What makes the Bloom around instruments . . .

one rarely hears "bloom" from a recording done in a studio.

I believe that this is one of the reasons why as the quality of recordings made outside of a studio and the low level resolution of my system have both improved, I find myself drawn to "remote" or live recordings, warts and all. Of course the interaction between audience and artist also improves the emotional aspect of the performance, adding to my enjoyment of those recordings. But then again, I am not an analytical listener.

Frogman and Swampwalker, love your additions to this conversation! I agree, Swampwalker, that one rarely hears "bloom" from a recording done in a studio. I think this goes a long way towards explaining why it is present on some recordings and not others. Good concert halls are of course designed to get the maximum "bloom" from the instruments and voices performing in it, whereas the recording studio is designed so that the recording engineer can make the recording sound how he wants it to - they are generally quite dead, and therefore usually kill "bloom." This is why so many studio recordings have that fake reverb added, to try to get some of that quality back, very unsuccessfully.

Byron,

I didn't think that you were. There had been a lot of posts talking about the XA30.5 and I was trying to clarify to everyone that in no way was I referring to the XA30.5 as anything other than having that magical Bloom that I really liked and want to have again.

I think that I unintentionally led some posters off of the question that I was asking about the Bloom by mentioning the XA30.5 by name.

Chuck

My question really didn't have anything to do with the quality of the XA30.5, only the Bloom that I got from it.

It probably would have been best if I hadn't mentioned the amp. I did it, not thinking, because that's where I had the Bloom and I really liked that part of the sound.

I didn't take you to be questioning the quality of the XA30.5, and even if you had been, it's no big deal. Nothing is perfect, and it's just stuff anyway. ;-) My comments were intended to offer the perspective of a person familiar with the XA30.5, not to defend it from any possible criticism.

FWIW, I'm guessing that the bloom you heard with the Pass amp in your system was a consequence of its interaction with other components, rather than being an intrinsic characteristic of the amp. But that may be academic at this point.

Bryon

Bryon,

No absolutely nothing else changed other than removing the Spectron and puting the Pass in its place.

I don't disagree with you, my result with the XA30.5 seems to be contary to everyone else in the whole world, look how the reviewers rave about it and the awards it's getting. My question really didn't have anything to do with the quality of the XA30.5, only the Bloom that I got from it.

It probably would have been best if I hadn't mentioned the amp. I did it, not thinking, because that's where I had the Bloom and I really liked that part of the sound.

All that I'm searching for is to have that Bloom added to everything that I'm getting right now from the Spectron, if that is possible.

I'm very fortunate to have arrived where I really enjoy sitting down with my system and listening to my music.

I've gotten here with the help and guidance of Roger Cullen (Irish65), Peter Israelson (formerly of Star Sound and the engineer who upgraded my speakers and built my crossovers) and Craig Hampel (an associate of Geoff Poor of BAT and the designer of the Running Springs HZ Crown Jewel power cord and owner of CH Acoustic).

The Bloom would be the cherry on top of my fully decked out hot fudge sundae.

Chuck

The XA30.5 had a strong bass and good high frequency extension, BUT, the instrument that was so prominent that it was masking everything else was the drums.

I have never heard an effect like this with the XA30.5. I don't doubt what you are hearing, but I'm wondering if there's some kind of unhappy interaction between the amp and outboard crossovers/speakers that's resulting in a skewed frequency response.

On the other hand, when I think of drums overpowering other parts of a recording, I usually associate that with room modes. But presumably you would hear the same room modes with the Spectron amp, so I don't know what to think. I assume you did not change the position of the speakers when you changed amps.

Bryon

I also agree with Frogman's description at the global level. Composer's such as Scriabin and Bruckner reveled in the sonic soup.

Now, here comes the controversial part. While resolving low-level detail is part of it (and I've gone off the deep-end to achieve this), the components are a big piece as well. I say controversial because terms such as neutral and colored are like audio philosophy and religion.

