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In Reply to: RE: See my most recent posting above. posted by Norm on June 28, 2011 at 06:37:06
". I am really saying what many pros have told me, FW does not have the liabilities that USB does, name only occasional access to the processor."
The issue is not Firewire vs. USB. It's the entire system architecture.
Most of the required access by a DAC (FW or USB) is to system memory (RAM) so I will focus on that.
Both Firewire and USB are shared buses. As such, only one device can use them at a time. However, because they are fast this is generally not a problem for many applications, since there is generally sufficient buffering that a small wait in access won't matter. However, for audio this may not be the case, since any delay impacts the exact timing of the packets and this can affect the sound (at least by second order effects using John S's terminology).
If there is only one device on a bus then no problem. Hence if one has two devices (e.g. DAC and disk drive) one can avoid possible conflicts by using a dedicated bus for each device. Since it is possible to have multiple controllers of each type one can accomplish this goal three ways: have two USB controllers, have two Firewire controllers, or have one controller of each type. Given that many computer systems come out of the box with multiple USB controllers this can often be accomplished without adding any extra hardware without using Firewire. However, since a USB controller is dedicated to a specific set of ports it will be necessary to understand which specific USB sockets are wired to which controller. This can be done by various ways as others have described. (One such way, albeit inefficient is trial and error.)
If one runs two controllers of either type and dedicates one to the disk and the other to the DAC there may still be conflicts in the computer system because there are shared resources that are accessed by both the disk and the DAC. (The most obvious of these is the RAM memory.) These resources are connected through various complex logic that juggles all the conflicting activity in such a way to maximum system performance while minimizing manufacturing cost, and this logic may be unique to each model of motherboard. Suffice it to say that the problem here is similar for both Firewire and USB. Certain brands of computer have a reputation for giving poor audio performance. This probably relates to this portion of the motherboard.
In order to understand these issues completely one needs a lot of knowledge in computer architecture and performance analysis, a subject that few audio professionals have. (I do not consider myself such an expert, but I have worked with these people and so I am familiar with many of the issues involved. My department designed high speed computer network interfaces and ran into many similar issues. )
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Follow Ups:
about universal bus not being universal. It's a money pinching solution albeit at high prices. I used to fiddle for hours with carburettors that were basically a device that didn't work. The number of compensatory measures that had to be built in mirrors that of usb trouble shooting.
When you say that USB isn't "universal" I think that's a quibble over a marketing term that has no meaning. I suppose it could be a veiled reference to "universal Turing machine" which might not be a term with which you are familiar.
As to USB not "working" this is a category error. The USB is, first and foremost, a technical specification which provides physical, electrical and logical details of how devices can communicate. It is sufficiently general, if not completely "universal" and as such can be used to do many things, some of which can be stupid. In addition, and this is my main beef with USB, it is quite complicated and so these implementations (primarily inside specialized chips) almost certainly have bugs and limitations. In addition, vendors take these chips and butcher putting them into computer systems. But the same can be said of simpler interfaces, e.g. SPDIF where people use the wrong impedance connectors.
I never had any trouble with carburetors. I learned how to tune the dual Weber carburetors on my Lotus Elan by ear and nose. Carburetors became unmanageably complex only after absurd government regulations were put in place. I've had many more problems with the electronic fuel injection systems that replaced them.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
is that we are discussing technical aspects of an interface and I personally give no truck to marketing terms.
If you give no truck to marketing terms then why do you constantly snipe that USB isn't "universal"?
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
I am not marketing usb but commenting as a user.
You appear to be.
If you look at the websites of some usb audio manufacturers you will see versions in praise of usb transfer which is on the edge, or crosses the line of truth.
If you give no truck to marketing terms then why do you constantly snipe that USB isn't "universal"?Fair point. As a mathematician, you are no doubt familiar with Charles Dodgson/Lewis Carroll. Remember Alice in the Looking Glass ? One of the characters Alice met behind the mirror was, of course, Humpty-Dumpty:
'I don’t know what you mean by "glory," ' Alice said.Humpty-Dumpty smiled contemptuously. 'Of course you don’t – till I tell you. I meant, "there’s a nice knock-down argument for you!" '
'But "Glory" doesn’t mean 'a nice knock-down argument,' Alice objected.
'When I use a word,' Humpty-Dumpty said in rather a scornful tone, 'It means just what I want it to mean – neither more nor less'.
'The question is,' said Alice, 'whether you can make words mean so many different things'.
'The question is,' said Humpty-Dumpty, 'which is to be master – that’s all.'
I find it hard to say whether fmak's incessant rants are as irritating as they are ill-informed or the other way round.
But perhaps it's just an optically-isolated illusion. In other words, there are no grounds for it.
Edits: 07/01/11
Good reference. Malice in wonderland.
> 'The question is,' said Humpty-Dumpty,
> 'which is to be master – that’s all.'
...
> I find it hard to say whether fmak's incessant rants are as
> irritating as they are ill-informed or the other way round.
Careful, fmak will take offense at being compared to a cracked egg. Or maybe just a bad egg. Or just the butt of the yolk.
Bill
"But perhaps it's just an optically-isolated illusion. In other words, there are no grounds for it."
Fabulous line!!!!!
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Tony, I am not one who is capable of evaluating what you say, but Daniel Weiss only uses FW as do others for a reason.
I just last night got the USB keyboard and mouse replaced with a bluetooth system, and heard a small improvement, which I again replicated today when I had to use the USB keyboard again.
The reason my have been valid for the equipment that Daniel Weiss compared, but that was probably several generations ago. There were certainly some serious problems with USB 1.0.
