Reverse RIAA curve

[steve]

I'll hold off with my vote on this feature as currently written.
My vote goes for a feature that allows users to easily "import" curves such as Bills excellent reverse RIAA.

Just as there is a section on the Audacity site where you can download and install plug-ins, it would be great to have a section where you can download and install useful Equalizer curves (without the user having to find the EQCurves.xml file and edit it manually - I'd like to be able to send an Eq curve to my Grandmother).

[Irish]

I have been doing some research on the web over the past while, on 78rpm equalisation, and I have found values for the EQ curves believed to have been used by many of the record companies. I can't vouch for them myself, but they represent the consensus of opinion as far as I can see. I can post them here, if anybody wants.

PO'L

[waxcylinder]

Irish,

several of the 78 RIAA curves are already available in the Equalization effect - have you seen those?

WC

[Irish]

I have. (Actually i'd forgotten about them until you reminded me!), but there are significant differences between them and the ones I've found, plus some I have that aren't there.

I don't want to turn this thread into a debate about "pre-RIAA standard" equalisation, but it does seem that the more you look, the more versions you find for each record label.

My plan is to create combined "Anti-RIAA plus 78rpm EQ" curves to transcribe my 78s, because the turntable I will use (a Bush SRP51 - remember them?) has an RIAA pre-amp built in, but for most users, maybe separate curves are more useful.

PO'L

[billw58]

My plan is to create combined "Anti-RIAA plus 78rpm EQ" curves to transcribe my 78s, because the turntable I will use (a Bush SRP51 - remember them?) has an RIAA pre-amp built in, but for most users, maybe separate curves are more useful.

I'd rather have the 78 rpm curves alone along with the anti-RIAA (I think I prefer that name!) curve.

Most users will be playing their 78s at 45 because it is hard to find a good turntable that plays at 78. So they need to 1) reverse the RIAA EQ, 2) change the speed of the recording, and 3) apply the appropriate 78 rpm curve.

The combined curves would be very useful for those who have a good 78 rpm turntable.

-- Bill

[steve]

This is exactly why I think it would be great to have an easy way for users to import Eq curves.
Curves such as these could be submitted on the forum, and the popular ones transferred to a "library" page somewhere for all to use. While it is not particularly difficult to edit the EQCurves.xml file manually, there are a lot of Audacity users with very little computer experience that could still benefit from access to these curves. It would also be much more accessible for visually impaired users. (Imagine what the EQCurves.xml file sounds like with a text reader!)

[Irish]

I agree entirely.

For those who would have difficulty editing the EQCurves.xml file, you can create accurate Eq curves using the graphic equaliser option in the Equalisation plug-in; when you click on a slider, the Up and Down arrows move it by 1dB and shift+Up/Down moves it by 0.1dB, but this is really tedious and prone to mistakes.

A "library" of curves that could be built up over time would be a valuable resource, and a simple way of adding them to EQCurves.xml sounds like an ideal solution.

That gets my vote.

PO'L

[waxcylinder]

I have moved this FR discussion to the Wiki's Pending Feature Requests page.

I have retained it on the forum too - but moved to to Audio Processing - as it is a thread that may well help others in the future.

WC

[jtp_60]

Hi!

Until the feature is added, op (or anyone) could prepare one(s) quite easily by himself/herself :

http://jiiteepee.fortunecity.com/riaafilter/index.html

Look @ bottom of the page ... there are coefficients for biquad RIAA filter ... and "instructions" how to turn one to type of production RIAA. To test (if VST version) just use Christian Budde's VST Analyzer.

Juha

[theSeaHawk]

Thanks, Bill, for posting the xml to perform reversal of RIAA EQ. I located the xml file in 1.3.11, opened as text, and copy/pasted the values above. Went to an older track that had come in with RIAA EQ, reversed it with the reverse RIAA now available in the EQ effect. Then I added the EQ appropriate to the label and date of the record and it sounds quite good.