In my experience, if one takes a highly conductive, low gauge wire to transmit power or signal, the result can be sterile, a black background, and an artificial leading edge with truncated decay. For some reason, fine-gauge, multi-stranded conductors of silver, gold, and platinum just sounds real. I will admit that this is altering the signal, but the means justify the ends. Same with tubes, because if you can create a real and intoxicating sound with juicy and dimensional detail, then a system will satisfy on an emotional level.

While trying to nullify weakness by combining different components can be a slippery slope with potential dead ends, combining strengths will open new possibilities.

Bloom cannot accurately describe a drum or cymbal's.So it can't be used for all instruments.

Frogman's description of bloom and the sound of real instruments in a real performance is awesome. Great stuff!!! I'd just like to add that these qualities are rarely present in a studio recording. It does not have to be "live" recording but if the recording is built up instrument by instrument in a conventional studio with all its acoustic treatments, its unlikely to be present. IMO, this is one of the ways that most people can immediately distinguish between a live performance and a reproduction, even when heard from some distance away.

When an audio product can't separate each individual instrument,singer,or other from each other,that would be the opposite of being articulated.When your system and recording is highly articulated,you should be able to identify everything separately,with it's bloom,and other sonic characteristics,as you would,if listening to it live.I still think someone that isn't familiar with the terms used,would be easiest to compare two products,one that has the quality,against one that lacks it,possibly with someone there to point out where the difference is on the recording.Another way would be to have a recording made by an audiophile with a short cut of music(10 seconds?)with it lacking in it(bloom),against the other that reproduces it good.Without Knowing some of these characteristic's,it could be easily confused with some other descriptive term.At least,that's my two cents worth.I didn't see the Stereophile's full list of them,to see how good they did at trying to make it understandable.

I guess that a more specific explaination is in order here. It seems that there's a lot of confusion with what I said or how I said it.

In my system, with my Wadia S7i directly feeding the Pass XA30.5 via $5,000.00 interconnects, then out to my $15,000.00 custom modified speakers and Duelund outboard crossovers via $6,500.00 speaker cables, the Pass XA30.5 was heavily bloated whereas the Spectron Musician III Mk2 was precise.

The XA30.5 had a strong bass and good high frequency extension, BUT, the instrument that was so prominent that it was masking everything else was the drums.

I said that the organ was masked and I couldn't hear it because I play keyboards. I know that the organ is in the song. But the organ was not the only thing missing or covered over by the drums. The quiet guitar parts at the end of the song were also unheard. Everything besides the drums was a lot quieter and covered up due to the drums being so prominent.

The only time that I heard the Bloom is during quiet or non-complex passages. During complex passages the drums were smacking my head against the wall.

Also, I don't listen at very loud volumes. I'm in a 10' x 12.5' room with the speakers 4' from my ears. I have the dip switches on the Wadia set to attenuate the output by -18 db so that I can open up the Wadia's volume to the recommended level without blowing my ears out.

I'm not saying anything against the Pass other than what it was doing in my system in my room.

Chuck

I don't have anything by Dire Straits to hear that particular organ with the Pass XA200.5.

But I would say that the organ and choir at the end of Mahler #2 would leave you speechless and sobbing uncontrollably.

Hello,
Frogman that was an excellent description of what`s called bloom. It`s most certainly a function of harmonic overtone/fundamental tones and when captured is utterly beautiful. It makes music sound more realistic,thus less canned and sterile. It is a reflection of a component`s noise floor and ability to retrieve low level detail/resolution. How the Pass amp can do this well yet bury the organ in the musical track as the OP stated seems very strange, as preserving the bloom quaility is the more elusive trait.

Pardon the night grammar.

