Your and my understanding of how phono preamps work I think are identical.
To my knowledge, the NPC applies the RIAA curve to the phono input and then for my configuration, outputs via the USB to my computer (working as an ADC). Vinyl Studio, running on the computer, in turn takes the incoming PCM signals (by reading the USB) and writes them to disk. As stated above, this has worked for me for 100+ albums. All the records I’ve tried that were published in 1960s/70s sound exactly as you’d expect (i.e. with RIAA applied by the NPC). Its only this one album I’m having issues with.
Vinyl Studio typically has 4 steps for recording:
- record each side to a file (typically in wav format - I record at 96khz, 2 ch, 24 bits)
a) you can apply equalization to the incoming signal if you wish but I don’t do that
- Split the tracks - which includes naming the tracks and then mark the beginning end of each track
- Cleanup - remove clicks/pops, apply eq (if required), etc
- Encode the tracks to their final destination (I usually use flac) and write to a network share.
a) this step writes the tracks just as if you had ripped a cd (which is how it appears in JRiver)
b) You can also choose to write to a lossy format such as MP3 (e.g for a phone)
As stated above, you can select from a set of equalization curves to apply RIAA, AES, etc., to the incoming PCM (step 1) or recorded PCM (step 3). Normally you’d only apply equalization if your phono pre-amp does not have RIAA or if you were recording a tape (via the NPC analog inputs). There are some preamps that can switch to other eq curves and I suppose that the makers of Vinyl Studio want to be able to sell their product to them as well. So the following screenshot is an example of some of the eq that can be applied via software)
All that being background, in my case I have a 2 record set with what the liner notes say has “New Orthophonic” equalization, an eq curve that was the precursor of RIAA (RCA published New Orthophonic specs and it became the de facto standard). So theoretically, if I record it via the NPC via Vinyl Studio with no eq applied either at step 1 or 3, it should sound good because the NPC has applied the RIAA. – It doesn’t! – But when I apply RIAA at step 3 above, it sounds great. How could that be? I don’t know…
- Was New Orthophonic eq applied twice in this pressing?
a) so that it requires removing once by the NPC and once by Vinyl Studio (?!)
- or was the New Orthophonic standard in 1954 significantly different from what finally became RIAA?
a) so that I am really over compensating by using NPC and Vinyl Studio to eq the signal
I really don’t know what happened for this one album but perhaps I’ve cleared up a bit of your question on how Vinyl Studio works…