Biwiring speakers: any point?

[greencalx]

I inherited my dad's amp and speakers which he had biwired, and since I didn't have the shorting bars I had to biwire them in my own setup. Not a big deal (one-off hassle factor in ordering some extra cable and wiring up eight plugs rather than just 4) but it left me wondering what the point is, if any.

The difference, as I understand it, is that instead of the woofer and tweeter terminals being connected together at the speaker end (as they would be if the shorting bars are in place and there was a single cable run) is that they are connected together at the amp end. I guess in my head I'm idealising the wires as components with zero impedance (where this would indeed make no difference, as the voltages would be the same at both ends): I can see that the attenuation / phase shift in the wires could be different in the two configurations, which in turn could lead to the speakers doing different things with the same signal from the amp, but it's not clear to me which would be superior from an audio point of view.

I'm fairly certain in any case that I'm too cloth-eared to tell the difference, but was wondering if there's even a theoretical difference, or if this is yet another psycho-acoustic scam. One for buzby, maybe?

[Endicott]

There is a theoretical difference, because the wires are not zero impedance, but whether you'd be able to hear it is another matter. Some people say they can, and some can't.

I'm not up on modern designs but the principle of a single earth point certainly used to be a part of the internal design of amplifiers, right down to the PCB design. Bi-wiring the speakers ensures you don't compromise it.

[greencalx]

Yeah the "I can see..." part was me thinking aloud about wires with nonzero impedance.

Can you elaborate on the earth business? Not sure how biwiring makes much difference given (if what I read on the net about the amp was accurate) each pair of red and black terminals are connected together. I am vaguely aware that an earth loop can give you a nasty 50Hz mains hum.

[Endicott]

Roughly, with bi-wire you are tied to ground at the back of the amp (the single point ground), and anything leading off from there can float independently. Whereas a single cable means there is a point in the speaker where the HF and LF filters connect to common ground, and it's claimed that that can introduce some distortion.

I think it's a bit academic, as actually hearing a difference is going to be difficult.

Here are two articles, one from a company that doesn't do it, and one from one who does, and who try to measure it.

https://www.cambridgeaudio.com/gbr/en/blog/should-you-bi-wire-your-speakers

https://www.qacoustics.co.uk/blog/2016/06/08/bi-wiring-speakers-exploration-benefits/

[greencalx]

Thanks for that. I hadn't appreciated that, by the same token that a voltage would be the same at both ends of a(n ideal) wire, the filtering at the speaker end can also be thought of as acting at the amp end, and therefore this is sufficient to separate the frequencies down the different wires. Makes sense now.

But no, I'd be surprised if anyone can hear the difference in practice.

[buzby]

Like most things in the high end audio world, it's largely a load of hogwash which delivers little if any measurable benefit (and can actually make things worse, as now you have two sets of cables per speaker that can act as antennas to pick up any RFI - remember that speaker cables are not screened). It's great news for speaker and cable manufacturers though.

Speakers with separate terminals for the woofer and tweeter were originally meant for bi-amping, where you use two output amps with different frequency responses or equalisation tuned for the two drivers (an active crossover, in effect). Presuambly at some point in the 80s some bright spark came up with the idea of using twice as much cable between the same two points must make things twice as good (maybe it was the same person who invented the 'green highlighter around the edge of a CD' wheeze). Single, thicker (i.e. lower impedance) wires makes much more sense.

You also get people suggesting that the link bars on 4-post speakers should be replaced with jumper wires made from speaker cable - any decent speaker should have been supplied with solid copper link bars and there's no way that replacing them with a pair of banana plugs and length of cable would produce a connection that has less resistance or impedance

The single earth point is more to do with trying to prevent ground loops and noise being induced into the power and audio circuitry. It's the chassis grounds that are all connected together and tied to the mains ground via a single connection (on the old Quad stuff it was via the mains lead on the power amp), usually though the shields of the cable - the older DIN interconnect standard made this more obvious. The positive and negative inputs and outputs of amplifiers are referenced from the amplifier's  0V rail, which is usually derived from a tap in the power transformer, not the chassis ground.

[greencalx]

Thanks buzby- that was more or less the answer I was expecting. Bi-amping I can at least understand as a concept but biwiring had me utterly perplexed. The audiophile world does seem to involve lots of pseudoscientific guff aimed at getting people to part with their cash. Anyway, that's how they're wired now and they sound so much better than my old speakers I can't see much point in faffing around further.

[Sebastian Cobb]

I think they could in theory reduce distortion if you had thin long cables as the low end wouldn't fuck up the top so much but as already described, just buy thick cables and run them once innit.

I did it with a set of kef bookshelf speakers I bought because I had mediocre cables and lots spare and then lost the link bars so now have to thread the cable through both eyelets on the terminal posts and it's just annoying.

I think the biggest clue it's largely bollocks is that plenty of well built older speakers can and do sound better than newer speakers that do it, at which point audiophiles will give them praise and just ignore the fact they don't have this previously-deemed-important feature.