Is biwiring worth it?

Knightshade said:
Hi Beastie,

My feeling is it won't make a blind bit of difference where you have it happening. In physics yes but audibly no.
Interesting though, I don't think I've ever heard anyone argue so convincingly for Bi Wiring.....:)

Thank you! Thats my whole point. Theoretically, what I am saying is correct. But does it make any audiable difference? I doubt it, but I'm not able to test myself as my speakers are not capable of bi-wiring (and I probably wouldn't bother if they were).

Cheers, Beastie.
 
Mason @ B&M said:
I'm going to go talk to some uber techies and ask them to comment on this ;)

I would love to hear what they say. I must admit, when it comes to harmonics, I feel I am on shaky ground as far as my knowledge and experience goes :thumbsup:

I believe the harmonics would be suppressed at the amp terminals due to the fact that the voltage at this point is fixed, wheras a 80Hz harmonic wave for example would be allowed to pass directly from cone to cone. To be honest, I I'm not 100% sure of this particular aspect. I'm looking foreward to learning somthing here.

Thanks for bearing with me throughout this debate.

Cheers, Beastie.
 
One point that should be remember is that even though most amps have an A-B speaker set, i.e. two sets of connectors for each speaker, these connect to the same amp.
So although you have have 4 physical binding posts per speaker the two set are connected to a single amp.

left A
\ _ Left Amp
/
left B

So the current ect.. drawn will be the same over both cables (as the sum of the possitives and negatives are all that the amp cares about), the only difference that could be made is if one cable was capable of delivery bass or treeble better than another. (do such cables exist?)
In which case you would use the best cable for the job, but then again as the source is constand and the sum of +/- would change this would change the properties anyway.

I think that bi-wire is more about deliveing a thicker cross section of wire, using two lengths rather than using one thick length.

Bi amping has benifits but does bi-wireing? it's probably all psychological but if it sounds better to you no matter what the course does it matter?
 
gazbarber said:
the only difference that could be made is if one cable was capable of delivery bass or treeble better than another. (do such cables exist?)

Some manufacturers do in fact claim this, I personally have my doubts however.
Another thought along similar lines, just as a speaker cone can deliver cleaner mid-range if it isn't also trying to play deep bass at the same time, would a speaker cable deliver a cleaner high frequency signal if the bass was on a seperate cable?

Probably not but just a thought.

Cheers, Beastie.
 
Whilst i can see that bi-wiring does not electrically change the circuit from amplifier to loudspeaker, surely you're not getting any benefit from it if you use the same type of cable to connect to each driver?

I personally am convinced of the merits of bi-wiring, but as far as i can see the main benefit of it is to allow one to use a cable with a good treble response for the tweeter and one with a good bass response for the woofer, which is exactly what i had on my old system.

Adam.
 
Beobloke said:
but as far as i can see the main benefit of it is to allow one to use a cable with a good treble response for the tweeter and one with a good bass response for the woofer, which is exactly what i had on my old system.

I think this could be another topic :D
 
Some more info from a friend

Tell him if the tweeter produced low freq harmonics (which it wouldn't do) it would be blocked by the crossover. The filters work both ways, not just in one direction.

Also unless the amp feedback is connected to the point where the bi-wires join there is still the possibility unwanted signals getting from one wire into the other
 
Thanks for posting that info. :thumbsup:

So it looks like the only advantage in bi-wiring is that the high and low frequency currents travel along different cables.

So in answer to the original question 'Is Bi-wiring worth it?', the answer is NO!

Unless of course you can hear a difference, then YES!

Cheers, Beastie.

Anyway, about cables suitable for high or low frequency signals.... :D
 
Cat 5 is pretty good......! :thumbsup::D
 
I actually find, that the description by B&W is quite good. Actually the description is very much in line with my own thinking over the last few days. In the following I will try to explain it with the help of a couple of small figures. See the attachment.

Let’s assume, that we have a speaker with 2 units, a base and a mid/high range. The arguments can also be expanded to cases with more than 2 units, but let’s keep it simple for now.

Let’s also assume, that we have an ideal amplifier. One of the characteristics of an ideal (voltage) amplifier is, that the output impedance is 0.

