Trappist: The quick answer ... No I do not have any recomendations for equipment. The resolution om a 16 bit system mathamaticaly is around 86 db. It would be higher for a higher bit a/d converter but that is not the problem with making high accuracy measurements. Yhe problem is the noise floor of the analog front end of the converter. Therman noise and resistor noise (thermally related btw) would limit the actual resolution of the system. It would require cooling (like liquid nitrogen) to get the thermal noise low enough to get 110 db range accuratly. I do not believe a computer can be effeciently used in a near absolute zero enviroment. Chris |
Thanks Chris. Clearly you're knowledgeable! Seems though that digital source equipment can't produce quality up to what we can hear, so we can probably measure at a similar quality level and get some meaningful results.
The dcs 904 will sample at 192 khz 24 bits.
But then of course, the cables could have such subtle effects that these measurements won't be meaningful. The differences I have heard with interconnects though lead me to think that they could be measured fairly easily. l liked lemme's idea of inverting channel polarity and comparing that way with different cables on each. Very clever.
Trappist. |
I have to say I would agree with those who hear differences in speaker cable. These differences are measurable with a SPL meter.
Here are some measurements of speaker cables I have taken with a Radio Shack meter. This was comparing Monster MC1 (I think that was the type) versus another cable. The differences in the cables were actually greater in the mid ranges and treble end (to my ear), but I took these measurements because I was trying to diagnose and tame some bass problems I was having with the speakers. I did alternating tests Monster - Other Cable - Monster - Other Cable - Monster - Other Cable, and the results were consistent. The source for these measurements was the Stereophile Test CD 3 bass decade 1/3 octave warble tones.
Freq. Monster Inexpensive Delta
200 83 84 +1
160 83 84-85 +1.5
125 81-82 83-84 +2
100 86 87 +1
80 92 92 +0
63 85 85 +0
50 82 82 +0
40 81 81-82 +0.5
31.5 74 74-75 +0.5
25 73 73 +0
20 66 67 +1
As you can see there are some very definate differences on this most basic of all tests, which is able to be conducted by anyone with $50.00 and enough gumption to do them. Forget measurements we can't make yet or don't know to make yet, while I think there are some out there, but let's stick to what we can measure now.
How about some people actually measure some cable out there instead of just making unsubstantiated claims that all cable sounds the same or vice vesa? |
Gpalmer, your test results have blown me away. I would have not expected them to be that different. I would like to see several people try to measure the differences and give a detailed report. Chris |
Waveform measurments are made all the time and no differences are foundusing the test as I suggested above. Your results are flawed because it is near impossible to gather accurate acoustic measuments in a standard reflective rool with a time averaged meter as the RS. You will have better measurments to use a dvm at the speaker terminals so all of the sound bouncing off the walls do not enter into your measurments. Good luck though!
leme |
Well, I think we might be setting out to prove different propositions. I am not trying to measure exactly how much difference exists. I am trying to show that a somewhat reasonable and impartial model of the human ear can detect and measure differences in the exact same environment humans listen in. I am not trying to demonstrate the exact amount rather that differences do exist and are easily measurable. The closeness of a SPL meter to the human ear is topic for another thread to debate.
The question of reflection of sound waves strikes me as a red herring unless you are suggesting that human beings also listen in a reflection free environment. Since I listen in exactly the environment I measured, I am reasonably sure that there's a match there :-). I am not trying to prove what causes the difference either. I am pretty uncaring about the reasons unless they can lead me in a direction which leads to improvement. Conjectures such as little green men following each speaker cable around and pushing a little harder in some spots than others is fine with me as long as it is repeatable and reproducible and directly related to the usage of the cable in the system.
The SPL meter was mounted on a tripod one meter away from the woofer and was never moved during the testing. The gain on the preamp and power amps was never changed. The speakers never moved. The input source material was exactly the same and for exactly the same time. Three trials of each cable were performed. The only part of the system which changed during the measurements was the speaker cable and each time it changed, the same results were obtained, except for a half dB on one measurement of one trial of the non-Monster cable.
So bottom line, I don't really see how measurable and repeatable differences in the target environment can be ignored, since that is exactly what I am trying to show, and exactly what a human would hear, but whatever. I would really rather see what some other peoples results under the same conditions and with different cables are. Those results says a lot more to me than any testing I myself perform. Could be I had a defective or unusual cable in there and no one else in the entire world can reproduce the results with any brand of cables, ever. Only one way to tell... |
My suggestion is just to confirm your measurements. If there are differences with the RS acoustic meter you will also see differences with a voltage meter. A 2dB bass hump due to cabling is unexplainable and unreasonable. Are you using music as a source? You state the measuments we taken at the same time during each trial. I hope you can try with a test cd with tones.
thanks for the help
leme |
I was using the Stereophile Test CD 3 bass decade 1/3 octave warble tones track. I agree the 2 dB hump really threw me also, since I had always believed that wire was wire and once you got a big enough one it didn't matter anymore. I was using the digital meter so under just the right circumstances it could have been a 1.1 dB difference.
There was a difference in the length of the cables, the Monster was 12 foot while the other brand was 8 foot, but I have never seen a calculated result showing that this should have made the difference in the SPL I measured. Even if it did make a difference, I would have expected this to have been consistent across the board, not varying by frequency. |
Lets pretend (cause it probably will not happen in real life) that your speaker has a strong impedance dip and drops from a nominal 8 ohms to say .25 ohms. If both cables were of simular guage then the longer ones could have a little more resistance in them and not deliver the exact same current to the speaker that the shorter one did at the frequency of the impedance dip. This type of situation is where the difference could be frequency selective.