I grew up in the tube days,and there are descriptive words that are being used now,that's different from what I've learned.The best way that I know of on how to describe a lot of these words that are used,is to have two different amps,one that has a lot of the characteristic,the other, very little.This was how I learned them,hanging around audio stores,since I was little.Basically it captures all the warmth,timbre,air,and the 3d imaging,full body of an instrument,hardly anything lacking.Upper end SS amps do capture more of it now,but not quite as much as a tube amp does,at least in my opinion.I may be wrong on my description.Threads like these are hard to post on,because the way the descriptions seen to very more and more.A person that's fairly new to audio,will start using these descriptive words,on what they think they are,and it may very.One audio dealer(in hi-end),that was around since the tube days, caught me of guard.He asked me this when tube amps started returning,what does the word liquid mean,that you tube amp guys tend to use.He asked me,because he knew I wouldn't embarrass him.It took a while,but I came in there with an old Dynaco(full of liquid),a old Nad(dry),and a couple of old recordings that had some instruments that were recorded on gear,that was real liquid sounding.He got it right from the beginning,just nobody ever compared it to him.He said he felt dumb,and seem embarrassed,should have known,but was relieved to know for sure.He was familiar the sound difference of it,but didn't want to use that word until somebody assured him.

Let's take our audiophile hats off for a moment, and ask: In general, what do we usually think of when we hear the word "bloom"? Speaking for myself, I think of a flower. When a flower blooms, what does it do? It radiates in all directions. In music/audio, that is exactly what "bloom" means. It is the sense that the sound of a sonic image radiates in all directions. It creates a sense of dimensionality, with an audible sense of the sound projecting not just forward, but also sideways, and to the rear. Additionally, contrary to the audiophilic quest for the elusive "black space between images", there is a sense of great energy in those spaces; rich with the overtones, and undertones of each image.

That is what happens when an acoustic musical instruments play in a real space. Their sound is projected in all directions. The fundamental tones, and overtones (harmonics) of each note that is played create "difference tones". These difference tones are the result of two notes (frequencies) creating a lower tone, which is the difference in frequency of the two original notes. This process is repeated a practically infinite number of times in the course of a musical performance, creating an incredibly complex sonic soup. The ability of a component to pass that much information through is also referred to as the ability to resolve, or pass low level information. However, "bloom" is not a quality that a component should bring to the table. True bloom is something to be retrieved from a recording. The test is simple: If all recordings sound "bloomy" through a given component, that "bloom" is a distortion. Recordings are subject to the limitations of the equipment used to make the recording. In other words, not all recordings have "bloom". Some were recorded in a way, or with equipment, that will sound really flat, and two dimensional, with little sense of the expansion of overtones; without any "bloom". But the great recordings, when played back on equipment that can resolve that subtle low level information will sound, as we all know, fantastic.

Fool,

If the Pass amp kills the organ on the DS song why would you want to hear it? =8>D

Chuck, the quote you posted from Rtn1 is as good a description of the quality called "bloom" as I have ever read (though as Elizabeth said, many call it "air," an even more vague term). To me, this is one of the most undefinable of all audio reproduction factors. I think a combination of elements contribute to it - Elizabeth, Noble, Bryon, Baranyi, and others all made good comments on it. To me, these factors add up to much more than one term could describe, but if some want to call it bloom, so be it - it has to be called something, if we are going to discuss it. For me, and for many fellow orchestral musicians, this is one of the most important qualities of sound reproduction - this bloom factor goes a very long way towards determining how "real" a system will sound. Digital and solid state have a very hard time reproducing this particular quality of instrumental and vocal timbres - as I have said before, I think it has a great deal to do with how much of the harmonics/overtones of/in these timbres are reproduced.

I have never heard one of those Pass amps - I would very much like to someday.

Went for a listen to the song mentioned and my AS S30 made the organ plain to hear. If the Pass amp kills the organ then I have struck gold.

i think bloom represents a balance between fundamental and harmonics.

using a violin or acoustic guitaras an example, bloom would exist when the wood body of the instruments was present as one observed the plucking of strings.

i don't think bloom is a treble phenomenon but rather what happens in the upper bass/lower midrange.

