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In Reply to: RE: Sound Quality Changes caused by Sata cables. posted by Ugly on July 05, 2014 at 10:20:02
The case was closed and the cable used was to try to be as neat as possible with short cabling. It is apparently a German Patented Design that looks the part and is offered a lot in Europe.
Grounding and power have been very carefully done and voltage rails have
extra bypass capacitors to suppress transients.
I am certain that it is not the external audio components but 'pollution' one way or the other of the usb audio output stream.
Follow Ups:
A PC is just a sum of it's parts. It only takes a single noisy component to ruin your installation. When building up from scratch one must scrutinize everything, especially when there are no plans to have the final configuration tested for compliance as a unit...like most of us home assemblers could never afford to do.
It's pretty easy these days to find parts which can comply with both EN55022-1 and FCC part15 B. I would never use anything less. FCC part 15 class B is pretty strict and good guideline but personally I require the CISPR B compliant gear for the fact that it must also comply with the rest of the fairly strict euro requirements beyond just the emissions part of it. Some of that stuff such as flicker compliance and the harmonics initiative compliance just makes sense to me.
Of course one must take some of these fly by night companies claims with a grain of salt. Reputable manufacturers who've proven their ability to not cease to exist due to lawsuits are the way to go in my opinion.
Most DIY PC builders are not aware of the strict compliance requirements that must be met by commercial PC makers, especially for use in the home. They also lack the costly equipment necessary to test for conducted and radiated emissions, or lack the funds to contract out the testing to a lab.
As such, a DIYer "closing the PC case with neat cabling" or blindly adding bypass capacitors to a power supply doesn't mean much. ;-)
"Most DIY PC builders are not aware of the strict compliance requirements that must be met by commercial PC makers, especially for use in the home. They also lack the costly equipment necessary to test for conducted and radiated emissions, or lack the funds to contract out the testing to a lab.
As such, a DIYer "closing the PC case with neat cabling" or blindly adding bypass capacitors to a power supply doesn't mean much. ;-)"
There is nothing special about the construction of commercial PC's. DIY PC's are often exactly the same with the same part etc. Although not tested, they will meet spec... Meeting spec IMO can be improved upon, that is what people are doing...
There is nothing special about the construction of commercial PC's. DIY PC's are often exactly the same with the same part etc. Although not tested, they will meet spec... Meeting spec IMO can be improved upon, that is what people are doing...
You don't know that for fact. I've seen several measures taken in commercially built PC's for EMI/RFI suppression that simply do not exist (and are not required) in DIY PC's. I'm not talking only about individual components but the methods used to seal case covers, additional shielding and RFI/EMI coatings within the case, additional shielding methods sometimes used around plug-in PCIe cards, ferrite chokes and specific value bypass capacitors strategically placed, etc.
Simply slapping together a DIY PC with off the shelf case DOES NOT REQUIRE passing any certifications and there is NO WAY for the builder to know how much conducted or radiated emissions are coming from his computer without very costly test equipment and a proper test environment.
That said, there is also no way for the DIY builder to know if simply slapping some 'bypass' capacitors on his power supply rails had a beneficial or detrimental effect without measuring it.
The OP is constantly ragging on commercial DAC vendors for 'measured proof', so lets see some measured proof on his shot gun whack a mole tweaks.
"Simply slapping together a DIY PC with off the shelf case DOES NOT REQUIRE passing any certifications and there is NO WAY for the builder to know how much conducted or radiated emissions are coming from his computer without very costly test equipment and a proper test environment.
That said, there is also no way for the DIY builder to know if simply slapping some 'bypass' capacitors on his power supply rails had a beneficial or detrimental effect without measuring it."
You are absolutely right. There is no way mere mortals can apply simple technology correctly. Of course capacitors cannot be used as filters, there is no math to predict their effect. They are just hit or miss when used in circuity... Thanks for the help...
You are absolutely right. There is no way mere mortals can apply simple technology correctly. Of course capacitors cannot be used as filters, there is no math to predict their effect. They are just hit or miss when used in circuity... Thanks for the help...
Thanks for misquoting me. I said nothing to that effect.
"Simply slapping together a DIY PC with off the shelf case DOES NOT REQUIRE passing any certifications
That said, there is also no way for the DIY builder to know if simply slapping some 'bypass' capacitors on his power supply"
You seem to use the word "slapping" repeatedly and you also have a monkey at a tag... Hmmmmm ok....
