Bi-Wiring, what exactly is it doing?

BlueFox wrote: »

I believe both pair of wires have the same frequencies between the amps and speakers. The cross overs in the speakers then separate out the frequencies they need.

Correct.

BlueFox wrote: »

I believe both pair of wires have the same frequencies between the amps and speakers. The cross overs in the speakers then separate out the frequencies they need.

Same frequencies, but when the impedance climbs from the crossover, the current is what is effected and where the differences may start to occur.

CJ

nspindel wrote: »

How'd I know this thread would turn into an argument about cables?

They ALWAYS do!! Cables & ICs: the most controversial topic in AV.

While your post about directionality might be accurate, without posting a link so that it can be read in context, the post is not very useful. It could be completely made up.

However, based on what was posted, it does seem reasonable that a cable could be better for audio in one direction versus the other. Whether it would be worth paying extra for is another matter.

Nightfall wrote: »

Why trust your ears? Useless things they are, right?

What a novel concept?!

In my experience lower impedance and/or more reactive loads "like" heavier wire.

nbrowser wrote: »

RTiA7, HK 3490 standard wired... ...two pieces of 12 gauge... ...hear a difference, better attack; bit better bass

Not surprising. 4 ohms below 125hz - w/lower impedance, size (gage) matters more.

nbrowser wrote: »

better top end.

? How so?

nbrowser wrote: »

Second power source HCA-1200II... ...more noticeable... ...low end gained some weight over single wiring... ...it IS power dependent as well.

Again not surprising.
The P'sound thumps the HK w/juice! Higher current, more (8ohm) power & 4 ohm rating w/even more power. Important points given 4 ohms below 125hz

PSOVLSK wrote: »

My question to the cable naysayers: Do you really think there could be a multi-million dollar industry that's been around for years if their products didn't work? Seriously??? Multiple companies can sell products that do absolutely nothing and somehow they stay in business?

I have lots of other very simple questions, but I'll start here.

Seriously? Apparently you haven't heard of homeopathy, a 7 billion dollar a year industry. Magnet therapy alone accounts for over 1.5 billion. People believe all kinds of nonsense.

http://nationalpainreport.com/study-finds-copper-magnetic-therapy-waste-money-8821693.html

cbridle wrote: »

The Polk Quick Start Guide that came with my 703's, 705's & 706 states "Bi-Wiring can provide noticeable improvements in the overall transparency of your loudspeakers.

If the speakers are designed so that best performance is achieved if the high frequency and low frequency parts of the crossover are powered from separate wire branches, and if your gear is resolving enough, then the lowering of electrical noise due to bi-wiring can result in audible improvements in sound quality.

It is similar to the concept of running dedicated AC circuits in order to reduce the noise from devices on one circuit affecting devices on another circuit. All of the AC circuits in a house are fed from the same tap from the power company, but running separate circuit lines from the same current source results in noise isolation benefits. Similarly, isolating low power treble signals from higher power, higher noise content bass and midrange signals can result in cleaner, more detailed sound.

Running a single pair of speaker cables to a speaker results in the amp "seeing" a single circuit with a single complex load at the end. Running a pair of speaker cables to the low frequency section of the speaker and a second pair of cables to the high frequency section results in the amp "seeing" two different circuits with two different complex load at each circuit end.

kevintomb wrote: »

To answer the first bolded part.
A cable has NO soundstage at all. Nor separation of instruments, placement etc. '
It conducts an alternating current signal.
It will either conduct the signal fully intact or degrade it some minimal amount.

The rest is sales talk.

You are correct that a cable, or any other audio component does not have a sound stage. Sound stage is a psychoacoustic phenomenon that occurs in the brain.

However, the electrical performance of a cable can alter the stereophonic perception of sound stage, imaging, and image weight.

kevintomb wrote: »

All facets of alternating current can be fully measured, at ALL levels down to below human hearing.

Sorry it really is that simple.

There is a lot that is unknown pertaining to how to correlate measurements to perceived audio performance.

If cable science were really that simple, telecom companies would not have invested billions over decades in cable research. Bear in mind that telco systems primarily transmit a very band-limited range of frequencies for voice. They are not primarily concerned with transmitting complex a complex signal like music. Nevertheless, telco research has resulted in cables with different dielectric properties, different twist geometries, and different copper formulations in order to optimize voice signal transmission. AT&T at one time owned a cable factory in Norcross, Georgia that manufactured cables to their specifications. If "wire was wire", they just would have bought bulk generic cable from outside vendors.

kevintomb wrote: »

Not everything alters the sound. That is a myth also.

Not everything alters the perceived sound, but every thing has a measurable effect on the electrical signal passing through it.

kevintomb wrote: »

SOME and even many things alter the sound true, but not truly everything.

The guys that design all this stuff we listen to, truly know what matters or does not, not the marketing claims.

