KM 184 vs OktavaMod MXL 603 "Complete Re-work" mod

[Michael_Joly]

In case you feel like debating some low end theory, there are .wavs of a KM-184 vs. OktavaMod'd MXL 603 shoot out in this post. My design goal was to deliver Neumann sound for a whole lot less money.

[TurboJets]

Originally Posted by Michael_Joly

In case you feel like debating some low end theory, there are .wavs of a KM-184 vs. OktavaMod'd MXL 603 shoot out in this post. My design goal was to deliver the Neumann KM-184 sound for a whole lot less money.

The comp's are awesome Michael, thanks for posting them. How would you describe the sonic difference (if any) between the modded 990 and the 603. I have a 990 I'm really thinking about sending to you.

[Kronos147]

Mr. Joly,

I checked out the OctavaMod site tonight. It looks interesting.

I see that you spent some time with the MXLs. I was still lost on what happens with the MXL604 Omni Capsule (604 being a 603 with the additional Omni capsule, I believe)?

Also, are there mods for the MXL 600, or are they a 'lost cause'?

I wouldn't mind having some sweet omni SDC's.

Eric

[Beyersound]

Interesting comparison. The 603 seems a touch brighter, but has a transient clarity in the mid/upper mid area that is really nice. I think this would be great on piano. Nice work!

[drBill]

Michael - thanks for the clarification of the mod to match the "184" instead of just the "84". I was having a hard time with that, having owned all the mics involved. Look forward to hearing the clips. Maybe I can take the 604's out of mothballs.....

[Michael_Joly]

Thanks for listening and for the encouraging comments!

Here are some responses to your questions and thoughts -

Re: 990 vs. 603 - Almost the same, but different

While the capsule and circuit in both mics are the same, the interaction of the capsule with the nearby environment is different. The front of the 603's diaphragm has no reflective surfaces (and almost no refractive edging) between it and a sound source. The 990 on the other hand sits in the middle of a cylindrical headbasket which does present a reflective path between the diaphragm and sound source. I do convert the 990's headbasket to a single layer mesh to make it more open, but it still remains partially reflective and does impart some shaping to the HF end of the mic. Secondly, there is a refractive edge at the juncture of the headbasket and body in the 990 not found in the 603. The effects of both issues are quite complicated, I haven't measured them objectively yet nor done a direct comparison to a 603 - so many tests to run, so little time!

In addition, the backside of the capsule addresses the external environment in a completely different manner in each mic. In the 990 the backside of the capsule sits in the middle of a large headbasket, but the 603 relies on body venting to provide sound access to the rear of the capsule. So there is going to be a difference in the shape and magnitude of the off-axis nulling between the 990 and 603 with the 990 providing a bit smoother off-axis response.

re: MXL 604 Omni -

Ah, good question. I see the confusion - my original "MXL 603 (604) Premium Electronics" upgrade just modifies the body electronics. Until now, I wasn't aware that the 604 also ships with an Omni capsule. So I would have to price my "Complete Re-work" mod differently for the single capsule 603 and dual capsule 604 (probably offering some kind of discount pricing for the 604).

re: MXL 600 - Never have seen or heard this one in person. But the specs seem to indicate it uses the same capsule as the 603. In addition, my Alctron (Chinese vendor) catalog lists both types of mics and the availability of cardioid and Omni capsules. So my hunch is the 600 would also be a good candidate for modification. As you might guess, for acoustical reasons I'm not fond of that slotted front end though.

[Osse_87]

Compared to the KM184, I think the Neumann has a more neutral midrange register, sounds not as scooped as the mxl's.

[Michael_Joly]

Its fairly well known the KM 184 is brighter than the KM 84. But what is not so well known is how this was achieved. From Neumann's site:

"Although the KM 184 has the same capsule as the KM 84, the...KM 184 has a gentle rise at about 9 kHz...This difference was achieved with just a slight change of the capsule’s rear opening".

The attached photo shows how I've opened the MXL 603's rear vents to more closely resemble the older KM 84 design and thus remove some of the stock 603s bright character ("Ultimate MXL 603 modification" engineering prototype top, KM 184 center and KM 84 bottom). Notice the larger open-area venting in the 603 mod and KM 84 relative to the KM 184.

[Michael_Joly]

Just got some drum OH sound files back from Alan Dossett.

Separate takes, slightly different mic positioning in each take (he's a monster drummer, not an engineer). So just ignore the stereo separation difference and concentrate on the bass extension, mid range impact and cymbal purity. Alan says the "Ultimate MXL 603 mod" kicks major booty.

SOUND FILE: Neumann KM-184 drum OH pair
SOUND FILE: OktavaMod "Ultimate MXL 603 Mod"

[danbronson]

Great job Michael, you've managed to bring clarity out of an MXL I never thought I'd hear. From what I've heard in these clips, I think $300 ($100 mic + $200 mod) is a steal for something that sounds like this.

