33 vs 45 speed quality

Zaikesman...My view about DBX records is biased, in that I actually have some. (But the decoder died about ten years ago and I have never fixed it). It is too bad that I can't suggest how you might have this experience. The audio quality is superb, but the catalog was tiny, with few well known artists. Although modern high end cartridges are "capable of tracking..." distortion (short of outright mistracking)is very much a function of modulation amplitude, and limiting dynamic range (of the groove) is very desirable. The electronic reexpansion process may not be perfect, but has much less distortion that that which would occur if the cartridge had to track the uncompressed groove.

Master tapes made before the days of Dolby and DBX were still compressed...manually by the recording engineer (called "Gain Riding"). This avoids peak overload while allowing higher recording level for quiet passages so as to minimize tape hiss. But with this manual compression the results varied according to the engineer doing the recording, and so could not be effectively reversed on playback so as to restore the original dynamic range (although there were expander electronics that tried). By precise control of both the compression and expansion algorithms DBX and Dolby can do the job without audible problems (eg: "pumping").

Eldee, I think we might be blurring a few different topics: Compression (or gain-riding) applied during the recording, mixing, or mastering processes for artistic purposes (to enhance the desired sonic effect); compression (or gain-riding) applied during the recording process for technical purposes (to prevent overload during recording); and compression applied during the mastering process for technical purposes (to prevent overload during playback). And then there's compression applied during radio broadcast for both technical and 'artistic' purposes. I view all of these as being different from complementary compression/expansion, which are mainly used during recording as part of noise-reduction schemes (Dolby A, DBX) and aren't supposed to limit the dynamic range of the resulting master tape (though it may still undergo compression when mastering the record, or CD for that matter). There's also the rather arcane distinction between peak-limiting and compression, which as far as I can tell seems more of a definitional, quantitative one than subjectively qualitative. Anyway, I agree that most recordings we listen to, audiophile pressing or not, probably make use of compression for at least one of the first two reasons I listed at the top -- compression and EQ are the best friends of the recording engineer, producer, and mastering engineer.

Zaikesman...You have come up with so many ways that compression is used that, contrary to what we often see stated, it must be a good thing!

I don't think that Peak Limiting is arcane...it's just a gain reduction that is applied only when the signal exceeds some high value. So almost all of the time it does nothing, and, if the setup is correct, it only activates when your amplifier was about to clip. I think that even audiophiles can endorse this.

Since we're already this far off topic...Until I bought my Alesis MasterLink, which performs both compression and peak-limiting, I probably would've described peak-limiting the same way you have. Apparently, I hadn't thought about it a lot in relation to compression, technically speaking. The compressor has all these adjustable parameters:

Threshold (level relative to full-scale 0dBfs the compressor begins to affect the audio)

Ratio (of input level to output level of the compressed audio)

Make-up gain (applied after the compressor to compensate for the level lost in the compression process)

Attack (time the compressor takes to begin affecting the audio after it's risen above the threshold)

Release (time the compressor takes to stop compressing the audio after it's fallen below the threshold)

Knee (controls the way the compressor behaves around the threshold by varying how quickly it ramps up to the full selected compression ratio -- a "hard" knee applies the full selected ratio at the selected threshold level, while "softer" knees progressively take effect beginning a selected number of dB's below the selected threshold level, increasing the applied ratio until at some level *above* the threshold it is fully equal to the selected ratio)

There are also controls determining whether the compressor is keyed to peak or RMS input levels, of the left or right or both channels, plus for what the meters measure. Fancier compressors than this one can have multiple frequency bands of compression per channel, each with independently variable parameters.

The peak-limiter in the MasterLink doesn't have all these adjustable parameters (just Threshold and Release, plus an adjustable Output level control, for if you want to preset the maximum output at something less than 0dBfs; make-up gain is applied automatically, equally and in opposition to the selected threshold level), so it's simpler to use. And because it's all-digital, it's able to "look ahead" and begin progressively reducing gain in advance of a peak exceeding the selected threshold (similar to the Knee control, but fixed), for a smoother dynamic compared to traditional analog peak-limiters. But conceptually speaking the two functions involve all the same processing.

According to Alesis, a traditional peak-limiter "is typically thought of as a compressor with a high ratio setting". Due to the look-ahead feature of theirs, they say it functions with essentially an infinity:1 gain-reduction ratio. (I presume the attack time must also be fixed at zero and the compressor keyed to peak level for both channels.) In other words, any signal exceeding the selected threshold level at the input is held to that threshold level at the output -- and that threshold level could be either high, low, or anywhere in between. So peak-limiting is compression with less potentially varied, more narrowly defined behavioral parameters.

Csmithbarc: Sorry man, I'm done! :-)

Csmithbarc, despite all the somewhat off topic discussion, I would have to say that I have not done one comparison of 33.3 and 45 rpm recording where the 45 was not clearly superior. This has caused me to invest hundreds of dollars in duplicates where 45s are available.

If you have friends with vinyl capability, I would visit them and compare 33.3 and 45s there, but beware, if you much prefer 45s, as I do, getting a resolving system and buying many 45s, some of which are out-of-print, is expensive.