Trevis Rothwell's weblog

Almost, but not quite, entirely unlike tea

Seagate 2TB Expansion Drive on Mac OS X

29 December 2014

A new Seagate 2TB Expansion Drive which I assumed would work just fine on Mac OS X since it connects with standard USB 2 or USB 3 came in a box with bountiful mentions of backing up your “PC” and notes compatibility with several versions of Microsoft Windows.

How does it work on Mac OS X 10.9.5? I plugged it in and was immediately asked if I wanted to use the drive for Time Machine backups, which I did.

Sharing here in case anyone wonders about OS X compatibility. Some Amazon reviews for the 3TB version complain that the drive doesn’t last very long; so far my 2TB unit has lasted fifteen minutes, but I will try to remember to update this post after more extended use.

[July 2017 Update, two and a half years later: the drive is still working flawlessly.]

Making eBooks with Texinfo and Calibre

14 December 2014

While I greatly enjoy reading, eBooks have mostly eluded me — I still prefer gazing upon ink printed on processed tree pulp, or when electronic texts are convenient, plain old HTML. But as an author, it seems questionable to ignore the multitudes of people who do favor reading on their Kindles and Nooks and iPads.

But how best to support those? I’ve done most of my serious writing by typing Texinfo word processing commands into GNU Emacs. Fortunately, it appears that I can continue writing with my ancient tools, thanks to file format conversion programs like Calibre.

I experimented using the most recent edition of The GNU C Reference Manual. The GNU Texinfo toolchain already easily produces PDF and HTML output, so I loaded the single-page HTML file into Calibre. From there, Calibre can produce a variety of eBook outputs, including the ubiquitous ePub and Mobi file formats.

The resulting ePub file I could view using Apple iBooks on my Mac laptop; delightfully, it looks like other ePub eBooks that I have seen. I don’t have a Kindle, but I presume that Calibre did an equally good job of converting to the Mobi file format.

So hooray! This toolchain will allow me to use my familiar writing workflow to produce eBook content in formats desired by readers who opt for electronic reading devices.

Three FireWire Audio Interfaces in Six Months

13 June 2014

In late 2012, I started using an Echo AudioFire 12 to route analog audio into my 2010 Apple MacBook Pro. On paper, the AudioFire 12 was exactly what I wanted: 12 analog inputs and 12 analog outputs converted to digital and sent across FireWire. I’m using outboard preamps, so I’m not particularly needing the A/D interface to offer built-in preamps. The AudioFire 12 didn’t offer anything fancy; it was an A/D interface with FireWire output.

Initially, all seemed well. Very occasionally when recording I got a spurious digital pop noise on a track. I thought I was probably overdriving something somewhere, and investigated possible causes as a background task.

After a few months, the popping noises increased. About a year after acquiring the AudioFire 12, I was using it for a series of recording sessions, some of which turned out flawless, while others were littered with pops, in some places so bountiful that it came across as a crackling noise.

I learned that these noises are called gaps: essentially, a brief lapse in successful transmission of audio data. In the recorded wave file, when you zoom in far enough, you can see that a normal audio wave is a generally smooth, continuous line. A gap introduces a sudden discontinuity; the wave line jumps from one point to another. Once you locate a gap in the wave file, you can manually fix it by repairing the wave line, making it smooth and continuous again. You can also use a number of software tools to repair gaps automatically.

So I was able to salvage my recording session data, but it was obvious that sloshing around with frequent gaps in recorded audio wasn’t an appealing path forward. Research on the web suggested a number of things to try different in configuring my system, but when all of those failed, I resolved that the problem almost certainly was an incompatibility between the FireWire chipset in the AudioFire 12 and the FireWire chipset in my computer. Had it been a full desktop computer instead of a laptop, I could have installed a secondary FireWire interface card that would hopefully be compatible, but that wasn’t an option for me.

MOTU 828

I decided to sell the AudioFire 12 and replace it with another interface. I had had good success in the past with an audio interface from MOTU (Mark of the Unicorn, based in lovely Cambridge, Massachusetts), and, not needing anything fancy, I bought an original MOTU 828 unit, reportedly the very first FireWire-based audio interface, with eight channels of analog inputs, only two of which sported built-in preamps.

The MOTU 828 was something on the order of 12 years old, but it worked perfectly. Its minimal ability for routing and monitoring audio felt a little archaic, and it lacked the convenient MIDI I/O tacked on to nearly every modern FireWire audio interface, but I was able to make do. It chugged away in service of my home recording studio for an astonishing four months before its internal FireWire chipset flaked out, connectivity between it and the computer failed, and it started emitting a high-pitched squeal which gave me a moderate headache as I tried to make it stop.

I read online that MOTU tech support could, as of 2011 anyway, replace the FireWire ship and refurbish an 828 unit for $75, plus shipping charges. I called MOTU the next morning only to learn that they no longer service the ancient original 828.

So I needed to buy another new interface. I ended up selecting a new interface from Focusrite.

Focusrite Saffire Pro 40

The Echo AudioFire 12 is fairly unusual; audio recording professionals favor using outboard preamps, and buy $2000 interface units that have no built-in preamps. For my needs, I wasn’t looking to spend $2000 on an interface, but, apart from the Echo equipment, I’m not aware of another <$1000 interface that isn’t cluttered with its own preamps.

Built-in preamps are not necessarily bad, but they almost certainly will not be as good as standalone preamps. I have a Focusrite ISA two-channel preamp that sells for $900. The Focusrite Saffire Pro 40 audio interface has eight built-in preamps, one on each input channel, and sells for $500. It doesn’t seem credible that these <$60 preamps would be designed and built as well as a $450 preamp from the same manufacturer. This does, though, get usable preamps into the hands of people who might not have bought them otherwise.

I’ve used the Focusrite Saffire Pro for all of about ten minutes and so far it sounds great. Or I suppose I should say, it doesn’t sound like anything in particular; it functions as an audio interace, converting between analog and digital signals. I have some extra built-in preamps should I need them, and the overall design is (not surprisingly) more modern than the old MOTU 828. It lacks clock input, but I don’t need to synchronize it with anything else at the moment. In addition to the eight analog inputs, it also has digital inputs through ADAT, so I could plug up a really nice A/D converter and use the Saffire just to feed the digital data to the computer over FireWire. The front-panel buttons feel cheaply made out of plastic. (The knobs and power switch feel fine.) I imagine that Focusrite could increase the price by $50 and use the same quality of buttons they use on the ISA preamps.

Basically, it’s a lot like many other similarly-priced interface units. I don’t find these extremely interesting in themselves, but rather, just a needful component in recording audio. They do though become very interesting when they don’t work correctly in one way or another. Hopefully this brand new Focusrite Saffire will function well for years to come.