If slapping means measuring the power rail with a 450 MHz analog scope, and suppressing the horrific transients inside the PC, then it is a complimentary term.
If this is used blindly, then the poster is blind to reasoning.
"If slapping means measuring the power rail with a 450 MHz analog scope, and suppressing the horrific transients inside the PC, then it is a complimentary term.
If this is used blindly, then the poster is blind to reasoning."
I do not believe he owns a scope. So I think it is more inline with the definition linked below.
As far him going blind... Let's hope not... :)
You seem to use the word "slapping" repeatedly and you also have a monkey at a tag... Hmmmmm ok....
It's representative of the 'tweak' discussions here, usually initiated by the OP. But what does that have to do with the price of tea in China? ;-)
Hopefully someone will explain it to you... lol...
you should be able to slap anything on MAC and it should sound great.
I agree with you about it being a crap shoot unless there is access to a good test lab. All you can say about more bypass caps, shorter cables, properly applied shielding etc. with all else being equal it most likely wont hurt anything....most likely, and may bring positive benefits. Choosing good off the shelf components likely not to be a problem is key in my opinion. Copying those who do in fact test for compliance is a game I often play.
Compliance is not equal to sound quality. Those who don't understand the need to have good voltage rails are just ignorant.
We are dealing with a very complex system and lower spectral emissions can mean higher energy over a broader bandwidth. This can be very bad for SQ.
It is the understanding of physical principles and their appropriate application that matter and textbook tools are used by the average designer may use to meet safety and other standards..
"Compliance is not equal to sound quality."
Indeed. The compliance tests are concerned with interference with TV and FM reception, not even AM radio reception, let alone audio. The frequencies involved are completely different. About all that one can say is that some of the methods to achieve compliance also minimize the effect on audio, but some have adverse effects, e.g. adding jitter to clock signals which makes it easier to pass compliance tests.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Compliance testing absolutely could be used to indicate directly the performance of audio equipment in typically noisy environments up to several various levels of testing intensity conformity. Immunity testing is designed to highlight performance of equipment while subjected to a battery of disturbances designed to be similar to disturbances encountered in the real world. Some pieces of gear are required to get it other types may not be(I believe, I know what I work on is required testing but not sure on audio gear).Edit:audio gear is likely required to pass EN61000-6-1 but I'm not sure and am also unsure of what is in that test or how it is conducted. ie whether the grading aspect of the immunity testing on the gear I work on is similar for this class of testing or not.
Edits: 07/07/14 07/07/14 07/07/14 07/07/14
It's not a loophole. The specific issue was interference to narrow band receivers. Spreading the signal around does not reduce total interference, which is minimal. It reduces the probability that specific interference will be noticed.
The proper solution is to declare that all the older narrow band receivers are obsolete and to reassign the spectrum under the assumption that all receivers and transmitters are "smart". This would improve available bandwidth many times over. Instead, we continue to use 1920's radio technology because of politics. That's what this is all about, politics, not technology.
Receivers should be require to work properly in the presence of interference. This is possible with modern radio technology. It has always been possible with modern audio technology, since the frequencies involved do not come close to overlapping. You are correct that DACs, preamps, and amps should be tested under extremely high noise environments, both using objective and subjective methods. (There are subjective factors that can be heard by good listeners that as yet we do not know how to measure.)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Going to have to concede to your points regarding the history of the laws. Fact is I wasn't paying attention back when said laws were created.
Regardless of how the testing techniques originally came into existence, how they are currently being used is what is relevant here. I absolutely do not agree that bouncing the clock frequency around as a method to come in under limit lines which in my opinion are probably too high already is somehow not taking advantage of a loophole. It is how spread spectrum is being used now to leverage so called quasi peak averaging that matters. That is to allow energy levels on clock signals which would never be allowed if instantaneous peak levels were the only consideration. You said it yourself old radio receivers where it would be annoying are mostly gone. The method of skirting the overly reasonable limits persists.
The reason is, audio gear susceptibility is rarely if ever selective as radio receiver front ends are designed to be and therefore the degradations are potentially even more annoying with audio gear which can't reject it. Spreading the energy up and down by a couple megahertz is not going to make the problem less annoying than with smaller levels of this clock jitter for most susceptible audio gear cases I'd say.
Clearly none of us here care about radio recievers designed to detect bands from the 20's. There has been at least one poster on this thread to lament the awfulness of out of band RF etc energy in their audio systems. I will add my 2 cents to that complaint for all the times in my past when I had less robust setups and when I'd be affected by ultra powerful CB radios passing nearby, light switches contacts, hard drive seek motor activity interference, cell phone activity sounding like total crap when they'd make themselves apparent in my non radio receiver sections of my stereo.