If the interconnect (Firewire or USB) makes a difference in the sound of a DAC this indicates an interaction between the interconnect and the DAC, specifically input circuitry that is not providing adequate rejection. As I recall, Daniel Weiss has supported the idea that well designed DACs aren't sensitive to these factors. This seems contradictory to the statement he made that you referenced, assuming that he believes his DACs are well designed. Of course, sometimes manufacturers make statements that are deliberately misleading for commercial reasons. I have no idea if this is the case here.
I have no problem with people reporting what they hear. However, when they go on to generalize to an entire technology I don't pay much attention to these generalizations unless they come with some indication of a deep understanding of the technology or a wide range of experience with many implementations. These kind of generalizations are how "audiophile myths" get propagated. I would go no farther than to say that some Firewire implementations are better than some USB implementations.
BTW, I have not been a fan of USB. Indeed when I first learned of the proposal that Intel was pushing I thought it was a bad idea. Since those ancient days USB has improved and my initial concerns have been addressed. Like most computer technology both USB and Firewire have been over hyped.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
good post.
> However, when they go on to generalize to an entire technology I don't
> pay much attention to these generalizations unless they come with some
> indication of a deep understanding of the technology or a wide range
> of experience with many implementations.
Amen!
Bill
Although my computer has a FireWire port I've never used it. However USB in it's current state of development is fabulous compared to where we were. To the user it is usually plug and play, these are halcyon days!
I've got perfectly good perherials that I can't use because the SCSI card won't fit in the bus sockets. And it's been quite a while since I've had to figure out what interrupts to use!
I used to design stuff that interfaced via RS-232 or keyboard wedge and in a word both sucked. Neither interface was designed for general usage yet they were the only ones typically available. From a manufacturer's viewpoint there is nothing worse than fleeting interfaces and despite a rocky start USB has been pleasingly long-lived with good support for legacy products.
Obviously the technical problems for audio use are solveable as they largely have been and it could get even easier with a little driver standardization and specialized silicon. For one thing with the higher speed versions it's becoming practical to do large dumps almost instantly allowing the play process to occur completely within the peripheral.
Your belief that adequate isolation should occur at the interface is spot on. There are already some damn good implementations and they wouldn't cost much in volume. It seems inevitable to me that stereos will ultimately cease to exist physically except for speakers as rendering nodes on an RF (or optical) network. At that point, galvanic isolation will be intrinsic.
Rick
> It seems inevitable to me that stereos will ultimately cease to exist
> physically except for speakers as rendering nodes on an RF
> (or optical) network.
The AVI ADM 9.1 speakers that Phelonious Ponk uses are pretty far along that road. The DAC, preamp, active crossovers and amps are integrated with speakers. And the speakers come with a remote control. The digital inputs are toslink so isolation from the aduio source is a given.
http://www.avihifi.co.uk/adm9.html
---
The Audioengine A5s I use are powered and have two analog inputs and a stereo volume control. Very handy for a near field office situation.
> There are already some damn good implementations and they wouldn't
> cost much in volume.
Lots of < $ 500 DACs coming out now.
Bill
It's been quite a while since I've had to figure out what interrupts to use!
Remember EISA? That was even more fun than SCSI. The latter was, of course, typically much better on the Mac than the PC. If you had a pocket full of terminating resistors and a prayer book, you could get almost anything to run. Eventually.
Odd things, computers. Normally, if something separates the men from the boys, it's the men wot can do it . . .
I thought it was the other-way 'round, if your computer has you pinned to the mat, call for a kid. Maybe that doesn't hold for HW?
Rick
'These kind of generalizations are how "audiophile myths" get propagated. '
Like usb audio has lower jitter and is the modern solution to audio streaming.
Like 14 bit dacs playing red book with cMP2 provides the definitive answer to good PC auio.
Like 16G Macs sound better than 8G ones.
The list goes on.
True audiophiles look for high quality replay systems regardless of setup.
Like usb audio has lower jitter and is the modern solution to audio streaming.A meaningless claim that no-one has ever made. OTOH, competent engineers have designed fine-sounding audio products using USB and got them out the door . Which is a damn sight more than you've ever done.
Like 14 bit dacs playing red book with cMP2 provides the definitive answer to good PC auio.
As you well know, no-one has ever made that claim - it verges on mendacious to keep repeating it here. In any case, you don't know what cMP2 sounds like. By your own admission, you couldn't get cPlay to run properly.
Like 16G Macs sound better than 8G ones.
How would you know? AFAIK, you don't own a Mac and you've never compared the two setups. There are still some field of expertise you have yet to conquer.
The list goes on.
And so, sadly, do you. About things you know little or nothing about.
True audiophiles look for high quality replay systems regardless of setup.
While others sound off on all sorts of topics they know little about. I'm increasingly convinced that perhaps the biggest audio myth on this list is that you are some sort of expert. The reality is that you're the most prone of all of us to making silly generalisations.
"Malice in Wonderland"? Well said. (Wish I'd thought of it. But, as the famous quip had it, "Never mind, you will".)
Edits: 07/02/11 07/02/11 07/02/11
nt
This part of the reason I have never been able to compare FW with USB. Again everything I say is based on what I hear. I am told Weiss relies on a bit by bit comparison. I think this all applies to USB2, but certainly not USB3.
You have a wonderful DAC Norm. But it's really tough to compare Firewire to USB on the same dac as a great deal of effort is spent on a particular interface by the manufacturer. There is really no benefit for both interfaces on the same DAC. There are excellent firewire DACS and excellent USB DACs. The total design has to be looked at, not just the interface.
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