I don't think either the spectron or pass amps have the frequency response characteristsics i have described, i.e., i think that both amps have a transistory sound.

i have heard the spectron driving the analysis epsilon. the sound was somewaht thin.

i have owned a pass amp, but not the one discussed here.
i have heard the pass x series amps at ces.

i doubt any solid state amp can "produce" bloom.

i think classic tube products are more likely to be associated with the term "bloom", as i have described it than either current generation tube or solid state.

it could be that the pass amp is more linear in its frequency response than the spectron, which sound a bit peaky in the treble.

keep in mind my experienece listening at home is panel speakers, including quads (esl and 63s), magnepan (1.65 and 2.7) and magneplanr 1 bs.

Bob,

You're right about my setup. The only difference between the Pass and the Spectron system was just the amps, everything else was the same.

As far as the Spectron goes, I've not heard another amp that has matched it. My personal list of the high-end amps that I've had in my system over time is:

1. Krell
2. Musical Fidelity
3. Herron
4. Karan
5. Burmester
6. BAT
7. Pass
8. Spectron

These are some pretty heavy hitters, but you're right about something more important. Because I've played music all of my life, I'm used to picking songs apart instrument by instrument as if I'm learning them.

I enjoy hearing what each musician is adding to the song rather than sitting back and just enjoying the song. That's what I couldn't stand about the Pass, I knew that there is an organ in Dire Straits "Industrial Disease", but with the Pass, it was washed out.

I know that if I played the organ in that song, I'd want people to hear what I contributed to the song. I don't think that I'm alone in my listening preference, and I also realize that many people want to just enjoy the song as a whole.

Given my listening preference, if I have to give up the Bloom in order to keep the detail, I'm much more comfortable doing that and knowing that it was my choice. I was just hoping that there was a way to have my cake and eat it too, and I'll do as much as I can to get there, if it's a place that I can get to.

Chuck

Did you ever think that the "digital" Spectron amps, although very clean and detailed, are just not able to recreate the natural bloom of an instrument because of their digital nature? I know the good digital amps I've heard, and I've heard good and bad, can sound very nice, but they don't sound natural to me either,and I doubt that I could live with one for very long. Too analytical for my taste's, though they seem to be getting better as manufacturers improve the technology.

I always attributed good bloom to good room treatments and speaker placement. But since the only thing you changed was the amp then I assume your room is set up to allow the bllom to radiate, if it is there. It could also be partially a simple cable mismatch with the Spectron, or a power conditioning problem. But I suspect that it's more in the nature of the 2 amps.

Krell_man do you live any where near NYC? Let me know.

Thanks to everyone! Now my heads spinning trying to explain my thoughts about what the Bloom is to me.

I have a soundstage that is detailed, wide, deep and layered. I think that the Bloom that I'm wanting is the glow or highlighting around each instrument. It does seem to be highlighted by a blacker void around it, which brings out even more minute aspects of the tones, making it more realistic sounding.

It sounds like you've all got me seeing that the most important ingredient is lowering the background even more to let the micro pieces show themselves first. Then maybe enhancing it further if I need to with either mods or upgrades.

Thanks again to everyone!
Chuck

Rob (Rtn1) posted this to my system accidently and has asked me to move his thoughts to this post, if some of you don't know Rob, he is one of the ultimate audiophiles on Audiogon.

"Hi Chuck,

If one deconstructs a single note played on an acoustic instrument, such as piano/violin/cello, the concept of bloom can be better understood. As the musician transfers mechanical energy into the instrument, the body goes from rest to vibration. This transition is the leading edge of a note. The note will then reach its peak, and evolves depending upon how much energy was used. The evolution is due to individual parts of the instrument interacting with one another, to reinforce or cancel the vibration. This results in a complexity of sound and hue that is still part of the main vibration. Next, the instrument will come to rest, and the note will decay and fill the space of the hall.