Further there have been audio gear manufacturers who have come on this forum to complain how really strong immunity circuitry causes their stuff to sound bad. None of us wants bad sound but I suspect there may be an acceptable compromise to achieve a balance.
I propose to you the correct way of dealing with this problem is a bit of manipulation of both sides of the equation.. ie we push for lower emissions from radiating gear and we push for stronger immunity from audio gear.
I'm all about quiet power. Not sure if you somehow got the idea I'm not.FCC part 15 testing covers up to 40GHz. Where exactly do you expect this whack a mole problem from a typical PC to even physically be capable of showing up? Do you have anything specific you are referring to?
I'm not saying your wrong just that if the full suite of euro and USA testing has occurred and the device passed, most of the bands where problems are likely have already been tested.
Personally I think Id rather deal with a lower energy broadband noise problem below class b lines than some high energy high Q spike above the line from a PC circuit board I didn't even design, have no schematics/bills of materials for and am clueless about it's layout. Maybe it's just me.
Edits: 07/05/14
'FCC part 15 testing covers up to 40GHz'
A spectrum is just a spectrum. How individual or groups of harmonics interact with hardware is another matter and there cannot be a generalisation about their effects on say, a well shielded and grounded dac some way away. For example, a dac may not be affected by a sharp harmonic at 40GHz but may well be excited by broadband emission at a much lower frequency.
So, it is a good thing that computers should satisfy emission requirements but that does not mean that a computer with an active interface such as Thunderbolt (satisfying an emission standard) will replay audio better and produce better sound.
I have several other industrial PCs built like tanks (and to code) that actually do not fare any better than my self built ones.
Again, it is the understanding of the physical principles and their applications that matter, not the application of any code that does not relate directly to audio reproduction.
As to buying FCC/EN components, unless one has the volume to buy direct, there is no certainty that retail houses will actually supply a component to a quoted spec. There is not really any guarantee that any product with a label will do so unless individually checked. Price prohibits this. The usb2 (usb3 too) label is a case in point, for example.
Equipment with tendencies to exhibit susceptibility problems will exhibit the problems less in the presence lower energy disturbances. Equipment likely to radiate will be less disturbing to the environment if it radiates less. If I was a betting man I'd take the tested, marked gear every time.
You're right that without specific knowledge of each equipments peculiarities in these regards you still can't be positive there wont be unexpected negative interactions with random combos of gear.
I've stated it before here about my desire for more comprehensive published results, both for emissions and immunity, from manufacturers beyond what is required by laws. I'm not holding my breath waiting for it to happen.
"As to buying FCC/EN components, unless one has the volume to buy direct, there is no certainty that retail houses will actually supply a component to a quoted spec. There is not really any guarantee that any product with a label will do so unless individually checked. Price prohibits this. The usb2 (usb3 too) label is a case in point, for example."
Precisely the reason I recommended to go with established name brands. Manufacturers claiming compliance beyond what production tolerances allow simply don't last in the european market once the law catches wind. Corruption aside, there are plenty of compliant pieces at your local retailer which can be trusted with fair levels of confidence. I can almost promise the euro authorities aren't granting favors to many of the outsider manufacturers who sell there even if it does look like they give some of the locals a pass sometimes.
"Precisely the reason I recommended to go with established name brands."
When you say "name brands" What exactly do you mean? Parts? Systems? If systems, can you please explain the difference between a system assembled by a manufacture vs DIYer?
regards
Bob
I was talking about DIY pc's and was referring to the components used to assemble with."If systems, can you please explain the difference between a system assembled by a manufacture vs DIYer?"
Companies like HP, Dell etc when selling systems into Europe need declarations of conformance and to display the CE mark as required by law in order to legally sell there. While it's possible to self certify, if one doesn't actually meet the requirements to pass there are stiff legal penalties which can get applied. DIY assembled PC's exist with no legal scrutiny presumably other than the applicable requirements on the components purchased used to create them. Often subtle but important construction/configuration differences can be found in compliant systems as compared with DIY boxes...spread spectrum possibly being turned on by default for example. Not to say DIY boxes can't ever be good just that until someone tests it there is no way to know.
You can get these declarations of conformance for the systems off the websites usually. They are legally required and so are available by request if not posted.
