Guess I didn't get that last post out quickly enough!
Yea, I guess you get a pass for not having an iPod in light of all of that. 😉
PS Guess the impetus is now on me to get my stereo a notch better, since you seem to have the low end covered, and I definitely don't have the high end covered nearly as well!
I think that we have more in common than you first supposed. Please remember, however, audio is my profession, not just my hobby. I do get exposed to all kinds of interesting stuff, from the very old to the newest and most expensive.
Please do not equate iPod with MP3.
Do note that you can put Apple Lossless or AIFF files on your iPod, and then the only quality limitation of the iPod is the quality of its internal DAC and there are becoming more & more ways to bypass that.
My iPod has never seen an MP3 (or AAC)
dave
Do note that you can put Apple Lossless or AIFF files on your iPod, and then the only quality limitation of the iPod is the quality of its internal DAC and there are becoming more & more ways to bypass that.
My iPod has never seen an MP3 (or AAC)
dave
Of course! All for different reasons. Edison cylinders offer a glimpse into a rare and short period of music when 'not live' was a novelty, plus I always found something special about live performances into a single mic, right up to the Fifties. The Gaza Strippers on MP3 blasting in the truck is a different form of enjoyment, as is a 96/24 live jazz download on the main system. Too often audiophiles are grouped with the sorry lot who need a precise mix of midgets and tentacles to tickle their pleasures. T'aint so.
Do you have to be rude, RDF? Why not just listen to what others say and ignore what you are not interested in.
I referred to Edison cylinders as a REFERENCE in the past, that still sounds better, in some ways, than much of modern music reproduction. Why this is so, should be of interest to designers, because it can be shown. Others, without the interest or inclination, should just ignore it. A childish attempt to discredit me with this will get you nowhere.
I referred to Edison cylinders as a REFERENCE in the past, that still sounds better, in some ways, than much of modern music reproduction. Why this is so, should be of interest to designers, because it can be shown. Others, without the interest or inclination, should just ignore it. A childish attempt to discredit me with this will get you nowhere.
Planet 10, we used a $20,000 digital server at RMAF, in early October. I found nothing wrong with the design, which was 384K 32 bit, or something like that, and open loop tube analog electronics. About as good as can imagine I could ever do, even if I even tried to do it, myself. Still, I was not impressed with the sound quality, mostly because of the CD sources, and their inherent limitations.
John, my reply was to dfdye, I initially raised Edison cylinders, not you, and my post was in defense of audiophiles.
Sorry, RDF, I mistook you for someone earlier in regards to Edison cylinders.
However, it is not the COPY of Edison cylinders that I am referring to, but the absolute originals, played back on original equipment. Anything else would most probably add the problems that the Edison cylinders avoided, without knowing it.
However, it is not the COPY of Edison cylinders that I am referring to, but the absolute originals, played back on original equipment. Anything else would most probably add the problems that the Edison cylinders avoided, without knowing it.
No problem. 🙂 I haven't had the pleasure of hearing cylinders directly so restricted my comments to their unique performance aspects. Nothing would surprise me, one of my favourite listens is a golden anniversary Segovia disk on Decca, pressed fifty years ago.
I never doubted either that we have a ton in common, or that you knew WAY more about audio circuits than I. Hope I didn't come across as having the opinion that I was dismissive of your experience. As I said, my job is measuring what are sometimes minuscule signals, so I am pretty familiar with data collection techniques and what impacts signal quality. Thus the reason I feel pretty comfortable piping in regarding cabling (even though most of my lab signal cables are simple RG-58/BNC's, we do have some interesting stuff that we occasionally have to use).
So, let's get this back on topic, then, shall we?
1) We pretty much all agree that oxide coatings on connectors adversely impact the signal transmission and sound quality of cables, and that there is a high degree of variability between the quality control of RCA plug manufacturers, most notably within the most recent discussion the quality of the gold plating.
2) Most of us agree that some sort of analytical testing should reveal perceived differences in cabling (if there are any 🙂) within the audio frequency range. John, you obviously disagree here, but Simon7K seems to be on board with this and has published a procedure for testing. (I still can't find an AudioXpress vendor in town, so I am still trying to get a copy of Simon's article).
3) A well shielded, solid core copper or silver wire directly soldered to an input should have the fewest contact issues of any connection method.
