If i Bi-Wire my speakers, what is the power going to each? rms/2 ?

[gurjitsidhu]

hi,

i have the Yamaha A-S500 amp and B&W 684 speakers. I was thinking of bi-wiring them.

When i bi-wired with my AV amp ad 2050i speakers, I was using an extra channel so that was actually bi-amping them and that made a huge difference! 90W per channel it was. 90 to the tweeter and 90 to the main drivers.

However, with using a stereo amp, the output is only 85W per channel and it has 2 channels. so if i bi-wire them (i have 4 posts on the back of the amp- A&B), will i be getting 42.5W to the tweeter and 42.5W to the main driver? the tweeter needs less power than the main and i belive this is why bi-amping is impportant since the main driver sucks the majority of the power and leaves little for the tweeter so the highs suffer. This is okay for an AV amp since it has 7 channels and you can give up 4 channels to drive the front speakers

Now if im getting 42.5 W to tweeter and same to the mid, my tweeter doesnt need 42.5W and will my main driver need more than that? so essentially am i starving my main driver of the power it actually needs? or will the amp divide the power needed over the posts depending on where it is required.....but then thats no different to wiring normally and using the jumpers since it splits the power to the driver that needs it most?

thanks

 

[nopiano]

I suggest you stop fretting and listen to some music!

Biwiring makes no difference to the total power to each speaker.

 

[MajorFubar]

Same power is available to each, just as it is single-wired.

 

[busb]

There is medication available for extreme anxiety. More seriously, just take nopiano's advice. The total current drawn is going to be virtually identical to single wiring & the instantaneous current down either cable when biwiring will depend on the frequency content at any moment in time.

 

[gurjitsidhu]

Lol it's not extreme anxiety! It's engineering thought

so if the same power is scalable to each speaker, how is it split between tweeter and mids? 42.5W In each in which case bi wiring is worse when at high volume since my woofers are only getting 42.5W where as not biwiring means I let the speaker take what it needs and where it needs it for example 10W to the tweeter and 75W to the woofer

its really food for thought no? This whole biwiring thing could be limiting the output to your speakers

 

[nopiano]

its really food for thought no?

No! I suggest you read up a bit on the topic, and electrical principles. In practice, tweeters draw virtually no power anyway, but biwiring makes no material difference. The notion that the available power is divided by two is simply wrong, sorry.

 

[BigH]

You will still have the crossover so will be filtered by that, high freq. will go to tweeters and rest to woofers.

 

[MajorFubar]

Think you just need to get your head round the fact that as far as power and current goes, there's no difference. All you're doing is feeding the two halves of the crossover via separate cables from the amp, instead of with one cable feeding both halves of the crossover via metal links on the binding-posts.

This is not a great example, but for analogy's sake, imagine a 9V torch-lamp wired to 9V battery with a yard of cable (this is your speaker wire). Then wire a second identical lamp to the first lamp in parallel using just 6" of cable (these are your links on the blinding posts). Both lamps are going to be the same brightness, more or less. Now disconnect the second lamp from the first and connect it to the battery with a second yard of cable, just like the other lamp (so effectively you've bi-wired the lamps). Disregarding the effect of the longer cable's resistance which for example's sake let's say is minimal, both lamps are still going to be as bright as they were before and the drain on the battery will be the same, or negligibly different.

 

[busb]

Lol it's not extreme anxiety! It's engineering thought

so if the same power is scalable to each speaker, how is it split between tweeter and mids? 42.5W In each in which case bi wiring is worse when at high volume since my woofers are only getting 42.5W where as not biwiring means I let the speaker take what it needs and where it needs it for example 10W to the tweeter and 75W to the woofer

its really food for thought no? This whole biwiring thing could be limiting the output to your speakers

This is completely & utterly false logic. Instead of the Xover in the speaker being fed through one cable that has a certain resistance, the Xover is spit, fed by two cables connected at the amplifier's output terminals. Bi-wiring effectively halves the resistance of the cable compared to normal single wiring. Cables also have capacitance that increases with the length series inductance. Both are generally far less important than the loop resistance over sensible cable runs in a home Hi Fi system.

