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Thread: bi-wiring

  1. #26
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    Quote Originally Posted by Thomas_A
    For lowest inductance keep connect wires like described in:
    http://www.jenving.se/pro.htm
    T
    From the link: ""for lowest inductance Connecting Rondo as shown in the figure below will make a lower inductance of 0.25 and 0.35 µH/m, respectively, which in turn makes them top class high-end loudspeaker cables.""

    A typical zip cord measures .19 uH per foot, or .57 uH per meter. Two in parallel will give about .285 uH per meter. I'm not sure what in that makes it a "top class" cable.

    Unfortunately, they do not provide capacitance figures, to show the tradeoff..

    Here's a graph showing the C-L tradeoff for a double braid coax capacitance is pf per foot, inductance is nanohenries per foot.(zip cord is about 200nH per foot.)..Where would that wire fit in?

    Or, are they saying R and L are the only relevant parameters?.

    Cheers, John
    Attached Thumbnails Attached Thumbnails bi-wiring-image2.jpg  
    Last edited by jneutron; 03-15-2004 at 08:29 AM.

  2. #27
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    For typical loudspeakers with typical speaker wire lengths in home installations, may articles have documented the high end rolloff for most commonly used speaker wire including 16 gage lamp cord at well under one db at 20khz due strictly to the LC effects of speaker wire. Considering the other variables in a sound system which affect frequency response, this rolloff in absolute terms and certainly in terms of one wire to another seems not to have any significance in practical (audible terms.) DC resistance can be a factor where poorly damped speakers can have exaggerated low frequency resonances but the best solution to that problem would seem to be heavier gage wire and selection of an amplifier with an adequate damping factor.

    Are there any documented non linear parameters worth considerning? I haven't seen any reported. Now that would be something to take seriously.

  3. #28
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    Wink

    Quote Originally Posted by markw

    You might find this link interesting. Or maybe not. It might not be exactly what you want but it’s pretty durn close.
    http://www.audioholics.com/techtips/...bleFaceoff.htm
    Interesting results, eh?
    That article has within it the caveat ""within the context of electrical test performance.""

    Meaning, it's intent was solely to guage cables based on test metrics. not connecting them to speakers, seeing a difference, then applying the difference to hearing capabilities.

    At no point in time, has the author stated he does or does not hear a difference, just that the metric is a reproduceable, test based one..

    Course..he does quote some amazingly intelligent, articulate, and witty people in the article......:-)

    Cheers, John

  4. #29
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    Quote Originally Posted by jneutron
    That article has within it the caveat ""within the context of electrical test performance.""

    Meaning, it's intent was solely to guage cables based on test metrics. not connecting them to speakers, seeing a difference, then applying the difference to hearing capabilities.

    At no point in time, has the author stated he does or does not hear a difference, just that the metric is a reproduceable, test based one..

    Course..he does quote some amazingly intelligent, articulate, and witty people in the article......:-)

    Cheers, John

    Seeing your post just reminded me. Your candle burns every bit as bright, if not brighter, than Steve's.

  5. #30
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    JNeutron,

    their claims are that for loudspeaker cable, inductance and resistance are the most important parameters. Nothing more fancy than that. Capacitance is more important for interconnects.

    Even if the "worst" cables of normal length show only 0.5 dB drop or so for 20 kHz due to high inductance it can be a good idea to have the values as low as possible. It's not uncommon with 0.5 dB deviations at 20 kHz from a flat response from many amps and CD players. It is thus possible that different combinations of CD players, amps and cables can reach a total difference of a couple of dB at 20 kHz, and thus display audible differences lower down in frequency.

    T

  6. #31
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    Quote Originally Posted by Thomas_A
    their claims are that for loudspeaker cable, inductance and resistance are the most important parameters. Nothing more fancy than that. Capacitance is more important for interconnects.
    Ah. It would be interesting to see their documentation showing how they actually tested that premise...I find that at 4 and 8 ohm impedances, measurement of voltage, current, and phase relations is not an easy one to do accurately. So, I would believe that the guys at most of the cable companies don't know how to do it correctly.

