Homebrewed Music

I’ve been moving my audio processing to REAPER over the last year or so. It’s a powerful and reliable program in a fast moving package, with a very active and helpful user community. All these factors make it a real pleasure to use.

Now for the icing on the cake – the development team has linked in the FFmpeg video libraries and given REAPER the ability to do simple video editing. I’m totally happy with my video editing system since I moved to Edius Neo 2.5, but when I played around with video in REAPER I realized that this is a tool many musicians want and need. (more…)

Mics are fun. They are a great gear fetish item, because they’re collectible, a bit esoteric but still familiar, come in a wide range of types and sizes, and most of them have a bit of a phallic quality (grin). Even better, when I read about microphones on the internet or in recording magazines it seems that each mic has a dramatically distinct personality, and a big part of the job of a recordist is choosing the optimal mic for any given source and style.

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. (more…)

In my last blog entry I described the process for merging audio and video recorded on two different devices, for instance, replacing the audio in a Flip Mino HD video with audio recorded on a Zoom H2. This is a very handy technique, and can give great audio quality in the final video, but sometimes we only have camera sound available. So this post will describe the steps involved in separating the audio from the video, processing the audio, and merging the improved audio stream back to the video. (more…)

I have a lot of fun with Flip Mino HD camcorder. I’ve already done a few music videos with it and in my opinion the audio is far behind the quality of the video. Of course, even with expensive video equipment, having the mic on the camera keeps it some distance from the subject. Having a separate mic, much closer to the subject, gives a much better result. (more…)

This post will reveal the identity of the comparison clips in the post comparing the M-Audio Profire and the Lynx and John Hardy recording chain. But before providing the answers, I’d like to pose a question.

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

(more…)

This is probably about as close to a political post as I am likely to write. I think that listening “tests” that are not conducted as double blind side-by-side comparisons are just wishful thinking. We wish that human hearing were not so totally dominated by the vagaries of our brain/mind, but it is. We wish that we could retain accurate mental images for more than a few seconds, but we can’t. We think we can discount the impact of small volume differences, but we can’t, and the smaller the difference the more likely we are to describe it as anything but a volume difference. We think we can trust our ears but all the evidence gathered from controlled experiments tells us plainly that we should not.

Since my interest in recording began only a few years ago, I’ve always had the internet as a resource for learning about the subject, I researched in every forum and magazine site I could find. And I now firmly believe that most of what I learned there was incorrect. (more…)

During the learning process that was my first CD I found Ethan Winer and learned a bit about his ideas for improving the acoustics of small rooms. Since then I’ve learned about the Acoustics forum at StudioTips.com, another great source of information on small room acoustics.

Even though it’s not strictly necessary, it’s interesting to use some kind of acoustic measuring tool to evaluate the room and gauge the results of treatment. I recently learned of a free program that works with a PC or Mac and their audio systems to measure and display room response. It’s called Room EQ Wizard and it’s available for download at the Home Theater Shack. The Shack is a discussion forum focusing on home theater (well, duh), but Room EQ Wizard, or REW as they call it, is just as useful for recording spaces as it is for home theater.

The home theater users seem to have systems that are a bit more complex than my simple recording rig. I don’t have a subwoofer and accompanying crossover, nor do I have an equalizer in my playback chain. So my connections were simpler than those illustrated in the REW help pages.

I bought one extra piece of equipment for this project, a Sound Pressure Level (SPL) meter. These are available from Radio Shack and other sources. The Radio Shack unit I bought is accurate enough to measure a baseline volume setting for all my readings. It’s possible to use the SPL meter as the measurement mic, but it is not accurate above about 3Khz, fine for tuning subwoofers but not much help for a full range monitor system. The Behringer ECM8000 is widely recommended for an inexpensive measurement mic, but I have a couple of DPA 4061 miniature omni mics in my collection, so I chose that for my measurement mic.

The first step in using REW is a soundcard calibration procedure. This procedure compensates for nonlinearities in the soundcard and also ensures that the basic system is working, with REW finding the soundcard inputs and outputs as needed.

I use a LynxTwo-C soundcard and REW found it easily. Here’s the Settings page where the soundcard is configured and measured.

