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In Reply to: Jon Risch, please see bi-wiring question in Cable forum posted by bdiament on March 03, 2003 at 06:20:53:
Hi!I am not John Risch, simply an electrical engineer, MDRiggs's explanation on how "does not" work a bi-wiring is completely wrong.
The circuit in bi-wiring has different electrical characteristics that "can" audibly affect the performances, but MDRiggs simply seems to be unable to recognize, beside the acoustical, the electrical difference (but curiously it is writing about it!).
He shows clearly not to be an axpert in electrical circuits; it is difficult to explain to those "surface scrappers" where to look for.
Impedance is probably a simply strange number that must match between loudspeaker and amplifier datasheets or you will get problems (nobody knows what)!
No consideration is made about the currents and frequencies selectively crossing in a bi-wiring system in respect to a single wiring; intermodulation (complicate word, what is this?) remain a number another time to be enough "small" on data sheets and "inaudible" in an hi-fi component review.
How can current and frequencies select to cross on one cable or in the other ? Probably somebody suppose because of the brand of the cables.
MDRiggs has not in mind that, i.e., a hi pass crossover offer low series impedance above the crossover point and high impedance below the same? (the same happens on all crossovers sections except on series crossovers that cannot bi-wired).
Thus the signal current is maximum above crossover point and minimum below it in way of the series impedance (and obvious relation with the cable impedance!); this "magically" gives the effect to separate the signals between the cables ! (thus the current in each cable is practically relative only to the relevant frequency band).
MDRiggs has not considered i.e. the peak transient current on a cable driving a woofer and the relevant voltage drop and phase rotation occurring along the cable in way of this.
In this case, and with the example MDRiggs has so clearly given to the audiophile world, the medium and high frequencies current flows, on the same single wiring cable, undisturbed respecting original relative phase and amplitudes at amplifier posts!
Absolutely untrue and unprofessional statement; there is need for this kind of opinions ?.
I know that my hears are far to be perfect, many peoples has better extension and sensitivity of mine, but those articles convinced me that exist peoples, like MDRiggs, with so bad acoustic perception (or may be not good systems or setup) that are unable to detect the acoustical difference between single and bi-wiring (clearly perceivable on most of the setups and more on three way systems).
If MDRiggs simply explain "I am not convinced of bi-wiring because I cannot hear any difference between mono and bi-wiring setups" STOP! it will be credible and honest, but try to give an absurd technical explanations based on ignorance of electrical principles is uncorrect and misleading.
Circuit simulation, like on SPICE, give results not easy to understand, but in any case DIFFERENT results between the single and bi-wiring setups (otherwise the circuit has not been electrically simulated in the proper way considering really all parameters involved!).
The effect of the change of those parameters on sound cannot be stated by the simulation circuit, but only by direct audition.
Bi-wiring (or generally multi-wiring) works for the best electrical characteristics he can offer to the separate signals paths; some time the benefit is dramatic, on most of the systems clearly audible, on very few Hi-end setups inaudible.Finally, Bi-wiring it is not a tweak in the common sense, is an application of known tecniques to obtain clearly audible system improvements on most systems, ... sometime not (but also in this few cases the system has improved, you simply cannot hear it!).
Best regards
Franco
Follow Ups:
Hi, Franco.I agree what you posted yesterday. Yet, I don't advocate 'labelling'
people across the board when you said "J.R., simply an electrical
engineer". There are many professional working in the electrical
engineering industries, like yours truly, who put audition on a par with science.You have said it right: Bi-wirng & multi-wirng do improve the performance of loudspeaker systems, e.g. sound perspectives, distortion level & power capacity. It brings subjective improvement
for sure, even though it may not be measured discretely.I have gone through personally hands-on experience of upgrading
different bandname speaker systems by converting standard single-pair
wiring to bi-wirng & tri-wiring, with flying colours. This
includes my own KEF two-way bookshelf speaker system. It really works I am ready to challenge any nay-sayers on this issue.For those unbelievers, ear-muffed & blindfolded denyers, there are quite a few major speaker systems manufacturers which build & supply world-renowned brandname models with by-wirng & tri-wirng hookup configuration. Bowers & Wilkins from U.K. (B & W) is an excellent
example. These speaker system designers use both instrument & ears
to perfect their works. Let me pick one DM bookshelf model. The bi-wiring is done so 'perfect' that the two-way cross-over network
is supplied in an 'out-board' box separately with the speaker systems. To my knowledge, it is probably the first speaker system with out-board cross-over network design commercially available on this planet! This out-board design is technically more advanced than conventional bi-wiring design whereby the bi-wired cross-over network board is always housed inside the speaekr box. This model sounds very good & has won rave appraisals from critics worldwide.You are right there is interference occured when signal comprising high, mid & low frequencies travelling on the same cable. For radio
frequencies, it is called 'skin effect', whereby higher frequencies tend to travel near the 'skin' of the conductor. The solution is to use multi strands to form the conductor instead of one solid core so that the higher frequenceis can travel more freely along the strands close to the wall of the conductor.For audio signals, I would call it intermodulation. Music signals is made up of complex harmonics of high & low frequencies, which do
interact with each other while travelling on the same conductor.