Well, the OP started off with a quote from his speaker manufacturer that recommended bi-wiring. Last time I checked, Polk doesn't sell speaker cable. Therefore, if Polk advises that their speakers may sound better with bi-wiring, I am inclined that this may be true in certain situations.

cbridle wrote: »

Surely Polk would not include the statement (my words) "Bi-wire is better & connect heavier gauge to lower terminal" if there was no benefit?

No, they would not.

WilliamM2 wrote: »

Bottom of page 10:

http://www.audioquest.com/pdfs/aq_cable_theory.pdf

And I agree, it sounds like they just made most of it up.

Copper wire, depending on its composition and on how it is drawn, can have different mechanical and electrical properties (directionality) in one direction compared to the other.

The concepts discussed in the AudioQuest Cable Theory paper are backed by solid science. Again, I would refer you to telco research, most notably that of AT&T Bell Labs, on the subjects of dielectric absorption, twist geometry, copper purity, and directionality. If you go to the IEEE Xplore website, you can search on these key words and find references to many peer-reviewed engineering journal papers on these topics. For example:

"Murray, H., "Characterization of copper-beryllium alloy C17510," Fusion Engineering, 1991. Proceedings., 14th IEEE/NPSS Symposium on , vol., no., pp.280,283 vol.1, 30 Sep-3 Oct 1991"

Abstract:

"The BPX (Burning Plasma Experiment) toroidal field coil conductor is fabricated from plates of C17510, a copper-beryllium alloy. Results of tensile characterizations of this alloy at room temperature and liquid nitrogen (IN2) are presented with room temperature fatigue results at R=0.05. The R=0.05 characterization data represent the constraint on the design curve of stress amplitude versus cycles-to-failure. Data are also presented from precision, four-wire electrical conductivity measurements. These measurements include samples of material extracted from key process steps of the C17510 manufacture and span the temperature range of IN2 to 300 K in increments of 25 K. The grain structure of the material is also reported for key process steps and material orientations. The directionality of key properties is discussed."

By the way, the electrical and mechanical properties of beryllium copper, as explained in the paper cited above, provide a scientific basis for why higher-end audiophile grade AC receptacles, such as the PS Audio Power Port Premier and Oyaide R1, use beryllium copper rather than the ordinary tough pitch copper used in regular residential receptacles.

xcapri79 wrote: »

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Running a single pair of speaker cables to a speaker results in the amp "seeing" a single circuit with a single complex load at the end. Running a pair of speaker cables to the low frequency section of the speaker and a second pair of cables to the high frequency section results in the amp "seeing" two different circuits with two different complex load at each circuit end.

The amp doesn't keep track of separate wires. The amp sees the pretty much same complex load with two connections at the same amp terminals as it sees for a single connection at the same amp terminals as long as sufficiently large conductors are used.

I didn't say the amp keeps track of separate wires. I said the amp (source) becomes connected to two different complex loads with two different impedance characteristics when you bi-amp. In other words, one circuit loop with one impedance characteristic is replaced with two circuit loops with two different complex impedance characteristics. I further said that such isolation can reduce electrical noise just similar to putting different household electrical devices on different AC circuit branches.

xcapri79 wrote: »

The amp is a time varying multi-frequency source and the currents from the amplifier will flow into the speaker load in accordance with Ohm's law, and Kirchoff's current and voltage laws. The speaker essentially operates based on Faraday's law of induction. All these are well understood scientific and engineering concepts.

Again, my point is that splitting a complex, reactive, electrical load into two parts and placing each part on a separate circuit branch is not electrically identical to the same load combined on a single circuit branch.

xcapri79 wrote: »

Telco companies are running wires over hundreds of feet if not miles and are involved in numerous commercial, industrial and military applications. The engineering design requirements are different for those applications vs consumer audio interconnects. It is ridiculous to extrapolate extreme properties, requirements and applications to audio equipment based on performance.

Actually, the signal integrity requirements between telco audio transmission and stereophonic audio are very similar. I have some knowledge of the topic because I spent 12 years in telco engineering and 4 years in telco R&D.

xcapri79 wrote: »

The science is misapplied and pseudo-science created to market esoteric cables because they earn tremendous profits.

Yes, I agree that some cable manufacturer's claims are not grounded in scientific validity. There are scam artists in every field of commerce. However, you make yourself look like someone on a hysterical witch hunt by claiming that all high performance audio cable manufacturers are peddling snake oil.

F1nut wrote: »

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BlueFox wrote: »

I believe both pair of wires have the same frequencies between the amps and speakers. The cross overs in the speakers then separate out the frequencies they need.

Correct.

Yes, but wouldn't each pair see a different load impedance given the same frequency (except at fc)? Yes, the same signal is applied to both pairs but the signal flow is going to be different through each pair as dictated by the reactive impedance of the high frequency network and the low frequency networks in crossover and the drivers themselves.

