[bigshot]

http://www.hometheaterfocus.com/receivers/amplifier-sound-quality.aspx

 

[Tilpo]

Better power supply caps providing a better return path fr the signal coming back from the speakers or source. On most amps the power supply is in the direct signal path.
[...]
The ear can in some cases pick up on what scopes miss. The biggest differences I hear with my mods is when I modify the power supplies for lower output impedance across as much of the audio band as possible, that is after D.C. coupling that is.

I still don't see how that could affect the sound quality, and especially not how it can lead to a perceived increase in detail.
Besides, what effect would a better return path have? Higher slew rate and less ringing? That should be measurable.

 

[jnjn]

Quote:

On points 3/4, it's more of a majority issue. There exist less popular approaches to both recording and playback that account for both.
Yes, those studies are easier to carry out and so they dominate. Specific concerns can be allayed by a later meta-analysis that could make recommendations for novel study design. I think this hits on one of the important differences between your skepticism and that of other posters to this thread. You're pointing out the flaws in synthesizing audio image localization and it is indeed a complex field. Leaving it on the back burner for a bit, there's still value in conducting simple tests based on the tonal changes in mono or (gasp!

) panned-mono stereo.
Bingo! Which is why I think it's fair to suggest that most high-end cable manufacturers' internal "studies" are even less worthwhile. This is also why it's worthwhile to suggest to people asking for advice that they stay away from cables designed by science mysticism rather than science. Finally, it is also why my skepticism leads me to conclude that the default conclusion is that psychological processes play a greater role than physical changes. Notable changes produced by cables would be far easier to find, and indeed they are, when there's a clearly audible deficit (noise, drop-outs and the like).

Very good point. I pretty much do the same.

I read the vendor written science papers for comic relief.
Quote:

Better power supply caps providing a better return path fr the signal coming back from the speakers or source. On most amps the power supply is in the direct signal path. Two amps can spec the same yet sound quite different as specs  don't tel how the amp responds to complex signals, only simple signals are used to test amps for distortion & such. The ear can in some cases pick up on what scopes miss. The biggest differences I hear with my mods is when I modify the power supplies for lower output impedance across as much of the audio band as possible, that is after D.C. coupling that is. The differences are quite huge yet frequency response plots still show the frequency response is still flatter than the proverbial pancake.

Testing on the bench with a resistive load does not take the amplifier into 4 quadrant operation.  Half of the amplifier's responsibilities are ignored that way.  Since mids and highs are riding on a (hopefully) large bass current, it is important to characterize the amplifier with a real load from the field.
Quote:

I still don't see how that could affect the sound quality, and especially not how it can lead to a perceived increase in detail.
Besides, what effect would a better return path have? Higher slew rate and less ringing? That should be measurable.

The supply cap and surrounding ground topology will certainly affect what the amplifier does.  Even if it doesn't reduce rail ripple, changes can indeed affect the ground.  If the star point is not very good, it  could be heard.
 
jnjn

 

[Tilpo]

The supply cap and surrounding ground topology will certainly affect what the amplifier does.  Even if it doesn't reduce rail ripple, changes can indeed affect the ground.  If the star point is not very good, it  could be heard.

Don't most amps have a large power supply rejection ratio? Meaning that small ripples in rail voltages should have close to zero effect on sound.

 

[jnjn]

Quote:

Don't most amps have a large power supply rejection ratio? Meaning that small ripples in rail voltages should have close to zero effect on sound.

Yes, they do.
 
The issue is, current ripple.  The caps can have lots of capacity, they can have low ESR and ESL, but how the supply is arranged can also impact the system.  PSRR shouldn't be affected by the load impedance, but it can be.  And it gets more difficult when the load returns energy to the amp.
 
jnjn

 

[proton007]

I see a lot of science/formulas being thrown around. I'm no audio expert, but I do have this question: whatever we are discussing here, has it been used in audio theory elsewhere? Any papers/books/references you've read?
I mean how serious are the scientific folks when it comes to audio? My guess is not much. Hence the lack of resource and tests.
Or maybe its all been figured out ages ago. We can argue all we want, but at the end its just one post against the other.
I seriously do feel though, and I think I repeated this in a similar thread, if there's any advantage to be had from using a better cable, the audio maker would happily embrace it, as it can enhance the product. The fact that they don't or are silent on this issue seems to say something.

 

[Magick Man]

I see a lot of science/formulas being thrown around. I'm no audio expert, but I do have this question: whatever we are discussing here, has it been used in audio theory elsewhere? Any papers/books/references you've read?
I mean how serious are the scientific folks when it comes to audio? My guess is not much. Hence the lack of resource and tests.
Or maybe its all been figured out ages ago. We can argue all we want, but at the end its just one post against the other.
I seriously do feel though, and I think I repeated this in a similar thread, if there's any advantage to be had from using a better cable, the audio maker would happily embrace it, as it can enhance the product. The fact that they don't or are silent on this issue seems to say something.

