I don't know anything about vinyl but I find this an interesting topic of conversation that comes up sometimes. I've googled for the answer but can't find anything quantitative about it.
This should be a fairly straightforward experiment to run. Get multiple presses of a record, put them on a turntable, and record them using high resolution/high frequency recording hardware. Compare the recordings somehow. (The comparison could be a little complicated and mathematical but still seems very doable to me.)
To control for the recording hardware, you could record the same song being played multiple times from the same digital source.
The reason you can't find anything quantitative about the bandwidth of vinyl is because there is no hard and fast answer. There are a number of things that we can say about the overall limits for most vinyl records, but every record company did things a bit differently and used different equipment with different capabilities. First of all, all LPs made in the USA, Western Europe and Japan since the late 1950s conform to the RIAA (Recording Industry Academy of America) equalization curve. Without getting too technical here, basically in order to keep low frequencies from causing needle (stylus) excursions so big that they break through the groove walls into the adjacent groove, on recording, low frequency signals are attenuated by a certain amount following a fixed, standardized set of parameters. On the top end, high frequencies are boosted, again, using a fixed, standardized set of parameters. This is done for two reasons. First of all, high frequencies don't contain as much energy as lower frequencies, so the waveforms being cut into the record are much smaller, sometimes so small, that if they weren't boosted, the playback stylus couldn't resolve them al all. Secondly, the low level of the highs are often quieter than the noise of the record vinyl itself. By boosting them on recording, and attenuating them by an exact reciprocal filter on playback, their level is returned to what it was naturally. A side benefit being that when you attenuate the boosted highs, you also attenuate any high frequency record noise that might be inherent in the vinyl. The round trip frequency response of the RIAA equalization curve is from 30 Hz to 20 KHz. Does that mean that this is frequency response that is on all LPs? It does not.
In the beginning, the RIAA stipulated that un order for an LP to be considered High-Fidelity, it must have a frequency range of at least from 50 Hz on the bottom end, to 15 KHz on the top end. Most LP mastering equipment, especially since the advent of stereo, exceeds that by quite a margin. As was shown in the JVC Q4 "quadraphonic" 4-channel surround recordings of the late 1970's it is possible to encode information on an LP that extends well above 50 KHz! That product was short lived, however, because even though special stylus shapes (the so called
Shibata stylus, for instance) as well as new vinyl formulations were devised to play back this ultra-high frequency material, it was found that the ultra-high frequency material (containing the information for the two rear channels) wore away rather quickly. While most records could have frequency responses that went below 30 Hz and above 15KHz, It doesn't mean that the material recorded on them had that wide of bandwidth.
The reason has to do with the fact that almost all LPs were mastered using magnetic tape. The tape captured the performance and then it was edited on tape and then the master was transferred to a copy which was used to actually "cut" the LP. The problem with Magnetic tape was maintenance. While the tape recorders of the day could, theoretically, capture and playback frequencies up to 20 KHz, the amount of work it would take a technician to get the tape recorder to maintain that frequency response was not economically practical. So most recording studios maintained their mastering machines only to 15 KHz. That's not to say that these recorders "brick-walled" at 15 KHz, but they were only "flat" to that frequency, after which the frequency response rolled-off rather rapidly. Also, the more tracks that an analog tape recorder had, the more difficult it was to keep all the tracks flat to 15 Khz dues to slight misalignment that occurs between each track's head gap.
On the low end, analog magnetic tape suffers from a technical problem called head fringing. This occurs generally below 30 Hz and is caused because of the relationship between the width of the head gap vs the wavelength of the ultra low frequency signal being recorded. So, most tape decks had little response below 30 Hz.
You can pretty much be guaranteed that any undamaged/un-worn vinyl record will have a flat frequency response (assuming proper RIAA equalization on playback) of from at least 50 Hz to 15 KHz, and often they will do a bit better.
I hope this answers some of your questions.