That is why electronic cross-over technology comes in a big way.
This is an active device to provide separate circuit paths for signals of high, mid and/or low frequencies. One of the objectives is to eliminate intermodulation or interference among the music harmonics using one sngle circuit. We call it bi-amp or tri-amp.Speaker bi-wiring & multi-wirng use the same principle of signal path division as 'bi-amp' or 'tri-amp'. But it is done in a somewhat 'compromised' way (or should I say 'simplier' way). The signals coming out of the amplifier to the loudspeaker system are already strong enough to waive the need for further amplification.
No bi-amp or tri-amp is needed. It is a scientific approach. No gimmick.For those who screamed their throats out without knowling what is what, let me tell you the very sad experience I went through before I switched my speakers from standard single-pair wiring to bi-wiring.
I am glad I did it. I am a happy camper, always since then.A few years back, I blew the KEF B139 woofer (13"x9") of one of my KEF 2-way bookshelf speaker systems on testing it with the track "Les temps passez" of my tweaky test CD of Michel Jonez at a very loud volume of some 98-decibel. The repair technician of KEF local rep. office said the voice coil of the blown woofer was "badly banged up". He suggested it could have been overdriven by some excessive power of up to 300 watts! Or, someone kicked at the cone. But it did not happen as he suggested. Further study found out it could be the intermoduation distortion in the amplifier-to-speaker circuit that generated the transient excessive power which blew the speaker voice-coil.
My solution to prevent blowing my speaker again at very loud volume
was bi-wiring the speaker. So, I took out the very basic 5-component cross-over network boards from the speaker boxes, & re-built a new board for bi-wiring using the same basic circuitry. Of course, I replaced all the old electrolytic capacitors there with non-polar poly-propylene metal film capacitors. The new bi-wired cross-over board is then housed in a box of non-magetic material sitting just 8 inches away from the power amplifier. I only use #10 dirt cheap
speaker wire for all the by-wirng there. No exotic cables involved.The result: improvement like night & day! No more worry of blowing the speakers any more with the same sound track even at higher volume.
You are right. Bi-wiring is a science, not a tweak. Period.
Good listening
cheap-Jack
March 4,2003PS: I appreciate your gut of speaking out. Keep it up. I am going
to give those bad months a show-down - politely.
Hi cheap-Jack,I agree in full with what you said about bi-wiring and the benefits you can obtain by such setup.
About the external crossover, for my knowledge, there some other loudspeaker manufacturers that supply the external crossovers (like Zingali and a special version of Diapason Adamantes at least).
My DIY three way system too has external crossover, with very short connections to amplifier posts and the longer wiring between crossover exit and drivers.
This arrangement gives great benefits during the time consuming fine tuning (you can made it only by audition!) of the crossover components values; everything can be updated very quickly without intrusive operation on loudpeaker boxes, but moreover gives you more space to work, no component vibration and less magnetic interferences with drivers magnetic field.
Another couple of box in your room may reduce the WAF of your system, but nothing is perfect !As direct experience, beside the capacitors quality improvement (I try several brands, polypropilene up to astronomically expensive Jensen oil capacitors, finally coming back, on my system, to polyprop) there is a major audible change in mid and treble grain using Solen Eptalitz air core inductors; astonishing sweet and clear!
Are some 6 years now since I have finally upgraded my system with active + passive crossovers, vertical bi-amping (with two identical stereo power amplifiers each one dedicated to one channel) and tri-wiring, this is a "final" setup I cannot (and I do not want, being "fully satisfactory" to my hears) futher improve.
I have suggested and applied the bi-wiring tecnique to some systems of my friends using the "bi-wiring by example" as I call it.
I have hooked up their system with some my spare cables, leaving them (and to their wifes ...) the time to listen and evaluate the results; no one has gone back to single wiring! also the wifes has recognised the difference in sound perception approving definitely the new setup!.Results are every time the same: increased acoustical scenario, more air between instruments (more focused and stable), clear and less fatiguing listening (due to reduced intermodulation distorion).
But only direct experience and a basic skill (not to make mistakes on connections) bring to the knowledge of the benefits of bi-wiring; I was also a little bit skeptical on cables and bi-wiring one time, but I have not refused to take into consideration that if so many peoples report better acoustical results at least a parth of thruth must exist.
I verify it by myself: by audition and by technical considerations ... both carrying me to a definite results:
bi-wiring sound better and there are technical reason for that!.Good listening!
Franco
Hi Franco,I agree completely about bi-wiring and as I said in my original post, I "find the result of bi-wiring not only audible but a qualitative improvement".
The post came about after a visit to another site's audio forum (the AVS forum's "Audio theory, setup and chat" section) where the great number of participants seem, like Mr. Riggs, to deliver "theories" as to why certain things are "not audible".
In the case of a thread on bi-wiring, I mentioned Jon Risch's well thought out and written articles from his own web site. The responses were more "theory" and "explanations" like the one I quoted.
What most of those participants seem to have in common is an aversion to simply sitting down and listening (to equipment designed for nothing else but being listened to).
Oh well. The way I see it, it is their loss. While they believe we're "wrong", we continue to enjoy the benefits in our listening rooms.
Happy Listening!
Barry
(nt)
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