I hear a bit of a difference. It's not huge (certainly nothing compared to what the stock mic would sound like!), but it's there. The first thing that struck me was how the Neumann's low midrange was really broad and rich sounding. On the modded MXL it seemed less so, like it rolled off earlier or something. Also, the MXL seems to have an EQ dip at maybe 1 kHz or something, giving it a slightly scooped sound in comparison. They are close but ultimately I feel like the MXL sounds a little bit thinner. Once again, nothing to complain about at this price. I wouldn't hesitate to go this direction if I wanted the KM-184 sound on a budget.

[danbronson]

Originally Posted by Michael_Joly

Just got some drum OH sound files back from Alan Dossett.

Separate takes, slightly different mic positioning in each take (he's a monster drummer, not an engineer). So just ignore the stereo separation difference and concentrate on the bass extension, mid range impact and cymbal purity. Alan says the "Ultimate MXL 603 mod" kicks major booty.

SOUND FILE: Neumann KM-184 drum OH pair
SOUND FILE: OktavaMod "Ultimate MXL 603 Mod"

By the way, one of the mics on the Neumann clip is 180 degrees out of phase. It might help to fix that and post an in-phase example.

[Brad McGowan]

A suggestion for Michael:

If you post more clips you should just label them Clip A and Clip B so that people aren't biased by what they think "MXL" and "Neumann" means. It would be way more interesting to get people's reactions when they don't know which mic is which.

Brad

[Beyersound]

Originally Posted by danbronson

Great job Michael, you've managed to bring clarity out of an MXL I never thought I'd hear. From what I've heard in these clips, I think $300 ($100 mic + $200 mod) is a steal for something that sounds like this.

I hear a bit of a difference. It's not huge (certainly nothing compared to what the stock mic would sound like!), but it's there. The first thing that struck me was how the Neumann's low midrange was really broad and rich sounding. On the modded MXL it seemed less so, like it rolled off earlier or something. Also, the MXL seems to have an EQ dip at maybe 1 kHz or something, giving it a slightly scooped sound in comparison. They are close but ultimately I feel like the MXL sounds a little bit thinner. Once again, nothing to complain about at this price. I wouldn't hesitate to go this direction if I wanted the KM-184 sound on a budget.

Listen carefully again, you might perceive it differently. To me it seems that the MXL is much more open and has cleaner transients in the upper midrange, that may be why the balance sounds different to you. Listen to Michael's other comparison files, the jingle bells and spoken word files will demonstrate this.

[Michael_Joly]

Just fixed the polarity problem on the Neumann clip. I put these up straight from Alan without even listening to them. His chain is Mogami Gold into Daking IV preamps into RME adi-8 into RME Fireface 800.

[jkretz]

Michael,

Can you do these mods to a pair of 991s?

Thanks,
-Josh

[Stratfreak]

My 2 cents. I liked the sound of the Neumann. It sounded more natural.
Of course I better for more than twice the price. Does the Neumann sound twice as good though? Nah.

[jnorman]

michael - no offense, but why would you want to make any mic sound like the km184? i have owned 3 pairs of 184s, and never liked them on anything - they were brittle, and particularly thin at a distance, and even harsh on many applications. if you are going to spend time modding mics, how about trying to make them sound like the original km84, or a schoeps cmc6/mk2 (omni), or a DPA 4011? thanks.

[Michael_Joly]

Jkretz - Yes, my modifications work well on the 991 - this is a unique model number of the 603 for a few retailers but otherwise the same microphone.

jnorman - good question. As the KM 84 and KM 184 both use the same capsule, but have different body vent openings (the 184 being smaller and thus brighter) I chose to address two issues that would economically bring the MXL 603 (and Apex 180 / 185, Nady CM-90, CAD GXL1200) more in line with the KM 84 design. (I ignored for economic reasons, modifying the mic into a transformer-based circuit like the KM 84.)

The most important issues, in my opinion, that need to be addressed in the 603 are front-of-diaphragm cavity resonance & diffraction caused by diaphragm set-back and its narrow vent openings. The impedance conversion and transformerless balanced output circuit is based on the proven Schoeps-style circuit. No, its not a single FET / transformer output circuit like the KM 84, but one has to draw the line somewhere in terms of modification affordability. I believe the MXL 603 with upgraded electronics, modified capsule housing and body vent enlargements offers professional SDC performance comparable to top shelf mic brands - at a fraction of their cost.

Regarding comparisons to the KM 184 - The KM 184 is a current-production Neumann microphone used in thousands of professional studios every day. The KM 84 is a discontinued, hard-to-find and expensive relic. Yeah, I know the story: "the 184 is no KM 84". But many of us think the KM 184 is much maligned and is an entirely servable and professional SDC microphone.

