How to read a source
Every recording here carries a source tag and a rating. This is what AUD, SBD, FM, Pro and Matrix mean, how I tell them apart, and what that 1 to 10 number really is.
The source tag is provenance, not a verdict. A great audience tape can beat a dry soundboard, so read the tag for where the recording came from and the rating next to it for my ear.
AUD (audience)
Microphones out in the crowd. You hear the room: the PA, the reverb of the hall, the people around the taper. Quality swings hard with the spot, the gear and the night. At its best it puts you back in the room; at its worst it is a phone in a pocket.
SBD (soundboard)
A feed taken straight off the front-of-house mixing desk. Close, clean, no air. The balance is the one the engineer rode for the hall, which is not the balance you would build for headphones: vocals can sit oddly, and effects added live in the room can go missing. Direct, but often clinical.
FM (radio broadcast)
Captured off a radio transmission. The broadcast itself is usually a professional mix, a desk feed plus ambient mics, so FM often sounds balanced and easy on the ear. The tells are radio compression, the occasional station ident, and sometimes an incomplete set or fades between songs.
Pro (professional)
A professional, usually multitrack recording made for an official release, a DVD or television. The cleanest, deepest sound. For video it means a proper multi-camera pro-shot, not a phone in the stands.
Matrix
A blend of an audience tape with a soundboard or broadcast, mixed to keep the clarity of the desk and the air of the room. Done well, it is the one to beat. It is its own category, not an AUD and not an SBD.
The grey zones
The hard call is FM against SBD, because a broadcast is built on a desk feed, so FM can sound like a better soundboard with atmosphere. If it came off the air, it is FM; a raw desk that never went to radio is SBD. SBD against Pro is a raw two-track off the desk versus a properly mixed multitrack. And a matrix is the easiest of all to file wrongly as one of its parents.
How I classify
Lineage first, ear second. I go by what the Info.txt and the taper declare: a microphone means AUD, a desk or console means SBD, a named station or "broadcast" means FM, multitrack or pro-shot means Pro, a stated blend means Matrix. The ear is for verifying, or for the rare case with no paperwork at all. When the source is genuinely unclear I leave it unknown rather than guess, because the whole point of this archive is that you can trust the tag.
The rating
The rating is mine, and it is the only quality mark here. The number from 1 to 10 next to a recording is my own listening judgement: how much I enjoy putting it on, everything weighed together.
I do not hand out an "objective" grade, because nobody can grade a live recording objectively. One collector's ears are not another's.
A tape can be clean and still rate lower if it leaves me cold, or rate high in spite of its flaws because it captures the night. Higher means I reach for it more often.
Take it as one ear, then trust your own.