    Quote Originally Posted by Thomas_A
    Even if the "worst" cables of normal length show only 0.5 dB drop or so for 20 kHz due to high inductance it can be a good idea to have the values as low as possible. It's not uncommon with 0.5 dB deviations at 20 kHz from a flat response from many amps and CD players. It is thus possible that different combinations of CD players, amps and cables can reach a total difference of a couple of dB at 20 kHz, and thus display audible differences lower down in frequency.
    T
    I would agree, keeping inductance as low as practical is probably good..

    I'm at the moment, reviewing a paper where the researcher is showing test results that are rather amazing...human perception capability in the 1.5 to 2 MICRO-second realm. (Thanks, Mtry)

    If that is in fact an actual human capability, then inductance may indeed be a big player.

    Cheers, John

  7. #32
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    JNeutron,

    I have corresponded previously with Supra Cables regarding their measurements as depicted at:

    http://www.jenving.se/ply.htm

    As shown, their measurements of a cable with its conductors wide-spaced, they find a loss of around 4 dB at 20 kHz, while standard "zip" is below 1 dB. In my specific question, I asked for the lenght of the cables and the answer was 10 meters ended with a 8 ohm resistor (but he was not sure, since it was such a long time since the measurements were made). It seems however, that the test was performed on longer cables, perhaps 20-30 meter.

    Now, Supra might appear to be "exotic" high-end cables abroad; the price for their "zip"-cord like cables (Classic) is about 2 times that of a no-name brand here in Sweden. The Ply cable is more expensive though.

    Although some of their claims are not scientific (i.e. bs), I regard Supra as being less bs among AudioCable Makers. Also, they are one of the few that actually braid their own cables at their factory, perhaps one of the reasons why prices are a little bit higher.

    http://www.tnt-audio.com/intervis/suprae.html

    T
    Last edited by Thomas_A; 03-16-2004 at 06:28 AM. Reason: speling misstake

  8. #33
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    Quote Originally Posted by Thomas_A
    JNeutron,

    I have corresponded previously with Supra Cables before regarding their measurements as depicted at:

    As shown, their measurements of a cable with its conductors wide-spaced, they find a loss of around 4 dB at 20 kHz, while standard "zip" is below 1 dB. In my specific question, I asked for the lenght of the cables and the answer was 10 meters ended with a 8 ohm resistor (but he was not sure, since it was such a long time since the measurements were made). It seems however, that the test was performed on longer cables, perhaps 20-30 meter.

    Although some of their claims are not scientific (i.e. bs), I regard Supra as being less bs among AudioCable Makers. Also, they are one of the few that actually braid their own cables at their factory, perhaps one of the reasons why prices are a little bit higher.

    T
    Thanks for the link..interesting read. The format was a PITA, because the three long columns fold over to page two when printed..rather discontinuous...

    I'll address the simple errors..

    ""Conventionally, fat conductors’ high loop inductance (which raises impedance at +6dB/octave) is further raised due to internal eddy currents causing ’Skin effect’. This acts like ’the square root of an inductor’, i.e. progressively adds a +3dB/octave component to the cable’s series inductance. ""

    NO...NO...NO...

    The skin effect will only remove the internal inductance from the wire as the frequency goes up. The internal inductance of any wire is 15 nanohenries per foot, when skin effect does NOT occur...As skin effect occurs, the inductance will start to go down, and in the limit, the internal, 15 nanohenry inductance (per foot, per wire) is gone.. Skin effect does NOT cause additional inductance, it makes the internal go away.

    It will, however, start to increase the cable resistance by cross section reduction and current re-distribution.

    Geeze...this is not rocket science...it's very easy stuff....how come these guys can't get the easy stuff right!!! :-)

    ""Supra Ply is able to be a large-section, low resistance cable, while also overcoming skin effect and transversal distortion, by using a proprietary, pure tin plating. This has the double benefit that tin and copper meld without forming a diodic barrier (as with many silver-plated copper ’audiograde’ conductors) and that tin strongly resists most common causes of metal corrosion, and hermetically protects the copper""

    NO...NO...NO..First, tin plating is never pure..And, the plating process does NOT make the copper and tin "meld". Tin plating is porous..to make it hermetic requires fusing the tin, bringing it over 231 C to reflow it. At that point, it will form two intermetallic compounds, a non solderable one against the copper (using R type flux), and a second one over that, with the pure tin over that (assuming there is any free tin left over after the heating).

