The saga continues - the Samson Zoom H4n

After having pointed out the complete neglect of theoretical considerations and empirical observations with regards to the relationship between intra-microphone- and recording-angle in my theoretical appraisal of the Samson Zoom H2 I find the Samson Zoom H4n:

"The mics also adjust for variable recording patterns at either 90° or 120°. Our unique design lets you rotate each mic capsule from 90° (standard) to 120° (wide-angle) stereo for the ultimate versatility in any recording situation." [Link]

The surprises don't end here. Samson states that their "Unique X/Y mic design captures perfect stereo images." X/Y was invented in the 1930's by Alan Dower Blumlein. And who knows what the image labeled as "Conventional Stereo Mic" pertains to. It might be ORTF (2 cardioid capsules, facing +-55° off axis at an intra-capsule distance of 17 cm) but a more accurate specification would have been interesting.

[All © by their respective owners]

A theoretical appraisal of the Samson Zoom H2

Samson states that "The H2 is the only portable recorder with 4 mic capsules on-board for 360° recording. [...] For maximum flexibility, you can record from the front of the H2 in a 90° pickup pattern or the rear of the H2 in a 120° pickup pattern [...]" [Link]

A view of the capsules can be found here.

As can be seen from the graphics Samson provides they expect the pair of forward-facing cardioids, arranged at +-45° off axis (for a total of 90°), to result in a stereophonic recording angle of 90°. This is not correct. According to Eberhard Sengpiel the recording area is much wider at 196°.

For the rear-facing microphones the arrangement of +-60° off axis (for a total of 120°) is said to result in a recording angle of 120°. This again is not correct. The calculated recording angle is 158° --less than the 196° found in the frontal configuration.

The fact is: a greater off-axis angle results in a smaller recording angle! This is not only mathematically correct but can be easily verified in practice.

In sum, the total recording area of the 4-Mic-setup in the Zoom H2 covers 354°, composed of a larger forward-facing and a smaller rear-facing area.

What should it sound like?

Both (near-) coincident pairs employ cardioids, which will result a high degree of diffuse-field correlation, perceptually compressing both the frontal and the rear-facing soundstage. Whereas I have not personally experimented with this recorder I believe a more complex setup is required to capture a realistically enveloping experience.

I find both the coincident approaches (Soundfield, Double-M/S) and runtime-based solutions (Atmos, Surround Decca-Tree, OCT/OCT2) interesting. My XYtri features a composite approach. But all of these are definitely way more involved than a compact, handheld solution. As such it might meet many user's needs.

[All © by their respective owners]

Innovations in recording technology

In recording technology you have...

1. The microphone capsule
   
2. The microphone-internal amplifier
   
3. Gadgets to support the microphone and decouple it from structure-borne sound
   
4. Gadgets to protect the capsule from the elements, especially wind
   
5. The microphone-preamplifier (mic-pre)
   
6. Cabling
   
7. The sound recorder
   

Digital technology originally introduced an additional step before the sound recorder:

• The Analog-Digital Converter (ADC)
  

In the case of digital microphones the ADC is placed either right after the capsule or after the microphone-internal amplifier.

I analysed the latest press releases by five of the main microphone manufacturers: AKG, DPA, Neumann, Schoeps and Sennheiser. This is what I found...

AKG

"The AKG C 414 has been successful for more than 30 years due to continuous improvement of technical specifications, useful features, and ease-of-use. [...] Our new C 214 was designed as a budget-friendly alternative to the leading-edge C 414 family." [Link]

"The new AKG Perception Series [based on the P 100, P 150, P 200 and P 400] includes the P 120, P 170, P 220 and P 420" [Link]

DPA

"DPA Launches 5100 Mobile Surround Microphone at IBC 2008. [...] Optimum channel separation and directionality are achieved through a combination of DPA’s proprietary DiPMic (Directional Pressure Microphone) technology, which mounts interference tubes on the L/C/R capsules, and the use of acoustic baffles that further preserve the accuracy of levels between the discrete analogue output channels. [...] The centre channel can be overridden by an external boom or lavalier microphone attached via a built-in XLR-F connector." [Link]

ProAudio Review (03-2008): "DPA has defined a new microphone sub genre [in Fall 2007]: 'the musical shotgun.'" [Link]

