Audacity Forum

Hi All,

I want to make decent recordings of my fiancé performing together with a friend (piano and trumpet) for the purpose of making a demo-CD. They will perform in small to mid-size university concert halls.

I use an Asus EEE PC 901, Edirol UA-25EX USB soundbox, Octava MK-012 microphones (matched pair with omni-directional, cardioid & hyper cardioid capsules), good quality cables, fairly nice microphone stand with adjustable microphone holders. And of course Audacity

The idea is to put the microphones on stage, if stage-size allows some 5 meters (15-16 feet), form the sound sources. The microphones will be aligned according to the NOS principle; 45 degrees of-center (like a V-shape), capsules 30 centimeters (1 foot) apart.

My fiance and her friend usually are not too far apart; trumpet approximately 2 meters (6 feet) from the piano, and the trumpet does not move much.

Is there anyone around that has experience doing stage recordings that can give me some advice or useful tips? Maybe I am going in a completely wrong direction here!!!

Thanks in advance for any input you can give me!

Peter

Peter:
Although I am not personally familiar with that mic pre-amp and those microphones, the specifications look very good. I applaud you for recording from the stage or audience rather than trying to close-mic the piano and trumpet.

I think your are wise to stay at least 5 metres back from the performers. If time allows (if there is some setup or rehearsal time before the audience comes in), it is often useful to try the microphones in different locations (5 metres, 7 metres, 10 metres, etc.), then listen back on good headphones. The distance of the microphones from the performers will affect not only the spread of the stereo image but also the ratio of direct to reflected sound. The further back you go, the more "room sound" you get in the recording.

I am not familiar with the NOS principle, but it sounds similar to ORTF. I am not a fan of any kind of spaced microphone technique for this type of recording. Arrival-time delays between the two microphones lead to phase cancellation (comb filtering) when converted to mono. Also, the ears/brain are confused by the time difference leading to a "hole in the middle" effect, and the squashing of the stereo image to the left or right speaker unless you sit perfectly still in the sweet spot. I am an advocate of "coincident stereo" recording. In your case this would be the "X-Y" cardiod setup. This involves setting up two cardioid microphones one above the other and as close as possible without touching, angled at 120 degrees. For hypercardioids the angle is 105 degrees.

This article: http://www.soundonsound.com/sos/1997_ar ... iking.html is pretty good.

It sounds from your description that there will be several concerts? If you feel it is appropriate you could try NOS on some recordings and X-Y on others.

-- Bill

Hello Bill,

First of all: thanks for your input! I am a complete "newbie" with regards to recording techniques. But luckily I am a fast learner

I started looking for mics about 6 months ago. Mostly on the Internet, but that turned out to be a "can not find the forest because of all the trees" scenario. So I called Sennheiser (my favorite headphone brand), and got some advice from a friendly fellow who told me the best thing to get was a pair of Neumann KM-184 (I believe). Neumann is Sennheiser's top-of-the-bill brand. But the price of these was "slightly" above budget. I did some Internet searches for the KM-184's, and surprisingly enough I found quite a few comparisons between the Neumann's and Octava MK-014. At first I was skeptical as it is a Russian brand, but in every review it was said that the Octava's come close for a fraction of the price.

So, I decided to get the Oktava's. Maybe I bought crap, but they will be put to the test soon

The Edirol device I got was sort of a gamble too. However, I know it has a fairly good analogue to digital (and vice-versa) decoders, and buying a device that was more expensive would have been a waste of money, at least for my purposes.

The NOS microphone technique was developed by the Dutch Broadcasting Foundation (that's the translation for the Nederlandse Omroep Stichting). I have heard quite a few recordings made that way, and it always sounds nice. From what understand, it's sort of a "mix" between the ODTF and XY techniques. It (supposedly / arguably) has some advantages over ODTF in the problematic areas you describe for it.

But, as you suggested, I will try both of them. Fortunately, my fiancé and her friend are able to do rehearsals at the places they will perform, so that will give me plenty of time to play around...

If you would like it, I can send you the demo-CD when it's done. If you like Brazil classical music that is

Again, thanks for your help!. I really appreciate it.

Regards,
Peter

There is a stage recording technique that eliminates the floor reflections by putting the microphones on the floor. Not directly on the floor, of course, but Electro-Voice makes or used to make a "Stage Mouse" which was a little half-sausage with a hole in it to slide the microphone. The floor reflection effect vanishes, the directional characteristic of the microphone is preserved, the assembly is dark gray and out of sight, and the sensitivity of the microphone doubles.

http://www.electrovoice.com/download_do ... p?doc=2333

Page 3.

Koz

Hello Koz,

I have heard about the technique you mentioned. I tried to find some more info online, but this time Google was not my best friend. Also, the manufacturer's website did not mention the stagemouse anymore...

Maybe I will try to produce something similar out of a soft foam and experiment with it. You never know what it's good for

Thanks for the info, Koz!

