Volunteer sir sanders zingmore Posted March 5, 2014 Volunteer Posted March 5, 2014 I've read in a few places that analog EQ (eg tone controls) play havoc with phase. Just wondering whether this also applies to the RIAA EQ that is applied by phono preamps?P
Volunteer sir sanders zingmore Posted March 5, 2014 Author Volunteer Posted March 5, 2014 Is it possible that it is messed up as the EQ is applied in the recording process and then corrected by the inverse EQ curve on playback?
LogicprObe Posted March 5, 2014 Posted March 5, 2014 Is it possible that it is messed up as the EQ is applied in the recording process and then corrected by the inverse EQ curve on playback? That is part of the argument about the different curves.
davewantsmoore Posted March 5, 2014 Posted March 5, 2014 I've read in a few places that analog EQ (eg tone controls) play havoc with phase. Just wondering whether this also applies to the RIAA EQ that is applied by phono preamps?P If the inverse EQ (applied to the record) and the EQ applied to the playback, are opposites of each other, they will sum to flat phase. If they are not the same, then you will have amplitude and phase error in the result.
Addicted to music Posted March 5, 2014 Posted March 5, 2014 If the inverse EQ (applied to the record) and the EQ applied to the playback, are opposites of each other, they will sum to flat phase. If they are not the same, then you will have amplitude and phase error in the result. Ideally yes, in real world, I don't believe so. The equipment that is used to provide the RIAA is going to be different to the consumer playback. therefore it will never cancel out to zero phase error. 1
Owen Y Posted March 6, 2014 Posted March 6, 2014 I've read in a few places that analog EQ (eg tone controls) play havoc with phase. Just wondering whether this also applies to the RIAA EQ that is applied by phono preamps?P Unfortunately, any active circuitry can tend to mess with phase. The more circuitry the signal has to go through...RIAA pre-emphasis, RIAA EQ, phono gain...all of this has potential for phase inaccuracy. Also, from what I know, this tends to vary with frequency, eg. it may be relatively easy to achieve accurate response at 1kHz, but it's a more difficult exercise down at say 20Hz or up at 20kHz. We're at the mercy of the skill of the electronic engineer. This is slightly different from 'absolute phase' or 'polarity'....the +ve & -ve polarity of the complete (AC voltage) music signal. Cheers, Owen Dark Lantern blog - http://darklanternforowen.wordpress.com/ 1
davewantsmoore Posted March 6, 2014 Posted March 6, 2014 Ideally yes, in real world, I don't believe so. The equipment that is used to provide the RIAA is going to be different to the consumer playback. therefore it will never cancel out to zero phase error. Of course... That's what the second sentence was for
davewantsmoore Posted March 6, 2014 Posted March 6, 2014 Unfortunately, any active circuitry can tend to mess with phase Filters with active electronic circuits (and special passive ones) ... are able to adjust the phase without adjusting the frequency. Everything else... like 'regular passive filters' (ie. regular RIAA) affects them both (because phase and frequency are just different viewpoints of the same event)
Owen Y Posted March 6, 2014 Posted March 6, 2014 I've read in a few places that analog EQ (eg tone controls) play havoc with phase. Just wondering whether this also applies to the RIAA EQ that is applied by phono preamps?P The more important Q I think, is whether it is audible. It's not uncommon to see phase shift on the bench, on the scope, but however the amp will sound just fine. OTOH 'absolute phase' (ie. inverted polarity) is quite audible. IMVHO Dark Lantern blog - http://darklanternforowen.wordpress.com/
Volunteer sir sanders zingmore Posted March 6, 2014 Author Volunteer Posted March 6, 2014 presumably it's not audible. I mean I jitter at the thought that audiophiles would obsess about something that's not audible, imagine that !
Owen Y Posted March 7, 2014 Posted March 7, 2014 We can't have Jitter in analogue! Cheers, Owen Dark Lantern blog - http://darklanternforowen.wordpress.com/
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