Edits: 07/06/14
"Often subtle but important construction/configuration differences can be found in compliant systems as compared with DIY boxes...spread spectrum possibly being turned on by default for example. Not to say DIY boxes can't ever be good just that until someone tests it there is no way to know."
Just wanted to clarify. Thanks... But... There really is nothing special or much different that manufactures are doing other than testing.
In fact DIY can be much better. Check out what is being done and the discussion on the JPlay forum regarding RFI reduction and shielding.
Granted we cannot test the completed systems, but IMO this is really unnecessary with proper understanding of the technology involved.
We are also attempting to reduce internal RFI, something which manufactures have no real interest in.
regards
Bob
I can certainly appreciate the effort of experimenters and would never try to discourage it. However, without testing there leaves too much uncertainty for my taste for the most part. I just don't have the time to waste on things that aren't guaranteed... for the most part.I'd really enjoy an opportunity to one day meet up with one of low power PC software tweaking types to compare the capabilities of what I'd consider a well vetted high computing performance hardware but standard software system compared with one of these stripped down tweaked out systems on a sufficiently high res analog front end. Don't know if I'll ever make an effort to get it done but it does seem interesting to me.
thanks for the tip on the JPlay forum I'll be reading through it.
Edits: 07/06/14 07/06/14
What tests are appropriate as indicators of sound quality? Certainly not just a spectrum sweep which is an indicator of emission compliance only.
If you drop preconceived notions of what is good, there are plenty of intelligent audio modders to talk to (and perhaps learn from).
Obviously the ones related to immunity and the performance grading are quite applicable even if no manufacturer I'm aware of reports on the details of these tests.
My point is not that shielded sata cables can never be a good thing but that in most cases I'm skeptical that is the best place to start. Knock yourself out shielding your cables. It will be interesting to hear about what you find, more interesting if you had an accurate way to measure the performance difference but still interesting.
Perhaps you ought to drop pre concieving ridiculous attitudes and trying to attribute them to me, learn more about what the testing actually does before globally condemning it, and consider learning about the ways these things may be applicable to achieving your own goals.
I'm perfectly willing to entertain ideas I come across which strike me as reasonable per my understanding, but sometimes lose interest very quickly when confronted with irrational, emotional saviors who have convinced themselves they have it all figured out and are spewing peusdo technical garbage as fast as possible across the forums. Seems these guys forum presence far out weigh and out voice the more logical methodical experimenters. I mentioned earlier about my lack of patience.
Based on what I've read and in my opinion many of the experimenters out there, not necessarily you per se, have yet to figure out the basics and need to focus outside their PC's, fixing the glaring issues before addressing the minutia. My recommendation is to take these experimenters advice with a gigantic truckload of salt.
Where on earth did you get this notion from? It's clearly a preconceived notion about what I was posting.
Where? Duh, by leaving it in the context of the rest of the sentence which went with it. Are you serious right now?
In the same sense that a (MAC) thunderbolt drive and cable may perform differently, AND in the same sense that 2 external USB cables may perform differently, and in the same sense that a different linear power supply may perform differently: what is the best way to test and measure whether or not an internal SATA cable performs differently? Wouldn't more than one test be helpful.
Clearly, FMAK conducted several tests.
"Asylums with doors open wide,
Where people had paid to see inside,
For entertainment they watch his body twist
Behind his eyes he says, 'I still exist.'"
"What are you calling minutae, and why?"
An example: the perceived benefits of addressing the usually huge and readily audible problems associated with improper grounding of multi component systems will in many cases far outweigh the benefit of addressing some lower energy noise problem where the effects falls well under the noise floor of the larger problem.
Not to accuse anyone one in particular of incorporating improper grounding techniques. The point is it is nearly impossible to know from which level of experience and success each poster speaks. I've seen spectral plots of sampled analog inputs by guys who I'd figured had it together suggesting severe setup flaws. I've learned to try not to over/under estimate anybody I don't know.
Thank you for your response.
Certainly improper grounding either by the manufacturer of 1 component, - or inherent in the system due to a grounding mismatch is a BIGGER issue than a SATA cable in the transport.
Likely, however, a big issue like that would've reared its ugly head long before FMAK or anyone got involved with a computer as transport.
Someone with Fred's experiences and knowledge shouldn't be questioned on the former IMO: especially given the history of his posts, and his related experiences with other components. AND, as Carcass pointed out, this is just about the easiest thing that anyone could try, the difference between a $.90 and at most, $40 shielded cable that anyone can unplug from the mainboard, and into their internal HD.
