Class D Technology

Kijanki 11-21-2016
One can argue that this phase delay might be beneficial since many speakers have positive phase shift at these frequencies.  I don't have data for my speakers, but I picked one of the speakers reviewed by Stereophile.  As you can see on the phase diagram (dotted line) speaker actually accelerates phase at the highest frequencies.  Phase delay caused by the bandwidth limit of my amp would improve summing of harmonics (Al, am I missing something?).  

No, I don't think you're missing anything, Kijanki, and that's an interesting point.  As is frequently the case it's possible that non-ideal behavior in one part of a system can to at least a loose approximation offset or compensate for non-ideal behavior in another part of a system, and turn out to be subjectively preferable.  And it is true that dynamic speakers in particular commonly have impedances in the top octave or two that are inductive, meaning phase angles that are positive.  On the other hand, though, there are of course many other factors besides impedance and bandwidth that contribute to a speaker's overall time domain performance.

Best regards,
-- Al
 

BTW has anyone ever noticed a reviewer complain about phase shift when reviewing gear at a show? They can find all kinds of faults but seldom if ever that. Are they not listening right or is it just not there? Gotta wonder.....

You see them writing about it all the time. Don't look for them to use the expression 'phase shift' though. Look for them to talk about the soundstage, how deep and expansive it is. That's one indication (but not the only one).

The thing is, you can build an amplifier that only goes to 20KHz or so that can still sound pretty good (lots of SETs only go that high). The effects of phase shift are more subtle but they do exist. So you might be happy with what you have (which is good) but ultimately its all in comparison to what, and if you've not heard that 'what' then you just don't know how much better it can get. That's why many people listen to boom boxes. They just don't get how much better it can be.

Companies such as Devialet are creating hybrid AD Amplifiers. In theory, that could be the best of both worlds with sound & efficiency. Are the hybrid amps subject to the same issues with phase & bandwidth?  

Wading through this discussion, I found myself reminded of the late neurologist, Oliver Sacks. He was, as I’m sure you all know, hugely interested in music and how we experience it. He was an enthusiastic devotee of the music of Johann Sebastian Bach, and was pretty indifferent to the music of Beethoven. He volunteered for a brain-scan to see how he reacted to the music of each composer, and the results showed that Bach noticeably increased his brain’s activity, while Beethoven showed no such effect. http://mentalfloss.com/article/23288/inside-oliver-sackss-brain-he-listens-music

I mention this because what I’m taking away from this lively discourse (apart from the technical details which is mostly beyond me) is that we all have our innate preferences. A sound that lights one person’s candle might have no effect at all on another, and some of these sounds might be actively irritating to a few. Our ears and our brain-wiring are all different, so what appeals to one group of us won’t appeal to another. Hence our differing preferences for and reactions to various classes of amplification.

Personally (and I’ve alluded to this subject in my review of the Wyred4Sound reclocker, q.v.), as a professional musician, I like to be "inside" the music, that is, to be able to discern its details and building-blocks, but I still want the overall sound to be pleasing (musical) enough to be enjoyable. It’s a balancing act. As stated in my previous post in this thread, my ARC STi200 achieves this for me. It might not for you, though, which is fine. I’m not a tube-person, but I certainly can see (hear) why this sound appeals to so many of you. Would be very interesting to see what MY brain looks like on music.

atmasphere, I’ve pretty much heard it all , including Atmasphere amps.

phase shift is just one factor that might acount for an expansive soundstage. You can’t equate the two or infer a large soundstage necessarily means phase shift being heard. if its truly phase shift that is there and not being mentioned then the reviewers need to go back to school perhaps.

For example, my setup has expansive soundstage only on recordings made a certain way conducive to that. on others it is quite the opposite. So there is no evidence there of artificial effects of phase distortion that would persist constantly. Certainly nothing that I can hear with any of my speakers large or small. You might measure something but I doubt anyone could single it out listening.

Maybe young pups with 20-20khz hearing and speakers with awesome bandwidth, but frankly there is a good chance that other forms of noise and distortion are what’s mostly occurring at the highest frequencies for various reasons, phase shift being one of many nasty things that occur there predominantly. Very little music does. Mostly just "air" at 20khz.. See the reference here:

http://www.independentrecording.net/irn/resources/freqchart/main_display.ht

So based on a combo of facts and experience I still see it as one of theoretical things that exist but do not add up to much if anything in practice for most.