Currently, I don’t have a modern 78 RPM turntable. But I’ve read somewhere that you can record a 78 at 45 RPM and resample it to speed it up to the correct pitch for 78. I use Adobe Audition (the new version of Cool Edit Pro). The way it shows the calculation for pitch change is by ratio, although it’s not like the scale in any other software I’ve seen.
100 is no pitch change. To shift it up a semitone, the ratio is 94.387. Up a whole tone is 89.089. Up a further semitone is 84.089, one more is 79.37. This is where I get lost trying to figure it out. By this scale, can anyone help me figure out the correct ratio to enter to make a 78 recorded at 45 play at the right speed? We have to know how many keys up it is, and then figure out a numerical value for the ratio.
100*(45/78) = 57.6923.
The numbers you give are the frequency ratios of the semitone and full tones, multiplied by 100. (The octave, a doubling of frequency, is 12 semitones: 0.94387[sup]12[/sup] = 0.5 .) You just want to speed up the recording by the ratio of the two frequencies (45rpm and 78rpm).
Vinyl records are recorded using a non-linear frequency response (the higher frequencies are boosted and the lower frequencies reduced when recorded, then this is compensated for on playback). I think you’ll end up screwing up the frequency response a bit if you play back a 75 at 45 speed then speed it up again since you are effectively going to shift the frequency compensation curve.
Good point, but did 78’s use the RIAA curve to begin with? Would it work better to skip the usual phono preamp and run the cartridge’s output into a mic input? Once you’ve got the recording in the computer and at the right pitch, you can EQ and clean up as needed.
the other solutions seems more elegant stoopid math but you always to this. This guy’s using Cool Edit, not Audition (but they’re damn near the same), and going the direction, but it seems relevant.
I would personally use CuBase or ProTools, but then I’m not as familiar with Cool Edit/Auditon.
Audacity also has a pretty damn good bit sampler for freeware.
I’ve seen that - it’s really cool. Too bad it sounds like somebody playing a 78 on a hand cranked Victrola in a closed phone booth.
Back to the OP - I poked around in Audacity cause I remembered that there was a bunch of presets in the compression module for older recording standards. With the EQ, too - old 78 and 45’s, and most old labels - RCA Victor, Decca, et al. You can also set whatever sample rate you want manually, or they offer a host of common presets. I’m gonna guess that since they pay so much attention to the old formats in other modules, some of those presets are samplings rate of the old formats and gear.
For those of you who don’t know about Audacity, it’s a really powerful (for a free program) multittrack wave editor under the GNU license. Link.
A modern stereo stylus has a size of about 0.7 mils. The groove on a 78 RPM record is much bigger than this - a typical 78 stylus is 2.8 or 3.0 mils. If you play a 78 with a stereo stylus the sound will be pretty awful, because the stylus will bounce around in the bottom of the groove (i.e. it won’t be constrained by the groove walls on both sides at the same time).
What engineer_comp_geek and gotpasswords said about equalization is correct. First, most 78s were not recorded with the RIAA equalization standard (which only became standard in 1953, near the end of the 78 era). Prior to that, each record company used its own curve (which changed over time). Prior to 1925 all records were made acoustically (i.e. without the use of microphones or other electronics), so no equalization was possible.
Playback equalization curves boost the bass below some frequency (called the turnover point) and cut the highs above some higher frequency (called the rolloff). If you play a 78 back at 45 RPM, the pitch will be 45/78 of what was recorded. If you plug the turntable into the phono input of the pre-amp, the RIAA equalization curve will be applied to the signal as received, as if the recording were not slowed down. Then, when you speed up the recording digitally, the turnover and rolloff points will be shifted up by 78/45, along with the rest of the recording. The bass boost and treble cut will both be at frequencies that are too high. The result will sound awful, with boomy bass and screechy highs. Combine this with the poor signal from using the wrong-size stylus, and the result will probably be unlistenable.
My advice is that if you want to play 78s, get a turntable with a 78 speed setting and a 78 stylus. I’d recommend a used Dual turntable and a Stanton 500 cartridge - these are rugged and not too hard to find. You can do equalization digitally, or you can get an equalizer and fiddle with that.
Another tip: mixing the two stereo channels to mono usually gives greatly improved sound. The motion of a 78 groove is entirely lateral, and mixing to mono gets rid of any noise from vertical motion of the stylus.
