The Best Tuner Is Built-in

It’s hard to appreciate just how convenient this device is. First, it’s always handy, your picking buddy can’t borrow the tuner unless you lend him the whole guitar!! You’ll never put it down and forget it, never leave it behind at a gig, never have one of the kids play with it and run the battery down. Another hassle you avoid is the visibility problem. The lights are bright and the tuner is in a nice dark space inside the instrument, so visibility is better than any other tuner I’ve ever used.

The tuner is fully chromatic, that is, you can tune to any standard pitch, not just standard guitar tuning. This is very handy for my slack key because we tune to flats and sharps as well as natural notes up and down the scale. The Wittman has a clear marking for the sharp/flat interval between the natural scale notes.

It’s Not Perfect

There are some limitations to the Wittman MiniTuner. The reference pitch is not adjustable, so it doesn’t have the ability to match an out of tune piano or horn. The tuner senses body vibrations, so it can be difficult to use in very loud conditions where your instrument is affected by the sounds around you. If your bass player is tuning up or noodling at performance volume the Wittman is going to be very hard to use. The other big issue is that you wind up buying a separate tuner for each instrument. This makes the Wittman an unhappy choice for those on a strict budget.

I Got A Freebie – It’s Going in a Uke

Perhaps I should economize, but the darned thing is just addictive. In fact, many of my friends, even those who scoff at first, wind up installing one of these tuners. Apparently many people have mentioned my name when buying a Wittman MiniTuner, and Mr. Wittman showed his appreciation by sending me a pair of tuners. I decided to try installing one of them in my `ukulele.

This one is a lovely little Pono tenor cutaway, mahogany and spruce.

Pono Tenor `Ukulele, cutaway in mahogany and spruce

Pono is the off-shore brand of the Ko`olau Guitar & Ukulele Company, the Kitakis family of O`ahu. My Ko`olau tenor is a treasure and my favorite uke, but I’ve always had a guitar geek’s desire for a cutaway tenor with a pickup, and this Pono fits the bill perfectly.

Here’s a video of the installation process.

Now that I’m reviewing the process I can see that I did it quite the hard way. The sticky-back velcro attachment system makes it easy to fit just one half the velcro first. With the velcro in place it’s a snap to install the battery holder and tuner. Still, even if I didn’t demonstrate the best way, I hope you can see that it’s a pretty simple job to install one of these. And if you’re like me, once you try it, you’ll be hooked.

My understanding of microphones and audio says this myth is not true. I’ve been told by knowledgeable experts that mic sensitivity is linear below physical clipping regardless of the transducer technology. I actually asked this question some time ago over on rec.pro.audio – a usenet discussion forum where professional audio engineers hang out. Some of their responses were rude, but they basically established that preamp gain is all that is required to match sensitivity between a dynamic and a condenser mic. Here’s a link to that thread.

Now I believe those guys. I thought it might be interesting to devise a demonstration of sorts, by plugging in a dynamic and condenser mic, playing a reference tone through a speaker in front of the mics, then adjusting preamp gains so the levels match. Then I could generate a quieter and quieter test signal by walking away from the mics making noise. Recording this diminishing sound with both mics would tell me if one could “hear things” the other could not.

Oh No!! Is the Myth True?

To my amazement, when I did conduct a demonstration for myself, I could hear more distant, quieter sounds on the condenser mic. It seemed as if the myth was true.

I knew the error was not the physics or engineering of mics, but rather something I had overlooked in setting up my test. After a day or two of research and pondering the light came on. I realized that the different pickup patterns of the two mics made my calibration procedure wrong. I was calibrating for direct, on-axis sound, but I was measuring diffuse off-axis sound. I needed to do the calibration using only the diffuse sound field, which meant moving the speaker some distance from the mics during the calibration.

A Better Test Design

At this point I also figured out that I didn’t have to move the noise source to reduce the level of the test signal, I could create test tones that got lower and lower in level and play them back from the same spot as the calibration (well, duhhhh).

Here’s the result. For the best fidelity, here’s 45db-66db-xt.wav. Or if your connection is a bit slow, the compressed version is 45db-66db-xt.mp3.