I am impressed with your testing method. Three identical measurements with test signals would imply valid results. I for one feel that the differences are very large and would like to have others see if they can find results of this magnitude. Was the test conducted while only one speaker was playing? That would help to remove some reflection problems and the effects of the other speaker. Chris |
Yes those were recorded with only one speaker driven as you suggest. I should have mentioned that. I tried both methods and found that there was more than enough bleedthrough from the second speaker to skew the results so I stopped it. |
Well I'm impressed by your diligence. Thank you very much for sharing your results and for taking the time and putting in the effort to do this. Here I am conjuring up all kinds of digital computer measurements, and you just go out and do the obvious test. Bravo!
Since I've heard big differences in midrange performace from cables, I can easily believe a 1db difference from cables. Frankly, from what I've experienced in the difference between the cheapest and some of the best silver cables, I'm surprised it isn't closer to 3db difference in the 3k-5khz band.
Gpalmer, you rule. |
I presume the meter was FIXED on to a stand or tripod, and that the equipment was not changed in setting or other value. I think you said that you ran several iterations of the test to verify results - which would tend to verify them.
One also has to be certain of YOUR physical position at the time you take the measurements, it should be the same (of course, ideally, you wouldn't have to be close to the mic at all.
I'd like to know what the physical geometry of the cables are, both like zip cord? And what speakers and amp are you using? Do you know the impedance and phase plots for it?
The next relatively easy test to make is a gross inductance and gross capacitance check using a DVM that has these functions. Of course slicker methods would be nice, but at least you'll have a first step.
Anyhow the results you find are indicative of either major differences in C & L between these two cables, and perhaps a major interaction with the crossover components in the speakers.
_-_-bear
bearlabs.com |
The meter was fixed on a tripod. My position varied, it was behind the meter, but I made no attempt to position myslef in one place.
The Monster was Zip cord, while the Argent cable was a shielded design (not sure of exactly what was inside). The speakers were a set of Legacy Classics, the amplifier was a Denon AVC-3030. No idea of the impedance and phase plots for the speakers.
I have made some major changes in my system since then. The Classics are now being driven in a vertical biamp configuration with a Sunfire Cinema Grand, which really flattened the bass.
I will be getting some JPS Ultraconductors as soon as the person I bought them from ships them (They've been very delayed). I can post some new results then.
Bear -> I don't have a DVM. Can you recommend one of reasonable quality and price for a hobbyist? I no longer have the Argent cable (returned it to the person who loaned it to me), but it would be interesting to have one around for occasional use. |
Gpalmer , the DVM to own, is made by FLUKE. The industry standard |
Apparently the way to measure these things is with a nice high end digital oscilliscope with storage and analsysis capabilities. |
Heh, the oscilliscope sounds great but isn't in my budget :-) Frap, how good is the model 8010a of the Fluke dvm? Found a used one which fits my budget (El Cheapo!)
Greg |
Every human voice has a different sound signature. I seriously doubt that any of the tenors mentionned would "measure" the same. I am not quite sure what type of measurement is implied or suggested though. Whatever note they sing (assuming they hit it just right, which they should on any given day)would have the same fundamental, but the harmonics would be different The harmonics are what gives each voice its character, its timbre. The harmonics would not measure the same. How this would help any of these fine singers perform is highly dubious. How any such measurement would increase the appreciation of their art by the listener is equally suspect. I hesitate to say the "tenor" argument is specious in this context, and leave it up to others to decide. If the example was between two guitars, at least the makers could attempt to duplicate the sound of a highly prized instrument on the basis of their findings, but since we can't manufacture singers the example is a bit wonky. No two guitars of the same maker would, if properly scrutinized, measure exactly the same anyway. Audiophiles might learn something by hearing the new modeling amps though. Ne less a guitar player than Buddy Guy felt that the new Fender could reproduce the tone of a vintage Fender Bassman. I wonder how Fender found the way to have digital circuitry mimic one of its own icons? |
Pbb, very interesting post. By the way, Bob Carver of Sunfire fame, maintained quite a few years ago, that he could voice his electronics in any way he pleased, to emulate the sound of say earlier tube gear and, so I am told, he proved it successfully more than once. |
I heard it for myself, at Bob Carvers home in Snohomish, Washington.
I heard Bob's Dahlquist DQ 10's, first driven by a big Conrad Johnson Tube Amp, then by a Carver Solid State Amp.
The sound was identical.
The problem was, it was not possible to do, in production.
Too many variables
|
Hey, cool! A 16 year old thread brought back to life.
|
Why stop at cables? There are just as many engineers that will say the same about any other piece of audio equipment. Some people just know everything and have this hobby figured out. Just buy good but not too expensive speakers, buy the cheapest amp that will adequately drive them, (because all amps sound the same as long as they are not being stressed) buy the cheapest CD player (because digital is digital, and is perfect) hook it all up with zip cord and viola! The worlds best sounding stereo. Man I wish I would have figured that out for myself years ago. |
chrissain. The funny thing is, you could do exactly what you just said, with today's equipment, and you might just wind up with a decent sounding system..... |
There's an interesting read on the QED website. At the bottom of the homepage, choose QED ACADEMY at the bottom of the page. You will find the genesis report, part 1 and 2. |
