I’m afraid that in some cases, simple physics is the culprit, helped along by our experience listening to modern recordings. We’re used to bigger than life sounds and close mic positions because that’s how most pop music is recorded. When we put our Q3HD in a location that gives us a conventional picture of a seated guitarist the camera is usually about four feet from the guitar. That four feet make the sound of the guitar weaker, and allow more of the room sound to intrude. This is called the direct to reflected ratio, and while we need some reflections to make a natural sound, the quick reflections of a small room generally don’t make for a pleasing recording. There’s another important ratio that suffers from a distant placement – the signal to noise ratio. Less guitar signal means we notice the surrounding noise more.

Several people have complained about the low level of the recorded audio and suggested that the Q should provide more preamp gain. But when you consider things for a moment you realize that more gain means more room reflections and more noise along with more guitar, because these ratios are established before the recording begins. So more preamp gain gives the same result as simply turning up the volume on playback in terms of room reflections and background noise.

The real solution is to move the microphones closer to the source. But that’s going to mean our conventional picture loses its head, and its hands. Since the conventional picture won’t work, we just have to get a little more creative, and find a new way of looking at the guitarist. Let’s start by positioning the mics in a good location for the audio, then see if we can find an interesting picture.

I usually use mic stands to position the camera – I have several boom stands, and they give me more flexibility than a typical tripod. I use the Zoom MA2 Mic Stand Adaptor or the Edirol OP-MSA1 to attach the camera to the mic stand. Interestingly, the Edirol adapter costs more and looks much more sophisticated, but the simple stick from Zoom does a great job and is handier in many ways.

I put together a video showing some different locations for the Q3HD using this concept of positioning for audio first. The first is the classic “off the 12th fret” location nearly universally recommended as a starting point for recording acoustic guitar. Actually, I used two variations of this, one below the guitar pointing up, one above and pointing down. From there I moved to the “off the bridge” lower bout position, and finally I tried the “over the shoulder” position that places the mic near the player’s ear.

In the video you can see the locations and quick samples of the audio and video that result from each position. All of these could be improved for both sound and picture by some extensive tweaking, and of course it’s a lot easier with two people than one.

In the process of creating the tutorial I realized I had enough material to put together a music video, a somewhat quirky one but perhaps an interesting project. I decided to try to edit the clips in REAPER, and with a bit of patience I was able to pull it off. I used Cockos LICEcap and the GIMP image editor to create a title, and rendered the results as a 1280×720 29.970 fps .MOV using the FFmpeg libraries. Here’s Waialua Slack Key as seen through the Zoom Q3HD at various angles:

I wouldn’t call the video an artistic masterpiece, but it serves to demonstrate the different angles and differing timbres of the audio captured from different locations. Hopefully it will serve as a bit of inspiration for other folks trying to get great audio and video from their Zoom Q3HD.

Another thing missing on both these cams and many others below the professional ($2000 and way up) level is the lack of metering and monitoring. There’s not a way to tell if the audio is being recorded well until playing back the clip, when it’s too late to make any corrections. Even when I’ve done multiple test shots I’ve always considered myself very fortunate if I manage to capture some useful audio with this kind of gear.

The Q3HD Arrives

A couple of years ago, Zoom introduced the Q3, a pocket video recorder that emphasized the audio quality. It included stereo directional mics in an X-Y configuration and didn’t inflict excess processing on the audio. Unfortunately, they released this SD format camera just when HD video took off. YouTube switched to HD format, Flip put out the MinoHD, HD video recording began to appear in phones, HD was everywhere except in the Q3. But earlier this year Zoom announced the new Q3HD, which addressed the format issue, offered improved low light performance, added special settings for difficult lighting conditions like concerts, and added a Line Input for stereo audio. In the past, new products from Zoom have arrived long after their planned date, so I was expecting to see the Q3HD sometime in 2011, but happily the first shipments have arrived in the US and are available from a number of retailers. I bought one from BSW and it arrived the day after Thanksgiving.

