Preference vs. audibility - please keep them separate.

[NorthStar]

I'd be curious if anyone else has listened to Amused to Death by Roger Waters. At the start where there is what sounds like a radio interview going on, where does that sound seem to be coming from when you listen to it on your stereo speakers?

Stereo phase manipulation: illusion lacking discretion.

 

[NorthStar]

Yes- this is well known, which is why the times 10 thing is considered an engineering rule of thumb. You will hear artifacts (loss of bass impact) up to 50Hz if the cutoff is at 5Hz. If you cut off at 20Hz (and a lot of amps do, particularly SETs, which might cut off well above that) you get artifact to 200Hz.

Wow, time for me to upgrade.

Ralph, can you shortly in few concise words explain zero feedback, and is it best?

 

[Groucho]

Stereo phase manipulation: illusion lacking discretion.

Clever though, isn't it? I put it onto a list of recordings to listen to because I heard about the surround processing it had had done on it, but forgot about it and nearly jumped out of my skin when it first came on.

 

[Atmasphere]

What about systems that use DSP to invert each driver's measured impulse response (including the amp in the measurement) thereby achieving (as close as possible) zero phase shift and a perfect impulse response? e.g. Meridian 7200

If it all works could be good. Don't think I've ever seen a DSP system that works but I've yet to see everything...

Clever though, isn't it? I put it onto a list of recordings to listen to because I heard about the surround processing it had had done on it, but forgot about it and nearly jumped out of my skin when it first came on.

I played that one for a pretty skeptical engineer one time. Skeptical= didn't beleive in tubes or horns. He complained that a neighbor's dog was barking that interfered with the recording. He was a little incredulous that the dog was in fact what I was having him listen for. He didn't think 'antiquated' technology could do that, on an LP no less.

Ralph, can you shortly in few concise words explain zero feedback, and is it best?

Concise?? No.

When you hear/see me talk about 'zero feedback', I am using that as short hand for 'zero loop feedback', just so we are clear. The idea behind such circuits is that feedback causes increased levels of odd ordered harmonic distortion while overall lowering distortion. In addition, intermodulations can occur at the feedback node in the circuit, causing bifurcation (to use Chaos Theory terminology, i.e.: distortion) with the result of harmonic and inharmonic distortions describing the noise floor of the circuit (rather than just hiss) up to the 81st harmonic(!). This information has been known since the 1950s, see the writings of Norman Crowhurst.

The result is an increase in artificial loudness cues; essentially the use of loop negative feedback causes the resulting circuit to violate one of the more fundamental rules of human hearing/perception, that being how we detect sound pressure or the volume of a sound. It is my opinion that such a circuit can thus never sound absolutely real because of this violation. I forgot to mention that it also results in a tonal coloration known as 'bright' compared to the original signal.

That is why there is a sizable contingent in high end audio that designs without loop feedback. There is a price to be paid, especially in amplifiers, where the amplifier will no longer exhibit Voltage Source characteristics; instead may act more like a Power Source. Fortunately there are a good number of loudspeakers designed for this, and if there were ever an argument for equipment matching, this is one reason, as such speakers have been around since the dawn of audio and are still in good supply. An amplifier with Voltage Source characteristics will not sound right on such speakers as the crossovers are designed for different rules (voltage response) in the amplifier, resulting in a tonal anomaly.

Since circuits can't be made with a zero second propagation delay, this effect of loop feedback can not be avoided. That being the case, zero feedback circuitry actually has the better chance of sounding like real music, so in that sense, yes, its 'best'...

 

[Phelonious Ponk]

Hi Northstar

If you think about it, it's remarkable that the incidental distortions that happen to sounds that have been been converted into electrical currents, should have certain specific meanings for humans. So the insertion of a high end cable "opens up the sound stage" (= makes the recording space bigger which would normally require an architect and team of builders), "tightens the bass" (= improves the bass player's technique which would normally require payment to a qualified teacher and/or years of practice), "adds mellowness" (= transports the performance from the city to a small cottage in the country, changes the season to Autumn and introduces some gentle mist). And all these are accidental by-products of small amounts of resistance, inductance and capacitance. Why these apparently unconnected effects and not "makes the singer sound slightly impatient as though he has to rush off to an important appointment" or something equally random? Even when audio is completely scrambled into digital bits and back, remarkably similar things happen to the sound while in the alternative dimension, apparently.

Were we separated at birth?

Tim

 

[Robh3606]

Hello Groucho

Clever though, isn't it? I put it onto a list of recordings to listen to because I heard about the surround processing it had had done on it, but forgot about it and nearly jumped out of my skin when it first came on.

I use it as a set-up disk. Lot's of fun stuff going on

Rob

 

[mep]

Were we separated at birth?

Tim

If you are referring to Groucho, I believe you were separated at birth.

