Lobby > Amp and DAC Measurements
Standard Distortion Spectrum Measurements For Amps (Changstar)
Armaegis:
--- Quote from: maverickronin on August 05, 2015, 01:17:10 AM ---There shouldn't be much, but since nobody can hear it anyway who knows what kind of weird noise or interference is actually hiding up there.
Considering there are SACDs that are just upsampled redbook I would be surprised if there were plenty of recordings with lots of weird ultrasonic noise that nobody bothered to do anything about.
--- End quote ---
But can't that ultrasonic garble lead to IMD in the audible band?
ultrabike:
--- Quote from: Armaegis on August 05, 2015, 01:54:05 AM ---But can't that ultrasonic garble lead to IMD in the audible band?
--- End quote ---
Well yes. That's what I think the Vorbis dude showed. We can try it. We would have to agree on what represents worst case and typical ultrasonic levels and frequencies.
Some, if not most, amps do not filter input ultrasonics coming from DACs. Proly not even the mighty Hoe-2.
Armaegis:
--- Quote from: ultrabike on August 05, 2015, 03:31:47 AM ---Well yes. That's what I think the Vorbis dude showed. We can try it. We would have to agree on what represents worst case and typical ultrasonic levels and frequencies.
Some, if not most, amps do not filter input ultrasonics coming from DACs. Proly not even the mighty Hoe-2.
--- End quote ---
(making crap up because I'm only wikipedia smart about this...)
Maybe something like 1000 Hz, 82000 Hz and 85500Hz
produce a 3.5kHz blippityboo, see if that interacts with the 1kHz tone to make something at 2.5 kHz.
or whatever values work to create spikes that won't overlap with the natural harmonics of the test tones, or even the first order of imd products
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