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In Reply to: RE: Distortion measurements with and without a smoothing cap posted by cpotl on September 13, 2014 at 18:00:58
This was my fault.
When I labeled the pictures on my computer, I used the '%' sign.
It appears this character has a meaning in computer lingo.
Follow Ups:
OK, now I see them.
Could you please give a bit of further explanation, for those (such as myself) not familiar with the measuring hardware and software you are using for the distortion plots?
The upper photo (Mundorf_distortion_003.JPG) is with the 1.2uF bypass capacitor, and the lower photo (Mundorf_distortion_004.JPG) is without the bypass, right? Now, in each photo, there is a blue trace and a red trace. What is the significance of each of them?
Thanks,
Chris
Hello Chris
The measuring software I use is 'Arta'.
My signal generator comes from my laptop (which Arta manipulates).
The microphone used is the Behringer 8000.
Arta measures the purity of the signal going out (from the computer), against the DUT (device under testing, which is my entire system).
Since I am testing my entire system, Arta is testing the final output.
The blue trace is second order harmonic distortion, with the red trace third order distortion.
In order for me to test the pre amp on it's own, or the amp, I would need to build a 'measuring box'. I am only concerned with the entire system, which is why I've never bothered to build 'the box'.
Thanks for the information. It seems like rather useful software.
One thing surprises me a bit. I have no direct experience of measuring distortion on the acoustic output from the loudspeakers, so I may be a bit off base here. But based on what I've gleaned from articles I found on the web, loudspeakers in general seem to have pretty bad distortion figures; something like a couple of percent or worse at low frequencies, and of order 1% in the mid to high region. Your figures seem to be hugely better than that. It leaves me wondering what could account for the very striking disparity with the typically quoted figures.
Chris
Chris, you are absolutely correct. Most speakers do not measure this well.
A quick overview;
My tweeters are the Accuton 3/4" diamond tweeter. A few independent websites have measured the Accuton, and call it the cleanest tweeter they've ever measured.
My midrange is the 5.5" Accuton ceramic midrange. Now most of the time people/manufacturers use the 6.5". Me, I didn't like the 6.5", especially above 2,000Hz.
There is NO multistrand wiring anywhere in my system. Don't get me started. If you slowly remove the multistrand from your system, you too will notice lower distortion levels. This becomes more evident at higher listening levels. I will call it 'micro-arching' between the individual strands in the wire. Copper stranded wire which is getting a little older is better. The copper oxide which starts to form along the individual strand does not conduct electricity, so this micro-arching diminishes.
It took a few years of experimenting, but I now have a first order crossover which adds to the purity.
All my crossover parts are Duelund CAST PIO in nature. Caps and inductors.
Did I mention NO multistrand wire anywhere, not even my power cords.
I took my speakers to TAVES (Toronto Audio Video Entertainment Show) last year, and those that sat and listened, where floored.
So, Cousin Billy, what wire do you use with your speakers? I was about to go with Cardas before I read your jnteresting post.
throwback
My speakers have an active woofer section. This negates the need for a thick cable.
My speakers are bi-wired, meaning I use a separate cable for my tweeter, and one for the mids. 4 wires in total per speaker.
I use the Duelend Silver Foil Silk and Oil wire.
My tweeter is fed with the smaller of the two (1.0 I believe), while my midrange uses the 2.0.
I think I will say this next part correctly;
My 4 wires per speaker hang freely, and are seperated. This slightly increases inductance, while lowering capacitance. I found keeping all the wires separated gave a clearer treble presentation. Experiment for yourself.
Using the Duelund wire cost around $400.00 per speaker.
Time for my medication.
wire manufacturers model their designs of cables on waveguides. Could very possibly explain your results with solid core (I do agree, BTW, FWIW). Of course most waveguides are rectangular and then serve two frequencies.
Kimber has an interesting hook up wire 23 Ga, SF 23, which is oval in cross section, two to one ratio. To y ears a n extremely good sounding wire.