You’ll need to download one of the files and pull it into a player that can select only the right or left channel. The mic in the left channel is the condenser, a Shure KSM141. The mic in the right channel is a dynamic, the Shure SM57. This is a little excerpt from the demonstration recording. I selected the area from -45 to -66 dBFS, which is where the test tone slipped into inaudibility. I raised the level of these files substantially and there is plenty of broadband noise, so be careful not to play them too loudly. The condenser mic is in the left channel, the dynamic in the right. Listen to first one side, then the other, and see if you can hear tones at lower levels from one mic or the other.

Conduct Your Own Demonstration

If you’d like to conduct this demonstration with your own mics and room, all you need is a calibration tone and a test tone series. You can generate the calibration tone in most audio editors, and you can download my test tone series.

If you can’t figure out how to create a tone in your favorite audio workstation software, download Audacity and install it (I recommend the Beta 1.3.xx or later version). Start Audacity and choose

Generate | Tone

then fill out the Tone Generator form:

Waveform: Sine
Frequency (Hz): 1000 (a 1 Khz test tone is the normal industry standard for basic testing)
Amplitude: .6 (a very loud long 1 Khz tone can damage your speakers and possibly your ears)
Duration: 600 seconds (10 minutes should be enough)

Click OK and you’ll see a strange solid waveform. That’s your calibration tone. Just export it from Audacity:

File | Export
Save as type: (either MP3 or WAV Microsoft signed 16 bit PCM)
(Choose a directory and file name)

You can download my test tone file here. The test tone file contains volume level announcements and 1000 Hz tones starting at -9 dBFS and going down to -90 dbFS in 3 dB increments.

Here’s a screen shot of the test tone file:

Mic sensitivity test tone in Adobe Audition 3

and a sample of the tones, starting at -9 dBFS and going to some of the lower level tones:

To conduct your own demonstration, connect two mics to your recording system. Place the mics at least 6 feet from the speaker, then play the calibration tone. Adjust the preamp gain so the two mics show the same input levels. Do this very very carefully, this is the most critical step in the process.

Next, simply play the test tone file while recording the two microphones. You’ll want to wait until a quiet part of the day, and be prepared to sit very quietly while the test file plays. When you’ve completed recording the test tone sequence, listen to one of the tracks you just recorded. When you can no longer hear the test tone, switch to the other track (other mic) and listen again. If your experience is like mine, the test tones will fall into inaudibility at the same level for both mics.

Better Recording By Knowing Our Tools

Mics are fascinating devices, but they’re engineered objects in the physical world. We can make better use of them if we have a better understanding of the way they really work instead of relying on incorrect assumptions and erroneous analogies. In the past audio testing required lots of expensive dedicated equipment, but now with our computer audio systems we can easily perform simple but fairly sophisticated evaluations of our audio gear, and learn to make better recordings in the process.

For a number of years builders have worked on more stable replacements for the wood in our guitars, and now we have plywood, aluminum, and a range of composites including fiberglass, kevlar, and carbon fiber. In fact one of the pioneers in carbon fiber guitars, Rainsong, started their business in Hawai`i and attracted a number of local players to their instruments.

Composite Acoustics is a relatively young company that started with a dreadnaught and bluegrass focus, but thanks to my encouragement (hey, I wrote them an email) they’ve developed some very fingerstyle friendly models, especially the new OX body style.

I’ve been very curious about the Composite Acoustics OX since I saw the first pictures, and when I found a used one offered in one of the guitar forums I visit, I snapped it up. Here’s my new baby in all its carbon fiber glory:

An old leather strap holds up the high tech carbon fiber OX.

