MXL 990 Mod Comparison/Shootout

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Potsy24

New member
I've never modified a microphone before, so I figured a good place to start would be the MXL 990. It was the first condenser I ever bought, probably close to 10 years ago. It hasn't been used in probably 7 years. So no big loss if I render it useless, right? I'm sure this has been done before, but at least this is another example. I recorded a comparison of this mic before and after 2 simple and free mods. I removed the 2 inner grill layers, and dampened the inside of the body with silicone caulk (when disassembled the base literally rang like a bell before).

In each recording, I recorded a spoken description (with a pop filter) and then a short drum section (it's the only instrument I play). The drum section is repeated 3 times in each example:

  • The first is the MXL 990 only.

  • The second is the MXL 990 plus a Shure Beta52 on the bass drum and a Shure SM57 on the snare.

  • The third is the Beta52/SM57 only in the first half and all three mics in the second half.

Each is of course the same drumset and the same mic placement. I recorded the first example, took the mic out of the shockmount, did the mods, and put it back in to record the second example. They are both recorded using a Presonus Firestudio Tube in Studio One Pro with no eq, compression, or any effects. I used the non-tube channels on the Firestudio. The gain settings are all the same except for the 990 on the 2nd example (it had to be lowered because the mic output was higher post-mod). Here are the 2 recordings:


I think the results are pretty amazing. Everything is much more open, top and bottom end. The two inner grill layers were basically acting like a sock placed over the mic. I'm not sure how much difference the caulk made, but it probably helped too. The output of the mic after mods was about 3 dB higher as well. I had to lower the fader on the voice in the 2nd example to even the volume with the stock one, and actually had to bring down the gain on the preamp with the 2nd drum section.

I might actually be able to use this mic for something now. I never used it as an overhead before, but I think it handled the job well after the mods. Maybe it would do ok as a hi hat mic. It might even be an option for a backup vocal or acoustic guitar. If anyone has one of these collecting dust, this is a pretty easy and free way to breathe some new life into it. I'm considering replacing the capsule as well, with either an RK47 or RK12 from microphoneparts.com. Let me know what you guys think of the results so far.
 
Here are a couple pictures as well. The first is to show what I did with the caulk. There is a thick layer around the first 1/2" or so of the base and then just a thin smear over the rest of it. This was the most I could get in there with getting in the way of the electronics or threading. The other picture is just in case anyone was wondering about mic placement.

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Yeah ..... the voice is most noticeable! Nice work. Any vocal work with that modded microphone will now stand out in a dense mix.
 
Yeppers, That was defo worth doing, good tip.
thanks for posting the comparaison
 
Whoa, cool, man - thanks for doing this! :D

It sounds very different, indeed. To my ears, the vocal part sounds better in the modded clip. The transients in the drum parts where it's just the 990 in the modded clip look different, too. Like it's responding faster to the kick drum. They kind of look "sluggish" in the old one, by comparison (I can't actually hear a difference in transient response, tbh, but I do see it). I wonder why that is...or maybe I'm imagining things? :p

Despite sounding very different, the resonance frequencies seem to be unchanged between clips. I kind of hoped the silicone would kill at least one of them. I guess that means it's something else in those 990s resonating at 700, 1900, and 2300 hz (mine do the same thing, btw, and I don't use them because I have to butcher too much out of the signal to work around it).

edit: I re-read the OP, and I see the output was hotter post-mod. That explains the louder noise in the first one, I suppose. That's pretty cool that it made that much difference in the audible noise.
original: Also - what's with the bass hum/noise in the vocal parts? It's about 10db louder in the stock clip than the modded one. I don't see how what you did would have made that change.

Now I wanna go dig mine out and start messing with them, too! :D
 
TyphoidHippo said:
Despite sounding very different, the resonance frequencies seem to be unchanged between clips. I kind of hoped the silicone would kill at least one of them. I guess that means it's something else in those 990s resonating at 700, 1900, and 2300 hz (mine do the same thing, btw, and I don't use them because I have to butcher too much out of the signal to work around it).
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I was reading somewhere in a modification article that silicon can only help so far with this housing problem and that applying mole hair will do a much better job in taming that nasty resonant ring.
 