Of course YMMV
"Some wire manufacturers model their designs of cables on waveguides. Could very possibly explain your results with solid core (I do agree, BTW, FWIW). Of course most waveguides are rectangular and then serve two frequencies."
The design criteria for waveguides are totally different from those for audio cables, and to model the latter on the design criteria of the former would make no sense at all. And, by the way, waveguides are almost always designed so that the propagation of the frequencies they are intended for can occur only in one mode (the lowest mode). Rectangular is usually preferred over square in order to avoid a twofold degeneracy between modes, so that the propagation occurs unambiguously in one and only one mode.
Chris
Subjectively, I prefer solid core wire, too. But I would never dare to say that I know why or that stranded wire induces grossly measurable distortion that is not present with solid core hook-up. Like cpotl, I am a bit nonplussed. People who do not care for stranded wire often do indict the interaction between the strands as a culprit, but some very smart people (in the field of electronics) call it hogwash. Thus, I don't try to explain or justify my subjective preferences (this one and many others). Since the adjacent strands in a conductor are in continuity, I would not think "micro-arc-ing" occurs; the strands would tend to act in concert as a "non-solid" core conductor. Oxidation of copper wires internal to the surface of a stranded copper conductor would tend to be inhibited by the presence of outer insulation and the close packing of the internal strands.
Nice speakers. Remind me of the Coincident Pure Reference, which also uses Acuton drivers for treble and midrange.
Hey Lew
I've owned a few if Izzy's speakers. Loved them all.
When I went to Isreal's home to audition the Pure Reference, I asked him to build me a pair, only using the Accuton Diamond tweeter. He said no?.
Thus started my path of DIY speakers.
My neighbor up the street has the Pure References driven by a brand new Novacron. He's very happy with that combo. Prior to that, he owned my old Sound Lab U2s, driven by MA-2s. Problems with the U2 caused him to give up on ESLs, sadly IMO. Which Acuton tweeter does Israel use, if not the diamond one?
What are the odds that two audiophile nut jobs, like me and my neighbor, would live on the same street?
Hey Lew
Izzy uses the Accuton Ceramic 1.2" tweeter. It can be crossed as low as 1800Hz. It's also not as particular about crossover components.
The diamond tweeter on the other hand needs the best crossover parts to shine.
In the near future I will take a set of measurements with my present wire, than I will swap in some multistrand.
I'll start with speaker wire.
Now ya'll gonna hav ta excuss me, my Sophia 6sn7's just arrived, and there's another thread that wants some input.
I don't mean to throw down any gauntlets. I only wanted to point out that there are many possible reasons why your data might be falsely positive. To really nail it down, try making some measurements across the wire, only, eliminating upstream and downstream variables and with necessary controls.I think the ear/brain processes aspects of the music reproduction that are either not measurable by standard methods or are due to the net effect of a collection of separately measurable variables which are thus not so easily understood as to cause. Plus, listener bias is HUGE, no matter what one might think.
Edits: 09/17/14
Luckily, on this occasion the claim that is being made is an indisputably objective one. about the distortion that is measured by an instrument. I agree completely, that the extraneous factors associated with with acoustic measurements should be removed from the experiment, and a purely electrical measurement of the distortion from a stranded wire versus a single-conductor wire should be performed. As far as I am aware, no documented differences of any significance have been found until now. I seriously doubt that there are any to be discovered.Chris
Edits: 09/18/14
Some minor information;
I have a dedicated listening room.
Isolated sub-panel, independent ground, one feed off one side, and one off the other.
One receptacle feeds my BPT isolation transformer (source components), with another receptacle feeding a Torus Power station (amplifiers).
All connections have a conductive paste (similar to Walker SST) to prevent my theoretical micro arc-ing. Even in the sub-panel.
Midrange measurements first.
The first picture is with multi-strand speaker wire, with the second picture using solid core.
There appear to be fewer spikes which touch the 0.1 line with solid core.
Next post is for the tweeter
I think that trying to extract meaningful results for the relative distortion caused by stranded versus solid core speaker wires by means of acoustic measurements in the listening room is a process fraught with too many measurement uncertainties. Any effect, if there at all, is going to be tiny, and is liable to be "lost in the noise" (literally!).
