FuzzMeasure – some praise, comments, and rants

FuzzMeasure is an audio measurement software for Mac OS X. The operational princple behind FuzzMeasure is the same as with most other computer based audio analyzers (e.g., MLSSA, CLIO, ARTA, or my own MATAA). FuzzMeasure sends a test signal (sine sweep) to the speaker, records the signal produced by the speaker, and calculates the impulse response by deconvolution of the original and the recorded signals. The impulse response measurements are stored in a project file, and each measurement can be evaluated using different analyses either in the time domain or in the frequency domain (this is very similar to what I did with MacSpeaker in the good old times of Mac OS 7). For instance, FuzzMeasure can filter the impulse response using different window functions, calculates step or frequency response, and produces waterfall plots.

I decided to try FuzzMeasure Pro 3 to see how I get along with it when I did some work on my AOS S24 speakers recently. After playing around with the free demo, I pulled the trigger and payed 120 EUR for the full version.

Here are some random notes from my first days with FuzzMeasure:

  • Using FuzzMeasure is very easy and straightforward most of the time. I didn’t need a manual while getting started with the first few measurements. This is not only because I know how this stuff works from my experience with programming MacSpeaker and MATAA, but also because the user interface is designed very carefully. However, there are a few things that didn’t work, most likely because I couldn’t figure out how to achieve them (see below).
  • FuzzMeasure is very nicely integrated into the whole Mac OS environment. Exporting plots or configuring the audio devices is a piece of cake (except if you’re left with an M-Audio FW410 interface, which starves the microphone with poor phantom voltage and comes with the worst driver software, which tends to crash your computer every few minutes even in the year 2014 – but I can’t blame FuzzMeasure for that).
  • Repeating measurements that need to be evaluated in the same way over and over can be cumbersome. FuzzMeasure just applies it’s (hard-wired?) default time window to every new measurement. When I optimized the crossover filter of my speakers and measured the effects of my modifications, I had to adjust the window manually for every new measurement, which takes a minute or two to get everything right. My life would have been much easier if new measurements would just inherit the window settings from the previous measurement, or if a default window setting could be specified. With MATAA, I’d just put the window function into the script that handles the measurement and the subsequent processing and analysis – no tweaking and fiddling necessary.
  • FuzzMeasure exports frequency domain data to *.frd data files, a file format that is commonly used by other audio analysis tools. Time domain data, however, are exported to *.aiff sound files, which are pretty useless for most audio analysis tools. Why is there no *.tmd export, or even a *.tmd import?
  • The only test signal available with FuzzMeasure is a sine sweep. Sometimes it would be nicer to have other signals, too. I like using noise signals (red, pink or white), maximum length signals (MLS), sine bursts, square or sawtooth waves, etc. Such signals can provide a wealth of information that is hard to get with a sine sweep.
  • How on earth do electrical impedance analyses work? I was able to dig out a very brief description of an impedance jig for impedance measurements. But how do I tell FuzzMeasure Pro 3 to actually do the impedance analysis? This functionality seems to be hidden in a quirky «plugin», but it’s use is a mystery to me.
  • Frequency plots extend to ranges below the minimum frequency equal to the inverse of  length of time window. If an impulse response (or step response) is cropped to length T, the result does not contain any sensible information about frequencies lower than 1/T. Plotting data at lower frequencies is misleading and just wrong.
  • Measurements seem to go very wrong if the sound devices for input and output are set to different sampling rates. I can’t see a need for different rates, but users that are similarly stupid as me will have a hard time to understand what’s wrong. FuzzMeasure should check for equal sample rate settings of the input and output to avoid wrong measurements.
  • Newbies (and everyone else) would probably love to see a list of different audio interfaces, microphones and other hardware with a brief description of their strengths and weaknesses and their suitability for specific applications.
  • I couldn’t find a manual for FuzzMeasure Pro 3! Yes, there is a manual for version 2 floating around the internet in the form of a PDF file. And yes, I was able to get me started without the manual. But no, that’s not enough. There are a few quirky operations that are not obvious to me, as mentioned in the points above. And here are a few more: What are the different curves in the distortion plots? Why can I set colors for some plots, but not for others? Why do the measurement notes sometimes apply to the currently selected measurement, and sometimes they go into the next (new) measurement? FuzzMeasure costs a lot of money, so a manual is mandatory!

Overall, FuzzMeasure is a shiny and convenient software tool for audio engineers and DIY enthusiasts like me. While FuzzMeasure provides a number of elaborate and useful analyses,  its use is mostly straightforward (if you know the theory behind its operation and how to use the software), but does not work as expected in some other cases (even if you know what you’re doing). The functionality of FuzzMeasure Pro is not unlimited, however.

My conclusion is that FuzzMeasure may be SuperMegaUltraGroovy and stuff, but I still prefer MATAA for serious work. At the end of the day, MATAA is a workhorse that does everything I want and need, the way I like it. If I need more, it’s easy to add new functionality due to the GNU Octave / Matlab foundation. MATAA is way more powerful and convenient for me due to the its seemingly endless scripting, data processing, and plotting possibilities.

After my somewhat disappointing conclusion, I asked Chris Liscio for a refund which he allowed with no issues. Nice touch, Chris!

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