Mix Online (04-2005): The "DPA WINDPAC Folding Location Windscreen [...] incorporates new thinking about an old problem." [Link]

Neumann

Solution-D Digital microphones [Link]

Schoeps

"The 'Open Cardioid' directional pattern, occupying a point on the spectrum between the wide cardioid and classic cardioid patterns, was developed by SCHOEPS in 2008." [Link]

"The SCHOEPS CCM microphone series [...] has now been enhanced with a top-class elastic suspension. [...] Attenuation of solid-borne noise from the boom is achieved by the unique architecture of the CINELA OSIX series." [Link]

Digital Microphone Amplifier CMD 2U [Link]

Sennheiser

"With the launch of the MO 2000, the audio specialist has expanded its portfolio with a new type of transducer that represents acoustic signals on the basis of variations in light intensity." [Link]

"In the optical microphone, light from an LED is directed onto a reflective diaphragm via an optical-fibre cable (transmitter optical waveguide). The membrane reflects part of the light into a receiver optical waveguide. If the diaphragm is moved by sound signals, a displacement of the reflected light beam occurs, with the result that more or less light is coupled into the receiver waveguide. At the end of the receiver waveguide, a photodiode converts the light intensity variations into electric signals. [...] The optical principle is the only microphone principle in which the microphone head and the electronics can be located far away from each other." [Link]

According to the specifications this technology is not yet usable to record music, but as a completely novel approach it definitely deserves attention.

"Audio specialist Sennheiser is unveiling the MZD 8000 digital module at AES 2008." [Link]

MKH 800 TWIN studio microphone: "At its output, the dual capsule microphone provides both audio signals separately, allowing the mic’s pick-up pattern to be adjusted freely and remotely at the mixing desk, and then optimised later in the calm of the post-production studio." [Link]

Interestingly enough I had a discussion with a microphone specialist about outputting discrete signals from a dual capsule around this time. Besides the flexibilities in post I see a useful application in generating surround-channels from the sides of the microphones facing the audience.

Summary

Of the five microphone manufacturers I researched DPA looks to me to be the most productive in terms of in-house innovations pertaining to recording music. Sennheiser is a runner up with it's dual-output-capsule and for investigating a completely novel transducer-design. Neumann and Schoeps primarily announced their moving into the realm of digital microphones. What I like about Schoeps is their embrace of surround setups developed by forward thinkers, although DPA also sports a wide range of mounts for various surround configurations.

[All © by their respective owners]

Why double sample rates? (88.2 kHz / 96 kHz)

I just read a short description of Why is 96/24 better than 44.1/16? in an otherwise quite knowledgeably assembled FAQ. While it is true that "a sampling rate of 96kHz gives a better digital representation of the waveform and yields a usable audio bandwidth of about 48kHz" this does not explain why recording made at double the usual sample rates (of 44.1 kHz / 48 kHz) should sound better.

Just consider...

• What is the limit of your hearing, frequency-wise?
  
• How many instruments have harmonic content above 20 kHz --that you really care to hear?
  
• How many microphones record linearly --or at all-- above 20 kHz?
  I recorded Gaita, an incredibly overtone-rich spanish bagpipe, optimized for open-air usage) twice. Once using a Blumlein-setup of two RoyerLabs SF-1 ribbon-microphones, with their characteristic, gentle high-frequency rolloff, and once using an AB-setup featuring two Earthworks QTC-1's (now called QTC40), practically flat from 4 to 40 kHz. Which do you think sounded more real, and which sounded more pleasant? ;-)
  

Well?

Listen to the Jata da Mahia for a sample of Gaita recorded with Blumlein-ribbons.

I believe it's more about the optimal SR the ADC was designed for, as well as the quality of the filters used, as all content above the Nyquist frequency has to be filtered out before the conversion.

Then again many audiophile are intrigued by the "24-96" label. If you are a true sonophile this may not be quite as much of an issue. Trust your ears!

Choosing microphones

These are my thoughts on choosing the right microphones for a variety of scenarios, based on my way of approaching recording projects.

First of all, here are a few of the fundamental observations I have found helpful:

• The more live a recording situation is, the easier it will be to make it sound live. Simple ;-)
  
• The fewer microphones are used in the mix, the clearer the result will be. This is due to...
  