My initial impressions are really positive. The build quality seems a bit better than my venerable H2, and it’s noticeably more solid feeling than the Kodak Zi8. The menu system is easy to manage, there’s audio metering and monitoring during recording, it even comes with a 2 GB memory card and a set of AA batteries.

Three Way Comparison

I mentioned the other cams that I purchased because they had audio input and some degree of manual control. It seemed reasonable to use them in a comparison with the Q3HD. So I setup in Digital Duck studio (also known as the spare room upstairs) and shot some video, first using camera mics then external mics.

I chose 720p for the video format for all three cams. The Zi8 and Sanyo don’t offer control over the audio format, but on the Zoom I selected CD quality PCM (44.1 khz and 16 bit word length).

For the external mic shots I connected an Audio Technica AT822 to the Zi8, a Rode NT4 to the Xacti HD2000, and a pair of Shure KSM141s through an M-Audio DMP3 to the Q3HD. Here’s the video that resulted:

When I listen to the clips on my “junk reference” computer speakers, the difference in audio quality isn’t that great, but as soon as I put on headphones or turn on the good monitors, the audio from the older cams sounds dreadful in comparison to the Q3HD. My Zi8 sounds worse than I remember, so perhaps it’s dying, but even the HD2000 features burbling noises in the quiet moments and an odd tonal balance. I also feel that the video quality of the Q3HD was noticeably better than that of the Zi8. Looks like the Kodak is going in the drawer.

My First YouTube Clip from the Q3HD

The Q3HD has minimal built-in editing, just “Divide” and “Trim” – minimal but sufficient to create a clip for YouTube, so I figured I should put up something straight from the camera. I chose the Rode NT4 stereo mic just to simplify the setup, and fed the mic into the M-Audio DMP3 preamp. From there an adapter chain converted two 1/4″ outputs to a single stereo cable ending in a 1/8″ stereo plug, which went into the Q3HD Line In jack. I took advantage of the meters on the Q3HD to check my levels, aiming for average levels around -20 dBFS and peaks around -6 to -8 dBFS.

With that set I chose the highest resolution video, 1080p format. I chose PCM (uncompressed WAV) audio, but stayed with the basic 44.1 Khz sample rate and 16 bit word length. After a few test shots to get the framing right I recorded a few takes of an old R. Alex Anderson song, Haole Hula. With a little scrolling around in the playback, I was able to trim the clip down to the performance I chose.

Based on my experience with other camera software, I didn’t load the Handyshare package that comes with the Q3HD. I simply removed the memory card, stuck it in my card reader, and copied it to my hard disk. From there I uploaded to my YouTube account. Here’s the result:

Since I was determined to use only in-camera editing, my clip has no title, no fades, no credits, but I feel that it presents the song in fine fashion anyway.

Framing Changes with Format

One thing I stumbled on while shooting my clip – changing the video format also changes the framing of the shot. I framed the image then decided to switch from 720p to 1080p. I made the format change and shot a clip, and when I played it back my head was gone! Here are a couple of snapshots that illustrate the difference:

Framing at 1080p

Framing at 720p

As you can see, the change is pretty dramatic. So be sure you check your framing whenever you change the video format, or you might lose your head.

Not Quite Perfect, But Pretty Darned Good

On the frown side, I’m a bit annoyed that I have to buy the AC adapter separately. My brief attempts to shoot in lower light were not a big success. And while I was really pleased when I learned that Zoom added a Line In jack on this new camera, I’m already wishing it had a 1/8″ stereo mic input as well. With that extra feature the NT4 and the Q3HD would make a fantastic package for portable recording. As it is, I’m shopping for a battery powered two channel preamp with P48 phantom power that won’t bust the budget … and I’m not having a lot of luck.

On the smile side, I expect to have a lot of fun with this little camcorder. The video quality is reasonable in good light and the audio sets a new standard for a consumer cam. It’s nicely made, easy to use, an all around fun toy.

Figure 8 mics have a pickup pattern that looks like this:

but it’s important to remember that this diagram is a 2D representation of the 3D pattern in space. Basically the pattern looks like two balloons on the front and back grills of the mic, with a null, or area of minimum sensitivity in between.

