In this blog post I’ll explain several stereo techniques often used to record classical guitarAB, ORTF, XY and MS (Mid-Side). You’ll be able to hear the difference for yourself and vote for whatever sound(s) you prefer!

The microphones used for this experiment were my Oktavas Mk-012 modded by Michael Joly with cardioid and omni capsules.

The composition on this track is Manuel Maria Ponce‘s Sonata III – 2nd movement, played by me several times over on my Bernd Holzgruber guitar.

 

 

AB Stereo

The AB Stereo Technique uses two spaced microphones to record audio signals. Recommended spacing between the two microphones is between 4060 cm and the microphones can either be pointed forward or angled slightly outwards. In this experiment I used a combination of all these settings.


AB Stereo, mics pointing forward


AB Stereo, mics pointing slightly outwards

1st Sample – AB Stereo, cardioid capsules, microphone spacing [s] 40 cm, pointed forward, distance between the guitar and either microphone [d] 80 cm, height [h] (distance between the floor and the mics) 115 cm.

2nd Sample – AB Stereo, omni capsules, pointed forward, [s] 40 cm, [d] 80 cm, [h] 115 cm.

3rd Sample – AB Stereo, cardioid, pointed slightly outwards, [s] 45 cm, [d] 65 cm, [h] 107 cm.

4thSample – AB Stereo, omni, pointed slightly outwards, [s] 45 cm, [d] 65 cm, [h] 107 cm.

5th Sample – AB Stereo, cardioid, pointed slightly outwards, [s] 60 cm, [d] 65 cm, [h] 115 cm.

6th Sample – AB Stereo, omni, pointed slightly outwards, [s] 60 cm, [d] 65 cm, [h] 115 cm.

 

ORTF

ORTF is a stereo technique that uses two microphones spaced 17 cm (spacing between the diaphragms) and angled 110º creating the stereo image.

7th Sample – ORTF, cardioid, [d] 70 cm, [h] 115 cm.

8th Sample – ORTF, omni, [d] 70 cm, [h] 115 cm.

 

XY Stereo

XY Stereo Technique uses two cardioid microphones in the same point, angled typically 90º. This is achieved by placing one microphone on top of the other with the diaphragms vertically aligned (see the photo below).

9th Sample – XY Stereo, cardioid, [d] 70 cm, [h] 110 cm.

 

MS Stereo

MS (Mid-Side) is a special technique using one cardioid or omni microphone (Mid) and one bi-directional [Figure 8] microphone (Side) in the same point and angled 90º creating a stereo image through the MS-matrix.

This means the signals of both microphones should be rearranged separately with the MS-matrix that can be understood by these simple calculations:

Left channel = M + S

Right channel = M – S

This can be done with an MS decoder or a Direction Mixer plugin (for those using Logic Studio). Alternatively, you can do this manually by leaving the Mid channel in the centre and copying the Side channel, panning one copy hard left and the other hard right, reversing the phase of the latter.

10th Sample – MS Stereo, cardioid, [d] 75 cm, [h] 108 cm.

11th Sample – MS Stereo, omni, [d] 75 cm, [h] 108 cm.

 

So, the sound of which microphone technique did you prefer? Any comments will be highly appreciated!

30 Comments

  • Thanks a lot for posting it! The sound is really beautiful in all samples, the Joly mod seems to be great and your studio too…
    I love the ORTF – cardioid and omni – and the MS cardioid. IMHO they keep the image well focused having at the same time a beautiful open spacing. The ABs give a sound with less core, the same does the MS omni but with more character.
    But, as I said, all the samples have a wonderful sound.

    Listened on a MacBook with Kapsch Image S4i earphones

  • Very interesting and illuminating recordings, thank you! All clips sound good, but like the first respondent, I also prefer the cardioid ORTF and especially the cardioid MS. Amazing how well ORTF captures the direct sound of the guitar, even though both microphones are pointed away from the source.

    • Thank you for your insights, Jan and Luciano! While I do agree both ORTF and MS produce a great impulse and a clear stereo image, I must say I’ve been convinced the most by the width and richness of omni spaced pair (AB) technique, especially the 45cm off-axis sample. But since MS is completely new to me and I’ve been positively surprised by it, I will definitely experiment some more with this technique! BTW, I forgot to mention neither sample has any compression or EQ added – it’s just pure mic signals going far left and right with a slight reverb added. Thanks again and hope to hear from you soon!

