[rlw3]

what is the electrical and sonic difference a vsa speaker with a double set of binding posts "sees" with  a complete double set of cables, a single cable with 4 connectors on speaker side, and a single cable with  2 connectors and a jumper?? i am especially interested in any electrical engineers or speaker designers take on this.

[JackD201]

VSA instructions are to wire from amp to the MT or tweeter post then down to the bass or woofer when jumping. The rationale is a simpler signal path to the tweeters/and mids which we are more sensitive to hearing wise. When bi-wiring you get both that simpler signal path to the highs and mids as well as the (RLC) benefits of doubling up the gauge of the wiring. A lot will depend on the RLC properties of the cables to begin with so there really is no hard and fast rule. I used to use a jumper set of Verbatim cables by Paul Garner that sounded exactly the same as two separate runs. The same could not be said for my Audience Au24s or my AP Oval 8s where two sets allowed more bass energy through.

If Gavin gets out of his probation I'm sure he'd gladly show the math. You there o' dinged one? 

[rlw3]

Jack, thank you for your response. What is RLC? How does a single run with four connectors(there must be a term for this) on speaker side fit in? Are you saying the differences are cable specific and not the same due to unchanging electrical math values? I hope Albert might be able to comment if time allows.

[JackD201]

I was hoping our more electrically adept members would chime in by now. I'm rather a dunce with the numbers  RLC is resistance, inductance and capacitance, I know it refers to a type of circuit but perhaps got appropriated as cable slang. Different cables have varying values of each depending on any number of things ranging from material, the construction, length, etc. etc.. There's a lot of reading on transmission line theory if you are really interested. In any case these differences can and often do effect changes in frequency response by attenuating certain frequencies. How which any of the three relates, I'm a bit foggy about. I'm more a home audition kind of guy rather than a measurement type. I do send multiples more items back than I keep so I figure I am not a lost cause......at least not yet. 

As for the terminology of the single run with four connectors, I think it varies from manufacturer to manufacturer but in general they are just called bi-wire. It's a contentious issue on many forums. Many would argue that if the gauge is essentially the same as a single run with just + and - on each end you aren't going to get much benefit. In my limited experience I would agree with this for smaller gauges. They are more for convenience IMHO although they do allow you to remove the jumper plates which again in my experience never do much harm anyway. In other words I am pretty sure I'd fail a blind test. To make things more confusing there are those that say "true" bi-wire because the cables are actually doubled. I'm pretty sure I'd pass a blind test between a single 14 gauge vs. two 14 gauges. At a single 6 gauge vs. two of them I'm not too sure.

I wish I could be of more help but this really isn't my department

[Delacroix]

Hi rlw3

You might get some informed perspective on this question over in the Lab Circle or perhaps, The Path of Least Resistance circle here which discusses all matters cable: http://www.audiocircle.com/index.php?board=166.0

Let us know back here if you get an answer

Best

[Albert Von Schweikert]

Hello Fellow Audiophiles,
I'd like to address the topic of bi-wiring, since it is not generally understood due to a lack of scientific information.  Since most VSA speaker systems are designed to be bi-wired, it makes sense to completely understand what is involved before spending the extra cash for another set of cables. After all, since there are many highly regarded brands of speakers that do not provide for bi-wiring, it is a highly debated topic on Internet audio forums. However, the positive sonic benefits of bi-wiring are well known to audiophiles who have done A/B comparisons and more importantly, the math supports bi-wiring as a totally valid concept if sonic purity and an accurate sound-field is to be reproduced by the speaker system.

THE PHYSICS AND MATH BEHIND THE SONICS
Although there are several interacting factors involved, the main concept is the measurable effects when high current pulses of low frequency information travel along the same conductor path as the low current pulses of high frequencies.  As is well known in transmission line theory and general electronic equations governing the flow of current in a twin conductor path (the speaker cable), a magnetic field is generated around the circumference of the cable since music is actually an alternating current. 

As each half- cycle of a musical note consists of a positive half- wave and a negative half- wave which alternates between the amplifier and speaker, a magnetic field is generated through induction (interaction between the positive and negative wires in the cable) due to the close proximity of the + and - conductors.

If you look at an oscilloscope screen calibrated in either volts or amps on the vertical scale with frequency calibrated on the horizontal scale, you will see that a bass note (concert drum whack, electric bass guitar, etc) has about 10 or 20 times more amplitude (power) than a treble note (overtones of cymbals, guitar or violin strings, etc). Now picture this: if you have two currents of water flowing down a pipe, with a very strong current flowing against a weak current, which one of the current flows will be most affected?  Yes, the weaker current would be affected, you're correct.  Taking this analogy further, if you send a bass drum whack through a speaker wire along with a delicate brushed cymbal, you can measure (and hear) the effects of magnetic wave- field interaction very clearly.

That is the key to the benefit of bi-wiring: by providing twin signal paths for bass and treble waves, the weaker treble waves are not modulated by the bass waves, leading to cleaner mids/highs and a more dimensional sound stage. 

Now, before some of you (not well versed in electrical theory) start to yell about "the bass and treble signals are mixed at the amplifier binding posts, requiring an outboard electronic crossover between the preamp and twin power amps," think again: only one power amp is required for bi-wiring. Well, how are you going to separate the bass waves from the treble waves, then?

Simple! The internal crossover filters to separate bass and treble frequencies provide high impedance (the rejection of the unwanted frequency) to the frequency range that you select as the designer of the speaker. For instance, a woofer crossover filter generates a very high impedance to midrange and treble frequencies, while a tweeter crossover filter generates a very high impedance to bass frequencies.