  • Phase issues: the fact that all sounds occurring will to some degree be present in all microphones, but at slightly differing time; they might also be colored due to non-linearity in off-axis pickup.
    
  • Additive background noise, which can also cause problems when spots are panned to a specific location.
    
• Music is a temporal and spatial event. Musicians generally move (their instruments) and this causes a movement of the sound source which dynamically interacts with the recording space.
  
• Never forget the importance of the microphone preamplifier & the ADC!
  
• There is a distinct difference between far and close-up use. The character of a microphone's sound is much more significant in the latter case.
  
• A microphone does not know what it is recording. Be suspicious about type-casting (guitar-mic, snare-mic etc).
  

Based on the above assumptions there are a few questions to be asked about what you wish to record.

Hauptmikrofon / main mike setup

You need a set of closely matched high quality microphones for this purpose. The key features to look for are neutrality, resolution and quietness. You don't want off-axis sound to be coloured, especially when using omnidirectional microphones in an AB-setup.

Blumlein-setup

The Blumlein pair requires two fig-8 microphones. Keep in mind that all bidirectional condensers exhibit (a pronounced proximity effect when used close up and) a significant low-frequency-rolloff in the far field. Interestingly ribbon microphones don't necessarily share that characteristic.

>= 88.2/96kHz-recordings

If you plan on recording high resolution audio it is advisable that the microphones (capsules and capsule-preamplifier) reach up to half of the sample rate, preferably in a linear fashion. Check out the Nyquist frequency for details.

Ambient microphones

Since these microphones will be way out in the reverberant field where the sound pressure level is relatively low, low self-noise is desirable. It is when you want to make the most out of directly approaching sound that the use of boundary layer microphones is indicated.

Spot microphones

Spot microphones is the area where recordists can get most creative. Any microphones' sonic character becomes more pronounced when used close to the sound source, especially with directional characteristics.

The blumlein records microphone closet

• 1 * Earthworks QTC-1 (QTC40)
  This used to be one of a set, but a musician literally killed one in a session --tripping over a cable and making the mic crash tip-down. I often use it as the mid-channel for an M/S-setup.
  
• 2 * Earthworks QTC50 (matched pair)
  Optimal for high-resolution AB-recordings. Their miniature capsule is extremely linear and amazingly fast.
  
• 2 * Elation KM201 MSP4 (matched pair) - 2 Capsules: cardioid & omnidirectional
  A good general purpose spot microphone. I have also frequently used it as an AB-spot within choirs when recording oratorios.
  
• 2 * DPA 4060 (matched pair)
  A beautifully unobtrusive microphone. It does have a self-noise of 23 dBA but works great as a close spot inside a bass, auto harp, udu etc. I also frequently used it as a boundary layer mic taped under a grand piano.
  
• 2 * Oktava mk102 UM-mod (matched pair)
  The United Minorities tuned Oktava cardioid is fabulous for ORTF-recordings, as a mid-channel for M/S, and as a close mike for extremely quiet sources.
  
• 6 * Rode NT-5 (3 matched pairs)
  This inexpensive microphone is a good spot for many applications.
  Currently all six of these microphones are the basis of my XYtri-setup.
  
• 1 * Rode NT-4 (matched pair)
  Using the same capsules as the NT-5 this microphone is quick to setup and does a good job. I have used the battery-powerable mic as an external microphone feeding my Mini-DV-camera for many interviews.
  
• 2 * RoyerLabs SF-1 (matched pair)
  A beautiful ribbon microphone. Great for sonophile Blumlein recordings. Also a very nice spot for many overtone-rich instruments: gaita, trumpet, violin-overhead, ... due to it's gentle high-frequency roll off.
  
• 2 * UM-1 (matched pair) - Switchable: cardioid, fig-8, omnidirectional
  Since I have received this United Minorities microphone it has been the staple for many of my recordings. It is very linear, extremely accurate in the time domain and eminently usable in a multitude of recording situations. I love it!
  

Disclaimer: I have occasionally used the famed microphones by Neumann and Schoeps, but I never felt the need to buy one of them. Equally good microphones are available --at a more reasonable price range. Let your ears be the judge :-)