The body on this beauty is pretty slick, so the soft old leather strap helps hold it in position. Note the perfectly smooth and comfortable (if graceless) merging of the neck, body, and cutaway:

The neck flows smoothly into the body

I like the simple detailing on this very reasonably priced guitar. The tuning pegs are some I’ve never seen before but they work nicely. I would prefer a bit lighter peghead, but that’s true of almost every guitar I try:

The tuners are attractive and work very well

The black woven look of carbon fiber is so hip now that you can buy fake carbon fiber decorative parts for your car or motorcycle. The drama is evident in this shot of the top of the OX. This is the simplest, least expensive finish offered by CA, they call it Raw. The bridge, saddle, and bridge pins are all fabricated from composites. The sound hole decoration is a thin sheet of brushed aluminum that floats above the weave. You can catch a glimpse of the Wittman Mini tuner peeking out of the soundhole. I’ve installed these in almost every guitar I own:

Dramatic weave of carbon fiber, a Wittman Mini tuner in the soundhole

I was hoping for a lot when I bought this guitar, and I’m not disappointed. I think Composite Acoustics has figured out a bunch of stuff very well to create the OX Raw. Here’s a bit of video, an old hula song called Papalina Lahilahi showing some of the fun of playing this lovely instrument:

The guitar is tuned to taropatch F, open G tuned down one whole step. From low to high: C F C F A C. The sound on this video was recorded on the Zoom H2, you can see the top of it just edging into the bottom of the shot. I pulled the audio file into Adobe Audition and tweaked the EQ just a bit, but there’s no reverb, compression or other effects, you’re hearing the sound of the guitar.

The only bad thing about finding a nifty new item like the OX is the sudden urge to explore other Composite Acoustics instruments, like that cute little Cargo travel guitar …

I’m pretty pleased with this new camcorder. Let’s look at the pros and cons:

It’s Pocketable

It’s compact. It’s right on the edge of being too big for a pocket camcorder, but I’d say it still works. Here’s a shot of the Zi8 next to a Motorola Razr:

Zi8 and Razr Side by Side

I’m embarrassed that I shipped my Flip Mino HD off to a friend before I did this comparison so I can’t show them side by side or show comparison videos.

Another factor that makes a good pocket cam is a low price, and the Zi8 does fine on that score. And while the user interface is a bit more complicated than the Flip or Vado cams, the Kodak has a bit more flexibility as well. The options are easily accessible with the control layout. It takes decent stills along with several video formats.

It’s Expandable

Compact Flash memory continues to ride the price curve down, down, down, so the ability of the Zi8 to use accessory cards lets the user take advantage of bargains when they appear. I often shoot a set of music that continues for an hour or longer. A 16 Gbyte SDHC card combined with the included AC adapter makes the Zi8 a great tool for my kind of shooting. For places where AC isn’t available, the battery in the Zi8 can be replaced with a fully charged spare.

The other big feature for my use is the stereo microphone input. When I shoot my solo guitar performance videos I usually record the sound separately, then synchronize the audio and video in post production. Recently I’ve been using a Sanyo Xacti HD2000 camcorder that has many great features including an audio input, so I’ve been able to record direct to the camera using high quality mics. The HD2000 is a just a little too bulky to be a true pocket cam, and it busts out of the “disposable” price range by quite a bit as well. Now with the Zi8 I have an affordable shooter that I can feed audio into.

The reason for needing an external mic is simple physics – the camera has to be some distance from the subject, but the microphone needs to be close to the subject, at least for the kind of stuff I do, recording solo acoustic guitar in less than optimal rooms.

Here’s a picture that gives an idea of the problem:

Zoom H2 audio into the Kodak Zi8 camcorder

The room in this picture is a screened lanai, or porch, in Kailua. Beautiful Kailua beach is about 50 yards away, so the surf is always audible in the background. The trade winds are usually blowing through the surrounding trees, and a fairly busy street goes by the back door. There’s no soundproofing or room treatment of any kind, so getting a decent sound is a challenge. Notice how far the camera is positioned from the guitar – 5 to 6 feet away. At this distance, the guitar is not very loud, while the surrounding waves, wind, and cars are quite obtrusive. But with the audio input in the Zi8, I can use the Zoom H2 as a stereo microphone, and place it about 1 foot from the guitar. Here the signal to noise ratio is much better.

