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Is bi-wiring worthwhile? (not bi-amping)


MeloManiac

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2 hours ago, glens said:

 

Even during / after repeated comparison both ways?  Just curious as to the extent of your acquired experience in reaching that determination.  Not calling you out on it.

Nope, experienced on a number of speakers over the years otherwise I wouldn't have purchased as much of the cabling for building my speakers and speaker cables as I did.  Mind you that is my experience compared to several not totally cheap speaker cabling.  Everyone hears things differently so YMMV.  Likely also depends on other factors though I could not pick out what though I seemed to nice it more with some speakers and less with my KLFs.

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9 hours ago, glens said:

Haha!  I can't remember why I didn't refute that when it was posted!

 

As I'd said, the potential energy at all frequencies ends up at both (separate, and separately fed) crossover input terminals.  The impedance is so high for the unused portion (either way) that the energy merely goes unused for all intent and purposes.  So it does effectively "just go away."

 

As to the "common-wire IM," well, what about the internal wiring in the amplifier?  I've seen probably the same "look at the IM" graphs you've seen, and I merely shrugged my shoulders at the author's inability to understand why they appear that way (hopefully he wasn't merely being dishonest).  If there's IM being generated in a common wire (or transistor lead), it's already been introduced within the amplifier and no amount of separate external wire will make it go away!

What about adding to it? The length of the circuit traces or wires in an amp are short compared to the length of the speaker wires usually. This has sparked my curiosity and I am devising an experiment to more fully understand. In my searching this is what I found:

How are bi-wireable speakers wired up to an amplifier?

Fig. 3 shows how a typical biwireable speaker is connected to an amplifier. It has four terminals instead of two, one pair for the HF network and one pair for the LF network. Two speaker cables are used to connect the HF terminals and the LF terminals to the same pair of terminals on the amplifier.

Fig 3 Bi-wiring connection diagram Bi-wiring Speakers

Fig 3 Bi-wiring connection diagram

How does current flow in the bi-wired speaker cables?

Consider the above circuit before the amplifier provides any potential at its output terminals. The traffic jam will be stationary – it’s nose to tail trucks and motorbikes all the way from the amp, down both speaker cables, inside each of the LF and HF networks and back to the amp again. Nothing is moving. Suddenly the amplifier gives the green light. In the HF network are a set of bollards too close together for trucks to get through – only motorbikes can slip through. So in speaker cable 1 only the motorbikes will be moving. Yes, the trucks are still there but they are all parked – can’t move. In electrical terms only high frequency currents will be flowing in speaker cable 1. Even though the filter circuitry is at the far end of the cable there will be no low frequency current present in the whole of the cable leading up to that point. This is a hard concept to grasp first time. If you get it great, read on. If not then keep re-reading to this point until you do.

The same goes for speaker cable 2, except in the LF network there is 2 foot six feet of water which the motorbikes cannot negotiate so they are all stationary, whereas the trucks can plough on through. So, in speaker cable 2 only the low frequency current will be flowing.
Effectively, as if by magic, we have separated the high and low frequencies and sent them down different cables to the correct driver. If you are still asking “but how do the different frequencies know which way to go?” or saying “ don’t talk rubbish, both cables have all the frequencies in them the same, right up until the crossover” – then try re-reading the above until you understand it.

 

Are you saying this is incorrect? What is their mistake?

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If you don't get it, stop thinking about voltage and start thinking about current.

 

Voltage doesn't make magnetic fields, current does.  Magnetic fields cause cross-talk and modulation distortion.

 

Stop the frequencies, stop the magnetic fields, stop the modulation distortion.

 

Now your cables don't have to be full-range (think Lowther), with all the quality demands that requires.

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2 hours ago, babadono said:

Are you saying this is incorrect? What is their mistake?

 

Well, pretty much what DirtyErnie just said is what I've been saying, and the article is wrong in the mental image it's depicting.  The bollards and water traps do not exist anywhere but in the crossover components.  As I'd said, the same potential at all frequencies is present at all points in all the wires at all times (assuming they're not grossly undersized, of course).  As I'd also said, but not as succinctly as did Ernie, the current at different frequencies will be different because of the crossover elements at the far end of the wires.  

