Bear,
As I mentioned, I did some (informal) tests with my new ABX box and I noted that the differences between my speakers stood out much clearer with the box than before, when I rewired the amp to the one or other speaker and played some music.
Especially at the moment of switching I had this 'wow' moment; then as listening progresses the mental sound image of the exact difference slowly blurs. My € 0.02.
Edit: maybe I should tell you to run some tests ;-)
Jan
No theories were involved, just measurements, it was a practical engineering development project. The test fixture was a booger to get settled, lots of tightening of connectors, changing of cables when they got weird. The fixutre consisted of two 200W UHF power amps, four variable passive power notch filters, circulators, hybrid couplers, varous sets of three custom-built hi-Q bandpass filters, fan-cooled attenuators made from copper jacketed semi-rigid cable (power attenuators of the usual type caused too much IMD themselves), and low-noise amplifiers. Quite a setup (there were actually two build).
The thing about nickel might be something related to magnetic saturation? Though that wouldn't explain the issues with stainless steel I wouldn't think. Gold plated connectors also seemed good, if I recall,, though we didn't have many of those then (mid-80s), but silver-plate seemed the most reliable. A nickel connector anywhere that levels of two signals were present stood out many dBs above what you'd get with silver. This was applying two signals of about 50 Watts each to a UUT and looking at stuff narrow-band down in the dirt -110dBm or less. It was originally built to look at IMD from expected to be stellar PIN-switched networks. As it turned out, nowhere near that much dynamic range was needed to see IMD3 from PIN diodes, even inside filters (which appeared to behave pretty much as the established equations predicted concerning forward currents and reverse voltages). The fixtures later were used to work with multicouplers and diplexers and other fully-passive stuff and to see effects of platings inside coaxial filters (nickel even under other plating on the inside surfaces could be detected).
Distortion products followed the expected non-lnear-with-level track (3rd order IM products increasing 3dB for each 1dB increase in applied power*)
*if everything else was sorted that is, but when more than one IM generator was 'in the zone', all sorts of odd cancellation effects would happen. Hence all the fooling with cables to weed out the ones with (presumably) broken strands in the jackets.
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The usual problem is a nickel coat on the base metal to allow surface plating. Getting nickel iron free is a challenge and it doesn't take much to create IMD. Of course ALL RF has lots of IMD of course, comes with the territory so keeping it out is a big concern. Now you look at cell phones where you need to get at least 100dB isolation between transmit and receive. When they share the same feeder cable doesn't take much to mess with that.
Back in the early 90s silver plate was used a lot on connectors, but then hard nickel free coatings were developed (secret sauce so no idea what was in them) which were a boon.
I do miss filters milled from solid.
Jan,
A little unclear what was being switched?
Amps?
Or speakers?
Anyhow, something amiss with your description, perhaps?
When you have the 'wow' moment, that is when it switched. BUT, that is also
the moment when you could be switching 'A' to 'A' or no switch except the 'switching'. So, perhaps the 'wow' is/was the slight discontinuity only??
No, no, I was switching between speakers but in sighted mode. Still trying to get myself familiar with it, will graduate to blind mode someday ��
But to my surprise the differences stood out more than I realised before I had the box.
Edit - another surprise was that it is much more difficult to adjust the levels to be the same than I thought. With speakers, the tonal character can be different enough that it is hard to judge the level difference.
Jan
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a reasonable method, which works to some extent is to match levels with pink noise at the listening position - this tends to integrate the full range of the speakers as a single "level"... but differences between different speaker systems are so large, hard to know why you'd need or want to ABX or even A/B??
If you don't hear differences with pink noise, there is something seriously wrong. And yes, level matching is something of a chimera.
When I worked on the ill-fated preset-level line-level switcher to accompany the pneumatic speaker mover for Harman R&D, there was even a masking noise generated to obscure any differences in the acoustical noises generated by the mover, lest this give a cue as to what speaker was what. But it was rarely necessary. Now that I think of it I don't know what they wound up using for the switcher. And I don't know what criteria they use for level matching.
As far as the time per trial, a recently- and forcibly-retired speaker designer refused to submit to any testing. He was told he could take as long per trial as he wished, but with admirable candor he said that he had a reputation for having good hearing, and thus had nothing to gain and possibly much to lose.