The soundcard calibration starts by creating a loopback connection, that is, the output of the audio interface is connected to the input. This is easy with a recording oriented system, where balanced line in and line out connectors should be available. On the Lynx breakout cable the XLRs just clicked into place. On other systems a male TRS to male TRS may be needed. Don’t forget to turn off your power amp or mute your speakers – now how would I know to remind you about that??

I’ve created a YouTube account for videos related to the blog. You might stop by http://www.youtube.com/user/homebrewedmusic if you’re in the neighborhood. This video goes through the steps to run the calibration measurement.

After saving the soundcard calibration file we need to adjust the levels so we’re getting a good signal to noise ratio but avoiding clipping. First we restore the loopback connection to our normal hookup and turn on our power amp or unmute our speakers.

This video demonstrates the steps:

Since we’re moving these input and output volumes all the time we’ll probably need to run this level adjustment routine before taking measurements.

With the levels set we’re ready to measure our room/speaker response. Well, actually we’re also including the mic preamp and power amp, but those are probably quite linear, especially compared to our room and speakers.

Here’s a screen video of the measurement process.

And here’s the resulting graph. Looks pretty ragged to me, with huge swings between 40 hz and 200 hz, and lots of comb filtering in the higher frequencies. I suspect that this is the normal response of a medium small room. In our next entry we’ll see what we can accomplish with our current batch of broadband absorbers.

Recording acoustic guitar with a pickup is an extremely appealing idea. It eliminates the expense and hassle of microphones, soundproofing, and room treatment. The biggest problem is the sound quality – not usually that great in my experience. But recently I’ve run across some ideas that might make pickup recording a more useable alternative.

Over at the Acoustic Players Forum a Dutch fingerstyle player and Taylor enthusiast named Eltjo Haselhoff started a thread describing his technique for EQing various pickup systems to make them sound more like a guitar recorded using a microphone. He developed a piece of software that compares a piece of music recorded using a mic and a pickup at the same time. The software then defines settings to use with a graphic EQ to make the pickup recording sound more like the miked recording. His results are pretty impressive to many of us.

In the meantime, Doug Young has been demonstrating Har-Bal in some of our sessions together. This is a piece of software that the creator describes as the “worlds first visual mastering software.” One of the features of Har-Bal 2.2 is a quick tool to EQ one file so it resembles another tonally. I decided to experiment with Har-Bal and some pickup and microphone recordings.

I pulled out my Kathy Wingert Model E (You can see pics of it here.) This guitar has a B-Band AST 1470 soundboard transducer pickup system installed, and I’ve been told that it sounds pretty good in amplified situations. I set up a pair of EV RE16 mics in an X/Y configuration, pointing at the bridge at a 45 degree angle, and about 12″ from the guitar. I ran the mics through a John Hardy M-1 preamp, into my LynxTwo-C soundcard, and into Adobe Audition 1.5. I plugged the pickup into a Baggs Para Acoustic DI (PADI), took the XLR out and connected to Channel A of an FMR RNP preamp. This fed another channel on the LynxTwo-C, and I configured Adobe Audition to record this single channel on both sides of a stereo track.

I played a simple Hawaiian vamp and recorded both sources. I kept the recording short because I wanted to present the material as a .wav file instead of a compressed MP3 file. I normalized both files to -2 db so their peak levels match.

The pickup recording: PEQT-PUP.wav
The microphone recording: PEQT-RE16.wav

I don’t think it’s very hard to hear the difference, and I think most people would prefer the microphone recording.

Now what can Har-Bal do for us? I loaded the microphone track as a reference, then loaded the pickup track as the active file. I chose the IntuitMatch cursor and passed it over the pickup track. Har-Bal computed an EQ set that would bring the pickup closer to the tonal balance of the microphone track. The result was not identical, but much closer. And to my ear the result was pretty impressive.

The Har-Bal adjusted track: PEQT-PUP-EQ.wav

I still prefer the microphone track, but I could certainly live with the adjusted pickup track. Perhaps a little tweaking with reverb or delay might add a little of the “air” and “body” that are still missing. It certainly seems worth exploring further.