Having worked with a good number of master tapes, I might be able to help with the terms here.
Bloom: a function of harmonic distortion, part of a spectrum: neutral, warmth, bloom, thick or fat, bloated, muddy all describe distortion, usually lacking odd orders, so it is more of a coloration than an irritant (generally associated but with not limited to tubes). Odd-ordered colorations are harsh, chalky, clinical, bright, etc (generally associated with but not limited to transistors).
Thus an amp that is transparent will lack bloom (although it can sound natural), as transparency comes from a lack of distortion.
Holographic imaging is a function of soundstage. It comes from the ability to reproduce low level detail and maintaining phase relationships, so it requires wide bandwidth for the latter and low distortion at low levels for the former.
Transistors have traditionally had difficulty with retrieving low level detail, and so the slight ambient cues that exist around an individual image in a soundstage are less likely to get reproduced. This will give the image a 2D quality in the soundfield, and simultaneously cause it to stand out more. Newbee correctly identified this phenomena, although I would like to add that as the slight ambient cues that exist around each image get added, there will be the effect of a more 3D image, but also a more homogenous overall effect in the soundstage as the relative size of the 3D image will be larger than that of the 2D image of the same thing.
Tubes are better at doing low level detail, and so are more likely to have 3D images and greater ambient information, adding to the holographic effect. Any processing in the signal chain that is not part of the original recording can be regarded as a form of distortion, as most imaging systems rely on altering phase relationships to obtain 'holographic' effects. Tubes are not so great at keeping phase relationships correct, as often tube amps have less high frequency bandwidth, owing to the presence of an output transformer, but there are nowadays amps with wide bandwidth OPTs and of course OTLs :) that overcome this issue.
If phase issues exists at or very near the upper limits of human hearing, some interesting imaging effects can occur that seem to enhance the 'holographic' effect and I would not doubt that this has served as an inspiration to some processor designers! At any rate this accounts for why some tube amplifiers that are not great performers in the bandwidth department can have some apparently 'enhanced' imaging effects.
If there are no phase anomalies and low level detail is maintained, many 2-mic recordings will exhibit a height phenomena, which is a function of the mic placement in the soundfield.
Having master tapes so you **know** what the recording is supposed to be like is paramount to sorting this stuff out!
Sorry for the diatribe...
Bloom: a function of harmonic distortion, part of a spectrum: neutral, warmth, bloom, thick or fat, bloated, muddy all describe distortion, usually lacking odd orders, so it is more of a coloration than an irritant (generally associated but with not limited to tubes). Odd-ordered colorations are harsh, chalky, clinical, bright, etc (generally associated with but not limited to transistors).
Thus an amp that is transparent will lack bloom (although it can sound natural), as transparency comes from a lack of distortion.
Holographic imaging is a function of soundstage. It comes from the ability to reproduce low level detail and maintaining phase relationships, so it requires wide bandwidth for the latter and low distortion at low levels for the former.
Transistors have traditionally had difficulty with retrieving low level detail, and so the slight ambient cues that exist around an individual image in a soundstage are less likely to get reproduced. This will give the image a 2D quality in the soundfield, and simultaneously cause it to stand out more. Newbee correctly identified this phenomena, although I would like to add that as the slight ambient cues that exist around each image get added, there will be the effect of a more 3D image, but also a more homogenous overall effect in the soundstage as the relative size of the 3D image will be larger than that of the 2D image of the same thing.
Tubes are better at doing low level detail, and so are more likely to have 3D images and greater ambient information, adding to the holographic effect. Any processing in the signal chain that is not part of the original recording can be regarded as a form of distortion, as most imaging systems rely on altering phase relationships to obtain 'holographic' effects. Tubes are not so great at keeping phase relationships correct, as often tube amps have less high frequency bandwidth, owing to the presence of an output transformer, but there are nowadays amps with wide bandwidth OPTs and of course OTLs :) that overcome this issue.
If phase issues exists at or very near the upper limits of human hearing, some interesting imaging effects can occur that seem to enhance the 'holographic' effect and I would not doubt that this has served as an inspiration to some processor designers! At any rate this accounts for why some tube amplifiers that are not great performers in the bandwidth department can have some apparently 'enhanced' imaging effects.
If there are no phase anomalies and low level detail is maintained, many 2-mic recordings will exhibit a height phenomena, which is a function of the mic placement in the soundfield.
Having master tapes so you **know** what the recording is supposed to be like is paramount to sorting this stuff out!
Sorry for the diatribe...