This would be a great explanation if we were talking about the recording, but a bunch of folks here are not. They are talking about something that only exists in specific media. They are talking about feeling/hearing this "pressurization" before tracks begin, between tracks, even before the needle hits the record or the tape reaches the recording. They are hearing (we're not talking about deep bass or high spls here so I will now drop the "feeling") something that is inherent in the media when there is no recording present.
Above emphasis mine. No, not before the needle hits the record, only while the needle is on the record. Bruce touched on this in an earlier message.
I'm afraid it's not "room ambience that people characterize as pressurization," because in most of these cases, there is no room ambience present on the media when the phenomenon is heard. It is noise, heard as room ambience, characterized as pressurization. It's heard before the needle touches the vinyl? It's heard before and between tracks? This is all it can be. There is no other rational explanation.
In reading all of this thread, it's clear there are two different impressions of a pressurized room. The one that is a result of very low frequencies at high SPL can cause something like it (you feel pressure on your body before you hear it) but that's not what I relate pressurization to.
Actually, it isn't really even pressurization, it's a feeling of being captive in the sound stage. It almost pulls on you. One such cause is felt on a system with good controlled low frequency and phase response, that is playing vinyl, usually on a pivoted type arm which tend to boost and blend low frequency. The low frequency I'm referring to (and it's low, but also in the mid-range) is the noise of a very quiet groove wall. That is entirely vertical 'modulation' which places it out of phase left to right. It never becomes part of the music because it's not in the left-right sound stage, it sounds as if it's wrapped around the soundstage, and tends to enhance the way the sound stage is presented. The whole image becomes quite captive and makes you listen. If there are tick and pops or groove wall crackles also present, it seriously diminishes the effect. But a truly quiet groove has a very special sound.
Likewise, in some recordings which really sound 'close' to you, you'll experience that same captiveness, especially if there are low frequencies present that are the result of multiple instrument positions on the stage, and are very musical to other instruments. It takes a pretty high resolution system to reveal it. Add a solid groove wall sound to that and it really pulls on you. Using a single subwoofer will really detract from the effect.
I seldom hear this on vinyl any more since I've been using the Ortofon A90 on my ET2. It doesn't boost the low frequency information at all, so the groove sound isn't projected that much. But if I use my Zyx Airy 3 X SB, it starts to show some projection and is more captive in that range, but is not quite as clear as the Ortofon overall.
The presentation of R2R tape is a little different. LF is usually a little deeper and positionally correct, but there is also a component of hiss, which is a random noise in each channel, with no (or little) center channel coherence. You may not directly be aware of it, but it tends to 'wrap' the sound in a soft blanket which makes it sound more captive. Too much hiss and it's totally in the way and detracts from the effect. This also assumes a really phase coherent playback chain, especially in the speakers and room.
Since I've been using the B&W N801's, which are NOT time aligned (damnit), I don't hear either captivating effect as dominant as I have in the past, but it shows up occasionally.
I'm sure this won't make sense to some, but may ring some bells to others.
In one of my older systems it was so pronounced that I used to refer to it as 'walking into a picture' when you entered the room. Very striking.
--Bill
