I'll stipulate, from the get-go, that microphone shootouts are tricky business, and tend to be of limited value, there are just so many variables.

Now I need to figure out a way to conduct one. Mostly for my own use, but I will certainly share the results if it turns out decently.
 
I have this sound in my head - what I think an acoustic guitar should sound like - that I'd like to record. I have this deeply held conviction that only a pair of KM-84s will do the trick. I used these frequently years ago when they were a staple in every studio locker. I (almost) always liked the results.
 
It has over 15 years since I've used them. In that time I've stuck to the microphones I own, most of which are pretty decent.

• AKG C-451/CK1 (x2)
• AKG C-61/CK1 (x2)
• Audio Technica AT-4031 (x2)
• Earthworks SR-71 (x2)
• Neumann KM-84 (x2)
• Sennheiser MKH-405 (x2)
• Blue Dragonfly
• Mojave MA-101FET
• Tascam PE-120 (modified for P48)

All of them do some great things with different guitars, but none of the, so far, get that mystical sound I'm looking for. Hey, it could be the guitars, it could be me, it could be I just haven't figured out where to place the microphones.
 
I am borrowing a pair of KM-84s, and a pair of Telefunken M60s, and possibly a pair of Josephson C42s, although I think they are a bit bright. If I can, I'm also going to borrow a pair of Shure SM-81s, since they are a common go-to microphone for some talented engineers.
I need a way to evaluate the 8 pairs, and then the ten, maybe eleven singles.

My current plan is to record different guitars with each pair set as an X/Y coincident pair, and I won't play with placement, I'm going to find a good spot for the first guitar and then just swap microphones. This creates what one might call a level playing field, each pair is going to "hear" the exact same thing.

Then I will record each guitar with a single microphone, and for this test I will look for an optimal placement, this will show what each microphone is capable of capturing.

In all cases I will record a "reference" track with a Neumann TLM-193 or Sphere L22 placed behind the test microphones, and a Royer R-101 placed above the guitar. I'm not sure these are really necessary, but since they require little or no extra work I figure I'll include them. If they provide no additional information then I can just delete them.

In all cases I will play without headphones, I do not want to be influenced by what I hear through the cans.

I will use no processing, and editing will be limited to chopping the heads and tails. Gain will be left constant as well, although that one has me a bit concerned, since level can impact our impressions. I may end up with a copy of the tracks normalized to the quietest microphone.

That's my plan. If it works I can make a decision on whether or not to sell a couple less used organs to purchase a pair of KM-84s. It would be really lovely if I discover that I already have a pair of microphones that does the trick, and if that isn't the case I'd be happy if a modern (read in production) microphone is a good substitute.

As a good friend (and well respected engineer) pointed out this week, this could a fun folly. In his mind nothing sounds quite like the KM-84. Love the guy, but dang I hope he is wrong!

After all that, anyone have suggestions for how I can make this experiment more usable? Am I doing anything particularly brain dead?

Thanks!

It is interesting to me how many pairs of mics you have. I only have one pair... Km 184s.

I have never done a microphone test i didn't learn from.

Honestly, for me, Mic positions often have as much to do with convenience and not being in the way as sound.

Different mics make a huge difference. Ribbons are a Mic type i wish I'd discovered sooner and are used most of the time by me.

One thing i discovered testing mics is that my mics reverse the wave form phase. They all do it the same way. If i make an asymmetric wave, then play it through my speakers and record the sound with mics, the form is exactly flipped. This makes seems. A speaker push translates to a like pull.

A flipped asymmetric wave doesn't sound exactly the same. To me, this means if you want playback to sounds the same as the performance, it may help to invert the polarity on your master bus.

As far as asymmetric waves being flipped in the gswitz post I think something maybe going wrong there.  A polarity flip may be going on in Geoff's setup but he has not found where it is.  The only way you can really know that the waveform is being inverted or not is to use a CRO and I mean a real one.  You can start by looking at the asymmetric wave in your DAW. Then you need to check that with a CRO on the output of your interface.  Then check on the monitor output feeding your speaker.  Studio monitors generally will not flip the polarity.
 
When testing to see if a speaker is correctly creating the asymmetric wave you need to create a setup that involves a mic, its preamp etc. Once again the CRO is going to tell you if the phase of the output from the preamp is correct as well feeding the CRO.
 
I have been right through this process and found that everything was correct from the test signal right to the speaker with no inversion going on anywhere so I think Geoff is wrong about this.
 
What I did find though was most of my microphones were correct but some actually did invert the polarity of the asymmetric wave and I had to rewire them to match the others!

gswitzIt is interesting to me how many pairs of mics you have. I only have one pair... Km 184s.

Keep in mind this collection goes back maybe 30 years, when I was operating a 16 track tape based studio. Sometimes I needed all those microphones for a session. Not often, but I enjoyed the variety, it helped me get the sounds I wanted without EQ and compression - which were sorely lacking<G>!

gswitzI have never done a microphone test i didn't learn from.

