SY said:
Can anybody explain this math to me????
quote""Taking the example of a pre-amplifier of nominal 1 volt output with typical impedances, he showed that the actual voltage drop over a .1 ohm interconnect might be just 2 microvolts, and thus the real signal level in the cable may be in the range -114dBV to -174 dBV.""
Doesn't this mean that if I use heavier guage wires, the real signal level will be even lower??
There must be a translation error here.
Cheers, John
SY said:
Cool.
quote""However, then you come to the magnetic field modulator. This is another problem. I think many manufacturers are mechanical engineers, know how to wind a coil, know how to make a cantilever, but they do not know how to modulate a magnetic field. ""
Give me a break...... he must be joking...
Some manufactureres allow mechanical engineers to design the flux modulator????
Ewwwww....VDH is absolutely dead on here... I trust the mech guys to keep wire placements to 100 millionths of an inch in liquid helium with 10,000 psi forces at 10 kiloamps, but they don't design the magnetic field stuff...that's what the physicists are for...
Score a big one for VDH... The "thermal pump theory" is off kilter, it don't happen to any real degree.
I do agree with his concern on dielectrics..he speaks very well on that..Score another for VDH..
This has problems:
quote""The high-density polyethylene also copes with soldering: the solder runs inside and closes the wire for ever. ""
The precursor to "solder runs inside" is "FLUX runs inside" If the flux doesn't run inside, the solder will not...there will be no metallurgical bond to wick the melt in.
The HDPE would certainly slow down intrusion.
Of all he has stated in the article on wires, I believe this is what all should come away with, this is the most important thing he has stated:
quote"" And signal transport and shielding should be kept separate."" Score a very big one VDH..
This is what JC did not address with his distortion analyzer when he beefed up the electronics. What used to be in the mud is no longer..this is what all single ended input manufacturers do, and it is something that even the differential input guys do not do well (there are exceptions of course).
50 milliohms per meter is still too high for a speaker cable...but hey, to each...
The metals blocking low level zero crossing information...completely unsupported.
But I do like the guy...
Cheers, John
Wow there's more. Over my morning coffee I see that VDH measured the sylus tip temperature with a thermistor leads and all. That is an amazing feat of engineering getting that thermistor right down with the record and the stylus without perturbing the temperature of the system. The peak temperature is extremely localized, I can't easily imagine instrumentation to actually measure the stylus surface temperature.
Edmond Stuart said:What about the devastating effect of magnetic monopoles?
Hey, symmetry demands those puppies..
I'll let ya know how the monpole detector works out. I think they're installing in in the next couple of weeks. (I'm not joking)..
We made a styrofoam box 8 feet tall, 3 feet by 3 feet, radiused the corners, and covered inside and out with mu metal..then the physicist came to me and said""can you degauss this thing??? And no, we have no money...
scott wurcer said:
I'd have worried about the thermistor mass upsetting the moving mass symmetry.
I wonder if the readings were good ones, or if they were simply in the correct direction so assumed good..
The guys here would have used spectral absorbtion of the stylus, rigged up some kinda lazerbeam widgy.. I had to use an IR system with a confocal microscope (from edmund scientific) to measure a spot temp on a 60 mil diameter tungsten carbide, but was able to convince the powers that be...that an ultrasonic welding process for plastics doesn't rely on the tip temperature, but rather, the transfer of U/S energy into the plastics..
Cheers, John
ps..scott...don't you get e-mail??
jneutron said:
Yes, I answered best I could.
I have a question. How can there be repeatable peer reviewed studies proving the audibility of 1.5uS inter- channel delay and at the same time there not being any way to imagine how to measure this (I think you sort of said this)? You can’t have one without the other. I presume there was instrumentation and stimulus in place to do these studies in the first place. I have not seen the papers, are the results difficult to apply to the music listening experience?
That's .5mm is it not? Hard to make the evolutionary argument at this level. Considering performers moving around with respect to mics, or better yet the speed of sound vs T in air or relative motion of the air all swamp this. A quick check of a medical paper showed a difference of 10-20us for a couple of degrees C in tissue (conducted portion of what we hear).
scott wurcer said:
The procedure is simple..
1. Shave the subject head.
2. Duct tape the subject's head into a vice.
3. Superglue a septum down the center of the head.
4. Clamp the ears to some funnel shaped horns..
5. Test...
Most of the researchers use headphones, so refer to the testing as lateralization tests. I've not seen any studies that use a single speaker as the reference with two speakers setup as the stimulus for testing IID/ITD. That would be too close to what we actually do, wouldn't it??
Typically, the graph that comes out is like this:
Now, this is single tone with the subjects determining a difference. Other research also indicated the ability to be trained to get to this level of discrimination.
My point RE measurement is...do you think you could easily find a sibilance interchannel delay of even 5 or 10 uSec, with drums, bass, vocals, guitar, snares, tanbourines, piano, organ, some of it not correlated interchannel, or even with identical frequency distribution? This is a signal correlation mess...but humans do seem to be able to discriminate stuff like that..