    The tin overcoat will have a higher resistivity than copper, and will contribute very little to the reduction or increase of skin effect. It is entirely used as a barrier metal. Fused, it will indeed provide a hermetic protection layer for the copper..

    The diode explanation does not even warrant discussion..(beyond the scope of this text)

    The scope photo's...

    Why is it the flat DC portion of the signals is inching up? They have done something very wrong in the measurement technique. Without more details, I suspect that the IA circuitry they use to get the difference signal may be saturating during the transient portion of the waveform, and that upward slope is the recovery of the IA (many high speed circuits will take a very long time to recover from a transient overload)..not some signal abberation from the cable..If it is truly a circuitry problem, I would question all the waveforms..

    Overall, a rather professional looking presentation..I liked it..

    Given the errors found in Hawksford's essex echo skin effect analysis paper....I would be concerned about citing any of his HI-FI based papers, as his skin theory, test setup, and test results are not consistent with what has been known about wire inductance since the mid 40's.

    Cheers, John

  9. #34
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    Quote Originally Posted by sleeper_red
    is it worth bi-wiring the B&W 601 S3's and LCR60? I'm using Yamaha RX-V1400. thanks.

    Well, maybe, maybe not. If you are able to solve for all the variables(5 or 6), you might find a positive outcome - and then the question becomes, is that enough to be audible?

    So it's a crap shoot.

    -Bruce

  10. #35
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    Quote Originally Posted by Geoffcin
    Oh, I supposed that the only place to get "real" fact based opinions?

    Some people purport to know all the "true" facts when in actuality they discount what their own ears tell them in favor of some tech sheet specs.
    This is your own conclusion. A search will reveal that their position is that uncontrolled sighed listening is unreliable. Your ears are fine, it's what your brain does to the information it's receiving from all input sources.

    Then you have others that based on their "superior knowledge" [sic] of electronics that you could not tell the difference between two components, for that matter.
    Ah yes, the always useful ad hominem attack when there is no other argument to be had.

    My advise is to go out and listen to a speaker that's been biwired, or biamped if you can. Then make up your mind for yourself without all the noise that this forum generates.
    Considering you just slammed anyone here who actually knows something about electronics and physics, you have just failed miserably in your demonstraton of knowledge. Bi-wiring and bi-amping are two completely different configurations only related by the number of cables entering the speaker system.

    -Bruce

  11. #36
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    How To Bi-Wire Correctly

    PART ONE (original posted elsewhere in this disscussion forum under Bi-Wire topic -- reposted here F.Y.I)

    If you are really interesting in audible results from Bi-Wiring or Tri-Wiring the secret is to remove the crossover from the inside of the speaker and place it very near your amplifier output terminals. Run a short wire from the amplifier output to the crossover input. Run seperate and seperated wires from the crossover outputs to each speaker element.

    No matter how many wire runs you may make, running seperate wires from the amplifer to a distant crossover produces questionable improvements because the filtering action is after the wire runs.

    Try this simple test. Take two straight pins and connect wires from each pin to the (+) and (-) terminals of one of your speakers. Connect the other speaker using the standard bi-wire hookup. Poke the pins through the insulation of each of the wire runs going to the LF and HF elements of the speaker. You will hear the same signal coming down either wire run. It does not matter which speaker element wire you may listen to, as the filter components are at the speaker end of the wire. The above empirical test should dispell the back EMF theory as you can hear a full-range signal anywhere along the wire run to either speaker element. The back EMF signal has all that cable with which to interact. Some chocking of the EMF signal will occur -- the more resistance (smaller the wire) the more chocking due to the higher resistance, or in AC terms reactance. If you are using a heavy guage wire, the back EMF from the LF element just travels back to the amplifier where it reacts with the output stage and then back to the HF element along a long wire run before the crossover filter. This is why a high damping factor is important. A high damping factor does just that, it dampens the back EMF. Most transistor amplifier output stages have very high damping factors.

    Doing the same pin poking test with the crossover near the amplifier with seperate wire runs to each of the speaker elements will produce quite different results since this places the filter components and filter action at the proper end of the wire run. Now poking the pins along any pair of wires will produce bass for the LF element, mid-range for the MF element and treble for the HF element. The back EMF phenomena is now isolated back to the crossover. Any EMF produced as the woofer recovers is now filtered from the mid-range and/or tweeter before it can interact in a long wire run.

