Blumlein Stereo Microphone Technique
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- เผยแพร่เมื่อ 28 ก.ย. 2024
- In this video I give a demonstration on how to capture a stereo recording of a piano using two condenser microphones in the Blumlein array. I use two Rode NT2A microphones for the stereo technique plus a Rode NT 4 as a room mic plus a Sennheisser e906 close in on the harp. You might notice that the NT2A's are facing the wrong way (negative side of capsules facing the sound source) offering a brighter sound capture. Both mic's were phase inverted on the input channels to match the electrical polarity of the other microphones in the mix.
the thing is man you can set your mic facing the bass as omni coz bass frequencies are omni its the the higher frequencies that are directional so its those which are causing the distance get your mics closer to the high end. Have one facing the highs and one facing the lows. It wont matter that the one facing the lows is so far away from the low string cause bass sounds like its all around you any way.
thats a great sounding piano!
stereo sound implies a perspective, but whose? The musician? The listener? Many great recordings have been made with the listener perspective recording with the inclusion of the a room.
Imagine the mikes are your ears, would you place them above the strings on a grand?
To make this a Blumlein stereo recording, first eliminate the three extra microphones, then move the Blumlein pair so the piano subtends an angle of less than 90 degrees. This will get you partway there. Using ribbons will get you further.
Use of ribbon microphones has nothing whatsoever to do with the Blumlein array. It refers to placement of two-directional or "figure 8" microphones, whether they are condenser, ribbon, or dynamic ( of which none exist that I am aware of.) the demonstrator states very clearly that the room mics ar present only because the lid of the piano remains in place and not removed , and used only for a sense of ambience. If placed verly low in the mix these would have a minute effect on the stereo imaging created by the Blumlein technique. This comment was incorrect and for this most part invalid.
Diggin that console!
I was supposed to use a matched pair of AKG C414's which are a better choice but was very happy with the results from the pair of NT2A's. This recording takes in more microphones over time, the additional microphones appear in the mix as I introduce them. You can use that as a basis for critical comparison against another recording if you wish. You might also want to consider hiring a pair of mic's from your local pro music shop or film equipment hire service instead of purchasing.
Beautiful... As a classical guitarist I've been looking for a simple yet full bodied technique to record my instrument in my small studio. I have a pair of Neumann KM184 which are nice cardiods but I'm very curious about the NT2A's as a Blumlein pair. Do you have any experience with these only for solo instruments.
Kind regards
Per Lindhof
I just tried with a pair of my friends' CAD m179 in blumlein setup. placement is right above player's head. the result is fantasic! also tired different positioning with a pair of ksm141 in both patterns didn't get good result.
will post some videos later. thanks again.
Which song is it, that you played for this recording. Sounds amazing!
It's my own piece "Dancing With the Faeries". You'll find it on Soundcloud here soundcloud.com/thesymphonyoflight/dancing-with-the-faeries
amazing! wondering if this is gonna work for upright piano.
Will this work for omnidirectional mics, like the Shure KSM141?
Omnidirectional mic's will sound distant and there will be nothing you can do to make the piano "in your face" or "the centre of attention" within the mix. If you're looking for room ambience then by all means go with the omni's but you will need a good close mixing technique if you need the piano to sit forward in the mix.
Hope that helps.
enjoyed it
2:33 those are NT2000 microphones. Not too shabby for $700 mics, but not too great either.
Yeah... Its all I had for this recording.
I bought some 414's and fatheads
How can you tell that they are NT2000 rather than NT2A mics? The two mics look very similar from pictures I have seen, but I think these are NT2As as indicated above. I'm considering buying 2 x NT2000 mics to use in Blumlein configuration to record my harpsichord and spinet at home, and am wondering whether this would be a good choice. Quite an expensive investment for me, so I want to make sure it will work before buying them.