I have to agree that this giant thread is a "cult of personality" thing where anything that Fred says, (even if he agreed with the 'computers are wonderful' party line), he'd get piles of shite thrown at him.
"Asylums with doors open wide,
Where people had paid to see inside,
For entertainment they watch his body twist
Behind his eyes he says, 'I still exist.'"
I have used one point grounding and ac isolation for over 30 years. It is a given and I don't know why you had assumed that I placed Sata cables ahead of this.
Do you ground the various lumps of metal in your PCs? Even manufacturers with 'tested' machine don't.
Considering this was an answer to another poster, I see little point in explaining myself here other than to ask how could I possibly know your views on grounding until you just said so. I barely know anything about you. The original statement was obviously stated in the context that "most cases" of posts of random posters found here are likely users that have no clue about rf grounding. I still think that. That I even went on to state further down in my response to sordidman that I wasn't trying to specifically accuse you of poor grounding still I get this apparent temper tantrum.
"Do you ground the various lumps of metal in your PCs? Even manufacturers with 'tested' machine don't."
Please be more specific.
ask and please don't preach.
There is only one inmate that I won't respond to when asked, because, when you reply to one question, he asks ten others that either circumnavigate or show off his own 'knowledge' of everything.
I would hate to have been his employee and in any case, I used to deal with such people fairly effectively ie become his/her boss, or go elsewhere.
Clearly, FMAK conducted several tests.
Well, lets SEE his setup, his methodical approach, and his proof. He flames manufacturers for 'proof' all the time yet we are supposed to follow along as he plays whack a mole?
I would have to agree that Abe's logic is correct that Fmak provides no test method, posted results or any other data to back up his claim. If he has a TEK scope he can take snapshots and post the results for all to see, as well as his system to discern the sonic qualities of the changes made.
This is certainly not to much to ask from a so called "expert".... I am not condoning his purpose, just the delivery by which he states his position without any data. We did not achieve audio reproduction without sound technical engineering.
As another has stated, it would be nice to evaluate the sonic differences on another system with several different computers. I am certain my system is more than capable of resolving any differences. Anyone in the Chicagoland area is free give it a try at my residence.
MAK
I would hazard to guess that about 70% of your posts in PC Audio forum are dedicated solely to angry reactions to fmak's posts, picking fights with fmak, and threatening to complain about fmak to moderator.
Should it really surprise anyone, that you'll agree with whoever else hates fmak's guts - and the more, the merrier?
Fmak tired something, achieved a positive result in his system, and reported it, so everyone else could try for themselves - what's so fucking difficult to comprehend? He doesn't owe you, nor anyone else, any proof - go get it yourself, if you're so inclined.
fmak says he obtained a positive result in his system. My problem is that fmak never tells us what his system is and it always seems to be changing. I'm sorry, but I am suspicious. When I have an unsatisfactory playback I keep changing my system. When I get a positive result I stop changing my system and start enjoying music. Now it may be that fmak's system sounds great. Indeed, it might take only a few minutes actually listening to it to ascertain whether this is so or not. However, this is not an opportunity I have. All I have is what he posts. I don't see technical claims and justification for them, such as what a nerd would post. I also don't see the type of detailed and careful subjective reviews that a non-technical reviewer such as Mercman writes.
I also don't see interesting references to good, albeit unconventional music such as you occasionally post. :-)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Rummelsnuff - "Bratwurstzange"Won't win any prizes for sophistication any time soon, but together with video - is pretty enjoyable.
Edits: 07/08/14
"fmak says he obtained a positive result in his system. My problem is that fmak never tells us what his system is and it always seems to be changing. I'm sorry, but I am suspicious."
In this case what his system is not really important IMO. He found that a shielded SATA cable was an improvement. I also use a shielded cable in my audio system. You own a system from a manufacture I believe. Is it an Asus? If so you probable have a good SATA cable. Some of the generic flat cables are not good for audio, this is been discussed on other forums. A cable is only a few dollars, if you want to use some copper tape another few. How can this be faulted?
regards
Bob
which is not good either
"which is not good either"
I happen to use a 6in cable,but if read the thread on CA the ASUS 18in was also a good cable according to some posters. Someone also split and twisted it.
May not be a good thing as it disturbs geometry.
What cable do you use and are you sold on Paul Pangs's?