    Keep the connection length between the amplifier and the speaker's crossover as short as possible because you want the amplifier to "see" the crossover and the action of its filtering components with as little added wire resistance, inductance, and capacitance as possible. After the full-range signal is split into the approprate ranges for each of the speaker elements, the interaction of each speaker element will not find its way back to the amplifier as readily by way of seperate wire runs connected to a common point (the amplifier output terminals).

    Try to keep each speaker element wire run seperated from the other wire runs by a few inches or so. If the wires become close enough to each other they will couple though their respective magnetic fields and defeat the purpose of Bi- or Tri-Wiring. Don't bind the speaker wires together. In this case, neat appearance is not approprate for good sound. Remember, preamps produce voltage gain, whereas power amplifiers produce current gains. It is the current factor in the signal that generates magnetic fields in the speaker wire. Given a long run with the wires parallel for several feet, a fraction of one signal will couple to the other wire. Best to just let them hang/lie loose and sort of go along in a random path. Don't get too hung up on this, but just don't tie all your speaker cables together.

    If you are fusing any of the speaker elements, the fuse should be placed as physically close to the speaker as possible. The speaker fuse should not be at the amplifier terminals, it should be at the speaker terminals -- and it should be placed in the (+) positive side of the cable. This means a seperate fuse for each speaker element. I find that a powerful amplifier, capable of destroying the speaker, will control the speaker much better than an amplifier whos power rating is equal to the maximum the speaker will take. Use an over-powered amplifier and fuse the speaker to protect it from accidental burn-out. Think of it in these terms. If someone were to grab you and shake you who would be able to exibit more control over your body, someone of your weight or someone twice your weight? You see the more powerful amplifier will make the speaker cone go where the signal says, hence more dynamic and accurate reproduction, less back EMF distortion, much improved transient response and operation in a more linear part of the amplifier specification.

    Place the crossover near the amplifier, seperate the wire runs, use a big amp and fuse the speaker at the speaker. The resulting realism is well-worth the occasional blown fuse and trouble of moving the crossover.

    PART TWO (reply to various comments)

    First of all the improvement for this crossover approach to Bi- or Tri-Wiring is audible and not just one of those improvements you have to strain to hear or think you hear because you spent a ton of money and time making the so-called improvement. You hear a difference and to us experienced listeners (I count everyone posting here) the difference is definitely an improvement in the things we value in our reproduction systems, clarity, dynamic impression, openness, reduced fatigue, etc.

    When I first started using this technique, I ran listening tests by converting one of the two stereo speakers while leaving the other unchanged. A third party placed both speakers close together through a sheet over them both and feed them a mono signal. Only the third party knew which how each speaker was connected. Acoustic levels were matched using an SPL meter. Switching (or having someone else switch) between one or the other speaker gave sonic evidence to even the most inexperienced listener that something had changed in one speaker for the better. I've tried this on several different speaker models of different manufactures and always hear an audible result for the better. I can't say the same for similar trials with convention Bi-Wiring.

    I will be the first to agree that Bi-Amplification is superior to Uni-Amplification. But this technique is about Bi-Wiring or Tri-Wiring; that is, using one amplifier driving a multi-element speaker system. We assume the amplifier to speaker connection requires 10 to 15 feet of cable. We further assume the cable is common copper cable with parallel conductors; nothing esoteric.

    In order to understand that the benefits cited are not just technobabble let us first consider what the amplifier "sees" when connected to a loudspeaker. Most loudspeakers are coil and cone types, that is, linear motors. As such, the load on the amplifier is not just resistive but reactive and further varies with frequency. As the voice coil is driven it also returns to the starting point. The return motion of the coil through the magnetic field of the magnet gap produces back EMF into the amplifier. This should be taken into consideration when analyzing the effects of cable resistance, inductance and capacitance on the amplifier. The load may mathematically seem to be the same wherever the crossover is placed, but the reactance is not. At a given frequency the impedence load will be the same, but the load does not take into consideration the reaction of the speaker coil over (recovery) time, i.e., reactance. The effect of the connecting cable should not be viewed with respect to the speaker as much as with respect to the amplifier.