The brain processes all this information and passes judgment as to whether it sounds ‘real’. If the leading edge or decay is too short, or if the evolution is too simplistic, the result is mechanical, analytical, fatiguing, etched. If it does not have the correct decay, the result is the dreaded black background. If the leading edge or trail is too long, the result is syrupy, hazy, boring. If these elements are correct, the sound is natural, and has a paradoxical detail. The detail is a sense of roundedness, texture, depth, and a floating sensation. Because the brain perceives the sound as natural and right, it has more agreeable detail compared to the analytic sound described above.

What is the basis of this natural sound? As others have surmised, part of it is recorded and part of it is introduced by components and cabling. I no longer understand the concepts of neutral, colored, distorted, etc. The goal is to have a sound that is real and right. Just as with a great dish, it takes many ingredients.

You are correct that the Pass XA.5 has this element. That is why I believe this amp is so special. I do think there are other ways there.

1) Tubed preamp ($$$$): Lots of good choices out there. Less if you wish to run balanced, which I recommend because of the Wadia. I believe this is the most important missing piece in your system. I also am convinced that at a volume level <90, the Wadia suffers from lack of detail and dynamics.
2) Jade Audio Cables ($$): JD uses fine gauge, multistranded gold and silver wire to create this bloom. His cables are all about that natural bloom, and I have yet to hear a IC or SC that does this better. His cables are close to adding a tubed preamp, with none of that syrupy mid, rolled treble, or muted bass.
3) NVS Sound Power Cables ($$$): Nathan is using some very special wire and techniques to create this decay and sense of space. You should speak with him and describe what you need.
4) HiFi Tuning Gold Fuses ($): I tried the silver fuses, and they were mechanical. The gold ones are just right in my system.

Best of luck on your new obsession. This element has been my obsession for the past year."

Chuck

That definition of bloom by J. Gordon Holt correlates perfectly with Baranyi`s experience with his father`s violin comparisions.This presence of bloom is real and I`m aware of it when listening to live acoustic instruments be it a concert or friends practicing(piano,guitar,horns etc.)A good recording can capture some of this quaility and very good systems can reproduce it in your home. Based on the OP`s descrition aboveit seems the Pass amp has superior low level resolution/lower sound floor that`s allowing him to hear the natural bloom. The Spectron amp for what ever reason is`nt as resolved despite it`s other apparent advantages.

I have, with the Atma Sphere S30, what Holt's take on bloom is in my system. Having lost it with a SS amp/tube pre I went with the AS amp and recovered it.

From multitude owners of TRL SS amps I have been told that if brought into my system I would not lose that bloom I have with the AS amp.

I was convinced that a SS amp will not produce that bloom a tube amp can deliver. I hope to be wrong.

When I do get the SS amp in my system the AS amp will sit by and wait for the verdict.

My definition of 'bloom' is very close to Holt's/stereophile's listed in Bryon's post. I would describe it as a warm,euphonic sound quality that doesn't sacrifice or mask details. I like the earlier poster's analogy of a topograhic map of the music -very descriptive. If Chuck is looking for a warmer. more euphonic quality, then I would suggest trying a tube preamp (I don't see one on his system page so I'm assuning he's using the Wadia).
I may be totally wrong, but I thought you needed tubes somewhere in the signal path
(tubes in a cdp,preamp, amp,dac or even a line buffer) to introduce any 'bloom'. I was seeking this special quality in my system a few years ago and added a tubed preamp to replace a ss. It worked immediately. I replaced the stock tubes with NOS Mullards a year later which added a touch more magical 'bloom'. I'd even like a bit more if it comes in a powerful enough ss or digital amp to drive my inefficient speakers. So, based on your comments above, I might try out some other ss and digital amps.
I'm always learning new things from the guys and gals on Agon and just wanted to say I appreciate your knowledge and time. But I didn't want to hijack this thread. Chuck, did any of this and the above help you?

bloom: A quality of expansive richness and warmth, like the live body sound of a cello.