 

[NorthStar]

Clever though, isn't it? I put it onto a list of recordings to listen to because I heard about the surround processing it had had done on it, but forgot about it and nearly jumped out of my skin when it first came on.

Yes, Q-Sound is quite some' else, and this recording by Roger Waters - 'Amused to Death' is my favorite one from all my Q-Sound CD recordings (and LPs).
- Kind of sad that they didn't pursue that audio processing any further by not releasing more recordings in Q-Sound (I only have a dozen of them).
The effect is indeed quite pleasant for the ears, from the 'sweet' spot only of course.

 

[j_j]

Yes, Q-Sound is quite some' else, and this recording by Roger Waters - 'Amused to Death' is my favorite one from all my Q-Sound CD recordings (and LPs).
- Kind of sad that they didn't pursue that audio processing any further by not releasing more recordings in Q-Sound (I only have a dozen of them).
The effect is indeed quite pleasant for the ears, from the 'sweet' spot only of course.

Q-Sound is a form of Atal-Shroeder interaural cancellation coupled with a (now kind of primitive, but not then) headphone virtualization algorithm.

It is not a trivial phase effect.

Like all HRTF-related things, it is limited by how well your HRTF's and the ones used in the system match.

 

[Phelonious Ponk]

If you are referring to Groucho, I believe you were separated at birth.

No, no my brother from another mother, I was talking about you!

Tim

 

[Gregadd]

Control, repetition, statistical modeling. As I believe has been said here recently, more eloquently than this, it's not about proof, it's about probability. And if you listen sighted, and conclude that the big metal boxes full of components from the respected high end manufacturer are "better" than the slim little class D amp you've never heard of, how do you know that you're not the victim of expectation bias? You don't. But the probability is very high.

Tim

If you know how to distinguish between a guess and an actual correct answer then call the ETS that administers the SAT.They have been unable to do it.

You continue to assume I have some sort of bias,. The problem is Tim we are not playing the same game,

 

[jkeny]

No, no my brother from another mother, I was talking about you!

Tim

Yes, I doubt anyone would associate themselves with that post of Groucho's

 

[j_j]

You continue to assume I have some sort of bias,. The problem is Tim we are not playing the same game,

So, what game ARE you playing?

 

[andy_c]

delightful post!

Yeah, that was great. The whole idea of equipment conveying emotion is an interesting one. For instance, which interconnect cable does the best job of conveying the righteous indignation of Dylan's early work? Would the personality of that cable be appropriate for conveying the subtlety of, say, the erotic euphemisms of Laura Nyro? Or would that cable turn Ms. Nyro into some kind of snarling mistress and ruin the whole effect?

 

[Don Hills]

So, what game ARE you playing?

To me, it looks like he's playing with words. And through them, with you.

 

[j_j]

To me, it looks like he's playing with words. And through them, with you.

No, one does not make serious professional accusations and only be playing. Such issues are not jokes.

 

[jkeny]

delightful post!

Yeah, that was great. The whole idea of equipment conveying emotion is an interesting one. For instance, which interconnect cable does the best job of conveying the righteous indignation of Dylan's early work? Would the personality of that cable be appropriate for conveying the subtlety of, say, the erotic euphemisms of Laura Nyro? Or would that cable turn Ms. Nyro into some kind of snarling mistress and ruin the whole effect?

I knew my post would flush out further silliness - I just wanted to see who would be the ones. No surprises there.

 

[Don Hills]

No, one does not make serious professional accusations and only be playing. Such issues are not jokes.

True. But "playing" can imply malicious intent, as a cat plays with a mouse.

 

[Ethan Winer]

So Ralph, are you saying that an amplifier with a negative 3 dB point at 5 Hz is less than perfect in the way it can create phase shifts higher in the human/audible audio spectrum of the full frequency range?

First, this sort of phase shift is not audible, so there's no need to even consider that. But frequency response changes and ripples etc don't necessarily extend very far away from the -3 dB point. How far they extend depends on the slope in dB per octave, and that depends on how many sequential filter poles contribute to the roll-off.

--Ethan

 

[NorthStar]

First, this sort of phase shift is not audible, so there's no need to even consider that. But frequency response changes and ripples etc don't necessarily extend very far away from the -3 dB point. How far they extend depends on the slope in dB per octave, and that depends on how many sequential filter poles contribute to the roll-off.

--Ethan

I understand Ethan, and great to see you contributing. :b

An amplifier with wide band (frequency range) and linear (no deviation), say from 1Hz to 300kHz (+/- 0.5dB); should sound better than one with a measured frequency response of say from 10Hz to 100kHz (+/- 3dB).
And it does too (accuracy and audibility). ...Preference has nothing to do with it.

I am way far to be an expert, I'm just relating from my numerous readings over the years.

* Ethan, what is your take on Slew Rate?
...And Damping Factor, why not.