Audacity Forum

Applying 78 EQ to files recorded via RIAA pre-amps
by goellphoto on Sun May 04, 2008 10:59 am

Regarding archiving and editing 78 rpm (U.S.) records from the early 1930s through the late 1940s (Jazz, mostly) in Audacity 1.3.x:
Does the RIAA EQ curve first need to be flattened in Audacity with an opposite EQ curve before an appropriate 78 curve can be applied? Or is there a way to perform this in a single step in Audacity (any version)? And if not, wouldn't such an auto two-step filter make some sense?

Related question: has anyone had experience with an LP/78 EQ-switchable stand-alone pre-amp made by Phonopreamps, model number TC-778? Rek-O-Kut markets the same unit under its own name. It more or less maintains the RIAA bass curve below 1000 Hz (with a cutoff below 10 Hz) , but employs a flat curve above 1000 Hz, with no treble roll-off. I got it for use with Audacity, but I'm not sure that particular curve will do the trick. Any first-hand opinions out there?

Thanks.

goellphoto wrote: Regarding archiving and editing 78 rpm (U.S.) records from the early 1930s through the late 1940s (Jazz, mostly) in Audacity 1.3.x:
Does the RIAA EQ curve first need to be flattened in Audacity with an opposite EQ curve before an appropriate 78 curve can be applied? Or is there a way to perform this in a single step in Audacity (any version)? And if not, wouldn't such an auto two-step filter make some sense?
Thanks.

I think you are probably right in your supposition about thye need to reverse the vinyl RIAA curve - or you could record wthout RIAA (say by passinbg thgye signal from the TT playing the 78s through an amp impot that is not phono- and IIRCsome of the small standalone pre-amps on the market can be switched between phono or line modes). And yes an auto equalisation which removes tha vinal RIAA and applies the 78 RIAA is quite a cute ides.

You probably know this already, but just in case, just be aware that Audacity's effects come pre-fitted with several different 78 RIAA curves to deal with the different equalization applied by different manufacturers of 78s. (Update: I see from your further post in the Feature requests that you indeed know all about this already)
And also be aware that you should use a stylus or cartridge that is designed for 78's - and sorry if this too is teaching my granny to suck eggs.

Sorry I have no experience with the pre-amp that you mention - but the manufacturer is recommended in other places on the forum (a couple of the knowledgeable posters on the forums from this company). I suspect that the problem you may run in to is that it applies a particular 78 RIAA equalization - whereas there were several diffent RIAA equalization profiles from the various manufactures.

If you have a reasonable number of 78's to capture/clean - I would strongly recommend looking at Brian Davies' excellent ClickRepair software (it costs a little, but in my opinion and experience is well worth it). See: http://wwwmaths.anu.edu.au/~briand/sound/

He has also recently added a second program to remove hiss and rumble - I tested this recently on a blues LP that had obviously been made from old 78's and it worked quite well - and I suspect that by tuning the parameters can be made to work very well.

WC