So for the vocal mic we aim the “balloon” of sensitivity at the singer’s mouth and the plane of minimum sensitivity at the singer’s guitar or uke or mandolin. And we arrange the instrument mic with its diaphragm pointed at the instrument but the plane of the null at the singer’s mouth. It’s more complicated to describe than it is to do.

Here’s a video that demonstrates this technique:


Vocal - Guitar Separation using Figure 8 Mics from Fran Guidry on Vimeo.

Certainly other mic patterns could be used, but no other pattern has a deep a null, and no other is as easy to aim. If you need to record a self-accompanied vocalist, a pair of figure 8 mics, either large diaphragm switchable condensers, or bidirectional ribbons, would be a good investment.

My panel construction is crude compared to a lot of examples I see. I use no frame, relying on the rigidity of the compressed fiberglass to hold itself up. I simply glue together two 2″ panels and fold the burlap around them, then shoot the burlap with glue and hope they hold. They’re not very rugged, not terribly pretty, but they hold together well enough for my needs, they’re easy to maneuver, and do a nice job of improving the sound of the room.

Broadband absorber, quick and dirty style

Hardware Free Mounting

I’m lucky to have 8′ ceilings in my recording space, so the 4′x2′ dimension of the OC703 works great. I can easily shove two panels into a corner and they’ll hold themselves in place. I can place two of them on a wall with a 4″ spacer (like a small cardboard box) behind them and they’ll wedge into the space and stay there.

Here’s a model of Digital Duck Studio with 13 panels installed.

Digital Duck Studio with 13 broadband absorbers installed

and a picture of the business end of the listening setup.

Digital Duck listening position with broadband absorbers

My layout simply follows the advice given so generously by Ethan Winer, concentrating on the corners. The two forward corners are the easy ones, every other vertical corner in the room has some obstruction. The floor to wall corner is the next easy one to cover. The forward traps are out of the way, so I angle them out a bit, nearly 45 degrees straddling the right angle. On the side walls, where space is more valuable and also where we need mid and high damping, I stand the panels up and lean them against the wall at a small angle. They’re tall enough to cover the first reflection points on the side walls, and since they’re not fastened, they’re easy to move if needed.

On the left I have a pair of panels spaced 4″ from the wall, once again following Mr. Winer’s advice.

Mounting of two broadband absorbers using a spacer

These two panels are self-supporting by being wedged against a spacer, a conveniently sized piece of styrofoam. Once again, this arrangement can be altered in minutes.

Room Testing with Room EQ Wizard

Now lets fire up Room EQ Wizard and see if we can measure any improvement with 13 panels. Here are three measurements taken at three different locations, just as we did in the previous post. The first measurement is light blue, taken at the listening position. The second, green, has the mic moved back 1 foot. The third purple graph was taken another foot back.

Three frequency response plots - 40 to 1000 hz

and for comparison here’s the graph from the untreated room:

REW graph 40 to 1000 hz, 3 measurements combined

I’m pleased with the this graph in the area between 100 and 200 hz. In the untreated room measured in our last blog entry each measurement showed a distinctly different dip, right in the low strings of the guitar. The new measurements with the treatment in place may not be flat, but they’re much more consistent between positions which makes getting a good recording a lot less of a headache.

And speaking of recording, here’s a clip with the same mic layout we used in the untreated room.

post2clip1.mp3

or if your prefer, download the clip

Here’s the clip from the last post, in the untreated room.

post1clip1.mp3

or if your prefer, download the clip

To my ear this new clip in the treated room has a tighter stereo image and sounds much more like a studio recording. This recording shows how much the broadband absorbers do to control the early reflections that make a small room sound “cheap” and tinny.

Well, if a little is good, then more is better, and too much is just enough. In the next stage of the panel project I’ll buy some more compressed fiberglass and some more burlap and make a few more panels to try to improve the room a bit more.

A Look at the Room

Since we’re treating a room it makes sense to start by examining the room a bit further. After a little playing in Sketchup I came up with this:

Digital Duck Recording Studio in Sketchup

Believe me I feel lucky to have so much room to devote to recording. My space has no sound proofing features, and sits on a fairly busy street, with a playing field across the street, so serious recording has to wait until the late evening. Soundproofing is a difficult and expensive business, so I just live with the noise.