  • Hi Uros
    Thanks a lot for sharing this with us.
    Personally I find them all very nice. I guess that your instrument and the room matters most – they are very equal. I like the AB with omnis too. XY is a little narrow.
    I wonder how you can do ORTF/omni as omnis only are directional on the highest frequenzies? Don’t you just get a 17 cm AB?

    I have done a little experimentations and recordings of my own though I’ve not yet reached the quality of your recordings. Feel free to see my channel:

    http://www.youtube.com/user/Lindhofguitar?feature=mhee#p/u/0/UlGcA3U8wS4

    Kind regards
    Per Lindhof
    Denmark

    • Hi Per Lindhof, nice to meet you and thank you for your input!
      I’ve checked your Channel and some of the videos as well, congrats! Nice pieces, I reckon they’re all your compositions? Also, you’ve got a great place to record since the renovation! I’ve recorded these samples in my home studio (https://www.urosbaric.com/studio), which was in fact a similar DIY project to yours.
      Regarding the sound, I agree, all the samples do in fact sound similar – I am convinced at least 90% of the sound recorded comes from the player, their touch and the way of playing. Only secondary, in my opinion, come the choice of guitar, the sound of the room, strings’ choice, microphones, preamps etc.
      Regarding the ORTF, yes, you’re absolutely correct. The term ORTF goes for 2 cardioid mics, spaced 17cm and angled 110 degrees outwards. But, since the positioning of the mic bodies was exactly the same, I simply wrote ORTF omni as to not over-complicate things.
      I’ve just sent you my YouTube friend invitation, please check my recent videos of Bach and Sor if you have some time. Thanks again for posting!
      Best,
      Uros

  • I read this post a while ago, but finally got my own version of this test done. I used this post as a giude to my own test.

    For my room, etc, ORTF is out, but still deciding if I like Mid-side or AB omnis better. Still messing with the distance too.

    Thanks for a great blog!

    Nick
    Pulsipher Music

  • Dear Uros
    Your testings have become references to me. Thanks a lot for your serious work.
    I’m considering the MS technique as an option. It sounds very clear and full on your recording. I have a pair of Neumann KM184 which I use for strero recording. They sound nice but the traditional set up like ORTF, AB and XY seem a little two dimensional to me (flat image).
    I don’t know the Octavas as fig 8 mics. How do they work? Do you just add an extra capsule on the existing mic or???
    My alternative is a Neumann KM120 but this is a very costful experiment at first.

    Kind regards
    Per Lindhof

    • Dear Per Lindhof,
      Thanks for your comment. With Oktava mics it works like this: You take a Mk-012 Preamp Body, attach a Cardioid capsule and use this microphone to point towards the sound source (M). Then, you take another Mk-012 Preamp body and couple it with a Figure-8 Adapter – http://www.oktava-shop.com/view_prod.php?id=154, to which you’ve already attached two additional Cardioid capsules (Side). Alteratively you can use their Figure-8 capsule – http://www.oktava-shop.com/view_prod.php?id=192 instead of the adapter and two capsules separately. Either way, the setup should cost you around 300 Euro since you can use your KM184 as M. Anyway, the signal coming from the Figure-8 mic should then be split into two poles (L=M+S, R=M-S – Side w/ reversed phase) and combined with the M signal. The beauty of this technique is that you can decide later how wide you’d like the stereo image to be. I think Oktava is really ok quality-wise, but you can opt for a great multi-polarity mic like AKG C414 as well.

    • Thank you for your comment, Peh. In my opinion, though, the playing is irrelevant in this test – all the samples were recorded in a single take and none of them is very good. Instead, please give it another try with a pair of fine loudspeakers or headphones and notice subtle differences between the recordings (how wide the stereo image is, how clear the attacks are etc.), caused by different stereo microphone positioning.

  • Hi Uros
    I tried to make some MS recording with my KM184 and some different fig. 8 mics.
    I never really succeeded though. It sounded too hollow, maybe because my little studio is not too nice sounding.

    Hi Peh
    XY is definitely a nice and accepted set up for classical guitar.
    The positioning of the mics matters a lot.
    I’ve just tried to do it overhead – 45 cm above the guitar pointing down – and it sounded very nice indeed.

    Regards
    Per Lindhof

  • Hi Uros,

    I do have good monitoring. I know they are for comparison. XY tone is nice. XY is usual setup for me. I will add an AB pair on top of XY depending on situation.

    Hi Per,

    I find myself often doing overhead.

  • Dear Uros
    I start liking the AB versions.
    A Neumanns homepage I read that AB, with the mics pointing directly at the instrument, allows for a little more distance to the instrument. This makes for a bit more complete sound.
    I can’t decide though if I should go for omnis instead of my cardiods (KM184). Definitely omnis are nice sounding, but my room may not be the best.
    What are your experiences with omni vs cardiod?

