacitor upgrade MOD, body repaint, with sample audio

let’s take a look at how to modify this
common MXL 990 condenser microphone my name’s Eric Strebel
I’m an industrial designer welcome to my channel about product design I hope that
you like enjoy and become a subscriber I’m always trying to improve the quality
of the videos on YouTube so I thought modifying the microphone that I used to
record would be a good thing cost less than $8, I ordered my kit from
silent sky dotnet comes with a little piece of paper that gives you a link to
download a PDF it’s pretty comprehensive PDF and has all the information that you
need to perform the mod the modification is pretty straightforward it’s so easy
that my camera gal Kris was able to do the mod no problem let’s see how she
does so to this symbol of the microphone you remove the screw ring on the bottom
and then the main body comes apart like that next we’re going to take out the
two screws that hold in the head basket Chris doesn’t have a lot of experience
but she’s still pretty handy and is able to do this mod no problem next we want
to remove the little spacers so that we can slide the PCB out we’re going to
mark on the PCB where the wires come down from the condenser and that’s so we
can have better access to the board I’m going to start removing the components
on the back side this is c-13 this is the replacement part we’d pretend a pre
solder the leads so we can solder it into place next we’re going to remove
the two capacitors on the other side c3 and c4 I’m using a pair of tweezers to
help me remove it it definitely helps if you have somebody to help with this
we’re going to slide in the replacement capacitor from the other side into the
holes Chris heats up the board at the spot where the capacitors get
inserted and I’m able to push them through I trim off the excess and we’re
gonna reattach the red and black wires back on to the main circuit board next
we’re going to remove the two inner layers of a mesh on head basket we’re
gonna use a screw driver to lift up the screen that’s in there and we’re going
to insert a pair of pliers and rip the existing mesh away from the inside of
the basket we do that by sticking in a pair of pliers and then twisting and
rolling up the mesh that’s in there so that we can pull it out let’s watch how
Chris does this we need to repeat the same process for the second finer mesh
layer that’s inside the head basket but it’s pretty straightforward when you’re
finished you’ll be left with a relatively transparent head basket I
would definitely suggest using a pop filter at this point I complete the mod
on my nine ninety by painting it a gloss black with a red ring I really needed to
fix that because the champagne color on the stock nine ninety is durable so
let’s reassemble the entire microphone in the reverse order we’re going to
insert the spacer between the main body and
the printed circuit board and we’re going to slip the head basket over I’m
going to do the backside first screw the screws back into place do one side at a
time in just a matter of reassembling the body and the reverse order re
threading everything back together once it’s all finished should be able to
easily see that condenser I was able to lower the gain a little bit on my
microphone for a little bit nicer recording and I think the sound sounds a
little bit fatter and wider this is the sound of an unmodified 990 this is the
sound of a modified 990 I certainly can tell the difference and I like the
modified version a lot better I hope you enjoy the video if you did hit the
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17 thoughts on “MXL 990 condenser microphone capacitor upgrade MOD, body repaint, with sample audio

  1. I couldn't really tell any difference in the sound to be honest. I do like the idea of removing the internal foam pop filter as I use an external pop filter anyway. Removing the internal foam pop filter opens up the mic and gets rid of that muffled sound that you sometimes get with these mics, especially with higher gain settings on the mixer or audio interface. Great video!!!

  2. the biggest problem with the 990 is that cheep small condenser capsule, change that out with even a cheep u47 type, huge upgrade.ย  want a usable tracking mic, put a high end m7 capsule in.

  3. There is some misinformation here that I'd like to correct. By way of credentials, I've been manufacturing capsule and circuit upgrades for the 990 (and other models) for many years. I have personally modified 30-40 mics, including full circuit rebuilds, capsule replacements, power supply replacements, etc, from transformerless FET mics to transformer FET to tube microphones.

    I used to recommend the "single layer headbasket" mod demonstrated here. I loved the logic that the mic will sound "more open" with less mesh in the way. But then I did some audio testing (via swept sine wave using a measurement mic and calibrated speaker), and ABX testing, and concluded that this mod is usually a bad idea. One problem is that the audio effects are minimal, and not necessarily an improvement. The other problem is that you lose plosive protection and EMI/RFI protection. Sure, you can use a pop filter to avoid the plosive problem. But the pop filter won't prevent EMI/RFI from sneaking into your track through the open grille.

    The third and most critical problem with the single-layer grille mod is that the remaining layer of mesh resonates in the audio band. IIRC, I measured this at 13kHz for the 990. That means that your mic is making sympathetic resonance that YOU CAN HEAR IN EVERY TRACK you record. You can't EQ that back out of your mix.

    If you think you can hear a "more open" sound, but wish to avoid the problems with EMI/RFI and sympathetic resonance, do a Google search for [mxl 990 headbasket upgrade] to see a commercial alternative — a 2-layer mesh grille that looks nicer than stock. We based the design on the Neumann M49.

    Regarding capacitor swaps: it's doubtful these would pass an ABX test. Said another way, I doubt most people would hear that capacitor change in a blind test. C3/C4 are the main signal caps, and they set the low-frequency response point of the circuit. I don't argue with using film caps there, although I'd go with polypropylene rather than polyester, which is what those generic box film types in the video probably are.

    But the reality is that the 990 has much deeper problems that these mods don't address, such as:
    – the capsule sounds pretty awful, with a 3-5dB scoop around 7-9kHz and a 3-5dB boost at 12-15kHz, accentuated by the single layer grille resonance
    – the JFET has huge input capacitance, which acts like a pad
    – the JFET wasn't biased properly, so it distorts prematurely
    – the DC oscillator under-powers the capsule, which negatively impacts sensitivity and therefore noise floor
    – Every 990 made since about 2013 has a surface-mount circuit board, which cannot be modified using the techniques described in the video.

    If you want an upgrade that EVERYONE will hear, replace the capsule with an RK-47. (Full disclosure: I make that capsule.) This one change will significantly re-voice the microphone. No circuit changes are necessary. This will give you a night-and-day upgrade and probably will addict you to DIY microphone upgrades for life. It did for me. ๐Ÿ™‚

    If you have the chops and the tools to populate a circuit board, my company makes a drop-in replacement for the 990 that contains a full implementation of the Schoeps transformerless circuit. This kit has a full +60V DC power supply for the capsule, and employs low-noise parts throughout. The JFET is a NOS component with much lower input capacitance, and is properly and individually biased for each kit. The resulting mic has much higher output, much lower noise, and lower distortion. You're basically building something that competes with a TLM49, but it will cost you less than $500 instead of $1700. The MXL 990 becomes a "donor body," into which you're building a world-class mic.

    Some people say it's dumb to spend so much to "upgrade" a cheap mic. I disagree. If I can build a mic for $500 that sounds like it cost $1700 or more, that's a pretty great deal, no matter what brand name used to be on the mic body.

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