Thanks guys. I'm sure how much the silicone actually changes the sound. I was going to do 3 tests (one with just the dampening before the grill mod), but I got lazy. As for the noise in the vocal clips, idk what that is specifically. But it needed so much gain in general that I was bound to pick up something. It should only be 3 dB louder in the stock clip, maybe whatever the source was had changed. Sorry it's not the most scientific of tests, I only had one of these to play with.

It does seem to respond faster in the modded clip. To me, that was most evident with the hi hat by itself. The individual notes are more well defined and present. But this may just be an improved frequency response. Either way, the stock clip just sucked IMO. In the third repetition, everything sounds worse when the 990 comes in. In the modded clip, it blends with the 57 better and actually brings something to the mix. There's nothing worse than when your overheads are messing up your snare sound.
 
TyphoidHippo said:
I'd never even heard of this stuff until just now. I guess it's the same as "moleskin", which I'm finding some articles about using. Interesting... Have you ever actually used it for this kind of stuff?
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Oh yeah, what is mole hair? I googled it, but just came up with a bunch of gross stuff about people plucking the hair off their moles. Sick.
 
TyphoidHippo said:
I'd never even heard of this stuff until just now. I guess it's the same as "moleskin", which I'm finding some articles about using. Interesting... Have you ever actually used it for this kind of stuff?
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Potsy24 said:
Oh yeah, what is mole hair? I googled it, but just came up with a bunch of gross stuff about people plucking the hair off their moles. Sick.
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:facepalm: Sorry guys ...... Yes moleskin. Got my espresso in me and I'm all better now.
 
It could be anything like moleskin just some type of material that can be adhered to the inner surface of the housing.
 
Oh, ok - the bandage stuff for moles. That makes sense. It would have been easier than caulk too. A piece of soundproofing vinyl or maybe neoprene also would have worked. Either way, I'm happy with the results. I have to decide whether to replace the capsule or not. I also have an MXL 992 that would probably benefit from this process. Maybe I could replace that capsule with an RK47 or RK12 and put the 992 capsule into the 990.
 
Potsy24 said:
Oh, ok - the bandage stuff for moles. That makes sense. It would have been easier than caulk too. A piece of soundproofing vinyl or maybe neoprene also would have worked. Either way, I'm happy with the results. I have to decide whether to replace the capsule or not. I also have an MXL 992 that would probably benefit from this process. Maybe I could replace that capsule with an RK47 or RK12 and put the 992 capsule into the 990.
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You can check out what Oktavamod does to them HERE.
 
moresound said:
You can check out what Oktavamod does to them HERE.
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I've seen his website, that's what got the wheels spinning on this project. The comparisons to the Neumann are impressive, but I'd also like to hear the modded mics compared to stock. Obviously I've heard the stock mic, but the room/instrument/performance/signal chain is probably a bigger factor in these samples than the actual mic/modifications.

I know changing the capsule would help tame the brightness on this mic. It's actually brighter now with the 1 layer grill, but not in a bad way. I can't find exactly what he's doing to the electronics, but I've seen posts about replacing such and such capacitor and all that. The word on the street is the electronics upgrades can be done for a few dollars. But I've never found a comparison before and after. Maybe I should do that before the capsule swap. It would be nice to hear the difference that each step makes, it might help people decide which mods they wanted to do to their own mics.
 
Yeah just a few dollars would do the trick with the caps change.

Try an advanced search here in the DIY forum. Seems I remember something had been spelled out before.

I'll try and find it as well.
 
Potsy24 said:
The comparisons to the Neumann are impressive, but I'd also like to hear the modded mics compared to stock. Obviously I've heard the stock mic, but the room/instrument/performance/signal chain is probably a bigger factor in these samples than the actual mic/modifications.
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To clarify, I didn't mean to imply that the Oktavamod mods don't make a difference. I just meant that I can't compare my own recordings of a stock 990 to his recordings of a modified one, because all of the other factors (room, placement, instrument, preamp...) are different.
 
Awesome, thanks! Just 3 things to change? That's not bad at all. I was thinking it might be more work than it was worth, but I've got 20 minutes for sure.
 
Potsy24 said:
Awesome, thanks! Just 3 things to change? That's not bad at all. I was thinking it might be more work than it was worth, but I've got 20 minutes for sure.
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Could be a bit longer. Just be careful whist un-soldering the old caps. Don't let it get to hot as to mess up the circuit board.
 
Well, yes, I'll take my time. If this mic isn't a paperweight anymore, I don't want to go messing it up now.
 
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