 

In a graph showing the current flow as in that un-referenced article, sure, it appears as though there's less signal modulation in each of the separate wires.  But if the current is measured on the 4-inch leads inside the amplifier, it will show all the modulation which is always going to be there, and it's not a detriment.  It's not distortion.  That un-referenced article was either mis-informed or dis-honest in declaring the "removal" of the "modulation" a benefit of bi-wiring.  He'd get exactly the same graphs of current flow taken either side of the crossovers.

 

The only benefit to bi-wiring is the net effective increase in conductor capacity, if such results from the exercise.  If you bi-wired using wire with "X" capacity, or mono-wired using wire with "2X" capacity, you'd have exactly the same end result.

 

At audio frequencies the differential effectiveness of typical wire over typical lengths, due to frequency (skin effect), is totally a non-issue, in case you're wondering.

 

 

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56 minutes ago, DirtyErnie said:

If you don't get it, stop thinking about voltage and start thinking about current.

That's the same thing I tell people when trying to help them with ground loops and interfacing balanced and unbalanced equipment. You have to think where is the current going to go.

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1 hour ago, glens said:

 

Well, pretty much what DirtyErnie just said is what I've been saying, and the article is wrong in the mental image it's depicting.  The bollards and water traps do not exist anywhere but in the crossover components.  As I'd said, the same potential at all frequencies is present at all points in all the wires at all times (assuming they're not grossly undersized, of course).  As I'd also said, but not as succinctly as did Ernie, the current at different frequencies will be different because of the crossover elements at the far end of the wires.  

 

In a graph showing the current flow as in that un-referenced article, sure, it appears as though there's less signal modulation in each of the separate wires.  But if the current is measured on the 4-inch leads inside the amplifier, it will show all the modulation which is always going to be there, and it's not a detriment.  It's not distortion.  That un-referenced article was either mis-informed or dis-honest in declaring the "removal" of the "modulation" a benefit of bi-wiring.  He'd get exactly the same graphs of current flow taken either side of the crossovers.

 

The only benefit to bi-wiring is the net effective increase in conductor capacity, if such results from the exercise.  If you bi-wired using wire with "X" capacity, or mono-wired using wire with "2X" capacity, you'd have exactly the same end result.

 

At audio frequencies the differential effectiveness of typical wire over typical lengths, due to frequency (skin effect), is totally a non-issue, in case you're wondering.

 

 

 

 

 

 

 

I believe that is what I said back in August of last year

On 8/29/2019 at 9:00 AM, babadono said:

Yes it cannot hurt to do it(except the cash out of your pocket for more wire). Your speakers, crossovers, wires and amp are a system. In a single wire setup all the energy at all frequencies go down the same wire  where they get separated by the crossover and then are fed to the drivers. In a biwire system the low frequency and high frequency energy go down the two separate wires. I think sometimes there is a misconception that the energy of all frequencies goes down both wires in a biwire system and then when it gets to the crossover the low frequency energy that arrives at the high side crossover just magically goes away. And vice versa for the high frequency energy at the low side crossover. I have seen papers that show measurements of small amounts of IM distortion that are eliminated by biwiring because the low and high frequency energy are not traveling on the same wire.

Now that said can you hear it? I think only your ears can tell you that. Or do you just want to hear a difference because you spent more money on wire?

 

 

to which you responded

On 8/29/2019 at 1:40 PM, glens said:

 

Actually, unless it is bi-amplification in which there is a low-level crossover prior to the separate amplifiers, the signal going to both the (single-cabinet) speaker inputs on a (single) channel has the exact(ly-enough) same full-range potential available at the speaker, which means that both wire pairs do indeed carry the same full-range signal all the way to both halves of the crossover at the speaker cabinet(s), where the unused portions of the signal on a given wire "simply go away" (or more properly, simply don't have full effect).  But it's not by magic. 

 

I too have seen such documentation of lower measured levels of IM using bi-wiring.  It's smoke and mirrors.  That same IM, as depicted as being present only in the single-pair, is in fact (always) present in whichever internal leads/traces are between the semiconductor junction or tube element of the output device and the amp's internal point at which the signal diverges to the multiple outputs.  How can it possibly not be?  If the IM is unobtrusive while carried on a single wire within the amp, it's just as unobtrusive when it gets to a speaker 100' distant from the amp.  It's not like IM increases with the length of time (distance) the two frequencies are carried together on a wire.

