Published Research on Bi-Wiring Speakers

[brandonhall]

I was curious if there were any actual benefits to bi-wiring speakers and came across this piece from Q Acoustics. I always assumed bi-wiring was pointless since it's just a matter of signals and cables. Anyway, their research was published in 2016 and they build on prior research from 1998 to show a measurable decrease in IMD when speakers are bi-wired. I found it fascinating and would love to know what the community thinks.

 

[MaxBuck]

I was curious if there were any actual benefits to bi-wiring speakers and came across this piece from Q Acoustics. I always assumed bi-wiring was pointless since it's just a matter of signals and cables. Anyway, their research was published in 2016 and they build on prior research from 1998 to show a measurable decrease in IMD when speakers are bi-wired. I found it fascinating and would love to know what the community thinks.

Thanks for linking to this. I admit I've never believed that bi-wiring made any sense, but I'd be very interested to see whether our knowledgeable posters have an opinion on this paper.

 

[theREALdotnet]

It’s nonsense. It is nothing more than marketing garnished with diagrams. Just a few points:

• It is not counter-intuitive that in a bi-wiring setup the LF cable will carry mostly LF current and the HF cable mostly HF current. The low- and high-pass filters in front of the speaker drivers make sure of that.
• Intermodulation does not occur in cables, it happens in the amplifier, i.e. before the cables split into LF and HF.
• If you put the HF (red) and LF (green) current graphs together you pretty much get the blue curve (single-wired setup).
• A funny bonus: the HF cable appears to catch a mains hum that isn’t present in the single-wired plot.

 

[amirm]

They used a current probe for measurements. From past experience with headphones, back EMF from the drivers messes with any instrumentation of distortion. If there is really such massive reduction in IMD distortion they should just use a microphone in front of the speaker and measure its effect there. I suspect it won't even register there.

 

[DVDdoug]

Except for cutting cable resistance in half (which is usually insignificant anyway) by doubling the wires there should be no electrical effect.

Electrically it's the same circuit ... it would be the same schematic*... whether you connect the inputs together at the speaker-end or at the amplifier end.

To me, it seems like someone trying to get the advantages of bi-amplifying with only one amplifier per speaker. Even bi-amplifying doesn't automatically give you better sound quality.

* A schematic shows the electrical connections without regard to the physical layout.

 

[theREALdotnet]

They’re just hoping nobody will look closely, or check whether their conclusions actually follow from what the graphs show.

 

[JSmith]

any actual benefits to bi-wiring speakers

Audioholics did a long and detailed article on this back in 2007 (multiple pages);

The claim is therefore based on a misunderstanding of – and hence a misrepresentation of – the relevant physics, and how details of the signal carry the required information. The reality, as shown by the above equations and graphs and – more importantly – by measurements, is that no form of ‘intermodulation distortion’ arises in the situation described.

Bi-Wiring A Loudspeaker: Does it Make a Difference?

Bi-wiring a loudspeaker involves running two pairs of cables tied together on the amp side but separated on the loudspeaker side to the low and high crossover sections. But, does it make a difference?

www.audioholics.com

JSmith

 

[Mnyb]

It’s refreshing to see a good speaker without biwire terminals ,even good brands have them ( sadly ).

1 . “Serious audiophile” expect these .

2. Dealers like a product with another business opportunity built in already , and is happy to “inform” “serious audiophile” about it

There are some speaker manufacturers that spreads this fud , like audiovector . They have triwire in some models ( and other voodoo stuff ).

Also if for some reason one wants to use a series crossover in a speaker design , you can’t because marketing demands biwire terminals

 

[jasonhanjk]

The answer is no.
However bi-wiring with bi-amp does make a difference.

 

[test1223]

The answer is no.
However bi-wiring with bi-amp does make a difference.

No it is also snake oil. You can replace the crossover this way, which obviously can make a huge difference, but otherwise there is no point to use a bi-amp set-up.

 

[kchap]

Except for cutting cable resistance in half (which is usually insignificant anyway) by doubling the wires there should be no electrical effect.

I've used Bi-Wiring as a method of reducing the resistance of the speaker cabling. The speakers were capable of supporting Bi-Wiring and the distance was 2 or 3M longer than normal. I was assuming that would be a roughly 50-50 distribution of power between the LF and HF paths; it may well have been a waste of time.

Still, it impresses visitors.

 

[komhst]

It’s refreshing to see a good speaker without biwire terminals ,even good brands have them ( sadly ).