I remember talking to a Krell engineer at an event some 10 years ago and they were demoing their TOTL stereo and mono-block amps. While they weren't using pack-in cables, they weren't anything special either. The interconnects in particular were a heavy gauge Acoustic Research cable that retailed for about $100 at the time and the speaker cabling was just bulk 10AWG wire. I asked him about that and he told me that exotic/boutique cables were vanity products and marketing and from a functionality standpoint were unnecessary.

 

[ktm]

All reviews are skewed by the very nature of who does them. It's ok to read all of them, use what seems to be valid points of comparison, and
narrow down your choices. The point is, what gear they liked or disliked, and what was the criteria  used by the person.
It's like listening to Fox news or reading the New York Times.You can pull useful information without buying into the whole
thing. I don't believe rap is music(yes, I'm an ARRP member!) but that doesn't mean I discount reviews with that in there.
Beating up the whole audio hardware industry isn't going to help anyone pick a good set of cans.
If you don't like gear because it's $$$, get over it and move on. I use middle of the road audio gear and cable( no high or low end) and enjoy it immensely.

 

[jnjn]

Quote:

I remember talking to a Krell engineer at an event some 10 years ago and they were demoing their TOTL stereo and mono-block amps. While they weren't using pack-in cables, they weren't anything special either. The interconnects in particular were a heavy gauge Acoustic Research cable that retailed for about $100 at the time and the speaker cabling was just bulk 10AWG wire. I asked him about that and he told me that exotic/boutique cables were vanity products and marketing and from a functionality standpoint were unnecessary.

I looked at the Krell website, they make power cords..  Here's their verbage:  I've hilited the more interesting stuff.
 
You will instantly hear improvements in bass definition and control. Image outlines are more defined with greater elegance and finesse in the upper octaves. Use Vector HC in your video system and the results are equally compelling.
Technology Highlights
Engineered like signal cables, Hot and Neutral leads are twisted together at a precise rotational angle and twist rate, optimizing the relationship between resistance, capacitance, and inductance. Inductance, enemy of high current demand events, resists changes in current flow. Vector HC minimizes inductance insuring unimpeded access to the available AC wall current. Simultaneously, capacitance is increased to reject high frequency noise voltage. For minimal noise emission and maximum noise rejection the two main conductors are wrapped in a foil shield as opposed to generic braided wire shield employed in many designs. A foil shield is more effective than a braided wire at shielding the frequency ranges that affect audio components. The ground conductor runs outside this power delivery package for better RF/EMI immunity.
Construction
Three Conductors of finely stranded Oxygen-free 11 AWG Copper make up the conductor complement. Each conductor is separately insulated in a Teflon based material providing a linear and predictable dielectric constant.
 
And they make interconnects.
 
CAST technology expands the usable audio signal bandwidth well over 2 MHz; ensuring harmonic reflections are virtually immeasurable in the audible frequency range. CAST allows signal transmission over extended lengths of interconnect cable, allowing flexible placement for your components, without signal degradation.
The Voltage Signal Transmission and the Traditional Audio System
Traditionally, signal is transmitted in the voltage domain between two components. In an audio system, each component is a discrete entity with unique characteristics that act upon the musical signal independently. Each component is unaware of the other components in the system. The cables that connect the components also have their own electrical characteristics, which affect the sonic presentation of the entire system. CAST transmission unifies individual components and interconnects into an electrically linked whole. The original signal remains unaltered from source to speaker.
CAST Basics
Here's how a CAST audio system works. Internally, each CAST source transfers, or amplifies, current using Krell Current Mode circuitry. This current signal is then output using CAST circuitry. When the signal is received by a CAST input, Krell Current Mode circuitry again takes over until the signal reaches the loudspeaker. By maintaining the musical signal in the current domain from beginning to end, an entire CAST system behaves as if it is one component. With CAST, circuit board properties and signal transmission aberrations between components are eliminated. Cable impedances and their effects on the transmitted signal are non-existent.
How CAST and Krell Current Mode Interact
While CAST is a new method of transferring the musical signal between components, its origin stems from Krell Current Mode, the technology developed to transfer the musical signal within a component. CAST combined with Krell Current Mode takes circuitry signal transmission to the next evolutionary level. In essence, Krell Current Mode maintains the integrity of the signal within the component and CAST preserves the transmitted signal between components. Together, CAST and Krell Current Mode technologies unify separate Krell components into a single global circuit. Krell Current Mode technology enjoys bandwidth increases up to an order of magnitude greater than their voltage based counterparts. This dramatic increase in circuit bandwidth delivers near perfection in the audible band that typically suffers from phase distortions in voltage circuits.
Evolution CAST
By employing radical current mirror circuitry, the Evolution components elevate the CAST technology to another level. This advanced use of the technology increases the linearity, transient speed, and bandwidth of the Evolution components while reducing the distortion by an order of magnitude.
The Best Musical Performance
When you operate a CAST system, you will hear significant improvements in every performance area: speed, precision, dynamic range, depth and width of the sound stage, transient impact, tonal balance, harmonic distortion, and more. The goal for CAST is the same company goal used for all Krell products. Krell strives for the delivery of the best performance of a musical event for you, using the full expression of technology to date.
CAST® MMF Interconnect Cable
The Krell CAST MMF cable jointly developed by Krell Industries, LLC and Nordost has taken this concept a step further using Nordost's proprietary Micro Mono-Filament Technology. This technology uses spiral spacing and extruded FEP in a unique construction that creates a virtual air dielectric. The cable uses four silver plated 99.99999% OFC conductors in a Micro Mono-Filament FEP (Fourinated Ethylene Propylene) construction with a dual served shield. The revolutionary Krell CAST MMF cable design combines ease of use with very wide bandwidth and very efficient signal transmission at high speeds by reducing insulation contact with the conductors by more than 80%. The sonic improvements with the Krell CAST MMF cable are immediate - performances emerge from absolute blackness, with the speed, depth and dynamics realized only through the absence of ambient noise.
 