Amen to that!

gswitzHonestly, for me, Mic positions often have as much to do with convenience and not being in the way as sound.

Convenience counts, but distance can affect dynamic range, and angle can have a huge impact on timbre - play with them long enough and you don't need to add EQ or compression at mix time. Which may be pointless today, but it was certainly valuable when I didn't own 16 compressors!

gswitzDifferent mics make a huge difference. Ribbons are a Mic type i wish I'd discovered sooner and are used most of the time by me.

I love ribbon, and ribbon-like microphones. I have this goofy M88RP which uses a printed ribbon. Sometimes it is just what the doctor ordered. I recently "invested" in a pair of the Royer R-101s, and I've yet to find anything that they didn't flatter. I missed out on an auction for a used Shure (Tripp&Crowley) ribbon microphone recently, I'd love to have one of those for vocals, or possibly one of the better 77 clones.


As you say, they are all different!

I agree with Jeff that you may not have identified the culprit. From your description it sounds a lot more like mis-wired connector somewhere in the chain. An oscilloscope is one way to figure it out, but a cheaper, easier way is to use an audio polarity checker. There are several on the market, my personal choice these days is Studio Six Digital Audio Tools. It isn't expensive, and the polarity test does not require a measurement microphone. You might benefit from the iAudioInterface for checking the electrical stages, but you can make an adapter cable (just be careful with the wiring<G>) that will do the trick.
 

https://www.youtube.com/watch?v=2GMfM0hByWw&t=121s
 
This is a vid I made at the time.

My best results BY FAR came when I splurged for this...
 
https://www.sweetwater.com/store/detail/GTRFProKit--se-electronics-guitar-recording-package
 
But I upgraded the ribbon mic to the VR1, something Sweetwater was happy to do and still maintain significant bundle savings.
 
As a bonus, the VR1 has become one of my go-to mics for voiceovers as well. It really is a great mic!
 

I've been playing around for about a week now with the various microphones. I've discovered several things, some of which are not exactly news, but here goes:

1. A shootout is nearly impossible to do objectively, there are so many variables! Microphone placement alone makes such a difference that these tests really become more about what is possible with any given microphone. So I think I'm going to try to show off each microphone at its best.
2. Thus far at least matching levels has been much easier than I expected. I'm recording each microphone independently, so performances won't be identical, but overall perceived levels line up pretty well. To do this I send a 1kHz sine wave from a loudspeaker placed behind where I will be sitting, so the relationship between the loudspeaker and the microphone remains constant, even if the microphone is not pointed at exactly the same spot. I adjust levels using the first gain stage in the microphone preamplifier. So far so good - I was worried that level mismatches would make the shootout somewhat meaningless.
3. My fingers hurt!
4. This is fun! And I'm learning a lot!
5. There is some uniformity from any given microphone across all three guitars, and fingerstyle vs flat picked vs strummed. Not sure why I didn't expect this, but I didn't. I find this fascinating.
6. The original microphone and guitar lists were unmanageable. I've pared the guitar list down to 3, and I'm still trying to figure out what to do with the microphone list. But that first list was a pipe dream.
7. The Neumann KM-84 really is a remarkable microphone. There is something to the frequency response or the polar pattern or some long lost magic incantation, but it is different, and I really like it. The other thing I noticed is that it is really forgiving. Point it anywhere and it sounds good, and the difference between anywhere and the optimal (?) placement is not as noticeable as it is with other microphones.
8. The Audio Technical AT-4031 is also a really cool microphone. It is a lot more sensitive to placement, but I still get some really nice (to my ears) sounds with them. This was my go-to for a long time, so I guess I should not be surprised.
9. The Telefunken M-60 is a very nice microphone. It does not sound like a KM-84, but I really like the sound. It too is somewhat picky about microphone placement, but when I find a good spot I like what I hear.
10. The Royer R-101 works really well in this application. I've only tried that a couple times in the past, and for one reason or another didn't end up using those tracks. It sounds nothing like any of the condenser microphones, but it sounds cool. I can see me using it in the future, I must remember to remember that it is an option.
11. The difference between a naked track and a track in a mix is not inconsequential. (Yes, I was shooting for understatement.) Hardly a new lesson, but with my focus on the sound of the guitar for this exercise it was brought home once again. Some of these microphones sit beautifully in a mix with no effort. I don't even know it that's a good thing, but it is interesting.
12. Some microphone/compressor/equalizer combinations just work better, or are easier to use. I had honestly forgotten that.

No where near ready to make the shootout recordings, but getting closer.

And I am now quite certain that is not folklore, nostalgia, or a faulty memory. If I were still making money recording others I would invest in a pair of KM-84s. For recording my own stuff that's a much more difficult decision. I suppose if I start making more money from my own productions I will consider it, but for now it would simply take too long for them to pay for themselves. Pity!