What makes the Bloom around instruments . . .

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).

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.

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 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

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