But It’s Not Perfect

Naturally, the Zi8 has flaws, some minor, some a bit more troubling. I never thought about the flat bottom of the Flip Mino HD until I tried to position the Zi8 on a table without a stand. Oooopss. The Zi8 has a rounded bottom that requires some kind of support for any placement.

The feel of the Kodak is a bit flimsy compared to the Flip, but those flimsy bits give access to a replaceable battery and various connectors. The zoom capability seems like a bit of a joke to me, it works in digital mode so it impacts picture quality, and it operates in discrete steps that would be very distracting during a shot. The bundled Media Impressions software has a number of issues, judging by the discussions at the support forum but I was able to title and trim one clip with it.

**EDIT Nov 19, 2009**The italicized comment that follows talks about my problems with the AGC on the audio input, but I’ve since learned that there is no AGC. Ooops!! I must have been overloading the input pretty heavily. I plan to continue to explore the audio input in a future post.**End of EDIT**

The biggest negative issue for me is the AGC, automatic gain control, on the audio input. This function raises the gain when sounds are low, which raises the background noise. It also makes level setting more difficult. I don’t know if it’s possible, but I’m hoping for a firmware upgrade someday to turn off the AGC. In the meantime, I’ve come up with a setting that seems to get the job done, by setting the Zoom H2 to low sensitivity and turning down the audio sensitivity on the Zi8.

So How’s the Video?

As I mentioned at the beginning of this post I mentioned that I’ve done two video clips with the Zi8. Here’s the first one, shot in indoors daylight, an original composition I call Kui Lima:

and here’s one demonstrating the low light performance of the Zi8, an old song called Kalena Kai:

So that’s the story as I see it. For my particular application, shooting solo performer music videos, this little cam seems like a pretty good tool for the job. And like always in the fast moving world of consumer technology, we can look forward to the response this cam generates among competitors.

I’ve tweaked and fiddled with this guitar for a while, especially since I brought it to O`ahu. The humidity is pretty tough on instruments. The tuning machines have always been stiff and they’ve gotten worse lately, so I decided to swap them out for the new Grover Vintage Sta-Tite 18:1 machines. I’ve heard great things about these machines on various guitar forums, and the measurements looked right to be a drop-in replacement for the stock tuning machines. I ordered up a set of #4592 Grover 18:1 Sta-Tites from Stewart-McDonald.

Well, for once luck was with me, and in fact they work and look like they were made for this guitar. Screw holed lined up, the shaft diameters are different but the bushings that came with the new Sta-Tites fit right into the old holes. Here’s a pic of the back of the peghead with half the machines replaced:

Epi Peghead with old and new tuners

These new machines are basically totally different from the originals. The base plate is thicker, the gears are obviously different to provide the higher gear ratio, and the attachment of the gears is totally different as well.

Here’s the original tuning machine:

Original Epi Grover Tuning Machine

Part of the difficulty in turning it is due to the warped base, the rest because the curved arm that holds the shaft has bent, releasing the mesh of the right angle gears.

Here’s the new one:

New Grover Sta-Tite 18:1

Notice how solid and thick the base plate is, and more importantly notice that the shaft is held in a cast mount, a much more solid bit of engineering.

These tuning machines have another fine virtue, they’re not terribly expensive. I bought this set from Stewart-McDonald for $37.37 – I’ve already gotten my money’s worth the first time I changed strings.

As I expected, some folks reject the validity of these controlled tests, stating that different mics respond to different positioning in different ways, and their performance in their optimal position is the important issue. I can only suggest that they try some controlled testing in those different positions. After all, if the difference really exists, it should be apparent when levels and positions are matched, right?

And as I expected, some people pointed out that mics with different patterns and mics with very different transducer technology, like ribbon mics, sound different from the cardioid condensers I used. I absolutely agree.

Also as I expected, some people suggested that my use of a single source, the acoustic guitar, is preventing me from hearing the differences, which show themselves on cymbals and vocals. As Dirty Harry was wont to say, “A man’s gotta know his limitations.” I don’t record those sources so I don’t use them for testing .

One comment that has come up a couple of times is that the mics I chose were too similar, all large diaphragm mics from the low end of the spectrum. So I pulled out my highest priced mic, a Schoeps CMC64 small diaphragm condenser, and stuck it in the array.