Regards,
Peter

They used to use it to demonstrate their acoustically transparent foam. It didn't make the sound muffled like the corner music store universal foam. You can get the same effect by putting a thin layer of foam on the floor and then don't cover the microphone at all. The killer with this technique is picking up floor sounds by accident -- say the metro-rail under the studio.

Koz

Peter:
A couple more thoughts ...

Before you go to the first rehearsal or performance, verify that everything is working (obvious, I know, but better said than not said).

I'd run the Edirol at 24-bit, 44.1 kHz. Obviously, set Audacity to the same. When setting levels, ask the musicians to play the loudest thing in the performance, and set your levels in Audacity to be about -12 dB for the loudest part - this will give you lots of headroom. Turn off the analog limiter on the Edirol - once you've set levels this way you should not need it.

In post production, once you've selected and sequenced the tracks for the CD, run the Amplify effect to maximize the volume of the tracks. Export to 16-bit, 44.1 kHz (CD standard). Audacity will apply dither (a good thing) when it converts from 24-bit to 16-bit.

kozikowski wrote:The killer with this technique is picking up floor sounds by accident -- say the metro-rail under the studio.

Or the trumpet player stepping back and forth, or the pedals being depressed on the piano or ...

-- Bill

<<<Or the trumpet player stepping back and forth, or the pedals being depressed on the piano or ...>>>

No, it actually has to shake the floor. The foot "performance" noise isn't any worse than a microphone in the audience.

I've never seen one, but apparently stage performances use these a lot.

Koz

Hi Koz,

Do you know the these floor recording "sleves" are still available? I have spend quite a bit of time looking online for them, but I only can find a few lines in a google online book...

The idea interests me because (apart from canceling floor-reflections)I think an on-stage microphone-stand is somewhat disruptive for the audience. On the other hand, I have not been to any classical concerts that were recorded, so I really don't know if it really is...

Regards,

Peter

surfingalien wrote: I use an Asus EEE PC 901, Edirol UA-25EX USB soundbox, Octava MK-012 microphones (matched pair with omni-directional, cardioid & hyper cardioid capsules), good quality cables, fairly nice microphone stand with adjustable microphone holders. And of course Audacity

I don't know about the EEEPC, but you report that it works well. The other equipment looks good for the job, they have all received good reviews and provide a lot of options for how you do the recording.

The hyper-cardioid capsules are likely to "colour" the sound more than the others, but are useful if you have problems with picking up too much room / audience sound.
Cardioid capsules can give a nice balance and should work well with X-Y stereo microphone technique. If cardioid microphones (or hyper-cardioid) are used for close mic'ing they tend to emphasise the bass as you get closer to the sound source - this is not usually a problem, but just something to be aware of.

The omni-directional capsules are great for A-B stereo recording and will often produce noticeably cleaner/more natural bass response than other techniques (when listened to in stereo). While it is true that this method can cause phase problems if mixed to mono, how many mono players do you come across these days? AM radios, mono cassette player and the like usually have relatively poor sound quality anyway, so any phasing effects are unlikely to be significant. IMO the main practical problem with spaced pair/array recording is that setting up the optimum microphone placement can require considerably longer to set up.

NOS and ORTF use basically the same method - the only difference is in the spacing and angle of the microphones. Some Dutch sound engineer decided that the sweet spot was NOS, and a French sound engineer decided that the sweet spot was ORTF. If you have time, experiment and make up your own mind.

X/Y is probably the usually the quickest to set up as the only placement issue is how close to the performers.

NOS, ORTF, and XY are all pretty reliable techniques so long as the room is kind (nice acoustics, not too much room noise and the practicalities of microphone placement are achievable).

kozikowski wrote:There is a stage recording technique that eliminates the floor reflections by putting the microphones on the floor.

This can be (and often is) done by mounting the microphones on boom stands (providing that the boom is long enough to reach close to floor level).
It can also be done with PZM microphones - a technique sometimes employed in Theatre.
Other than PZMs, microphones should not be placed directly on the floor for the reasons given in previous posts - plus the likelihood that someone will kick it across the room.

billw58 wrote:I'd run the Edirol at 24-bit, 44.1 kHz. Obviously, set Audacity to the same.

Audacity could be set to 32bit providing that it will run smoothly with this setting. Up-sampling from 24bit to 32 bit will do no damage. For best sound quality, any processing done in Audacity should use 32bit audio tracks. Processing in Audacity is always done at 32 bit, so if tracks are of a lower bit depth it will introduce a small amount of noise. I don't think it will matter if you record at 24 bit then convert to 32 bit before processing, or record in 32 bit - whichever runs best on your equipment. This only applies to "processing" (applying equalisation, amplification, or any other effects). It does not apply to simple editing such as trimming the ends off or splitting tracks. 32bit recordings require more disk space than 24 bit (for the extra 1 byte per sample).