Need advice about how to compare mic specs

[Lawrence W. Pry]

I’m new to DSLR video and I’m shopping for a microphone to use with my Canon 5DII and JuicedLink preamp. I plan to use it primarily for two things: (1) recording solo and small ensemble classical music (esp. clarinet and other woodwinds); and (2) soundscapes while traveling.

Two of the mics I'm considering are quite similar in many respects, probably because one is the successor model to the other. But two differences have caught my eye: frequency response and sensitivity. Here are the numbers:

Mic #1: Frequency Response: 20-15,000 Hz -- Open Circuit Sensitivity: Phantom: -38 dB (12.5 mV) re 1V at 1 Pa Battery: 38 dB (12.5 mV) re 1V at 1 Pa

Mic #2: Frequency Response: 30-20,000 Hz -- Open Circuit Sensitivity: -47 dB (4.4 mV) re 1V at 1 Pa

I gather that a wider frequency response is probably better than a narrower one, at least if one is searching for accuracy rather than tonal color. Similarly, higher sensitivity would also seem to be a good thing. (On a related note, is the difference in sensitivity here at all significant in the first place?) But is either more important for my purposes? I know that it’s dangerous to base a microphone comparison only on specs, but how should I use this data to guide my decision-making? Please bear in mind that I cannot try either or both of these mics before I purchase.

[Pedanes Bol]

I am not an audio professional and cannot comment on your technical question, however, I have Mic #2 and record classical music (quartets) frequently. Mic #2 microphone either attached directly to my 5DII or to Zoom H4N (via XLR), provides great results. I like the sound better when attached to Zoom H4N. Also, it is better compared to recordings with internal microphones of Zoom (don't know the frequency range) or with another stereo microphone I have (freq. range 50-18,000). I am guessing that Mic #1 will record great audio since it is the successor, and also having a freq. range 20-15,000 (will pick up bass sounds better).

The only thing I don't like with Mic#2 is that it does not have a battery indicator or ON/OFF switch, so I end up putting a fresh battery every time I do a recording. But this is not a problem if you are going to use phantom power from JuicedLink preamp.

[Richard Crowley]

Sorry, you cannot select a microphone based on the published specifications. There are many reasons for this that we won't get into here unless you are interested in the philosophy and ethics of marketing.

"Frequency response" is pretty meaningless without seeing a graph of response vs. frequency. And even then getting a truly representative frequency response graph is almost impossible. Furthermore, it is very rare that you will ever use the bottom or top octaves of the response (or even the first TWO octaves). Also important is the polar response, i.e.what is the frequency response off-axis.

"Sensitivity" is also a very difficult spec to judge by. Because it isn't really possible to make any sense out of it without knowing the self-noise of the microphone as well.

If you want help selecting a microphone, you will need to actually reveal WHAT microphone(s) you are considering and ask for advice from people who own them or have used or tested them in the applications you need.

Keep in mind that recording audio on a DSLR is a rather tenuous thing, even with a mic preamp like the JuicedLink. Unless you can disable the automatic level "feature" your camera is ill-suited for either environmental or music recording.

It is not clear how Mr. Bol can talk about specific microphones when Mr. Pry does not appeared to have identified them? Am I missing something here?

[Brian David Melnyk]

if a mic is not covering the full range of frequencies then aren't a lot of the beautiful nuances of overtones and harmonics being lost?

[Paul R Johnson]

Richard is 100% right when he says never to choose a microphone on it's spec. There are obvious things in the specs that sometimes are critical for certain applications, such as sensitivity, but in general - it's very uncommon to see mics ever detailed as having less than 40-20,000Hz paper specs. Virtually all condensers can manage this. Some of the most expensive microphones have anything but flat frequency responses.

I'd also suggest that maybe video forums are the wrong place to get accurate audio advice. Some advice on audio matters on video forums is simply crazy! Look at the audio recording and live sound forums - their advice (and user demographic) is much better - quantity and quality. Having a foot in both camps, I note that when they give video advice, it's equally compromised.

The requirements of recording real instruments in proper spaces is far more complex than imagined. Microphone choice and placement are really critical factors. Even a solo instrument, in a nice space can be considered as a 'stereo' source - because of the reverberation and player movement, the instrument has identifiable width, so you are forced to consider stereo technique. The mention was made of overtones, and these are responsible for the listener being able to identify the instrument as having cylindrical or conical bore - reduce the upper range and the character changes. As we're talking about audio for video, you also need to consider the visual impact. Can you have microphones in shot? If not, then stereo technique is even more important. If we accept that distances may have to be greater than idea, then the important area to consider is noise - very few mics have poor performance in this area, even the worst ones are usually overshadowed by the preamp noise of the device they're plugged into. Having a sensitive mic means preamps have to work less hard, and are less noisy. Matching a low output mic like a ribbon with anything less than a properly designed preamp is not going to be good. That said, most of the popular condensers have pretty decent sensitivity.