Variety is the Spice of Mics?

For a little more variety, I replaced the Rode and AT mics with the Shure KSM141 and KSM44. So this set of clips includes two large diaphragm mics and two SD mics, and the price spread ranges from under $200 to over $1500.

I followed the same procedure I illustrated in yesterday’s post, aligning mic diaphragms by eye, playing a test tone through a small speaker about 1 foot from the mics, then adjusting gain on the M-Audio Profire 2626 to match their levels as well as possible in Reaper. Then I recorded the test tone followed by the acoustic guitar clip.

Mics and Clips

So here are the mics:

CAD M179
Schoeps CMC64
Shure KSM44
Shure KSM141

and here are the clips:

download 20090626-F.wav
download 20090626-G.wav
download 20090626-H.wav
download 20090626-I.wav

As before, I’ll post the key to the clip identities in a future blog entry. Or if you post your opinion and preference in a comment here or on one of the forums I visit I’ll email or PM the information to you.

Philosophical Musing

Please let me take a moment to wax philosophical here. No one has reported doing double blind ABX comparisons on the clips so far. Several posters have offered opinions on the sonic qualities of the clips, but no one has confirmed that they can actually hear a difference! This seems to be human nature, but I think that skipping the double blind check is missing a really valuable learning experience.

Sometimes when I’ve listened to mic samples I thought I heard these dramatic differences, but after a bit I realized that I was listening to different performances, not different mics. Sure the mics had been changed, but the player was hitting the strings differently and playing different riffs at a different volume – so how could I tell what part of the difference was the mic, and what part the player?

Since then I’ve tried to do some mic tests of my own, and I’ve tried to educate myself on audio testing. At this point I’m beginning to think that the differences in microphones are a lot more subtle than I had been led to believe, which makes a careful test even more important. As I’ve mentioned before, very small differences in volume are registered by our ear/brain combination as differences in quality rather than loudness. I’d like to demonstrate the steps I now take to try to make my mic comparisons, and preamp and a/d comparisons, meaningful.

Mic Setup

The mics need to be close together, but not interfere with each other. I try to determine the location of the diaphragm, the part of the microphone that gets hit by the sound waves, on each mic, and align them along that position. This is pretty easy with large diaphragm mics, often a bit tricky with small diaphragm units. All the mics should be on axis to the source or all should be equally off axis. Check pattern switches, rolloff settings, pads, any feature of the mic than changes its response. I’ve missed this step a few times.

I also arrange the mics so they don’t interfere with each other. For instance, it’s not a good idea to tie a bunch of small diaphragm mics into a bundle, because the ports behind the capsule contribute toi the frequency response and pattern of the mic. If those ports are blocked the mic is not performing normally.

There are three mics being compared in this example. The CAD M179 is a low cost continuously variable mic in an unusual looking housing. One salesperson began a drumbeat for these mics and they are now widely recommended in internet recording forums. The Rode NT2a is one I’ve used before. I think it does a fine job of capturing audio with low noise and no noticeable distortion, but many forum posts are negative toward Rode in general and the NT2a in particular. The Audio-Technica AT3035 has recently been discontinued, replaced by the AT2035. In the past I’ve read a wide range of comments about this mic, with some calling it a secret gem and others decrying its overwhelmingly bright character.

Here’s a picture of a mic array arranged for testing. A cheater clamp that fastens to the mic stand main tube can help fit an extra mic into the array. Adapters to attach mics at an angle can be very handy as well.

Three large diaphragm mics in an array for comparison

I often hear this arrangement, with all the mics equidistant from the source, criticized because different mics work best in different positions. I strongly suggest that if you wish to evaluate different positions you try all the mics in all the positions. It’s a little more trouble, but it’s a great learning opportunity, and omitting this step means no valid comparison can be made. We’re right back to asking what part of the difference is the mic, what part is the location with no way to answer the question.

Of course, my aim here is different from trying mics and positions to get a good recorded sound. I’m after data, not art. When the aim is art, the ears rule!