Thus, I propose a few criteria for objective testing of audio cabling (not that these are new ideas or anything, just the culmination of the recent discussions herein):
1. A reference set of cables should be defined as three feet of RG-58 with BNC connectors. This is not to say that they will be the "cleanest" or "best" cables, but they will be a readily available standard that everyone will be able to source pretty easily for very cheap. If we want to specify a little further, we should all try and use Pamona connectors since the quality control has been pretty good in my experience, and just about every supplier carries Pamona parts. Also, this will ease coupling to testing equipment since most off-the-shelf signal generators and analytical equipment like oscilloscopes are built with BNC input and outputs.
2. For CABLE testing, we should use a three foot section of the cable in question, terminated with BNC's as drop-in replacements for the reference cables. That way, the standard connectors should not contribute to the testing of the cables.
3. For RCA CONNECTOR testing, we should use something like this: Digi-Key - 501-1096-ND (Manufacturer - 4054)
to change one of the BNC's to an RCA plug. Yes, I know that it will introduce an additional connection to the mix, and yes, I know that the adapter's interference may swamp the impact of the new RCA plug, but it would be a reference and the change should be uniform between experiments. The reference cable should again be the RG-58 to keep things on the same playing field. Besides, if there is a known response from the adapter, then deconvolution of the contribution from the connector being tested is pretty straightforward.
The question, then, is what impact should we see between different cables and/or different connectors? Time smearing? Variable signal attenuation as a function of frequency?
We can easily test time smearing by sending a square wave into an oscilloscope and measuring the differential signal (A-B) to see what changes are observed vs. the reference BNC cable(s). The way I would personally do this is to hook up two 3' sections to ports A & B of my pulse generator, sync those up to the same trigger, or run them off of an internal trigger, and put each of those into the scope. My pulse generator is accurate to 250 ps, so I think it should be pretty good for our purposes. My scope is a Tek TDS380, 2 GS/s scope, so again, I have pretty good resolution here.
Simon has proposed what appears, at first glance (again, haven't had time to look at the details) to be a reliable method for testing frequency dependent attenuation within frequency domains down to 0.8 nV. I doubt the internal math functions on my scope could match that, but I can check it some time!
What other criteria should be considered? Any serious takers in actually trying to track down what John claims to have heard with his own ears? I'll admit that my system may not be good enough to hear what he is hearing. Maybe I need to rethink my assumptions regarding interconnects since my system's "clarity and accuracy" may be suspect in the first place! 😉
Still, before I go and spend thousands on a new preamp, build a spiffy set of Pass mono blocks, and spend God only knows what on drivers and crossovers for a new speaker project, all just to subjectively test cables, I would love to try and analytically quantify John's claims, and potentially set a threshold of audibility if we can measure differences in two components that John claims sound the same to him (if you would care to offer an example)
If anybody has a better methodology, please chime in! I would love to get a quick and dirty test fired off of my home-brew cables, but it wouldn't mean much unless we are all (or at least mostly all) on board with the methodology, so please chip in with any suggestions for changes or additions to the testing methodology.
David
PS I haven't fired up my TA spectrometer since getting back from Thanksgiving break, but I still plan to do the cap test on the ground pin when I fire it up over the next few days.
How I'd do it
Just to try to be complete... If I really cared much about cable terminations (beyond selecting and testing those commercially available that I find acceptable) i.e., if I had a contract to gold plate, say, OFHC copper or non-leaded brass RCA's, BNC's etc. This is what I'd do:
1) Electroclean in pH 10 NaOH/Na2Co3/surfactant solution @ 30 mamps/cm^2 @130 F for 5 minutes
2) Rinse and de-oxidize in dilute 10% HCl
3) Electropolish to ~10 uinch finish in 80% H3PO4 @ 300 ma/cm^2, RT for ~ 2 minutes (time depends on original surface finish and dimensional tolerances)
4) Rinse in DI water
5) Electroplate ~5 microns with high-phosphorous amorphous nickel alloy-preferred (or Bright Watts nickel), or palladium-nickel alloy
6) rinse 15 secs. max DI water
7) Electroplate with Co brightened gold @ 20 ma/cm^2 to ~2.5 microns or more (~ 20 minutes or so)
8) Rinse and dry thoroughly
This would qualify as mil spec 45204 Type I class 2 Grade C, and should be as robust as needed. With the Ni-P barrier coating and electropolishing (removes micro asperites and impurities) these should last a long, long time, as the NiP is very hard, inert, and amorphous.