-From J. Gordon Holt's Stereophile audio glossary.

This is what I thought Chuck meant by "bloom." Maybe he can tell us.

Bryon

I also think Chuck's speaker cables and such are more resolving than your anti cables. So maybe more details/resolution are heard in Chuck's system.

Hi Joe. This is certainly possible, though I don't know that it effects the likelihood of either scenario I described in my last post.

I suppose there is an argument to be made that Chuck's system, if it is more resolving, might reveal characteristics of the XA30.5 that are inaudible in my system. But I have a hard time believing that any additional resolution would reveal "bloom" as a consistent characteristic of the amp. I could be wrong about that. I also could be wrong about what Chuck has in mind when he uses the term "bloom." It seems there is some difference of opinion about what that term means.

My description of the XA30.5 is based on hearing it in two different systems (mine and a friend's). I have also heard other Pass amps from the XA.5 series in other settings, including some systems that are very revealing by any standard. It is on the basis of those experiences that I have characterized the XA30.5 as "neutral," rather than having "bloom." Of course, other people familiar with the XA30.5 may have different experiences and different opinions, which I am certainly open to hearing.

Bryon

I have been listening to the exact same Spectron you have for well over a year now and can tell you,as a former tube amp owner (BAT and Cary) that regardless of what reviews might say,or shall we say,reputation beckons,this amp has little to share with valve topography.Yes,topography,as in the multi dimensional relief of any surface,in this case the music as read by this amp as opposed to a tube amp.I understand what you mean by tube bloom and you will hear this on the Spectron,or something close to it,when a specific recording exhibits a magical,spatial quality and you are hearing the room the music was recorded in as the music hangs in the air.It really is one of those very special tinkerbell moments when you hear that and that is why this amp is so bleeping cool! Providing all the other stars are aligned in your system the Spectron is the mirror image of the recording and it's brilliance and downfalls.Yet it does one thing very,very well-it makes everything sound good and the great,well magnificent.
You know i miss that tube glow like a warm cat on your lap and i may return to it for the occasional fling, but i believe the Spectron will be my Pegasus.
May i suggest you investigate the Remote Sense cable option the Spectron affords.This will take you further down the path of better sound and instrument isolation and added topography.This is a must hear.

So bloom is being described more or less a type of glowing/radiating, of the air/sound around each instrument, not a tonal color variation?

I agree with Elizabeth, I think you've got it right.
I have more bloom using a really really good passive now, and with better hot rodded power filtration units. I think a lesser preamp can not get the bloom resolved also...

RX8 I have heard this sound. My father played the violin and would demonstrate the difference between a good instrument and a great one. The better instrument had a glow to the sound that was irrestible. The inferior instrument would just play the notes. Hope this helps. Bob

Define bloom. Different components can introduce attractive sonics to a system that some may call bloom. Some CJ components to me have bloom. I have also heard very good designed preamps introduce a more attractive sonic signature that some may call bloom but not the CJ sonic signature. For example, direct heated tube preamps, transformer coupled preamps, CDPs, DACs have a sonic signature that is very attractive but I would not call that bloom IMO. I have owned the Pass X-250 (not the .5 series) and that amp had a sonic signature that was sligtly softer with a kind of golden sound. To me the amp was trying to sound what some would say is a tube sound. They may be right. That is probably what you are hearing with the Pass amp. The specton will offer a clearer sound without that golden sound. That is probabaly what you are hearing. Rx8man is hearing some a very good preamp in front of his digital amps so he has a more attractive sound versus what I would call "bloom".

So I think the attractive sound comes from a components design.

Hope this was helpful.

I run a 6SN7 preamp in front of a pair of digital monoblock amps and asked the same question.

Secondly, has anyone really heard bloom in a live amplified/un-amplified performance ?

Bryon, I also think Chuck's speaker cables and such are more resolving than your anti cables. So maybe more details/resolution are heard in Chuck's system. Your two systems and rooms are different. Just a hunch, what do you think?