    Kind regards
    Per Lindhof

    • Dear Per Lindhof,
      In my room I prefer Omnis for most occasions as I can afford to place them further (around 1,5 m) away from the sound source, because they won’t suffer from proximity effect or low frequencies roll-off, as Cardioids do. There are, however, exceptions: For pop music classical guitar recording I’d normally go with at least 3-4 cardioid microphones, placed closer to the guitar (30-50 cm) for bigger sound. Besides, on a recent flute & guitar CD production I used one large and one small diaphragm condenser on guitar to avoid too much spill from the flute. Of course, figure 8 might have worked even better if I had a couple at hand. So, it all depends on the situation, given that you’re recording in a small room it might be a good idea to stick to the Neumanns for now and buy two additional Omni SDCs in the future.
      Regarding the AB stereo configuration, yes it gives the instrument a nice width and works best if at least 60 cm away.
      Regards, Uros

  • Well, omni does pick up a lot of things. My way is to make the gain lower(-12db or -20db). The mics are closer to the source most of the time. Drive your monitors up while recording. This will make the mic less sensitive to surround and have a pleasant tone. I alway make my gain lower in any type of mics.

    It is good to have omnis around even you will use cardiods most of time. At times, you need omnis to capture a large piece of instrument and have to stay near. I done a recording with a piano and a small instrument together without knowing and chaotic . One omni on piano and one cardiod on the small instrument. I process the material in mono.

  • I listen to all samples and compared some micropositions at home with my Damann guitar. The most important insight, independent of the micropositions there is always the same charakter of the recordings. I think the most important thing is the room, where you are recording.

    I am thinking one information would be senseful, what part of the guitar or of the player is in the center of the microphonpositions?

  • Dear Uros, I listened all your recordings with Yamaha hs50m pair. Thank you for your shares. They are very insturactive. In my opinion first of all high quality of these recordings comes from your fingers and musical way. They are great, I liked the bright sound of 7th Sample – ORTF, cardioid, [d] 70 cm, [h] 115 cm. and 8th Sample – ORTF, omni, [d] 70 cm, [h] 115 cm. But the ambiance of 10th Sample – MS Stereo, cardioid, [d] 75 cm, [h] 108 cm. and 11th Sample – MS Stereo, omni, [d] 75 cm, [h] 108 cm. are also great. You have done a great job in all recording technicks. Conguratulations and Friendly Regards.

  • Great sound! I especially like the ORTF and MS cardioid setups. What bi-directional mic did you pair with the Mk-012 for the MS recordings?

  • Great experiment Uros, it answered all my questions about stereo recording.All techniques work well, with my favorite being #1 with the Omni mics. The differences are quite subtle but this to my ears had the best balance of the bass and treble with great clarity. There seemed to be a bit too much bass resonance in some of the tests.
    I recorded the Bach Em Fugue but the quality of the recording is lacking.
    https://www.youtube.com/watch?v=Wt4jXss5Tow
    That was a close up Octava MC012 cartoid. I have since purchased omni capsuals for my matched set.of Octavas.
    Thanks for one of the best posts out there.
    The Ponce Theme and Variations is a great piece for any Manual Ponce lovers.

  • Dear Uros,
    It has taken me an age to respond to this blog, but I would like to thank you for your experimentation and thorough examples. I have been recording for some years now, and as a Classical Guitarist, searching for the best way of recording my own performances. Room/venue are vital but time factors can prove difficult here. I have had to resort to a well treated studio with artificial reverb, and as much time as I like to record an album. Baffle boards positioned in the right places can make a huge difference to the sound.
    I started with the original spaced Omni pair that have been my preferred taste in chapels with great acoustic, however, I love the sound of the cardioid MS. I was very interested to hear your example, and it just stood out to me as the most striking representation of your guitar and playing.
    Thank you so much for your references. There is not enough for Classical Guitarists on the web.

  • Hi Uros, sorry to be so late to the party here, but I really appreciate the work you have done on this. My preference is the 3rd sample, because the tone of each note is tight and direct, and the noise floor is very low. To me, this is the best combination. Some of the other techniques create more interesting stereo fields, but attack is diminished in the process, and in some cases, noise becomes more noticeable.

    I have experimented a great deal in my little home studio, but admittedly, my experiments have not been as scientifically approached since I have acquired new equipment little at a time, and on a very tight budget. Even so, I have personally begun to lean toward AB SDC cardiods at about a 36 inch distance, because they seem to capture a full range of sounds from the guitar without losing the directness of attack which I find pleasing, and without over-hyping the bass. I’m curios to know what you took away from this experiment. What technique do you like best?