Similar sequences could work for rhodium/ silver connectors, etc... but all would be overkill for the average audiophile system, and would be much more expensive than most commercial coatings (probably no more than 2 u nickel and .2u gold at best)
John L.
Just to try to be complete... If I really cared much about cable terminations (beyond selecting and testing those commercially available that I find acceptable) i.e., if I had a contract to gold plate, say, OFHC copper or non-leaded brass RCA's, BNC's etc. This is what I'd do:
1) Electroclean in pH 10 NaOH/Na2Co3/surfactant solution @ 30 mamps/cm^2 @130 F for 5 minutes
2) Rinse and de-oxidize in dilute 10% HCl
3) Electropolish to ~10 uinch finish in 80% H3PO4 @ 300 ma/cm^2, RT for ~ 2 minutes (time depends on original surface finish and dimensional tolerances)
4) Rinse in DI water
5) Electroplate ~5 microns with high-phosphorous amorphous nickel alloy-preferred (or Bright Watts nickel), or palladium-nickel alloy
6) rinse 15 secs. max DI water
7) Electroplate with Co brightened gold @ 20 ma/cm^2 to ~2.5 microns or more (~ 20 minutes or so)
8) Rinse and dry thoroughly
This would qualify as mil spec 45204 Type I class 2 Grade C, and should be as robust as needed. With the Ni-P barrier coating and electropolishing (removes micro asperites and impurities) these should last a long, long time, as the NiP is very hard, inert, and amorphous.
Similar sequences could work for rhodium/ silver connectors, etc... but all would be overkill for the average audiophile system, and would be much more expensive than most commercial coatings (probably no more than 2 u nickel and .2u gold at best)
John L.
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Absolutely! I just watched "Metropolis" the other day and loved it. Silent movie, terrible picture quality, brilliant piece of art! Like I said before, just because you like Kobe steak, it doesn't mean you can't enjoy a good hamburger.
Back on the iPod topic for a second, though: I appreciate that the limitations in the source material are John's gripe (I happen to be OK with it), and I appreciate that iPods can play lossless formats as well as MP3's. I have compared apple lossless to the high quality VBR MP3's that I have made, and through my Sure ear-buds in my noisy lab, I can't tell the difference. I CAN tell the difference between the 256 bit MP3's and the VBR MP3's, especially in the cymbals, even with the ambient noise. I guess it goes back to context on the listening environment--for me the VBR MP3's are not the limiting factor in the sound quality of my iPod.
Wouldn't be a shame to use rca to bnc adaptors in such a test?RG58 and some good quality bnc's are not expensive,so I think a better idea is to have properly terminated cables with bnc plugs.You may use the same bnc connectors on all cables on test.
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Was that the DAD stuff?
No amount of DAC is going to cover up what is lost when your quantize the signal so crudely as in a CD (i always imagine the big boot coming down outof the sky to squash whatever they are squashing in Monty Python). Sampling needs to be at least 4x higher IMHO to start getting to where well executed digital SW compares with well executed analog SW.
dave
You mentioned that regarding magic pebbles.
Can you give me full details on WHY you feel magic pebbles are rubbish?
I completely agree. For JUST CABLE testing, I would terminate with BNC's. The BNC-RCA adapter was for use testing RCA plugs. I haven't fully thought about RCA jacks yet. . .
Sure. They don't have any active or passive impact on the audio signal. As of now, my claim is just as valid of those claiming the pebbles work. Give me verifiable data that I am wrong, or I will continue to laugh in the face of anyone who claims there is any impact other than visual aesthetics. Close your eyes, and the effect goes away.
Like I said, feel free to prove me wrong. Ball is in your court. The impetus for proof is on the person proposing the effect.
Wasn't talking about the pebbles, only the nonsense that get brought up to distract a discussion, especially when it may lead to some new information.
Since we are talking about cables here, why must "magic pebbles" get mentioned, if not for stirring?
No, I've never tried them, I don't believe in "magic" thus wouldn't spend anything to get some to try also. You are welcome to send me a sample though. 🙂
I would call that your expectations informing your perceptions.
I have side by side compared a well recorded CD to its analogue counterpart and found except the missing surface noise no difference - but then, my hearing at the time was already down to 16kHz.
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