As a start, it would be good to compare several of your distortion vs frequency plots for the *same* wire configuration, to get some feel for how much variation there is between one run of the distortion measurements and the next one.
But in any case, if the object of the exercise is to measure the distortion caused by a length of stranded wire and compare with a length of solid core wire, then the precision and reliability of the experiment would be greatly increased if the measurements were made purely on the electrical signals in the two cases.
Chris
You might get into trouble with the differences being too hard to measure if you limit the scope (no pun intended...) of the exercise.
IOW, it is easier to see the differences (and hear) them when the change is a bit more global- such as building an entire preamp or amp with a certain brand of resistor, rather than just one resistor changed in one spot.
One thing that led us to solid core was skin effect- which (depending on the circuit impedances) can get down below 80KHz if the wire gets too small. In theory the skin effect could manifest as a differing impedance depending on frequency. Never really chased it down though.
We did do a set of measurements using a TDR we leased way back in the early 1980s, that showed that there was more noise associated with stranded wire than solid core. Of course, the TDR was operating at RF frequencies, but if you think about how you might have more RFI in the circuit due to the choice of wire... we all know that RFI can affect the sound of a circuit. Again, inconclusive as we didn't chase that one down, but we did find that there is a correlation at audio frequencies with the measured characteristic impedance of the speaker cables we tested on the TDR. Although this is all circumstantial, they were real world measurements and do point to the possibility of a difference between solid core and stranded.
I think Billy is on the right path- we often hear things but struggle with the bench measurements to confirm what we hear- but if we put a mic in the same room where we hear the difference, and measure **that**, then we have some substance to work with.
"You might get into trouble with the differences being too hard to measure if you limit the scope (no pun intended...) of the exercise.
IOW, it is easier to see the differences (and hear) them when the change is a bit more global- such as building an entire preamp or amp with a certain brand of resistor, rather than just one resistor changed in one spot."
Personally, I will stick with the tried and proven scientific method. If you want to test the assertion that multi-stranded wire creates more distortion than single-core wire, then do a clean experiment that simply measures one against the other. Don't introduce extraneous factors like running the signals through a loudspeaker and thereby introduce confounding factors associated with acoustic measurements.
Chris
I agree more with cpotl on this issue, but I do commend Cousin Billy for his attempt to understand why he hears what he (and I) hear. That said, the posted data could equally as well be interpreted as "proof" of a slight superiority of stranded wire vs solid core wire, as the converse. Note that at certain frequencies or groups of frequencies, distortion is very slightly (probably inaudibly) lower for the stranded wire, but to say so would make it seem as though I endorse the methodology; I do not.In my earliest days of moving over to solid core wire, I was told by Pierre Sprey of Maple Shade not only to use solid core but also to choose the thinnest possible gauge of solid core. My own experiments suggested that he was "right" (or at least that my ears and brain work the same as his). In fact, and paradoxically perhaps, I found that extreme low bass response seems to improve with very thin solid core wire vs thicker solid core wires of the same material. I tell myself that this has something to do with skin effect, but I have read too many articles positing that the skin effect is essentially irrelevant at audio frequencies.
Edits: 09/19/14
The following are tweeter measurements.
Similar results to the midrange measurements. With the solid core in place, there appear to be fewer spikes which touch the 0.1 distortion line.
All measurements where done twice.
"There is NO multistrand wiring anywhere in my system. Don't get me started. If you slowly remove the multistrand from your system, you too will notice lower distortion levels."
Do you have any references to where measurements of such effects are documented? We are, please recall, discussing effects that are showing up in distortion measurements, not in subjective listening tests. If there is a measurable phenomenon of significant distortion caused by multi-strand wire, it should be well documented presumably. It would have to have widespread ramifications in the design of all kinds of electronic apparatus.
Chris
Yup! There is a reason we went with solid core hookup wire so many years ago. Back in the 1970s, we used to strip the inner wire out of Belden coax as the wire and insulation inside was just the thing. Nowdays we get it made up for us...
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