The triangle represents the listening position, with a pair of Dynaudio BM6p speakers a little over 5 feet in front of the window. Here’s a pic that shows the layout:

Digital Duck Studio with Bobby and Chuck providing inspiration

Gear

The computer sits in the next room, our guests get to listen to the noise so I don’t have to. My audio interface is a LynxTwo-C, with 6 inputs and 2 outs. The recording rack holds a John Hardy M-1 preamp along with a pair of M-Audio DMP-3 preamps.

I have a half-broken mic boom stand that I use for a headphone stand. Since I’ve embarked on room my room measurement endeavors I’ve pressed it into service to position the SPL meter and the measurement mic. Here’s a shot of the boom – the phones are Audio Technica ATH-M50s and they’re terrific.

Boom stand holding SPL meter and measurement mic

Just to give you an idea of the level of engineering that goes on around here, a closeup of the DPA 4061 and the Radio Shack SPL meter. Note the NASA grade paper clip and masking tape:

Measurement mic and SPL meter up close

Measuring with Room EQ Wizard

I was fooling around with Room EQ Wizard and decided to try moving the measurement mic around a bit to see how the results changed. One of the usual problems with an untreated room is a wide variation in the sound in different locations in the room. I set up REW and took three measurements, starting at the listening position then moving back a foot each time.

At the listening position

This first shot shows the full spectrum from 40 hz to 20 khz, but in an untreated room the reflections swamp the signal in the higher frequencies. The problems at the low frequencies seem pretty fierce, with big swings between 100 and 200 hz. These are the bass notes on the guitar, extending from 73.42 hz for the low D I usually use, up to the third string G at 196 hz. The huge swings in response will make some of these notes boom and some disappear.

Here’s the graph for the same measurement, but 1 foot further away from the speakers.

1 foot behind the listening position

This graph looks a bit better, but we still see over a 20 dB swing in the frequency response between 100 and 200 hz, and we’re seeing that different notes will be emphasized and muted.

The third graph shows the measurement from 2 feet behind the listening position.

2 feet behind the listening position

Once again the specific notes impacted by the frequency response variations has changed. The effect is easier to see when all the plots are displayed on a single chart:

REW graph 40 to 1000 hz, 3 measurements combined

Each of these measurements has at least one steep dip between 100 and 200 hz, and each one will mute a different musical note. And these effects were found by moving only 1 foot each time.

The Sound of the Room

Since my goal is to improve my recording space it seems reasonable to do some before and after comparisons of recordings, so I set up a Jecklin disk mic array with my Shure KSM141 mics switched to their omni setting. This arrangement of omni mics with a baffle between them is usually used for concert hall recording and other classical music sessions:

Jecklin disk mic array with a Shure KSM141 pair

This mic arrangement uses omnidirectional mics, so we’re getting the great extended bass of a fine omni mic but we’re also getting a lot of the room sound. I positioned the mic about 2 feet from the guitar which gives a wonderful stereo image and very natural tonality, but once again brings in a lot of the room sound. Here’s a picture of the recording arrangement:

Vamping for the microphones

Most of us recording at home usually use directional mics and place them much closer to the guitar, in an effort to reduce the impact of the room. But directional mics exhibit a rising bass response called proximity effect which increases as the mic gets closer to the sound source. If we can help our room sound better, we gain a lot of flexibility in the mic techniques we can use.

Here’s the brief clip I recorded:

post1clip1.mp3

or if your prefer, download clip 1

Then as an experiment I moved the mics and chair both about 2 feet, keeping the distance between them the same, and recorded again:

post1clip2.mp3

or if your prefer, download clip 2

I don’t put much stock in listening tests where we hear different performances, because it’s impossible to tell whether the sonic differences are due to the recording technique or the playing technique. In this case I can tell you that the difference in the two recorded clips is much greater than the difference in the two performances, and I think it’s due to the wildly varying frequency response in this untreated room.