Cheers, John
Attachments
Gentlemen;
did I tell you that I experimented on alive people being a part of a traveling Philharmonic ensemble?
I did. Guilty. I created imaginations altering their perceptions. They paid money to get tickets to be used in experiments. And they love them.
But what I am going to tell, such delays like you speak about did not create any imaginations.
But, when I delayed one channel 20 milliseconds and around, they rotated their heads when our drummer performed his solo!
Can you measure distances between dishes, drums, and figure out time delays? Why 20 milliseconds? It was the time starting from which people reacted subconsciously rotating their heads. What is funny, they said they saw the sounds of our drummer rotating all around!
I told already how local audio engineers invited me to their studio and using vodka tried to unleash my tongue so I reveal them how I rotated sounds 4-dimensionally... I told them the whole trooth, ut they did not understand.
There is some threshold for special effects. But there is some threshold for absence of them. They are not equal. But I have no proof about such short delays you are speaking about,
...also I know how pan pots and delays work (you are referring to studio - recorded thingies, right?).
did I tell you that I experimented on alive people being a part of a traveling Philharmonic ensemble?
I did. Guilty. I created imaginations altering their perceptions. They paid money to get tickets to be used in experiments. And they love them.
But what I am going to tell, such delays like you speak about did not create any imaginations.
But, when I delayed one channel 20 milliseconds and around, they rotated their heads when our drummer performed his solo!
Can you measure distances between dishes, drums, and figure out time delays? Why 20 milliseconds? It was the time starting from which people reacted subconsciously rotating their heads. What is funny, they said they saw the sounds of our drummer rotating all around!
I told already how local audio engineers invited me to their studio and using vodka tried to unleash my tongue so I reveal them how I rotated sounds 4-dimensionally... I told them the whole trooth, ut they did not understand.
There is some threshold for special effects. But there is some threshold for absence of them. They are not equal. But I have no proof about such short delays you are speaking about,
...also I know how pan pots and delays work (you are referring to studio - recorded thingies, right?).
Nelson Pass said:
I would have been most interested in data down to 50 Hz or so.
I've never seen papers going that low. I would suspect one would have to use a sinex/x style impulse to test, otherwise the transient nature would allow keying on harmonics of the test signal, rather than the fundamental..
The Nordmark graph is log/log, and it appears to be a straightline on those scales..
I printed it out and extrapolated...at 100 hz, it's 25 uSec, and at 50 hz, it's 45 to 50 uSec.
But I've no idea if that extrapolation is even worth the time to type it.. Chances of that extrapolation being even close is probably zero..
Cheers, John
Nelson Pass said:
If you look at the graph with zero jitter, it looks like a bathtub, and a threshold of 15 uSec unjittered is between 200 hz and a tad over 1.2 Khz. Unjittered, Nordmark certainly agrees with Steven.
The truly amazing sensitivity with jitter is the weird part. It looks like the kind of thing we get when we dither an analog signal in front of a ADC to increase sensitivity beyond LSB..
How to interpret that in terms of the "hunter" in us....beats me.
But it would appear that this would have significant impact on a single driver system, or one where the 200 to 2K information is coming from the woofer cone, as the woofer displacement will certainly impact the jitter of the mids..
Cheers, John
Re: Why 20 milliseconds?
Mr. Linkwitz is always welcome here!
Some people asked why some of his designs have obvious flaws;
however I filter out flaws like personal preferences, but my friend when I said that I hear a nice coherence between drivers in a bath tub he said, "Naaah, such Doppler modulation"....
Any comments?
wayness_tamm said:
Mr. Linkwitz is always welcome here!
Some people asked why some of his designs have obvious flaws;
however I filter out flaws like personal preferences, but my friend when I said that I hear a nice coherence between drivers in a bath tub he said, "Naaah, such Doppler modulation"....
Any comments?
Just my 2 cents. Many years ago (probably about 1984) I was trying to adjust a tape deck - a nice Pioneer, closed loop dual capstan, 3 heads etc. Despite all my efforts I've found that the sound from the source and from the tape had a positioning difference. Both channels were flat and perfectly level matched. Only when I looked at the phase difference between channels I've found that the "sandwich" head was faulty - the recording and the playback sections were not quite parallel and one channel was delayed by about 90 degrees at 15-16 kHz, i.e. less than 20 us difference - and it was easily noticeable. I had to insert a simple phase-shifting circuit in one of the channels to make the difference almost imperceptible.
Alex
Alex
x-pro said:
I always used a store bought tape to align the playback head. I'd put the speakers right in front of me, about 6 inches in front, a foot apart..and adjust the playback head until the center images of the music (vocal typically) were precisely centered. Sibilance was always the best to key on.
Got some very good results that way without worrying about delay.
My computer sound card is mux'd, it has an 11 uSec delay interchannel, so it is impossible to use a balance control to put the soundfield exactly in the center.
Cheers, John
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