[78-L] Fake stereo

[Wes]

>From: "Michael Biel" <mbiel at mbiel.com>

>From: "Milan Milovanovic" <milanpmilovanovic4 at gmail.com>

>> Michael, are there consequences regarding eq while doing it

>> (digitally) on flat 78rpm monaural transfers? What really we can 

>> expect in that matter? Cancellation of some frequencies?

> Other irregularities?  Thank you,  Milan

 

>What was being specifically discussed in the presentation was "undoing"

>the pre-emphasis curve where the goal is a transparent unnoticeable 

>restoration back to the original.  Since the analog pre-emphasis had 

>filters would do some phase bending, that phase change would also 

>have to be undone, which does happen in the analog domain but 

>digital filtering doesn't -- unless it is purposefully built into 

>the program, which is expensive. ..

Digital audio program designers use a filter implementation that ensures
no change in phase - its called 'FIR'. But there is an alternative which
will change phase called 'IIR'. The IIR filter behaves much more like an 

analogue filter. Audacity EQ allows you to choose which implementation to 

use, so its worth trying both if you're trying to do inverse RIAA or any 

inverse pre-emphasis.

... wes williams