I'd simply draw up a shortlist of mics you can afford and then read the audio reviews on audio sites. They're using only ears to judge - video people often treat good audio as being the fact there is some, and it doesn't hum!

If you are starting out, then one of the popular single piece stereo mics (like the Rodes) can produce good results - and can be put in a windshield and used outside. Video people are often quite polarised on makes and models, often I feel, based on nothing but snobbery or poor assessment. People talk about rules, or insistence on certain makes - and nothing shakes them.

If you can't hire a mic or borrow one locally, then buy from one of the on-line retailers who accept returns. It could cost you the return postage but could be worth it.

I have dozens of microphones in the case. Some I use almost daily, others less often. For recording choirs or expensive traditional instruments I personally favour very different mics from those I have connected to my cameras. In fact, I've got one of my favourite quite cheap condenser cardioids attached to one camera almost permanently because I used it by accident once - and really liked the sound, which seemed to match the lens on wide angle much better than the short shotgun it has had attached since new.

Practical issues are simply
battery only, battery and phantom, or phantom only
Pick-up pattern. cardioid, hyper or omni (I never use anything longer on instruments as they don't sound real enough for me)
size - as in how ugly in shot!

To end with the specs - if you read the spec for the AKG C1000 microphone you will find it has everything, excellent frequency response, sensitivity, self-noise and battery and phantom. It is, however, in my opinion the most horrible sounding microphone I have ever owned. Some people say how good they are, and if they say this, I categorise them as never having heard anything else, or just confused.

Google it and see how divided opinion is - from a mic that SHOULD be excellent - reading the spec!

[Henry Kenyon]

Specs can be misleading and many times can look the same but have a different basis of measure.
Mics are designed to hear or reject.
They may have differing patterns even with the same freq. resp.
They have a proximity differing as well.
Some may sound great and some real cheap.
Your ears will have to help you decide. Go to a good shop and listen to them.

[James Kuhn]

I'd suggest taking a look at Oade Brothers website. They have microphones broken down by "use" and then further sub-divided by cost, i.e., Premium, Mid-grade and Regular. I found it very helpful. I'd also suggest finding a copy of "Ty Ford's Audio Bootcamp Field Guide". I find myself referring to both resources again and again.

I hope this helps.

Regards,

J.

[Jon Fairhurst]

Specs are a poor way to select a mic but are often a good reason to reject a candidate. I would reject mic #2 based on the low sensitivity. It would be fine as a close mic, but poor as a mic at a distance with a juicedLink and DSLR. You'd end up turning the DSLR gain so high that you would get too much noise from the recording system, regardless of mic quality.

For dialog (often recorded at 1.5 - 4 feet away and sometimes whispered), -40dB sensitivity is about as low as you'd want to go. For chamber music and ambient sounds, -30dB would be a better match for a juicedLink/DSLR. Generally, people who record ambient sounds go for the best sensitivity and noise specs they can get from both the mic and recorder. (The Fostex FR-2LE has good value in this regard and can be even better with preamp mods.)

Other important factors are the acceptance pattern of the mic and ruggedness, if you record in rough conditions.

Acceptance patterns are a compromise. If it's too tight (like a lobar shotgun), you can get boomy sounds from the room or a surrounding crowd. If it's too loose (like an omni or cardioid), you might pick up more off-axis sounds than you might like. This is where experience, placement, and possibly baffles can make a big difference. There's also the issue of the stereo pattern, which can be achieved with spaced mics, an x-y setup or a mid-side recording with a figure-8 mic.

So, yeah, a spec sheet doesn't tell you what will sound good, but it does tell me that mic 2 will likely sound bad with your recording setup for those applications.

[Pedanes Bol]

Hi Richard,

When I read the original post, the specifications listed were very familiar to me because I own Mic#2 (AT825) and I am also familiar with Mic#1 (BP8022, successor). Since the original poster plans to do classical music recordings with a 5D MII and the microphones in question, I wanted to share my experience of recording quartets using 5D MII + AT825. If the original poster is interested, I can post samples of my recordings.

I hope this helps.

[Lawrence W. Pry]

Wow! You guys have given me a TON of helpful information. (And believe me, I've already done my due diligence on this question!) And Pedanes is aboslutely correct: the two mics are the Audio Technica AT825 (#2) and AT8022 (#1).

So, does anyone want to recommend a particular one-point stereo mic? It must have balanced XLR output and be suitable for use it in a hot shoe mount. I do not need/want a shotgun mic.

I like what I read about the NT4 except for its size and weight (I've read reports of it falling out of its shockmount); besides, its price used on ebay is at the absolute top of my price range. One new brand I've discovered from your advice is the SuperLux, which has several different stereo models, and appears to be priced extremely competitively. Anybody have any experience with them?

[John Nantz]

Hi Lawrence - thanks for stopping by and throwing up your first post.

The good news it you got a lot of responses already. Unfortunately, data sheet numbers don't tell the whole story because mics, speakers, and the like "color" the audio. And so do the human ears because all our hearing isn't 20 to 20K Hz with a flat response capable.