Unfortunately the cables will never be ideal, there will always be some impedance present, consisting basically of a series resistor, a series inductor and a capacitance between the two wires. In the following the capacitance is neglected. The sum of the series resistance and the inductance is denoted by Z in the schematic.

Refer to fig. 1. Let’s assume, that the speaker has a cross over frequency of 400Hz. If you feed the speaker with e.g. a 300Hz signal, this will primarily go to the bass unit, but some of it will go to the midrange speaker. So far so good. The problem could be, that the bass speaker, or even worse, the cross over filter for the bass speaker, could be non-linear, leading to harmonic distortion. That would mean, that signals at 600Hz, 900Hz, 1200Hz etc. would be present on the input terminals of the speaker box. These frequencies may only be reproduced by the bass speaker at very low volume, if the bass speaker has a roll off above 400Hz, but the midrange speaker would reproduce them if they were present on the input terminals of the speaker box.
Distortion from the mid/high range is probably less of a problem, because harmonic distortion can only produce higher frequencies, not lower frequencies. Other types of distortion can, but then we are talking about intermodulation, which is a completely different story.

If we then look at fig. 2 with bi-wiring, the situation is different. Distortion from the bass part of the speaker will never reach the mid/high range, since the (ideal) amplifier will short circuit any signals coming back to the amplifier terminals. Thereby, no harmonic distortion from the bass part will be heard in the other part. If however, the amplifier is not ideal, or at least close to ideal, with a very low output impedance, then the situation could be different. This could be the case, e.g. with a tube amplifier with a relatively high output impedance. In this case bi-amping may be needed to separate the signals.

Now this was the theoretical explanation. Whether it really means anything in practical terms I don’t know, since I have no experience with this. My guess would be, that it depends on the speaker design (generation of distortion, filter characteristics, speaker frequency responses etc.) and the amplifier, primarily output impedance, but perhaps also current drive capability (could be described as a kind of non-linear output impedance).

I am not a speaker expert, but I do have a masters degree in electronic engineering, so I have a pretty solid theoretical background. I am generally sceptical about exotic cables, but of course increasing the cross section of a wire is always good, and bi-wiring or bi-amping could perhaps have some benefits in some (or all?) cases.

I hope this is useful.

Jens
M.Sc.E.E.
 

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Beastie Boy said:
Anyway, about cables suitable for high or low frequency signals.... :D
Knightshade said:
Cat5 is pretty good
Now there's the interesting topic that's best not discussed here :laugh:

Cables that are "better" for high or low frequency signals havn't been designed properly and are just adding unwanted effects to the speakers crossover.

Cat5 is good in some ways (very low inductance) but bad in others (very high capacitance). Regular zip wire is good in some ways (very low capacitance) but bad in others (fairly high inductance).

There are plenty of other geometries around too. I use the outer braid on twisted coax which has different properties, it's also possible to cross-connect coax cable which I think is technically the best design available although even then it can have some unwanted properties depending on the thickness of the conductors, dielectrics and outer sheathing. :)
 
Hi y'all,

Am I reading some of these posts correctly?
The general idea I'm getting is that when bi-wiring,the amp sends only the correct signal (L/F to L/F and H/F to H/F) down the seperate runs of cable?
Surely the same full frequency signal is present and identical down both cables (assuming identical cable is being used), or am I missing something??
I thought the whole idea of bi-wiring was that the differing frequencies were split prior to entering the crossover so they did'nt interact with each other,therefore giving more control to the respective drive unit for the frequency they can handle.
At the end of the day there are so many different variables (amp,cable,speaker combinations etc) to get a definitive answer,the only true answer lies with yourself:- after all if your system sounds good to you,then it probably is.What one person defines as fantastic sound may only register as merely average to another.

Sorry if this post has rambled :offtopic: but it's merely a point of view.
Feel free to verbally attack me, my wife always does (keeps me in check you see).

TTFN
 
With bi-wiring, we are not trying to prevent overloading on one of the cables, but to keep different frequency current apart to try to prevent harmonics from one circuit having an adverse effect on the other. Let me try and give an example.

Say we are playing a 2kHz tone in a single wire configuration. This would be sent to the high frequency driver when it reached the speaker. Now suppose that at this particular frequency, the driver produces a 80Hz harmonic wave. This frequency being induced onto the cable, if of sufficient amplitude, could be enough to drive the bass cone to play this frequency and hence colour or taint the resultant sound.