So to sum up - I didn't set out to make the 603 sound like the 184. But I did set out to make improvements to an inexpensive mic that would allow it to be judged next to the most expensive SDC in my collection - the Neumann KM 184. Many folks have written me to say they actually prefer the sound of the Ultimate MXL 603 Mod to the KM 184.

BTW - Tape Op issue # 70 (Sufjan Stevens!!) is now out which includes Mike Jasper's review of my "Ultimate MXL 603 Mod", "Hidden '84 Mod" and '84 Capsule upgrade. So you can read his take on the these mods as well.

[drBill]

Originally Posted by Michael_Joly

The KM 84 is a discontinued, hard-to-find and expensive relic.

Michael - you know how much I love what you do, but to malign the 84 as a "relic" ("a survivor or remnant left after decay, disintegration, or disappearance") is hardly fair to the 84. Maybe it was just an unfortunate choice of words, but I'd never view an 84 as a relic. They are workhorses that are found in almost every professional studio around the world and see heavy useage day in and day out. I've seen them so brutalized (drum sticks) that one would even be surprised that it would pass audio, but upon plugging it in.......syrupy, golden goodness!!!

Relic seems to imply that their day is past, and I'd say that nothing is further from the truth. As more people find out about the magic that the 84 imparts, it's becoming more and more sought after every day. As for reliability, mine have been far more reliable than my MXL mics. Although the 184 and 84 may share the same capsule they are about as similar to each other as a U47 is to a 47FET. Or a vintage U87 is to a TLM103. ie: they sound nothing alike. The 84 is my all time favorite SDC for so many reasons. The 184....eh..... (Even vocals are great with an 84, forehead height, back a bit, pointed towards the mouth. That's the motown sound.)

I'd love to hear your mod sometime. Hopefully it's as you say - better than the 184. Stock I have no use for the 603 other than occasionally on snare surprisingly enough. (Won't put those vintage gefell's, 84's or 451's too close to a wild drummer......)

Keep up the good work!!! thumbsupthumbsup

bp

PS - the 205's are still kicking the butt of EVERY other ribbon that I have......

[Michael_Joly]

Hey Bill!,

Thanks for keeping my mind and quill sharp. I didn't mean to disparage the KM 84 - just the opposite in fact. I think I should have said the 84 is "...a working relic..." and defined my use of the word a bit.

The definition of "relic" that comes closest to what I meant is found in Wikipedia: "A relic is an object or a personal item of religious significance, carefully preserved with an air of veneration as a tangible memorial. "

My intention was to emphasize the veneration of a working tool surviving from a by-gone day, still functioning beautifully, still working its sound magic worthy of reverence. "Certainly not a remnant left after decay" like an old brown shoe or bit of charred bone.

Those of us old enough to have experienced pre-2nd Vatican council Catholicism remember the tours of religious relics and special Masses celebrated for their veneration. I tend to dig deep into that past (and other magical / religious traditions) to find language when I'm looking for ways to describe the power of microphones and the reverence we have for them.

So yeah baby, we're on the same page here about my high regard for the KM 84. I really meant "KM 84 - great mic, hard and expensive to get a hold off. Let's compare the Ultimate 603 Mod to a commercially available, somewhat more affordable mic - the Neumann KM 184".

[drBill]

Originally Posted by Michael_Joly

Hey Bill!,

Thanks for keeping my mind and quill sharp. I didn't mean to disparage the KM 84 - just the opposite in fact. I think I should have said the 84 is "...a working relic..." and defined my use of the word a bit.

The definition of "relic" that comes closest to what I meant is found in Wikipedia: "A relic is an object or a personal item of religious significance, carefully preserved with an air of veneration as a tangible memorial. "

My intention was to emphasize the veneration of a working tool surviving from a by-gone day, still functioning beautifully, still working its sound magic worthy of reverence. "Certainly not a remnant left after decay" like an old brown shoe or bit of charred bone.

Those of us old enough to have experienced pre-2nd Vatican council Catholicism remember the tours of religious relics and special Masses celebrated for their veneration. I tend to dig deep into that past (and other magical / religious traditions) to find language when I'm looking for ways to describe the power of microphones and the reverence we have for them.

So yeah baby, we're on the same page here about my high regard for the KM 84. I really meant "KM 84 - great mic, hard and expensive to get a hold off. Let's compare the Ultimate 603 Mod to a commercially available, somewhat more affordable mic - the Neumann KM 184".

I suppose expensive is in the eye/hand of the beholder. I find the KM84's to be an outstanding value for a mic that's no longer in production. Even for one that is. And there were so many made that it's not too hard to find them. Of course, that's getting more difficult the more we talk about it......

Still looking forward to trying one of the MJ603's.....

bp