If the most important audio you want to capture with your rig is the quartets, what about providing information about the kind of venues - street, indoors, ?, can there be a mic stand? cables? is this just for personal enjoyment or will there be a higher standard? Those kinds of things. And then maybe ask for suggestions?

Since a mic needs to be close to the sound source then if it's a camera-mounted mic you're looking for then it'll be either nothing will work or anything will work but not do it well.

Mic selection for instruments can get really technical (string, reed, percussion, etc.) and, as previously stated, very opinionated. As suggested, going to some sites that specialize in audio can be helpful but there were already some very useful comments here.

Personally, I own a JuicedLink pre and the cost of my three mics - and I still don't have the one I really need for recording the instruments I want - cost more than probably 5x the value of my camera.

Mics are kinda like paintbrushes - an artist has a quiver full, a house painter has a couple, and they're all different and used for different purposes and with different paints. Talk to a guy who does varnish on his classic wood boat and he'll use a different brush depending on the varnish. Talk to two guys who do varnish on a boat and they'll recommend different brushes! And different varnishes!

Your job is to get all the input you can and figure it out! (oh, and good luck!)

[Lawrence W. Pry]

Thanks John.

Here's the expected set-up: I’ll be recording indoors with a mic stand placed as close to the performer(s) as possible without annoying either performer or audience. I anticipate placing my camera at the back of the room, which means that 25-50 feet of cable will be required (hence, balanced output). I’ll be recording both for personal enjoyment and for the use of the musicians and/or their teacher(s) (at the University of Minnesota School of Music). I’m inclined toward a one-point mic because I want to also have the option of using it on-camera. I’d consider getting a Rode Stereo Videomic Pro, which can be used both on- and off-camera, but the unbalanced output gives me pause.

I want to get good sound (don’t we all!), but it needn’t be broadcast-quality and I’m not really interested (and my wife is definitely NOT interested) in spending too much money for what is essentially an occasional hobby, and is definitely secondary to my interest in still photography (in pursuit of which I’ve dropped far more coin than I care to admit).

[Steve House]

Rode's Stereo Videomic is about the lowest price offering worth considering. Most mics in the same or lower price ranges are consumer toys not worth serious consideration. A pro-grade stereo mic offering balanced connections is going to set you back somewhat more than that. I see that B&H carry the AT8022 for $325 and the Rode NT4 for $529, You could always get a pair of cardioid pencil mics and a stereo bar for mounting them together on a single stand.

[Lawrence W. Pry]

And with the Audio Technica AT8022 we've come full circle.

It seems to fit the bill and everybody says nice things about it--though no one seems to have actually used it--but its frequency range tops out at 15k Hz. That's what gives me pause. Am I being unreasonable? Its predecessor, the AT825, shows a more complete frequency range, but its sensitivity is significantly lower.

[John Nantz]

Lawrence - here's my take:

Originally Posted by Lawrence W. Pry

I’m inclined toward a one-point mic because I want to also have the option of using it on-camera. I’d consider getting a Rode Stereo Videomic Pro, which can be used both on- and off-camera, but the unbalanced output gives me pause..

That's the same mic I use for generic family point-'n-shoot stuff and, like Steve said, it'd probably work as well as any for what you're doing. I'm guessing you'll be exporting (FCPX "Sharing") via YouTube, Vimeo (I prefer), or DVDs. Given that kind of Sharing it'll be 'good enough for Government work.' However, I can't speak for the wire run because I've only used it on-camera to replace the built-in mic. One thing for sure, it won't work on-camera from that distance, even for the assumed low-quality Sharing level. Nice mic, nice suspension, nice coiled pigtail cord. On/Off switch with LED, and low-cut switch. Good bang for the buck.

Originally Posted by Lawrence W. Pry

I want to get good sound (don’t we all!), but it needn’t be broadcast-quality and I’m not really interested (and my wife is definitely NOT interested) in spending too much money for what is essentially an occasional hobby, and is definitely secondary to my interest in still photography (in pursuit of which I’ve dropped far more coin than I care to admit).

Uh-oh. If you think the still camera hobby was expensive, just wait. You ain't seen nothin' yet! You're going into a realm that's a whole magnitude more expensive. If you have the least amount of perfectionism this new hobby area is going to cost you some major bucks. Just so you know what you're getting into and don't say you wern't warned. Sharing stuff with University people you're going to want to have some decent quality.

Look at the thread in the Audio section http://www.dvinfo.net/forum/all-thin...o-section.html and see what some pretty expert people had to say about recording pianos, choirs, and other instruments and you'll quickly see that good audio is a huge field all by itself. Audio on family videos is something that only a mother can love. Audio for your audience will probably like something above that but what you're doing is probably better than anything your audience has now. Go for it and don't accept any static (from your audience).

And speaking of better audio equipment, tell your wife that it can be better and remember, there are birthdays and other events so there is no end of things she can get for you. Does she sing or play an instrument? You could even make her look/sound good. Hey, if the answer to this is "yes" - (read: "bingo") does she have a birthday coming up???