Krell's current  line cord and interconnect stuff is being touted as the cure for line cord and interconnect problems.   The CAST system does look like it may be balanced, which would be good. But their current products don't seem to be in line with the guy you spoke to.
   
jnjn

 

[Magick Man]

Seems they've decided to jump into the boutique cable market and the profits to be had there. Doesn't surprise me, most will sell out if the money is right.

 

[jnjn]

Quote:

Seems they've decided to jump into the boutique cable market and the profits to be had there. Doesn't surprise me, most will sell out if the money is right.

As far as that CAST stuff, it may be that they've developed a nice signal method.  The picture looked  to have sufficient pincount for differential drive, and I think current drive might be more immune to loop voltages caused by ground currents. since it's proprietary, they may also have removed a pin 1 issue.
 
For the line cord, I'm really not sure what to think.  The material descriptors is shall we say, interesting?  But I'm also not sure about their topology, they've brought the safety bond ground outside the foil shield, but don't say if it follows the twist of hot/neutral or runs along the cable. 
 
Of course, a foil shield doesn't stop the magnetic field of the hot/neutral..but neither did a copper braid.
 
jnjn

 

[Clarkmc2]

I have to say that proton007 is on to something. This thread is so far off the rails. A couple of the contributors are going on and on, and around and around, about possible phenomenon for which not a shred of evidence has been presented about its audibility. This is Sound Science, a term in two parts. Science - present non anecdotal, provable demonstrable evidence - of it being audible by listeners - sound.
 
Not only has there been no physical evidence, say an o scope trace, of the existence of these conjectural phenomenon, but no demonstration of their audibility at all. Take it to the High End forum please and leave Sound Science to its titular domain. The High End forum is full of unsubstantiated conjecture about everything from break in to hearing jitter, no evidence required.
 
If posting here is in a member's future, reading something like Ethan Winer's book should be a prerequisite. Shouldn't be, but judging from this thread it seems to be a present reality. Speaking of sound and hearing, it is starting to sound a lot like posters enjoying hearing the sound of their own voice around here. The lession I have taken from this thread has altered my initial take on the initial question. At first my charitable nature and curiosity favored simply ignoring the ignorant sections, but after the brutal bull session that this thread has become I would be wary of anything written by the same authors. In other words, ignore the entire review. It will not be a trustworthy source of information or opinion.

 

[mike1127]

People sometimes define science as "evidence-based" but I think that leaves out a discussion of
 

1. what is considered evidence?
2. what methods are considered valid to collect it?
3. what paradigms are accepted?

 
I think there are some valid challenges to the paradigm generally espoused here. One of them is my observation that quick-switching ABX listening tests obscure features of sound that are experienced over time rather than in one instant.

 

[anetode]

One of them is my observation that quick-switching ABX listening tests obscure features of sound that are experienced over time rather than in one instant.

Cool, let's call that your hypothesis. How would you go about testing it? What background info might be useful from prior studies?

 

[dallan]

Pretty funny, the thread starter with the question hasn't posted here in over four weeks, you guys are like a top, pull the cord and let it spin.