Equipment wise, you can do a useful comparison with as few as two recording inputs. In fact, comparisons that are done two by two are probably the most revealing and useful. Still its fun to line up three or four mics for a single session – in which case it’s helpful to have four identical channels, especially if the comparison will be made public. In my experience, more posters will criticize a change in preamp than will mention a change in performance, amazingly enough.

Here’s a video that illustrates the setup process and takes you through gain calibration, discussed below:

Microphone Comparison - A Tutorial - part 1 of 2 from Fran Guidry on Vimeo.

Gain Calibration

Once we’ve arranged the mics to capture a single performance we need to minimize the volume difference in the our samples. I like to start with a test tone played into all the mics from a speaker only a foot or so away. A 1000 Hz tone is not very challenging, so even a low cost computer speaker can be used as the source. A test tone is easy to come by and it doesn’t need to be calibrated for volume since we’re interested in relative rather than absolute levels.

I’m using Reaper to conduct this test, and a little inquiry on the Reaper user forum and learned about MDA Test Tone, a plugin that provides the beep.

In Reaper I created a project with MDA Test Tone on one track, and three tracks for recording the three mics. I also adjusted the range of the Reaper console meters. With these connections in place I hit record and adjusted the preamp gain for each mic so they all were very close to -18 DbFS.

Next I discarded these recordings and captured three more tracks to store a consistent level for each mic. These 1000 Hz tones are used to fine tune the track levels later.

Recording

In the next video we actually do a little recording. After all the setup and calibration work, the recording process is anticlimactic. Move the calibration speaker, tune up the guitar, hit Record in Reaper, play a few bars, and we have our clips in the can. Be sure to record the clips on the same tracks as the reference tones we created in the last step. That way when we adjust the reference tones we adjust the clips at the same time.

For straight mic comparisons, I like to position the guitar about 32″ from the mics. This avoids proximity effect and hopefully presents a fully developed guitar sound to the mics, instead of one mic picking up the neck of the guitar while another picks up the bridge.

Here’s the video demonstration of recording simultaneous tracks and fine tuning the gain:

Microphone Comparison - A Tutorial - part 2 of 2 from Fran Guidry on Vimeo.

Volume Fine Tuning and Rendering

As the video illustrates, working with that 1000 Hz test tone can be pretty annoying, but we need to delve into it one more time. Actually, this time we can turn the volume down, because we’re adjusting levels “in the box” – that is, internally in the computer.

The helpful folks at the Reaper Forum pointed me to the Sonalksis FreeG plugin. This tool adds high resolution metering and gain adjustment we can use to tweak the levels of our clips that last little bit.

Simply place the Reaper track cursor so the recorded test tone will be played, reset the FreeG meter, and play a bit of the clip (the space bar starts and starts playback). Note the RMS level, and repeat for each track. Then, to be fair, apply a gain adjustment to each track so they all show the same RMS level. In the video I’m fiddling with the Gain knob using the mouse, but after I recorded the session I realized that you can simply type the desired gain change into the value box, making it very easy to get the level just right.

Finally, click and drag the cursor to make a time selection of the recorded clips, then render each track separately as illustrated in the video. It’s a good idea to render to 44.1/16 format if you plan to make the clips public, because everyone can play this CD standard format.

Blind Comparison

I have had the experience many times of listening to mic comparison clips and clearly hearing the difference between them when I knew their identities, then finding that I could not hear a difference at all when I hid the identification in some way. Even getting momentarily confused about the source of the clips has been enough to change what I “hear”. Our brains are at least as important as our ears in defining what we hear, and our brains like new stuff, shiny stuff, expensive stuff. So when we know a clip was made with our shiny new expensive mic, we’re going to “hear” how wonderful it sounds.

For a test to be meaningful, we need to hide the identity of the clips somehow. This is pretty hard to do when working by ourselves. The foobar2000 audio player offers one solution, with the ABX testing utility built-in, as described in this blog post. This is a powerful tool, because it not only offers a way to test clips double blind, it helps us determine if we can hear any difference at all before we try to determine a preference.