Now, if the speaker is bi-wired, the induced harmonic frequency is confined to the high frequncy circuit only, and cancelled out at the amp terminals. Thus it never reaches the bass cone.

The same applies for harmonics generated by the bass circuit. They remain isolated from the other circuit.

This is the whole point of bi-wiring. To keep the 2 circuits on a seperate feed and prevent one colouring the other. I'm sorry if I'm not explaing myself very wel.
No worries, I think you are expressing yourself perfectly well and you describe the intended benefit of bi-wiring correctly.
Obviously we agree that we are not sure if the theory also proves to be true in a practical environment.

Whilst i can see that bi-wiring does not electrically change the circuit from amplifier to loudspeaker, surely you're not getting any benefit from it if you use the same type of cable to connect to each driver?

I personally am convinced of the merits of bi-wiring, but as far as i can see the main benefit of it is to allow one to use a cable with a good treble response for the tweeter and one with a good bass response for the woofer, which is exactly what i had on my old system.
What do you do with a speaker that can be tri-wired (3-way speakers)? Are there different cables for bass, mid and highs?

IMHO cables do NOT sound, the only one making such claims are those manufacturing them and people who spent money on it. ;)

Refer to fig. 1. Let's assume, that the speaker has a cross over frequency of 400Hz. If you feed the speaker with e.g. a 300Hz signal, this will primarily go to the bass unit, but some of it will go to the midrange speaker. So far so good. The problem could be, that the bass speaker, or even worse, the cross over filter for the bass speaker, could be non-linear, leading to harmonic distortion. That would mean, that signals at 600Hz, 900Hz, 1200Hz etc. would be present on the input terminals of the speaker box. These frequencies may only be reproduced by the bass speaker at very low volume, if the bass speaker has a roll off above 400Hz, but the midrange speaker would reproduce them if they were present on the input terminals of the speaker box.
Distortion from the mid/high range is probably less of a problem, because harmonic distortion can only produce higher frequencies, not lower frequencies. Other types of distortion can, but then we are talking about intermodulation, which is a completely different story.

If we then look at fig. 2 with bi-wiring, the situation is different. Distortion from the bass part of the speaker will never reach the mid/high range, since the (ideal) amplifier will short circuit any signals coming back to the amplifier terminals. Thereby, no harmonic distortion from the bass part will be heard in the other part. If however, the amplifier is not ideal, or at least close to ideal, with a very low output impedance, then the situation could be different. This could be the case, e.g. with a tube amplifier with a relatively high output impedance. In this case bi-amping may be needed to separate the signals.
I don't agree with the latter part, because if the amp shortcuts the distortion it would shortcut all other frequencies, too.
And how would the amp know that the signal is "coming back"? AFAIK this is only an issue in HF applications where there is no or no correct termination at the end of the cable.

Now this was the theoretical explanation. Whether it really means anything in practical terms I don't know, since I have no experience with this. My guess would be, that it depends on the speaker design (generation of distortion, filter characteristics, speaker frequency responses etc.) and the amplifier, primarily output impedance, but perhaps also current drive capability (could be described as a kind of non-linear output impedance).
Given that lot's of high-end speaker manufacturers claim to have tested bi-wiring and concluded it is of no benefit, and hence their speakers don't have bi-wiring terminals, I reckon there is no benefit to bi-wiring itself, instead any benefit (or let's say difference) is caused by the change of the cable's cross-section.

Anyhow, this is something everyone can test for him/herself and if you find any improvement then good - who am I to tell you otherwise? :)
 
Thanks for that Jens. That is exactly what I was trying to get over but you do it so much better. And I should have known that harmonic frequencies can only be higher than the original :suicide: DOH!

Cheers, Beastie.
 
Reiner,

Maybe I didn't express myself clearly enough on the "short circuit" part. What I meant was, that the ideal (voltage) amplifier will keep its output voltage, e.g. a sine wave, at the desired output, no matter what signals (varying currents, coming from the distortion) are coming back from the speaker. If however, an amplifier has an output impedance different from 0 ohm (which a real amplifier will have), any distortion currents coming from the speaker will generate a voltage across the output terminals of the amplifier. Typically amplifiers have very low output impedances, but when this is not the case, bi-amping could be the solution as described.