Yamaha NS-5000 only one pair of terminals, doesn't accept bi-wiring:

 

[warthor]

I do bi wire my speakers, but not for a benefit in audio quality. (To whom should I confess my audio sins?) I was under the impression that doing so reduced the load on the amp. If that is true then less heat is generated etc. If that is incorrect I will undo this arrangement promptly.

 

[mj30250]

I don't think the amp much cares.

If you're thirsty and you drink some water, will you be less thirsty after drinking 1 full glass or 2 half glasses?

 

[fineMen]

They used a current probe for measurements. ...

In real science the instrumentation is checked first for reliability and accuracy. They didn't even bother to tell which "instrumentation" brand / model was used. Is it, naively, considered "ideal"?

Second, as was said before, the change is due to the x/over. Once summed up again, they get the same amount of, or even higher IM (em/interference).

Third, if there was an effect revealed, that would earn a Nobel price. Hence a serious and eager audio engineer, which they claim to be, would neither rest nor sleep once he found the reason. Despite that all too human expectation, no reasoning is given.

Anyway, IM in the speaker's drivers themselves reach up to 30% easily, but here we are told that a difference of 0,3% was significant.

 

[R Swerdlow]

It’s nonsense. It is nothing more than marketing garnished with diagrams. Just a few points:

• It is not counter-intuitive that in a bi-wiring setup the LF cable will carry mostly LF current and the HF cable mostly HF current. The low- and high-pass filters in front of the speaker drivers make sure of that.
• Intermodulation does not occur in cables, it happens in the amplifier, i.e. before the cables split into LF and HF.
• If you put the HF (red) and LF (green) current graphs together you pretty much get the blue curve (single-wired setup).
• A funny bonus: the HF cable appears to catch a mains hum that isn’t present in the single-wired plot.

They’re just hoping nobody will look closely, or check whether their conclusions actually follow from what the graphs show.

I agree with most of the posts above, especially with the 2 from theREALdotnet.

The link from Q Acoustics is well written in general. As an example, see the 3rd paragraph quoted below. The italics are mine.:

Proponents of the practice point to the obvious sonic benefits they can hear after bi-wiring their speakers, citing the fact that speaker manufacturers make the terminals available, as proof that there must be something in it. Detractors argue that manufacturers are merely maximizing the marketability of their products by offering a feature that costs little extra to implement but probably doesn’t make any sonic difference. They also point out that there is no real published evidence to prove that the practice makes any audible difference, whereas the bi-wire enthusiasts theorize that by separating the high and low frequencies into different wires, distortions caused by interactions between them can be eliminated.

Q Acoustics pointed out that "there is no real published evidence to prove that the practice [of bi-wiring] makes any audible difference …" The problem is that Q Acoustics also provides no evidence of an audible difference.

They did provide some unconvincing charts of current measurements. In Fig 6 (bi-wired tweeter cable), an area (at 1-2 kHz) was circled and labeled with the comment "IMD reduced dramatically". I couldn't see any difference between that area in Fig 6 and the same area in Fig 5 (single wired cable).

Furthermore, the background levels of measured IM noise, other than the frequencies of the test tones, appeared to be higher in Fig 5 than in Fig 6, but those measured levels were still quite low, no higher than 40 to 50 dBu lower than the peak of the test tones. Who hears noises 40-50 dB below a signal's sound level?

But, most importantly, Q Acoustics never showed any results at all of listening tests. As a result, they can say nothing at all about possible sound qualities introduced by bi-wiring speakers. This article is advertising copy – not research.

 

[xaviescacs]

What I never understood is is why stop at two wires. What is special about two wires? Why not three or four wires?

 

[dfuller]

Bi amping can reduce IMD - because you're splitting the signal before the amp. That said, there is essentially no point unless you're using an active crossover - which is better anyway - because in a passive biamping scenario both amps are still reproducing the full bandwidth signal.

 

[jasonhanjk]

No it is also snake oil. You can replace the crossover this way, which obviously can make a huge difference, but otherwise there is no point to use a bi-amp set-up.

It depends. If the crossover have more overlap, the overall impedance would reduce at that frequency.
Reducing impedance may cause increase distortion (amp dependent).

Best to do nowadays is have separate amp for tweeter and woofer with dsp crossover.

 

[Wseaton]

Bi-wiring requires you buy an extra pair of over priced audioquest speaker cables along with Cardas carpet elevation blocks from Virginia unicorn wood, so I doubly impress my friends. That's good, right?

/sarcasm

Where I disagree with responses is bi-amping. For larger towers I've heard astonishing differences with bi amp stacks, but its mostly due to the increase of available current with lots of heavy magnets to push.