Mic comparisons are useful for our own recording knowledge, but it’s even better to share. There are lots of folks hanging out at recording forums on the internet who are looking for information about mics and other recording gear. I like to contribute when I can by posting comparison clips, but I think it’s important to make the original post without identifying the devices used. It’s more informative, and more fun too.

So here are the three clips I recorded in the video, with no EQ, no compression, no reverb, no processing of any kind except to match volume levels and trim ends. To recap, the three mics being compared are the CAD M179, Rode NT2a, and Audio-Technica AT3035. Naturally the clips are not in the order listed.

download 20090625-J.wav
download 20090625-K.wav
download 20090625-L.wav

I’ll post the key to the clip identities in a future blog entry. Or if you post your opinion and preference in a comment here or on one of the forums I visit I’ll email or PM the information to you.

Naturally a cheapskate like me is only interested in free solutions, so the software tools for this project are Avidemux for video and Wavosaur for audio. With these two tools we can tweak our camera audio by raising volume, adding reverb, adjusting tone, and so on.

Trim Video and Extract Audio

We start by opening the video in Avidemux. Next we trim the video to eliminate alternate takes and start and stop activity that we don’t need to display. The A and B markers in Avidemux make this an easy task, just be sure to only set these markers on I frames, not P frames. Then set the container format to match the original video, and save the file, preferably to a new name, retaining the original. Avidemux will only save the portion of the video within the A and B markers. As always with Avidemux we must enter the file extension, and it should match the container format.

Next, open the newly saved trimmed file. We want to save the audio as an uncompressed WAV file in most cases, so set the Audio codec to PCM. Then save the audio from this video using the Audio : Save menu option, being sure to add the .WAV extension. Close Avidemux.

Enhance Audio with Wavosaur

Now start Wavosaur and open the newly extracted audio file. In our example we’ll only adjust the volume, and we’ll do that in the simplest way, by normalizing the file to -3dB. (Maximum volume in a digital audio file is called 0dB, so all volume levels are expressed as negative numbers.) Use the Process : Normalize menu option, then select Custom and set the value to -3. The audio file is now noticeably louder. Save the file and close Wavosaur.

Merge Enhanced Audio with Avidemux

Restart Avidemux and open the trimmed clip. Set the container Format to match the file type. Now merge the enhanced audio file using the Audio : Main Track menu option. Set the source to External WAV and Open the file we just ehanced in Wavosaour. We’re almost done, but we need to recompress the audio – it’s currently an uncompressed WAV file and we need to return it to the AAC format (or other as appropriate) that we started with. So set the Audio field to the AAC codec and save the file. Now you’re ready to upload your video with its enhanced audio.

Of course it’s a lot easier to follow these steps in a video demonstration, so please check this one out.

Audio Enhancement Using Avidemux and Wavosaur from Fran Guidry on Vimeo.

VST Plugins

Wavosaur is a handy audio tool with a simple interface and good performance, but it needs a little help from some other free software tools called VST plugins. These are software tools for audio that can be added to any program that knows how to be a VST host, and Wavosaour is just such a program.

Some of my favorite VST plugins are created by Kjaerhus Audio. The Classic series of effects are all free downloads, and no one should be without Classic EQ and Classic Reverb.

While I was perusing the Wavosaur tutorials I discovered another EQ tool, called PushTec 5.1 and I was startled by the excellent selection of presets. Be sure to spend a few moments going through the tutorials to better understand the power of Wavosaur and of this terrific free utility.

A Free Video Editor – and a Good One

In the past I’ve used Windows Movie Maker to combine my audio and video streams, but WMM is not compatible with the MP4 720P file created by the Flip. I was happy to find Avidemux, a free video editor. The program comes with a wide range of codecs and works on the compressed files without decompressing for simple operations like trimming length and replacing audio. And since that’s almost all I do to my music videos, it’s perfect for the job.

Avidemux is simple both in concept and use. You can peruse and search the Wiki and ask questions in the forum but there’s no substitute for a little experimenting.