As the wire pairs are an RLC network, you have an RLC network for the high pair in parallel with the mid and tweeter XO and mid and tweeter drivers. Then you have an RLC network for the low pair in parallel with the woofer XO and the woofer driver. The question seems to be, is there a change in the signal quality (shape and/or amplitude at various frequencies) due to the cables or is it simply a matter of reduced impedance for the signal going to the highs and to the lows?

I should try to simulate the difference between single and bi-wiring in PSpice, though I haven't not had much success in finding such differences.

In regard to cable directionality, there is a discussion on another forum about it, and this is what Caelin Gabriel of Shunyata said.

"

As is the case with many things - the answer depends.

Gary is right in that the signal is an alternating voltage so the current simply reverses direction. This means that whatever end of the cable is connected shouldn't matter. However, some speaker cables are intentionally designed with asymmetric conductors. That means that the physical size of one conductor is larger than the other. And some cables may have a different winding direction for one or the other polarities.

Some amplifiers push and pull current from both the positive and the negative terminals while other amps ground the negative terminal and only push and pull current from the positive terminal.

With an asymmetric cable and a grounded negative terminal amp it will matter sonically which way the cable is connected.

If a speaker cable is symmetrically made there will be no difference when the cable is first connected. However, as the cable burns in it establishes directionality meaning that you should hook it up in the same direction after that. So the arrows on the cable are simply a convenience for the user to connect the cable the same way.

The other reason there are arrows is that customers demand to know the direction to hook up the cable. We only make symmetrically designed cables and in the past did not put arrows on the cable. But customers wanted to know which way to connect them even though we repeated said that it didn't matter. It is easier just to put the marks on the cable.

http://www.audioaficionado.org/cables-galore/31622-speaker-cable-direction.html#post700472

xcapri79 wrote: »

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F1nut wrote: »

That said there are some here that buy into that explanation and believe a bag of charcoal on top of a speaker can improve its sound.

Once again, your reading comprehension needs serious work. The member who posted about the coal states that it did not make a difference when placed on top of the speakers.

He actually believed in it enough to actually try it. That was enough for me.

He said that he heard a difference when he placed this bag of charcoal on top of a bag of treated crystals on his PA transformers, and on his balanced isolation transformers that his power amp and linestage are plugged into, as well as one on top of a filtering choke. Ok.

Here is the full humorous post.

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drumminman wrote: »

I frequent Audio Asylum mainly looking at the tweaks and cables categories. There's a guy who posts quite a bit in the former named Uncle Stu, and he thinks outside the box. Way outside.

I've tried some of the things he describes, usually with good results, and here's the latest.

Charcoal. You can read the thread here: http://db.audioasylum.com/mhtml/m.html?forum=tweaks&n=185942&highlight=charcoal+tweak&search_url=/cgi/search.mpl?forum=tweaks&searchtext=charcoal+tweak

What he did was take charcoal briquettes (think Kingsford), put them in a plastic bag and place on top of his floor standers. The results he described were intriguing, so I thought what the heck. It's cheap, reversible, no downside really.

So I bought a bag and used some zip lock bags I already had. Total cost $8. I filled a large ~ 10' x 10" bag with briquettes and used a hammer to break them into smaller pieces. Initial placement was on top of my 2.3TL's, and the results were: couldn't hear any difference.

Next I tried placing the bag on top of a bag of treated crystals from Alan Maher that had been placed over the transformers of my PA. Didn't like what I heard. The sound character changed from being open to somewhat pinched, not markedly so but enough to remove the charcoal.

Then I removed 2/3 of the charcoal from the bag leaving around 6 oz or so and put it back in the same place. Slight change for the better. Inner details of instruments were a little more resolving, slightly more realistic tone, vocals maybe a little more fleshed out.

Then I took a several more bags and placed one each on the two larger balanced isolation transformers that my power amp and linestage are plugged into, as well as one on top of a filtering choke at the IEC connection for my Oppo, which is used as the source. Improvement was more of the same. It does seem like the improvement in sound quality has continued as the charcoal has remained in place.

Listening this weekend has been almost a revelation. Before this tweak I would characterize the sound of my system as very clean, well balanced throughout the audio spectrum, extremely easy to listen to at high volume. The charcoal has potentiated the best attributes.

Sounds crazy I know, but it's so easy - and cheap - to try. Love to hear of others experience with this.

Please do not reply to this post with negative comments if you haven't tried this or have no intention of doing so.

Cheers and happy listening.

And of course, you're too close minded to try anything that can't be explained with scientific measurements. Try not to be so dogmatic and be willing to test your assumptions, especially of a tweak is inexpensive and easily reversible.

Or don't you trust your ears?

This is basically what you are doing circuit wise when you bi-wire vs single.



Results likely depend on things cable lengths, speaker impedance (high drivers and low drivers), amplifier impedance and damping factor to name a few (placebo and psycho stuff aside). Perhaps you would get the same results by going with a heavier AWG? Try it and see what I like is my plan.

Yes, I haven't simulated it yet. I had to get back to doing real work that I get paid for.