The Altmann Creation ADC is a converter that contains ‘No Analog or Digital Filters.’ This is a really interesting claim. Non-ideal brickwall filters will introduce some phase shift, but the consequences of not implementing the filters at all seems much, much worse. Any content above the sample rate will alias down, creating a tones that are not harmonically related to the original signal.
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.)
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…