Since "impedance" is the same thing as "resistance" (but for alternating a.c. current, i.e. musical notes), bass waves CANNOT travel up the midrange/tweeter cable, since there is a low impedance path supplied by the woofer cable.  In effect, the frequencies are indeed "crossed over" at the amplifier binding posts!  Think of this analogy, if you pour water on a hill side, will the water travel up the hill or down the hill?  Stupid easy, right? In this case, the "impedance" is gravity!

Now, the last question is: why on earth would a speaker designer use a single pair of binding posts on the input of a speaker system?  Is his speaker simply not revealing enough of sound-stage space, so he never heard the differences offered by bi-wiring?  Or is he trying to save money by using a simpler, combined crossover network and a single pair of binding posts?  Only the designer knows, and he's not talking!

Hope you enjoyed this bit of science, if you have further questions or questions, please feel free to challenge me or ask more questions.  After all, we're all on the same path to build a stereo system that mimics "virtual reality."

Albert Von Schweikert

[duguyisheng]

Let me see if I have this straight. Most cables charge 5-10% more for biwire so I assume they are split at the speaker end and not two complete runs from the amp combined in one sheath. To get the benefits as you describe them, it would seem one needs either two single cables to each speaker or a biwire that is truly two runs wrapped in one sheath. Is that correct??

[rlw3]

First thanks to all for the good replies. I would re-ask duguyisheng's question thusly: Since the binding posts at the amp's output has a comingled signal, all the highs and lows -what is the difference between 2 completely seperate sets of speaker wires and one set of wires that has 2 sets of spades on the speaker side. in both cases the crossover networks in the speaker are going to reject the unwanted frequencies.....??

[rich58b]

Thanks to Alberts explanation, I have a better understanding, for the first time, of the plus of bi-wiring with two wires from the amp to each speaker. As an older retired guy, a pair of vr5 anni's and VSA cables are not in my future anytime soon.  So I'm wondering if anyone can tell me if I'm actually getting some audible benefit from bi-wiring my VR 2's using 12G Monster cable (don't laugh!) to my Anthem P5 amp. Or... if anyone has a better suggestion without spending a lot more money.
Thanks,
Rich

[JackD201]

Hi Rich,

The guy I would ask is Wayne (WGH) I think he probably knows VR-2s in and out almost as much as Albert and Damon.

That said, my guess is that there may be some improvement but it wouldn't be as obvious as compared to a VR-4jr and up. I say this because in the VR-2 the top binding post goes up to only the tweeters. The second binding post goes to the mid-woofer and the identical on the outside but beefier bottom woofer. Since our hearing is most sensitive in the midband bi-wiring the other models which include the midrange drivers get the automatic edge when it comes to audibility. Personally, I think replacing the stock jumpers with quality jumpers should be more than enough for most. That is, unless you want to shape the sound somewhat by using something like another material for cabling the highs like choosing between copper, silver clad copper or silver and what these bring to the table. Just my humble opinion.

[es347]

Pretty impressive opinion, humble or otherwise 

[JackD201]

You never fail to put a smile on my face Mr. Feldman! 

[es347]

Yeah everybody seems to get a kick out of that hump on my back...what hump??

http://www.youtube.com/watch?v=XaPZZJVDx6Y&feature=related

http://www.youtube.com/watch?v=AS1HIThPcz8&feature=related

[jeffreybehr]

One thing Albert didn't emphasize is the benefit of physically separating the low- from the hi-frequency conductors to minimize this magnetic interaction between the conductors.  That's why a biwire cable with pysically separated conductors,  rather than all conductors under one jacket, is preferable.

Another advantage to biwiring is to be able to tune the 2 sets of conductors for the frequency bands each is carrying.  That means one can use higher-quality material in the HF cable for the about same cost as lower-quality conductors by using smaller conductors.  For instance, I use a pair of 23g. UPOCC silver conductors in my HF cables but not in my LF cables.  The same logic then allows you to use larger LF conductors without spending much money.

My cables for my Vandersteen 5As use a pair of 18g. UPOCC copper plus a pair of 23g. UPOCC silver conductors for the MR/treble cable cable and 2 pairs of that copper for the bass/MR cable, all woven (into two 4-braids).  The bass is powered in the 5As and hi-gage cable is NOT required for good performance.  At the amp end, the 2 bundles are crimped into one pair of AQ direct-silver-over-copper spades.

[rich58b]

Jack,
Many thanks for your answer. I think you've provided me with both a solution and a new problem.  The solution  of course it to check out the various wiring options I have for upgrading the tweeter wiring. I suspect I could just continue with what I've got for the  woofer/midwoofer.  The problem is that I've had vague yearnings to upgrade to a pair of VR4jr's for  some time. I've been watching Audiogon, but never had a particularly good reason  to upgrade other than the the old "I need some new gear"  and of course the always present desire to upgrade. The upgrade to a pair of VR4jr's just might be affordable, especially given I have a valid reason to do it!
Thanks again  for your response.
Rich

[shmuyator]

my 2 cents:

i have vr2s and i found out that bi-wiring absolutely makes them sound better. but there's one caveat (and i am not sure if its because they are 2.5 way vs 3 way) - the cables going to bottom terminals have to be thicker gauge then the ones going to the top. otherwise, the balance is slightly off, which especially effects rock and metal. i suppose you can consider this 'tuning', but for me this worked out great.  as a side note - i did not observe much difference between true bi-wire and shotgun configuration. hope that helps some folks out there. 

[steve f]

I know this is reopening an old topic.  I have a question though. What about the law of superposition in which a voltage at one point is the same at another? Or is my remembrance of physics class grown cloudy?  Assuming bi-wiring does make a difference, instead of just doubling up on the power amp's output terminals, why not split the signal at the preamp output and use extra power amps too? Respectfully, and just wondering.

Steve