Previously I wrote a little about the Blu-Spec CD - a red book CD burnt with a shorter wavelength blue laser. In theory, the digital signal on the Blu-Spec CD should be less prone to errors in playback.
The SMH-CD is a very similar idea: a red book compatible CD created through a new process to reduce errors on playback. In the case of the SMH-CD (Super High Material CD), the base material is a special polycarbonate plastic designed to increase the transparency on the data side of the disc. The increased transparency means less distortion on the signal read by the laser, and a more accurate playback.
I can’t find any SMH-CDs for sale, and there’s very little information about them on the internet. It looks like Prince’s catalog was reissued in Japan at some point in this format, and there’s substantial debate about the sound quality of the manufacturing process. If you know anything else about this format, toss it in the comments!
I spent the evening doing some reading - trying to manage the flood of ProAud discussion list emails I’ve received in the last few days, and browsing the latest AES Journal (Volume 56, Issue 12). There are a few topics I want to dive into further, but there’s never enough time. I imagine the list will continuing growing, but hopefully I’ll be able to dig into some of these topics over time:
Fractional Delay Filters (for delaying signals by non-integer multiples of the sample rate - useful in musical instrument modeling). References to follow up on:
Principles of Fractional Delay Filters (Valimaki and Laakso)
Splitting the Unit Delay (Laakso et al.)
Efficient Algorithms and Structures for Fractional Delay Filtering Based on Lagrange Interpolation (Franck)
Grounding and shield termination - the work of Jim Brown, Bill Whitlock, and Henry Ott (among others). References:
Journal of the AES Volume 43, Issue 6
AES Standards AES54-1, AES54-2, AES54-3
Noise Reduction Techniques in Electronic Systems (Henry Ott)
Listening Quality Tests. References:
On Some Biases Encountered in Modern Audio Quality Listening Tests (Zieli’nski, Rumsey, Bech)
Are You Hearing What I’m Hearing? (Rumsey)
More to follow…