 

 

When the output voltage swings reach the levels of the supply rails you've reached the limit of "clean" amplification.  If the amplifier is capable of sustaining those voltage levels no matter the load, the "power" will double with each time the load is halved.  It's just relatively simple math.  Most amps are not built "strongly enough" to actually do that, and your example indicates that of your amp.  If you had two "identical" multi-way speakers (already not going to happen) attached to a fully-capable output, the power being dissipated would double.  However, that's not what you're doing.  In your case, there are not now two woofers getting signal, still just the one, so the woofer part of the signal is drawing exactly the same current as before the wiring split.  Same for the high-frequency content.  You are not gaining any advantage in terms of output power reaching the speakers unless the wire you're using is silly small.

so which is it?

Link to entire article:

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

not trying to hide anything, in fact the more that can be understood the better AFAIC.

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The "which is it" is that, indeed, the exact same electrical signal (full-range voltage, which is the potential) is present in all of the wiring.  Due to the varying impedance of the crossover elements, more, or less, of the present voltage will produce current.

 

Plug some numbers into the Ohm's Law equations.  At any point between the amp and crossovers in any of the wiring at any frequency, the V will be the same (with reasonable runs of reasonable wire, that is).  Determine what the terminal impedance is at some frequency and you'll be able to find the current flowing through the wire at that frequency.  

 

Remember, the presence of full-range current within a conductor is not a "bad" or "undesirable" thing in and of itself.  It's not a form of distortion and it will in no way confuse the wire or the speakers, nor degrade the sound quality.  The usual caveat applies: sufficient wire size for the application.

 

I'll look over that link in a minute and get back if there's anything more I feel needs saying.  If memory serves, all these recent posts should have it covered.

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Okay.  Yeah, that was the article I remember having seen some time ago.

 

I'd forgotten, however, that it was the creation of a Specialty Speaker Wire Manufacturer...

 

It's disingenous, flat out.

 

Quote

Going back to our Newton’s cradle analogy, if the balls are all stationary and then one is lifted and released the impulse travels quickly through the row and the end ball pings off in time “t”. If we now set all the balls swinging at a low frequency first and then repeat the same process the end ball pings off in a different time “t2”. This is analogous to the low frequency and high frequency signals being present in the same cable; they have combined within the transfer medium to create a new frequency which was not in the original signal in a process known as intermodulation. Wherever there is non-linearity in a system which carries multiple different frequencies there will be amplitude modulation made up of the sum and difference of the original frequencies and in addition, harmonics of these sum and difference frequencies. Unlike some types of harmonic distortion this type of distortion is not nice to listen to and although non-linearity in good hi-fi equipment is generally very small, it is enough to produce intermodulation distortions which are bothersome to the listener.

 

If that statement in red (my emphasis) were true, it will have already happened in the output transistor leads and wire connecting them to the output terminals on the back of the amplifier (or the equivalent tube circuitry).  Assume for the moment even one new spurious frequency has been thusly created.  Will it be made worse by a single 12' run of wire (is it a new new frequency produced per unit length or just the one-time creation because it's a single conductor)?  How could a dual 12' run of wire remove it?  Or does the dual run merely prevent further production of the anomaly?  What about the leads connecting the phono cartridge to the pre-amp, and all the leads/traces interconnecting processing/amplification stages?  Surely there must be nothing left of the original signal anyway by the time it even gets to the speaker wires!  There's more intermodulation produced than original signal by now, right?

 

Hogwash.  "But here are some confusing statements and pretty graphs to back them up.  Buy our wire, and all these problems will not be presented to your speakers" (which would be a true statement other than the implication the non-presentation is a result of their wires).

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On 3/30/2020 at 1:28 PM, babadono said:

Now that said can you hear it? I think only your ears can tell you that. Or do you just want to hear a difference because you spent more money on wire?

Again I will state only THE LISTENER can determine if it made a difference to their ears/brain. And they WILL be biased based on how pretty the new wires are and how much money they spent.

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