33 vs 45 speed quality

I'm going to join with Plato here. My experience has been that when all other factors are equal, the 45 rpm release will sound better in almost every sonic category you can name, assuming your system is capable of resolving these differences. If you're not hearing a difference, you've probably reached the limit of what your current system will resolve (as Plato suggests). FWIW, I've previously offered some comments about my comparison of the Classic Records classical reissues at 33 vs 45 rpm. More recently, I've listened to a lot of the Analogue Productions 45 rpm jazz reissues comparing some of those to AP's 33 rpm reissues of the same recordings. The overall sonic differences between 33 and 45 rpm releases continue to hold true, with the 45 rpm versions being clearly better in multiple ways.

Please understand that I have hundreds of 33 rpm LPs that are sonically excellent and often outstanding. I'm simply reporting that my experience consistenly has been that an excellent sounding recording at 33 rpm will sound even better when mastered at 45 rpm. Two quick examples from the Classic Records reissues: the Rozsa/Hendl/Heifitz RCA LSC-2767 and the Stravinsky/Firebird Mercury SR90226. Both are excellent in their 33 rpm versions, but both are clearly better in their 45 rpm incarnations.

While I obviously disagree with Jaybo's assessment of the sonic differences between 33 and 45 releases, I do agree with his caveate about the music being interrupted by the short playing sides of 45 rpm LPs and the impact this has on the "magic of continuity."
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I've bought quite a few albums on 33 and then the 45 version when available. These are with various labels, but my comparison is generally within a particular label. In all cases I've found the 45 rpm to be significantly better. Any album that I really treasure I will always seek out a 45 if it's available.

Thanks for all your input. In truth I have not compared similar recordings in both 33 and 45. I guess I was expecting something similar with the difference from LP to Cd which was a BIG difference. The switch to LP was real eye opener. The fuss over amps and speakers seems to be absurd with a system with only CD playback when a TT is such a huge upgrade.

There are a couple of other aspects worth mentioning. The higher rpm does better with more highly modulated passages, offering more articulation in the bass and greater dynamic slam, and allowing the entire record to be cut somewhat "hotter", improving the S/N ratio. (Provided, of course, that your cart and arm can keep up and take advantage of it, as well as your phonostage.) Another difference, not necessarily an advantage, is that what background groove noise you do hear will be in a higher frequency range at the higher rpm, which subtly alters the perceived character of the listening experience vs. the same recording cut at the lower rpm. But perhaps the dominant difference in a lot of instances could be that the 33 and 45 rmp releases of the same material may not have been mastered together by the same people at the same time in the same facility, in which case all bets are off and there's no reason not to expect them to sound noticeably different.

Zaikesman...Interesting ideas about effect on surface noise. I'm not so sure about the "dynamic slam". We are agreement about remastering for the audiophile market.

Have you ever listened to a phono signal without RIAA equalization? (You do this with a microphone preamp). The bass is so severely attenuated in the signal that it is a wonder that anything useful can be derived from it. I think that some enterprising audiophile outfit should toss the RIAA curve and 33 rpm speed in the trash can, and start over with the understanding that appropriate (special) playback equipment is necessary to use the resulting vinyl product. A niche market.

The DBX vinyl records of several decades ago were like this (required a decoder box) and the results were excellent. The DBX system addressed every troublesome aspect of vinyl playback. Too bad that the system came out just when CDs were introduced. Were it not for CDs, we would be using the DBX system today...IMHO.