I use an Ok gear nothing exotic, but I think it meets the criteria. I have not tried Paul's cables yet. I do use his USB card and I am impressed. From what I hear with the cards, and the feedback on the web I would expect his cables to be good also. He puts allot of time and effort into what he does, pretty cutting edge. He even updates MB clocks.
a similar one to yours but the distance in the case I posted was too large.
I have two SATA cables in my system, one for each disk drive. One SATA cable came with the disk that was bundled in my system. The other SATA cable is used with a 4 TB internal hard drive that I added. As far as I can tell, both cables are the same. Most of the SATA cables in my collection came with various disk drive kits that I have acquired over the years. They all look alike.
I also have an ESATA cable. This involves a regular SATA cable inside the box to a header to an external ESATA cable (which is shielded). This connects to a Blac-X device that has a slot into which one can drop an internal drive and use it externally. Normally this slot is unused ant the Blac-X device not powered up. I use this for off-site backups.
During normal audio playback there is no activity on any of these SATA cables, as far as I am aware of. As such, they are definitely not in the audio signal path on my system. It was a deliberate decision on my part to play out of a RAM disk, and this was based in part on sound quality issues. It also provides a convenient way for me to store my library in FLAC and yet play WAV files.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
have not addressed a single point about the topic regarding spread spectrum and how it may affect audio.
I posted about what I found wrt a cable which was not shielded. If you are unhappy with this, all I can say is that you are trying to apply preconceived ideas about how computers should be made to how computer audio can be improved.
Are you interested in audio at all?
You know fmak my intent was not to be offensive. I was just being critical. My kid hates it but I can't seem to help myself. Probably a big part of why the old lady is anow an ex.I do appreciate that you liked the result. To me it is now a noted data point suggesting it could be a useful mod in some cases. My frustration is simply that it hasn't been quantified in terms I can understand.
Edits: 07/07/14
I don't mind at all, provided that it is not based on assumptions about that are not true.
I also don't accept pomposity from those who think they know better without first asking about the circumstances.
Whatever. I started (see my first post to you) by asking you about your system. It was you who chose to not discuss that and deflect the conversation. Now you will whine about me not asking about your system??
"have not addressed a single point about the topic regarding spread spectrum and how it may affect audio."
It will likely be system dependent what the effect will be, both dependent on the noise source and dependent on the impressed noise problem. Reducing the emissions from noise generators will lower noise and/or distortion in devices susceptible to it.
How's this for you? I'm not going to speculate about how this quantitatively applies to the nearly infinite possibilities of equipment combos.
"I posted about what I found wrt a cable which was not shielded."
You mean this?
"Presto, sound stage, focus, as well as hf and lf balance have come back and I am a lot happier"
I have no idea what you are even talking about there. I speak in terms of things like noise and distortion. You know, things which may be measured.
"Are you interested in audio at all?"
Of course. Are you interested in something besides fairy dust and magic beans?
n
Generally agree. However,
''Equipment with tendencies to exhibit susceptibility problems will exhibit the problems less in the presence lower energy disturbances. Equipment likely to radiate will be less disturbing to the environment if it radiates less. If I was a betting man I'd take the tested, marked gear every time.''
This viewpoint is just a hope for the best as spread spectrum techniques create large numbers of harmonics that may excite and which will be absent otherwise. So, it is not really a statement of goodness.
The days of type approval testing seem to me to be over (I used to do it),
as Governments have conceded standard setting to some of the big boys. At best, standards are a compromise amongst vested interests anyway.
I used to manage some BSI/European Standards Committees and was aware of the intense sectorial interests, having raised £1/4 mil just by sending 80 letters to firms to fund one.
Good point. Spread spectrum techniques do seem like cheating. No one is saying the laws are perfect. It's the manufacturers of certain types of equipment who come up with this stuff, and consumers put up with it by mostly not having a clue. I don't know if audio, ham, etc has the lobbying power collectively to cause change but then I'm not hearing much clamoring from the manufacturers either. Sensitive anlaog system users unite!
"Compliance is not equal to sound quality."
There is no "cheating" involved with spread spectrum. The goal was to prevent TV interference, or interference to other narrow band signals because of the use of obsolete receiver technology. It's only "cheating" from the audio perspective if one expects that the solution to the TV problem somehow carries over to the audio case. This makes no sense, because the TV receiver and audio system are different devices with different characteristics.
I deal with the SATA problem on my system by not using SATA to transfer any files while listening to music. All the SATA action happens before playback begins, while the files are read off of disk, decoded from FLAC to WAV if necessary, and stored on a RAM disk.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
"The goal was to prevent TV interference, or interference to other narrow band signals because of the use of obsolete receiver technology."