    My “Scherzino Mexicano” is recorded recently, using my preferred technique as described above. I’d love to hear what you think. Thanks! Christopher Rude

  • Hi Uros!

    First, let me tell that I really like what you do in regards to recording the classical guitar. I am trying very hard to achieve good result and I am still learning the process.

    I recently began to look at recording with Mid Side technique and I have a question: I duplicate the side track, and then pan one left and the other right. I also invert the phase of the right one. Now when I listen to the sides only, I have the feeling the sound is coming only from the left side. Is there something you can tell me about that?

    • Thank you very much, Pierre! Hmm, this doesn’t sound right, something could be wrong with the routing. What DAW are you using? Can you send me a screenshot of the mixer? Best wishes,
      Uros

  • Hi Uros,

    Thanks a lot for these great videos it helped a lot. one question , is there a huge difernce in sound quality between modeded and unmoded okatava mics ?

    Regards,
    Murat

  • Hi Uros Baric,

    Many thanks for your instructive experimentations with recording techniques. There are not many attempts to explain it that clearly and underlined with sound samples of any consistency.

    Also congrats for the very consistent repetition of the same piece!

    Now, the only thing we all will agree on is that people do not agree on what is the ‚best’ sound, and that’s why it’s so important to know all of these techniques and also to know whether they’re going to work for the intended purpose or not.

    Because I respect your work very much, only a few general remarks (from my own experience with classical guitar):

    – Omnis and everything involving omnis (like MS with omni middle channel) will work best in a very good sounding. In theory one could bring the mics closer to the player with omnis because there’s no proximity effect, but recording classical guitar in near field is not at all desirable sound-wise IMHO. Bringing them further away from the guitar increases the proportion of the room sound in the pickup of the mics and here’s where all the problem start with not so great rooms.

    Your room is apparently very well treated so that your omni recordings all sound great.

    – MS is very critical on the mid to side ratio. You really have to tweak that until the localization and spaciousness are just right (guitar doesn’t need a ‚spread 🙂 ). Also MS in its proper sense depends heavily on use of a real figure eight side mic. If you don’t do that, you could just as well use a stereo pair for the side and a third mic for the mid. Then you don’t need to go through the pain of matrixing it, don’t need to buy a real fig 8 mic (expensive), have more spaciousness (because now you can go near coincident like e.g. an ORTF scheme plus a mid mic mixed to taste). I have done that a lot for classical recordings and it works very well!

    And if you really go MS, it’s worth to spend some money on the side mic, they can make a whole ot of difference. They should be also very quiet!

    – depending on the mics you use (how much off axis coloration they have) ORTF (which has been developed to record whole orchestras) may work or not, because you are sitting well inside the middle axis of the ORTF array and quite close, so you get what the mics get at this not so useful angle. This may actually be a bonus with very bright cardioids, off axis they sound softer, but maybe not too great.

    – ORTF and some other near-coincident techniques (like NOS etc.) absolutely depend on usage of directional mics (cardioids mostly). If you do ‚ORTF’ with omnis, it’s ORTF only by name, because in reality it is AB with 17cm spread and strongly off axis mics. The same goes for all other near coincident arrays that always use both, a run-time and loudness differences. Yu don’t have loudness differences just by angling an omni.

    – If you need mono compatibility, from the whole lot only XY and real MS will do it.

    – (this is mainly for all the people listening to your samples) For critical listening to classical guitar recordings listening through headphones (may they be as good as it goes) isn’t enough, you really have to listen through a pair of good loudspeakers. Only then you will know how naturally the guitar sits in the room and whether there are phase problems etc etc…

    Well, that’s a lot of stuff, but I hope it will help also people who are trying to find out the best way to record classical guitar.

    As to my own preferences:

    I quite like most of your closer spaced AB. Whether you use cardioids or omnis of course depends on what you have and like, but in a half-ways decent room and with some experimentation as to the players position and mic placement it’s almost certain to get good results. With larger spacing of AB there is always some kind of lacking focus, so I would avoid it.

    Your ORTF seems to work very well in the room you have.

    XY is also very nice, though a bit too compact to my taste. Maybe a spatial shuffler plug in would help that.

    MS with cardioid is great. MS with omni seems to exhibit some phase problems in my ears and also a slight instability of the image on loudspeakers.

    That’s it so far … I really admire the work you have done. Keep going!

    Robert Jaroslawski

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