For a simple music video I replace the camera audio with my separate recording and trim the start and end points of the clip. Naturally, when I shoot the video I clap in front of the camera so I have an obvious point to synchronize the two streams. As funny as it seems, getting a good clap important because it makes synchronization so much easier. Try to face the camcorder directly so the instant of contact is easy to see.

Synch Video with External Audio

To sync the video first File : Open the video file and find the “clap” point. Note the time. Then load the external audio file by going to the Audio : Main Track menu selection, choosing the format for the external audio file, and open the file. Now when you play the video, the external audio will play instead of the audio recorded by the camcorder. Find the “clap” on the audio track and note the time.

Take the difference between the two “clap” points in milliseconds. Check the Shift option box, and enter the difference value in the milliseconds value field. If the clap happens first on the external audio file, enter the difference as a positive number. If the clap happens first on the video stream, enter the difference as a negative number, with a minus sign preceding.

Now play the video the audio and video “clap” should be synchronized.

Trim the Video

Next, trim the video to length. Avidemux provides two markers, the A and B marker, which can be placed at any frame in the video. After the markers are set, any save, delete, cut, or copy will affect the section between the markers. My technique for trimming a video is to set the “A” marker to the beginning of the good stuff, and the “B” marker to the end of the portion I want to keep. When I save the video only the portion between the markers is saved.

Before saving, confirm that the Format field is set to the proper container format. If you’re not converting to a new format, it should be the same as the input video. You may need to set a codec for the audio stream, depending on the container format and the format of the external audio file. Once again, the format used in the original video file is a good choice.

When saving files, Avidemux has a quirk – probably because it’s a port from a Linux implementation – it does not automatically insert the extension on the saved file. You need to specify an extension that matches the container format when you save the video, and you should choose the appropriate extension for audio files and frame exports as well. And one more tip, I always save the file to a new name, so I can re-use the original file if needed.

Here’s a video demonstrating all the steps I’ve described. A few moments watching the procedure should make things much more clear. Try the full screen option in the lower right hand corner of the video control bar.

Audio for Video using Avidemux from Fran Guidry on Vimeo.

I’ve had a lot of fun learning and using Avidemux. If you need a nifty video tool that works quickly with minimal resources and minimal damage to your video quality, you should give this program a try.

I (naively) expected that people would embrace an opportunity to do some controlled testing, using an easy but very effective comparison technique. I have found that careful ABX testing, using Foobar2000 and the ABX utility included in the program, has made me a better, more careful listener. I learned that the perceived differences between clips became much less when I no longer knew the source of the clip. As a result, I learned to search out subtle differences in tone color and texture. I also learned that I can’t hear any difference between systems that I have been told should show night and day differences.

I’d hoped that a number of other folks would try careful ABX testing of these clips with a statistically significant number of trials, so I could compare my results to theirs. At this point, I don’t know if my inability to hear the differences is normal or unusual.

The Question

If you visited here, listened to the clips, maybe even downloaded and installed Foobar2000, why did you not go the next step and run a test of 20 comparisons? Foobar2000 makes it easy to save your results and share them with the world, or not. Wouldn’t you like to have a personal evaluation of the difference between a high end preamp and a commodity unit, or between 44.1 and 192 sampling rates? Wouldn’t you like to contribute to the knowledge of the recording community?

After all, if the huge differences we read about in magazines and online are true, it will be easy to pick out the different samples, and we can get busy saving up for high end equipment. But if those differences are actually imaginary, driven by normal human traits like confirmation bias, we can save a bunch of money and time and trouble by ignoring gear lust and concentrating on mic placement and room acoustics.

So the question is, what do you have to lose by conducting a thorough series of ABX comparisons and reporting the results?

The Answers

Here are the sources for the clips from the last post:

090420Test1A.wav – Lynx & Hardy
090420Test1B.wav – Profire 2626

090420Test2A.wav – Profire 2626
090420Test2B.wav – Lynx & Hardy

090420Test3A.wav – Lynx 192
090420Test3B.wav – Profire 44.1

I hope these clips provided some useful information for you. They certainly helped me feel confident that I can make recordings with the Profire 2626 that will fully measure up to those made with the LynxTwo.