In this blog I pose the following question:
Does a light diaphragm result in a fast sound character? Is lightness a virtue to good sound quality?
Follow up question number 1:
If it is, then what measurement metric can be used to identify this virtue?
Follow up question number 2:
Again, if it is, what measurement metric does not identify this virtue?
This blog post may be part 1 of multiple blog posts on the topic. It is a refreshing change from my heavy focus on intermodulation distortion.
There exists a polarization of understanding between the audiophile community and the more technical professional community. Generally it is understood that moving mass (mms) has little to do with actual driver performance in terms of what is achievable in terms of sound quality. While the audiophile community empirically observes that supposedly light drivers provide a faster more 'immediate' sound. I began this blog post siding with the professional community wanting to 'educate' the audiophile. However I decided to take a step back and ask myself if perhaps the topic was not so clear cut. Was there actually a test that could reveal a 'fast' driver compared to another?
If I take two tweeters with obviously different moving mass and I match the frequency response using DSP, will there be any measurable difference between the two tweeters using a standard suite of tests?
Visually it's quite obvious that the AMTPRO4 has a much heavier diaphragm, although it is not specified by the manufacturer. Below is the overlay after I've matched the responses to the best of my ability using the Hypex DSP software. I've limited the tweeters to the most linear portion of their frequency bandwidth.
Below are the DSP settings for each tweeter to get them matched up with AMT2-4 on the left and AMTPRO4 on the right. Click the image to enlarge.
If we now measure and display the full test data we can see there is little difference between the two tweeters.
Below are the results between the two tweeters, with the AMT2-4 on the left and the AMTPRO-4 on the right. Click to enlarge each image if needed.