Jens
 
I'm not a believer in biwiring in practice, and I think double blind trials have never shown any advantage. However, my understanding of the idea was that bass drivers can take large currents, and this induces a voltage drop in the cable proportional to the current. So the bass driver is responsible for making a voltage different at the two ends of the cable. Biwiring keeps the high currents out of the tweeter cable, and therefore the tweeter sees the precise signal generated by the amplifier leaving only the bass signal distorted by its greed for current. The human ear is much more sensitive to high frequencies, and quite soft high frequency sounds can be heard over loud but deep sounds. Hence the idea that e might hear the difference.

Biwiring can't help with distortion resulting from the amp's internal impedance.

Whatever the truth of the matter, you can biwire very cheaply (unless you are a "different kinds of wire" voodoo person), so go ahead and do it. No one has suggested it might be worse than single wiring. Minimising resistance in the speaker cables minimses the effect, whatever it is. Hence short fat cables are best for speakers.
 
OK, just to throw a very vague post in here - because I can't remember all the details unfortunately.

About 7 or 8 years ago Martin Colloms wrote a piece in Hi-Fi News magazine about bi-wiring. He had done some tests and concluded that the benefits of bi-wiring revolved around seperate earth returns from the speakers back to the amplifier (if I recall the article correctly).

He started off bi-wiring the speaker in the normal way and noted the improvements. Then he tried an alternative strategy: he used a 3 core cable, where one core fed +ve HF, the second core +ve LF and then a common earth return back to the amplifier. His original justification for doing this being that his cables cost a fortune, and using a common earth return would save him a single-core cable run. (This is where a diagram would save a thousand words).

Martin noted that this latter arrangement offered no improvement over single-wiring, even though independent runs were being used for +ve LF and HF.

I forget the technical rationale behind his conclusion, but he concluded that it was the earthing arrangement of bi-wiring that was having the major effect. Hence also why the daft idea of using different cable for HF and LF has no effect. Again my recollection is dim, but he might have muttered something about the benefits being centred around the fact that you are effectively star-earthing the speaker in a bi-wire configuration.

My profuse apologies if none of this makes any sense, due a faulty recall of this quite old article !
 
OK, just to throw a very vague post in here - because I can't remember all the details unfortunately.

About 7 or 8 years ago Martin Colloms wrote a piece in Hi-Fi News magazine about bi-wiring. He had done some tests and concluded that the benefits of bi-wiring revolved around seperate earth returns from the speakers back to the amplifier (if I recall the article correctly).

He started off bi-wiring the speaker in the normal way and noted the improvements. Then he tried an alternative strategy: he used a 3 core cable, where one core fed +ve HF, the second core +ve LF and then a common earth return back to the amplifier. His original justification for doing this being that his cables cost a fortune, and using a common earth return would save him a single-core cable run. (This is where a diagram would save a thousand words).

Martin noted that this latter arrangement offered no improvement over single-wiring, even though independent runs were being used for +ve LF and HF.

I forget the technical rationale behind his conclusion, but he concluded that it was the earthing arrangement of bi-wiring that was having the major effect. Hence also why the daft idea of using different cable for HF and LF has no effect. Again my recollection is dim, but he might have muttered something about the benefits being centred around the fact that you are effectively star-earthing the speaker in a bi-wire configuration.

My profuse apologies if none of this makes any sense, due a faulty recall of this quite old article !
I don't see how this could work since there is no such thing as earthing at the speaker end. AFAIK the + and - only ensure that you connect both speakers in the same way, i.e. the drivers of all speakers move into the same direction at the same time.
If you wire your speakers the wrong way it won't make a difference as long as both are wired wrong.
 
Ah, but where would the fun be in that...?
 
ADC said:
A simple yes or no would have done guys :rotfl:

You should know NOT to ask a simple question on these here forums, a lot of people will have differing opinions, (neither of them right or wrong).At the end of the day it's all down to personal preference, if you system sounds better with bi-wiring to YOU, then it is,if not then......................

Can of worm's opened ? ? ? ?

TTFN
 

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