Much is made of the alleged short-term nature of aural memory, and I suspect that for some things it is indeed quite short. For me some issues with equipment don't seem to surface immediately, the case in point being the learning curve for early digital hardware and software, which produced fatigue after several days. I also found myself thinking of the system, such as it was, as being more of a demonstration rather than a means to pleasurable listening experiences. And the demonstrations got shorter and shorter. A housemate accused me of having my mind made up to begin with, as he heard nothing wrong with any of it---but I reminded him that I had been surprised how good it sounded at first.
When I worked on the ill-fated preset-level line-level switcher to accompany the pneumatic speaker mover for Harman R&D, there was even a masking noise generated to obscure any differences in the acoustical noises generated by the mover, lest this give a cue as to what speaker was what. But it was rarely necessary. Now that I think of it I don't know what they wound up using for the switcher. And I don't know what criteria they use for level matching.
As far as the time per trial, a recently- and forcibly-retired speaker designer refused to submit to any testing. He was told he could take as long per trial as he wished, but with admirable candor he said that he had a reputation for having good hearing, and thus had nothing to gain and possibly much to lose.
Much is made of the alleged short-term nature of aural memory, and I suspect that for some things it is indeed quite short. For me some issues with equipment don't seem to surface immediately, the case in point being the learning curve for early digital hardware and software, which produced fatigue after several days. I also found myself thinking of the system, such as it was, as being more of a demonstration rather than a means to pleasurable listening experiences. And the demonstrations got shorter and shorter. A housemate accused me of having my mind made up to begin with, as he heard nothing wrong with any of it---but I reminded him that I had been surprised how good it sounded at first.
The equivalent of the film folk are shown, where a person in a gorilla costume walks through an office scene and none of the viewers notices. The perceptual system decides it's wrong and filters it out.
Similarly the adaptive filters in the audio perceptual system can cause people to clearly hear voices that are not there, if they listen to noise for long enough...
Bear, don't take this personally, you are one of many who are subjected to this frequent mode of behaviour, and I believe you are owed an apology as are many other members.
Stuart, will you please refrain from this negativism of yours.
You may think you are funny, but many others do not find your insults humourous in the slightest.
Your behaviour as moderator serves to encourage others, including other moderators on this forum to duplicate your bullying and insulting outputs.
There are plenty of other Forums on the net, and other threads on this Forum where the general atmosphere is one of politeness and cooperation, and the result is positive advance in the subject at hand.
Your jibes really do soil this thread and as often as not, derail the discussion.
For the sake of others, please resist the temptation in future.
Dan.
When someone has a link to this BEAR Labs' Philosophy of Design on their signature that kind of puts their cards on the table. I particularly like
There is a good book about this type of thing called, The Invisible Gorilla.
I have encountered this kind of 'off' sound in the past, in home systems and Pro sound systems.
In these cases cables were touching metallic items.
Typically live 'pub' sound guys wrap cables around speaker stands and mic stands...ime this is guaranteed to alter the sound, and not in a pleasing way.
Yes.
Dan.
So you disagree then??
That's a pretty mild, middle of the road statement.
Is your position that materials make NO difference whatsoever and ought to be ignored?
Unclear, sir.
Let's see your cards then?
_-_-
That was not stated in the story, and I'm sure CH would claim lifting with myrtle blocks off of an oak floor sounded like a "new pair of speakers". Please go back and see how exaggerated to a point the claims are. Some of this crap comes from Chardas another shyster. BTW he is wrong the myrtle is far from the rarest wood (most expensive) available as if that matters. You have to be smarter than this BS.
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Not wishing to deprive anyone of the joy of reading the entire account, I'll just quote an excerpt. The background is that the system had been set up for a month before the show, "broken in" etc. At the show:
"Something's wrong. This does not sound the way it sounded back home."...I spent five hours trying to figure out what it was. ... The show's about to start---it sounds wrong---something's wrong with the system---it's broken....But guess what? The power cord going from the wall to the preamp was missing one wooden block. So there was [sic] two inches of cord that looped down and touched the carpet. ... "
He asks why the block is missing (the setup guy ran out of blocks), and the guy is instructed to fetch another block, which is inserted under the loop.
"Aaaahhh. Now it sounds right---now we can go to bed."
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