    The differences in the impedance of any speaker in a multi-speaker system will run between 6 to 25 ohms in the audible range. The connecting cable (~1 ohm) and the output impedance of the amplifier (.01 ohm) is larger if the crossover is placed at the far end of the connecting cable. This makes the amplifier more dependent on the cable characteristics of capacitance and resistance. That is why hearing any improved performance with convention Bi-Wiring is so questionable. All you are doing in effect is using a heaver gauge wire, as someone correctly pointed out.

    Moving the crossover close to the amplifier causes the amplifier to react less with the connecting cable because the final filtering does not reflect the speaker's inductive reactance back to the amplifier through coupling in the connecting cable.

    The concept of Bi-Wiring is to give separate pathways for the various bandwidths provided to each driver of a multi-element speaker system by the crossover network. Separate cable runs from a common amplifier output to each filter section's input does not meet this goal. The virtues of the Bi-Wire scheme are only realized in concept if the multiple and separate pathways to each speaker element are after the filtering action of the crossover network. Only in this way will each speaker driver's reactance remain separated from other driver's reactance with respect to the commingling of back EMF forces in the multiple connection cable.

    With the crossover at the far end of the speaker connecting cable, no matter how many multiple pathways the cable(s) may take, it is the interaction of the cable with the one amplifier and the crossover that is in play. Because of the common amplifier connection, back EMG and cable characteristics will remain un-separated.With the crossover at the near end of the speaker connecting cable, it is the multiple bandwidth-restricted pathways that interact with the crossover and speaker. The effect of the connecting cable on the amplifier is minimal because the output stage is looking directly into the crossover filters, not down a connecting cable with additional resistance, inductance and capacitance characteristics.

    Actually, if you think about it, the crossover network is not -- NOT -- part of the speaker; it is the final circuit topology of the amplifier. We tend to think of it as being a function of the speaker, but only because differences in speaker design require the manufacturer to place the final filters in the speaker box. Filters (passive or active) should really be on the amplifier chassis as close to the amplifier stage they are filtering as possible. If you are going to split up the amplifier components, it makes as much sense to put the last amplifier stage in the speaker box too! Why stop at the filters? Or how about using Bi-Amplification and placing all the active crossover elements in the speaker box with cables running back and forth between the box and amplifiers. It makes no sense, electrically. The filters are a component of the output circuit, not a speaker part.

    Bi-Amplification is supposed to help the performance of the speaker, but it really is a help to the amplifier if you place the final filter components before the connecting cables. This is because a loudspeaker is a reactive device. The reactance reaching the final amplifier stage is more defined by the connecting cable if the cable is before the final filter configuration than if it is after filtering. The consequence of moving the crossover closer to the amplifier is better amplifier performance -- and that reflects into the performance of the speaker -- but, it is the amplifier that is really receiving the benefit.

    Other considerations for moving the crossover from the speaker box to the amplifier include eliminating the microphonic effect of the high acoustic (physical vibration) levels within a speaker enclosure on the capacitors. As you may know, capacitor noise is the primary cause of blurring when they are inserted into a circuit. Vibrations can cause microscopic holes to develop in metallized polypropylene capacitors. Even if self-healing, noise is produced. A good reason why foil and polypropylene capacitors sound cleaner than the metallized types. You may think this is the real technobabble, but when you get into high-resolution systems this sort of thing becomes audible.

    Likewise, but more in theory, the influence of the magnetic fields within a speaker enclosure will interact with the inductive elements of the crossover. Since the magnetic fields fluctuate, this interferes with the coil characteristics and ultimately interferes with the correct operation of the crossover.

    I too used to be one of the unbelievers in Bi-Wire benefits. I had trouble hearing any difference and could not technically explain why there should be any change. It seemed a marketing ploy more than anything. It wasn't until I tried moving the crossover that I heard any improvement to the fidelity. Further study made me realized there was more going on than I had previously understood (like most things in life) so that now I know if I move the crossover; I can expect a margin of improvement. Not an AM to FM improvement, nothing that vast, rather a slight advance -- one more notch up the ladder to better reproduction.

    I'm not here to debate the issue. I am here to share my findings with you. I am not a casual listener but rather a dedicated one capable of discerning sonic value. I know what my experience has told me. All I can say is that if you are going to buy into this Bi-Wire thing, try it this way. The cost is about the same, but the results are, at least in my opinion, audible and welcome.

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