Having great pre's and EQ like the ones in that Toft (Trident) sure helps. Great how-to and great recording. Thank you, karlsae
Great
Ahhh that explains a lot! I made a recording of my grand a little over a month ago (it's the most recent video on my channel) and I was wondering why the recording sounded so distant! It's because I put them in omnidirectional mode. What kind of microphone positioning would you recommend for classical music on a grand piano with two KSM141s in cardioid mode? Should I use separate mics to record the room and mix that in somehow?
cardioids will not work. Figure8 only.
so my question is what happens in post? you have a stereo sound one panned to right and the other panned to left and one above for capturing the room tone. in the DAW you have three recordings of the source, who do you deal with them in post meaning how do you mix them so that you have one output comprised of all these three inputs?
+Pissarrio Hi Pissarrio - The answer is entirely personal however, the mix is entirely dependant upon how much room tone you want. If you think in terms of an orchestra hiring an expensive concert hall, the reason they pay for this privilege is to capture the reverb character of the hall and this is paramount in the final product. Traditional electronic reverb doesn't cut it and this is why the room mic has been utilised. A Decca tree is normally employed for these larger recordings but in the case of a solo instrument a room mic will suffice. So... in answer to your question; There are five channels of audio in my recording (see the description above). The Blumlein pair are the focus microphones so have to be loudest in the mix. This does not mean you push the volume controls straight to unity as you want to stay below the distortion ceiling with the additional volume from the additional microphone channels (the sum voltage through a desk) . This is where a stereo buss (set to unity) should be used and you can set this up in your DAW just like a mixing console. So turn up the faders for the Blumlein pair and bring in the stereo room channels until you're happy with the mix. I measured the distance of the room mic to the piano harp according to the 3:1 ratio of the Blumlein pair to avoid comb filtering. Because I measured the mic distances I didn't have to fiddle with the alignment of any audio waveform in the edit window (protools). It's the same with the close mic on the bass end of the harp. I used the Sennheisser to fill out the bass end of the piano and again, brought up only enough to compliment the overall character of the piano. If I remember correctly this mic is panned slightly left (likely around 9 o'clock) as the Blumlein pair would have the bass in that end of the stereo field. By sending the output of all 5 channels to a stereo buss (post fader) I was then able to use the buss to control my final volume (Essentially as a Voltage Controlled Amplifier). This is where you can use a compressor, limiter, reverb (depending on what instrument/s you send here) to reach your final mix.
Now, I answered your question with a logical approach BUT mixed the close mic's first and added the room mic last. Mixing is about balance and that balance is entirely personal - I hope this helps.
Key concepts - Decca tree, focus instrument, unity gain, distortion ceiling, dynamic range, stereo buss, post fader, 3:1 ratio, comb filtering.
+MysterKarl Thank you so very much. What you have provided as a way of answering my question has been more than helpful and I intended to learn from it and experiment with it.
Sound Nice! Did you pan to the left side he microphone that you place on the bass strings? And, is this mic and extrabass o just a normal condensor microphone?
What do you do with the two channels of Blumlein?
Down two channels of the desk panned hard left and hard right and that's it. Don't put one of the channels out of phase.
did you need a phase reverse trick with a blumlein pair ? like the M/S technique ?
Meteotrance Yes, it is essential to have one out of phase with the other. When you have them mono on the console (both channels panned centre) you will hear a minimal amount of sound. Total phase cancellation cannot occur due to the two microphone capsules occupying a different position in space. When you pan each channel in the opposite direction (Left & Right) it is then that you will receive the maximum benefit of stereo reproduction. Some authorities believe this to be the best stereo microphone configuration.
Thanks you, for ambiance, yes it's probably one of the best stereo use, for surround capture maybe not, but a regular M/S too front and rear with some extra omni do the job right, im testing a lot of stuff for having wide stereo, or binaural and surround also some tricks with plug in that work with convolution or algorythm they have also benefit on none acoustic sound.
