Audacity Forum

I recently was given a record collection which includes 78 rpm records. I purchased an Ion USB turntable as input for Audacity to digitize the records. The WIKI for USB Turntables says to enter the "...reverse of the RIAA playback curve..." in the Equalization Effect to remove the equalization done in the turntable.

Approximating the reverse RIAA curve by moving the line around in the Equalization Effect panel is quite tedious and probably inaccurate. Is it possible to add a 'Reverse RIAA' entry to the predefined curves?

In Audacity 1.3.x you can save your settings in the Equalizer, giving each of them a name, just like the existing presets.

If you feel adventurous, you can even open the "EQCurves.xml" file in a text editor and create curves manually for new presets.

If we have a look at an example of part of that xml file: Here we see a very simple Eq curve that creates a frequency response similar to a telephone call.
The preset has an opening and a closing tag <curve></curve> and within the opening tag is the parameter "name". This means that the preset will show up in the Equalizer with the name "Telephone".

Now if we look at the lines between these tags, each is in the form:
<point f="number" d="number"/>
The first number represents a point on the frequency curve, and the second represents the value in dB, so in this example you can see that it is effectively a band pass filter with a pass range between about 230Hz and 2.5kHz

On slight snag - there's a few little bugs in the Equalizer in version 1.3.5 that may cause problems, so you may be better off using Audacity 1.3.4 - there's a link on the main Audacity website for downloading previous versions.

WebSorcerer wrote: Approximating the reverse RIAA curve by moving the line around in the Equalization Effect panel is quite tedious and probably inaccurate. Is it possible to add a 'Reverse RIAA' entry to the predefined curves?

WS - there is already a Feature Request for just this already in the Wiki - I have posted your additional vote for this - see the note on "2-step 78 EQ" under "Equalisation"on http://audacityteam.org/wiki/index.php? ... to_Effects

WC

Thank you stevethefiddle and waxcylinder.

I'll give 1.3.4 a try.

I installed 1.3.5, and the Equalization Effect allowed for saving a profile. I downloaded the RIAA profile, entered it using the Graphic Equalizer interface, and saved it. It worked flawlessly.

WebSorcerer wrote:I installed 1.3.5

Just to let you know in advance - there are a couple of bugs that have been reported that you may run into:

1) Select an effect. Click "Preview" and listen to the preview. Cancel the effect. Audacity may crash.

2) Preview an Equalization setting. Change the Equalization setting and preview again. The Equalization setting is not updated correctly, and may get "stuck" on the first setting - it may look like it has changed, but the effect that is actually applied may still be the setting that was chosen first, or even something completely different.

If you find either of these problems affect you, then downgrading to Audacity 1.3.4 may fix it (and keep an eye out for the release of Audacity 1.3.6 which will hopefully fix these bugs).

stevethefiddle wrote:

WebSorcerer wrote:I installed 1.3.5

Just to let you know in advance - there are a couple of bugs that have been reported that you may run into:

1) Select an effect. Click "Preview" and listen to the preview. Cancel the effect. Audacity may crash.

2) Preview an Equalization setting. Change the Equalization setting and preview again. The Equalization setting is not updated correctly, and may get "stuck" on the first setting - it may look like it has changed, but the effect that is actually applied may still be the setting that was chosen first, or even something completely different.

If you find either of these problems affect you, then downgrading to Audacity 1.3.4 may fix it (and keep an eye out for the release of Audacity 1.3.6 which will hopefully fix these bugs).

Thanks Steve, I entered and saved it, and didn't try changing, but, as they say, "A word to the wise ..."