Reverse RIAA curve

There have been a couple of posts recently about transcribing 78 rpm records. The problem is that virtually all phono pre-amps (and USB turntables) apply the RIAA playback equalization curve. This is not appropriate for 78s. What is needed is the ability to reverse the RIAA playback EQ, then apply the appropriate 78 rpm EQ for the particular disc you are transcribing. One could painstakingly draw the reverse RIAA curve and save it, but why not include it as a standard pre-set? Audacity already includes many 78 rpm presets, and it makes sense to me that anyone wanting to use one of those presets would first want to apply the reverse RIAA EQ first.

– Bill


there is a posting in the Wiki Feature Requests page that relates to this, which says:

Automatic 78 RPM EQ from RIAA-recorded 78’s: Flattens the curve to negate the RIAA EQ then applies the required 78 RPM EQ in one button press. Add more 78 RPM presets to facilitate this. (7 votes)”

See full list of FR’s at
and pending FRs at

I think that yours is a better idea as there are several 78 equalization curves that can be applied (there were no standards back in the earlydays of recording - each company had its oqn Eq curve - and sometimes more than one). unless ALL the 78 curves were reconfigured for first strip the normal vinyla RIAA and than apply it’s own RIAA the equalization would be incirrect.

I do vaguely remenber some discussion about a reverse RIAA curve - but can’t for the life oof me find it on the forum (or on the Wiki Pending Feature Requests or Feature Requests pages).

I knew I’d seen a similar request somewhere, but couldn’t for the life of me figure out where. I did search the forum, but overlooked the wiki Feature Requests page. :blush:

There’s another reason for separating the reverse RIAA curve from the 78 rpm EQ curves. Most users today will be transcribing their 78s at 45 rpm. You need to first reverse the RIAA EQ, then change the speed, then apply the correct 78 rpm curve. Combining the curves only works if the transcription was done at 78 rpm in the first place.

– Bill

You may be interested in the second half of this thread from the audacity developers mailing list:

Aahhhh …

I’ve just seen Bill’s updates in the manual for the upcoming 1.4/2.0 release - and see why this request has been posted right now.

Awkward to explain to users how to reverse the curve and awkward for users to do the work …

a reverse RIAA would simplify things.


I went and read that thread, and learned about the existence of EQcurves.xml. Very simple to create a reverse RIAA curve. Just copy and paste the existing RIAA curve then negate all the values!

– Bill


does that mean that you consider this FR to be redundant?


No, I think it is so trivial to add it to the default EQCurves.xml, why not do it?

The RIAA curve is only useful for people who connect a turntable directly to their stereo mic input and then need to apply the curve. We tell people not to do this (who has a stereo mic input?), but to use a phono pre-amp that applies the RIAA curve.

The reverse RIAA curve is useful for people who are transcribing 78s. This is admittedly a small proportion of Audacity users, but probably at least as large as those who connect a turntable to their mic input.

– Bill

Plus my vote then - I recall several times in the past few years when I have responded to folk who are (or planning to) transcribe 78s - telling what to do would be much easier with a reverse-RIAA.

OFF-TOPIC - Sady I am not one of those who has 78s to transcribe. I used to have a reasonable collection when I was younger (and a resonable collection of wind-up gramophones to play them on) all garnered from jumble sales when I was in the Scouts. But unfortunately my parents threw them all out when I left home to go to University - it’s a long story … :frowning:

Still, looking on the bright side, it saves a transcription chore I suppose :slight_smile:


Here it is. Until this is added to the default EQCurves.xml I’ll keep this around to give to people who need it.

	<curve name="Inverse RIAA">
		<point f="30.000000000000" d="-18.600000381470"/>
		<point f="31.000000000000" d="-18.500000000000"/>
		<point f="50.000000000000" d="-16.899999618530"/>
		<point f="63.000000000000" d="-15.899999618530"/>
		<point f="70.000000000000" d="-15.300000190735"/>
		<point f="100.000000000000" d="-13.100000381470"/>
		<point f="125.000000000000" d="-11.600000381470"/>
		<point f="200.000000000000" d="-8.199999809265"/>
		<point f="250.000000000000" d="-6.699999809265"/>
		<point f="300.000000000000" d="-5.500000000000"/>
		<point f="400.000000000000" d="-3.799999952316"/>
		<point f="500.000000000000" d="-2.599999904633"/>
		<point f="600.000000000000" d="-1.799999952316"/>
		<point f="700.000000000000" d="-1.200000047684"/>
		<point f="800.000000000000" d="-0.800000011921"/>
		<point f="900.000000000000" d="-0.300000011921"/>
		<point f="1000.000000000000" d="-0.000000000000"/>
		<point f="2000.000000000000" d="2.599999904633"/>
		<point f="3000.000000000000" d="4.699999809265"/>
		<point f="4000.000000000000" d="6.599999904633"/>
		<point f="5000.000000000000" d="8.199999809265"/>
		<point f="6000.000000000000" d="9.600000381470"/>
		<point f="7000.000000000000" d="10.800000190735"/>
		<point f="8000.000000000000" d="11.899999618530"/>
		<point f="9000.000000000000" d="12.899999618530"/>
		<point f="10000.000000000000" d="13.699999809265"/>
		<point f="15000.000000000000" d="17.200000762939"/>
		<point f="16000.000000000000" d="17.700000762939"/>

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).

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.



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


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.


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

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!)

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.


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.



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

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.


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.