Thanks for all of the responses. It makes sense.

Since it appears that it's a product of either my AC, Spectron or both, that's where I'll start to look.

It can't be the Wadia S7i since the bloom was there with the Pass but not with the Spectron.

Chuck

I own a Pass XA30.5. To my ears, it sounds pretty neutral. I'm not doubting you about the difference in bloom you heard between the Pass and the Spectron. But I am wondering whether the difference in bloom is attributable to something that the Pass amp ADDS or to something that the Spectron amp SUBTRACTS. Here are two possible scenarios:

1. The Pass amp ADDED bloom to the system, whereas the Spectron amp did not.

2. The Spectron amp SUBTRACTED bloom from the the system, whereas the Pass amp did not.

I don't know anything about the Spectron amp, other than its excellent reputation. But as an XA30.5 owner, I can say that it does not seem particularly additive, at least not in the way I associate with descriptors like "bloom," which makes me think of euphonic harmonic distortion. This observation about the XA30.5 is confirmed by Stereophile's measurements, which show that its harmonic distortion is mostly 3rd order, and that it is otherwise rather harmonically neutral.

In light of that, I am inclined to believe that scenario (2) is the more likely of the two, and that the Pass amp's advantage over the Spectron was that it was allowing the bloom from the recording, or from other components, to be heard, while the Spectron was masking it. Of course, this is speculative.

It would be interesting to hear more about the system used to audition the two amps.

Bryon

Kell_man,
I get that same 'bloom' you refer to when I use my Burson integrated. I don't feel it's distortion but the amps ability to pick up that last bit of info off the recording, intact, and sending it along to you speakers. That bloom is specific, and independent of everything else on the recording so it can't be distortion since its image and placement specific and nothing else is displaying it.
A very well regulated power supply can be the answer or if you believe what Burson says (and I do), being an all discreet design of high quality doesn't hurt.

I would say that it has to be captured in the recording too.An amp can't make it if it isn't there,in the recording.With a good recording,then the amp and speakers and rest of the system has to be able to reproduce it.Over the decades in this hobby,my big complaint is the recordings.I listen to music that I don't really like at times,because they did such a great job of capturing it.There's nothing more disappointing to me than buying some new music I heard on the radio or somewhere,and get a bad recording.It just happened to many times.I think it would be great if these engineers that do a great job at this,would start a school for other recording engineers,so they could learn how to do a better job at mike placement,and whatever else it takes to get it done right.

I always thought that "bloom" was associated with tubed amps and not digital (Spectron) or ss (Pass) amps. Its my undertanding that when tube amps distort they produce even order harmonic distortion which is percieved by most people as pleasant and musical- bloom?. When ss and I believe digital amps distort, however, they produce odd order harmonics that most people percieve as unpleasant and unmusical-grain?. I think Nelson Pass would try to reduce odd order harmonic distortion in his amp designs. But I doubt if he would, or could, introduce even order distortion to them. But I wouldn't put it Passt him(sorry but pun, unfortunately, is intended).

Elizabeth, I agree with your comments generally, except that I would say the amplifiers are not able to process the fine signal properly because of weaknesses, or problems, in the amplifier and its interaction with other components. Eliminate those weaknesses, and the amp will do its job fine.

And "general background haze" is just one of the audible indicators of, or ways of describing the unpleasant, low level distortion that seems to afflict most systems.

Frank

For me, "Bloom" is just lower levels of unpleasant, low level distortion, which your ear has to try to ignore so that you enjoy the music. Virtually all systems inject a decent amount of this distortion, that classic dealer showroom "in your face" hifi quality has high levels of such.

The power supplies of Class A amps have a far easier job to do, so if all else is equal there will be less of this distortion, and more "Bloom".

Frank

Without looking into the tech details of your post I would've answered 'Skills and spirits of musicians'.

The Pass is class "A"