Not true as I understand it. The goal is to spread out the energy of energetic peaks to a wider band which will allow the manufacturers to utilize a loophole in the test method to attain compliance. The goals in setting test limit values had to do with preventing unwanted interference in RF receivers such as TV's but also in limiting malfunctioning of other types of equipment not intended as receivers such as pacemakers.
"The goal is to spread out the energy of energetic peaks to a wider band which will allow the manufacturers to utilize a loophole in the test method to attain compliance."
The test method was not a "loophole". It was good engineering to address a specific technical problem that was a result of interference actually observed. My knowledge is based on conversations with engineers for a large computer company where I worked that were specifically concerned with achieving conformance and which, of necessity, had a thorough understanding of the issues involved. The requirements were designed to protect the interest of competing radio services that used narrow band modulation. The advantage of spreading the interference over a wide band of frequencies is that it minimizes the probability of interference in any actual situation, where there are a small number of frequency bands that are active and most others are inactive. However, the active frequencies are specific to the particular installation, e.g. the local TV channels and the ones the neighbor actually wants to watch at the time the offending computer is powered up. Spreading the bandwidth of noise is not likely to affect systems such as pacemakers which are not narrow band radio receivers.
I've seen interference between computerized avionics where the noise from the computer killed certain of the VHF comm channels. The fix was to change the software to move the noise to different channels that were unlikely to be used. (This was done by the manufacturer of the offending avionics who happened to be a personal friend and I have personally experience the "before" and "after" effect on my radio reception.)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
I guess we'll have to disagree about the semantics about whether it is a loophole that a single frequency clocks larger energy content at a specific frequency per time is some how better than the same amount of energy spread over a wider band by utilizing spread spectrum techniques and allowing so called "quasi peak" measurements of this energy to now fall under legal limits in cases near the line.
"Spreading the bandwidth of noise is not likely to affect systems such as pacemakers which are not narrow band radio receivers."
perhaps not but as I was saying the limits were definitely conceived to help ensure proper operation of a wide variety of electronics within reasonable ambient environments. Not just radios.
Semantics is the guy's strong point and this is why I do not debate with him.Anyway, I thought I would post a picture of a small no of instruments I have to make measurements.
This includes:
1uV 1Hz-1MHz AC Volmeter
8 digit volt-ohm meter
HP digital scope 150 MHz with FFT function.I also use others such as -110dB thd+n meter, 64 bit pro FFT program etc.
If I am younger and more keen on measurements as I was then, I would buy an AP2 or better a Rhode and Schwarz
Edits: 07/07/14
I was getting dizzy...
A 150 Mhz scope is not going to be useful for examining signal quality of interconnects such as USB 2.0 and SATA. Look at the recommended test equipment in the link below. Big bucks are involved in test equipment, probably more than most audiophiles have in their entire system.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
to say or assume that I use a 150MHz scope with FFT to measure usb eye patterns.
It is actually far more useful in looking at the harmonics of XOs, with printout capability.
In other words, you admit the obvious. You don't have the tools necessary to measure signal integrity on high speed cables such as SATA and USB 2.0.
Have you found a connection between harmonics of XO's and sound quality?
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
inappropriate comment that makes others wonder what you are up to. I never said |I have or did it.
''In other words, you admit the obvious. You don't have the tools necessary to measure signal integrity on high speed cables such as SATA and USB 2.0.''
And if it is obvious, why ask? Do you just want to read your own words as Ted posted earlier.
I posted because of comments inmates made regarding your equipment photo. It might have not been obvious to some that your tools were inadequate for the purpose of tweaking SATA and USB 2.0 systems.
I do not go into modifying computer hardware because I know what tools are necessary having worked with a hardware lab containing hundreds of thousands of dollars of test equipment. There are people here with adequate tools, but most (if not all) sport the (M) moniker. Because of the small size of the high-end audio marketplace, even manufacturers have difficulty affording the necessary tools. One advantage of IIS and SPDIF are the lower data rates, enabling less than a $20,000 scope to show eye patterns.
You did not answer my question about harmonics of XO's.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
you frequently put inappropriate interpretations on my answers to you, I decided a long while ago not to answer your questions and that has been made obvious to you. I note that you have also misinterpreted what was said by others about the picture of some instruments that I posted.
It is your privilege to ask and my privilege not to respond.