Meteotrance Actually, My answer above is incorrect. There is no need for phase reversal. I realise you ask this because I had the negative side of the capsules facing the sound source which is not as acoustically warm as the positive side - but brought out extra brightness from the piano. I had to phase reverse the Blumlein pair in order to match the electrical polarity of the other three mic's in the combined mix else I would have suffered phase cancellation. If you do change the polarity of one microphone the only effect will amount to the direction of the array moving from the front to one of the sides. The difference will equal the sound quality differences between the front and rear of each capsule. Looking at an illustration of the polar pattern bloom would better clarify the differences.
yep that exactly what i read, on some forums, they explain that with a polarity diagram. So you just need, to put two mic dead center on the mixing bus, and use only the phase reverse, when you have other mics added with phase cancelation issue ? right ?
Incorrect, the two mic's used for the Blumlein technique capture a binaural signal meaning, you need to pan hard left and hard right to reproduce a stereo (binaural) image through the speakers. As for other mic's it is important to consider the 3:1 ratio to minimise phase cancellation. This is when you need to consider measuring the distances between the mic's and the sound source thereby minimising phase cancellation. As you can see the mic setup starts to become complex so simply flipping the phase on a mic won't fix the problem. If you do have phase issues, try moving the resultant audio region/audio clip to align with the phase of the primary audio track. I have named several concepts that are lessons in their own right so have a look at other resources on the net to firmly grasp everything I have said here
Concepts (cut and past into your search engine):
Binaural
3:1 rule
Audio Signal Phase
Audio region/clips
What brand of mic stands are those?
K & M but not sure of the serial number.
some people at RCA in the 50's use also an interesting trick using 3 microphones, one cardioïds on center, the other left and right are pure omnidirectional, and it's also work with 3 cardioïds with the center bigger than the other mic. i try this and it's work also very fine with ORTF couple.
+Meteotrance -
I totally agree with this. The whole explicit L/R hard panned mic thing is not completely 'correct' in my opinion. There must also be one mic in the middle (not center) I'd say around 40-60%, but only on one side, then blended into the other side while delaying all three mics L/R/M&S a few milliseconds. Trying to do it otherwise (especially in a mix) is like trying to search for a needle in a haystack and will most likely only result in a thinner stereo image.
+ShadowⓋ The Blumlein array that MysterKarl describes is a classic stereo technique from the 1930s by the inventor of stereo mic'ing. Mr Blumlein also invented the mid-side mic technique you refer to with a cardiod and a figure eight. But notice in this video, it is two figure eight mics set at 90 degrees and NEITHER mic is pointing directly at the sound source. Whether you agree or not is irrelevant. This IS the classic Blumlein array, and if you want to get it precisely correct, check out the Royer SF12 stereo ribbon mic. Because Royer actually manufactures a single mic with two figure 8 ribbons built together in this format. And it rules. have fun recording! And most importantly, keep all the mics in phase. Then you won't have a thinner sound.
Ra Bob
That mic sounds interesting, but my question is why is the damn thing so god awful expensive?! Seriously, two and a half grand for a microphone? That's completely ridiculous. It better be gold plated.. or something.
Ha ha... All condenser mic's are gold plated, or more to the point... Gold sputtered. The diaphragms are literally coated in gold :D
+MysterKarl But the Royer SF12 is not an LDC. It's two Royer ribbons mounted on a single mic body at 90 degrees.
im probably using this with ribbon mic, cause i can make a matched pair for close nothing. and it's naturaly figure 8
You could always hire some mic's.
and the highs will be write up in your face
The essence of a grand piano, is that you listen to it in a concert hall. This is not about "stereo" mic techniques, but about using two mic's to capture the very broad and elaborate range of a grand. If you truly want to hear a grand piano in "stereo", go and listen to a good player in a good concerthall.
Update: my bad. Room mic's added. I should watch the whole thing before posting;)
And you obviously weren't listening, either. The room mics are obvious. How much recording have you done? Any?