If you don't like having your posts misinterpreted then I suggest you take more care in writing them. You might also consider that your inability and/or unwillingness to answer simple questions might not put you in a good light.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
that you need to learn to read properly. Noone else misinterprets my posts like you have bee doing.
I reckon that it is deliberate.
Deliberately reading improperly. An interesting concept, almost an oxymoron.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Nice stuff. I wish my own lab were so nicely equipped.
and who have the expertise will buy instruments. I know a guy who sells toys and is a nuclear physicist who bought a wavecrest to check jitter.
So many amateurs who don't declare their methods of assessment are quite knowledgeable. It's a case of web citizens accepting at face value what is posted.
Why, because they don't want to spend time arguing with some so and sos who think they know better. I am one of them. I spend my time improving my systems instead.
how ridiculous posters can get, stating that my 150 MHz scope cannot be used for usb eye patterns.
Edits: 07/09/14
"spread spectrum techniques create large numbers of harmonics that may excite and which will be absent otherwise. So, it is not really a statement of goodness."
Spot on Fred. About the only thing spread spectrum really helps with is the spectrum analyzer in the test chamber. Stuff with real-time, broadband susceptibility, say audio gear, could care less. It doesn't even need any processing gain to sound bad, just out-of-band energy.
Rick
"It doesn't even need any processing gain to sound bad, just out-of-band energy."
How does this bad sound due to noise at ~1-100's of GHz manifest itself audibly in our systems? What should we be listening for? My own system seems to be achieving spec'd SNR's for example and I don't even turn that spread spectrum stuff on presumably making my noise peaks even more intense on average.
Quite simply thru intermodulation and excitation over the range of frequencies.Ever had your mobile phone cause pops in your digital system or 2+ GHz satellite TV cause deterioration in SQ?.
These are real and the simplest example is the well known usb audio chip that simple sound bad due to spread spectrum techniques to lower jitter peaks - the energy remains the same however you 'spread' it.
Edits: 07/07/14
Well, to be fair there are many possible ways a pc can disturb an audio system and you didn't actually bring up spread spectrum until a couple posts back. I already mentioned I'm not a big fan of the spread spectrum technique.
I used to have pops and breakthrough in my system due to external RF sources. Spent a lot of time figuring out why they were there and finding ways to mitigate the problem. Haven't had those types of problems in a while. Magically, all the hard drive activity and other obviously pc related noise all vanished to a don't care, can't hear it with the volume cranked level of annoyance at the same time. Single point ground is a good thing.
"What should we be listening for?"
Good question. No singular answer. In general it's out-of-band amplitude variations that may get "detected" at various spots in the audio gear and the ilk of errors depends upon where the detection occurs and what the interfering signal looks like.
Back in my day sonny... The common problem was AM broadcasts and that was pretty obvious. Nowadays interference is likely to be more subtle. Not being a believer in the evilness of Z-beads, when I get a new component I usually make a pass of putting them on it's various wires like power and I/O's just to see if I hear any difference. I'd like to say that I'm thorough and analytical and chase things down to root cause. But... most of the time if they improve things, I just leave them.
One system instance in a single environment with a single user is a far cry from trying to insure adequate performance for everybody everywhere! Yes... our home stereo's really ARE about us!
Regards, Rick
the different stance taken by testers and those in R&D who work from first principles.
Those were the days when I was young....
@fmak:
Which sata cable did you use, is there a brandname ?
I saw this:
http://www.dx.com/p/double-hasp-straight-head-sata-ii-data-cable-blue-25cm-172140
Would that be good?
Shieldless this:
http://www.ebay.co.uk/itm/Sata-3-6Gbs-Cable-15cm-Ultra-Slim-Short-Connectors-/310941304827?pt=UK_Computing_Case_Mods_Stickers_Decals&hash=item48658bc7fb
short and sweet but no good in terms of SQ.
Shielded:
I don't know origin; it was supplied with a motherboard.
I have ordered a bunch of shielded cables from different sources. One claims to have 'elaborate' shielding (modDIY.com).
I shall try them and see if I can reach some sort of conclusion.
You should cut up your cable to see how well it is shielded and how good the conductors are. Some usb cables even have steel or aluminium weaved shields that require an argon arc to weld!
My work does not directly relate to compliance issues but I am often asked by my customers for copies of compliance certificates (EMI/RFI), power/cooling requirements, power supply efficiency at different loads / power factor, letters of volatility and such. We actually have 'compliance engineers' who expertly deal with this sort of thing on a daily basis. Fun stuff.
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