The displacement of a large cone is in mm & takes a certain amount of power to move backwards & forwards - has far greater mass than a tweeter whose displacement & mass are much much less. So the energy needed to to drive the tweeters is a fraction of what's needed to drive the bass. The upshot being that the current will never be split 50 50 (even on a single continuous tone close to the Xover frequency) any more than a three way speaker with two Xover frequencies would be 33.3, 33.3 & 33.3%.

 

[Thompsonuxb]

Think you just need to get your head round the fact that as far as power and current goes, there's no difference. All you're doing is feeding the two halves of the crossover via separate cables from the amp, instead of with one cable feeding both halves of the crossover via metal links on the binding-posts. This is not a great example, but for analogy's sake, imagine a 9V torch-lamp wired to 9V battery with a yard of cable (this is your speaker wire). Then wire a second identical lamp to the first lamp in parallel using just 6" of cable (these are your links on the blinding posts). Both lamps are going to be the same brightness, more or less. Now disconnect the second lamp from the first and connect it to the battery with a second yard of cable, just like the other lamp (so effectively you've bi-wired the lamps). Disregarding the effect of the longer cable's resistance which for example's sake let's say is minimal, both lamps are still going to be as bright as they were before and the drain on the battery will be the same, or negligibly different.

Is that right?

Taking your example if you run the 2nd bulb in parrallel - you will see a 'dip' in the brightness in both bulbs compared to running the single bulb. But running a seperate run of cable to the 2nd bulb from a single battery you will not see this dip in brightness. You will drain the battery quicker though - but while the battery can provide its full power the bulbs should shine as bright as they do if you have a single bulb on.

Bi-wireing works in the same way - depending on your amp and the quality of your speakers you will benifit from bi-wired speakers. better still use both A & B speaker terminals on your amp to drive your speaker mid/bass and tweeters.

theoretically the benifits are obvious - cleaner current/voltage better performance.

As with the other snake oil threads I often wonder how well many have thier systems set up.....lol

 

[Thompsonuxb]

Lol it's not extreme anxiety! It's engineering thought

so if the same power is scalable to each speaker, how is it split between tweeter and mids? 42.5W In each in which case bi wiring is worse when at high volume since my woofers are only getting 42.5W where as not biwiring means I let the speaker take what it needs and where it needs it for example 10W to the tweeter and 75W to the woofer

its really food for thought no? This whole biwiring thing could be limiting the output to your speakers

This is completely & utterly false logic. Instead of the Xover in the speaker being fed through one cable that has a certain resistance, the Xover is spit, fed by two cables connected at the amplifier's output terminals. Bi-wiring effectively halves the resistance of the cable compared to normal single wiring. Cables also have capacitance that increases with the length series inductance. Both are generally far less important than the loop resistance over sensible cable runs in a home Hi Fi system.

The displacement of a large cone is in mm & takes a certain amount of power to move backwards & forwards - has far greater mass than a tweeter whose displacement & mass are much much less. So the energy needed to to drive the tweeters is a fraction of what's needed to drive the bass. The upshot being that the current will never be split 50 50 (even on a single continuous tone close to the Xover frequency) any more than a three way speaker with two Xover frequencies would be 33.3, 33.3 & 33.3%.

again, is this right?

a speaker that can handle 200watts at 8ohm for example - if it as 3 drive units each unit will be able to handle 200watts into 8ohms from an amp...er...supplying 200watts into 8ohms. So if you just ran 200watts into the tweeter alone it would work fine & because it only works within a certain frequencie band a clean 200watt will make it work at its best its what its designed to do.

an amp won't discrimante it'll just provide its power the drive units operate within their range with said power.

example put a 200watt into 8ohms tweeter in a box with a 50watt into 8ohms woofer and see what happens when its driven continuously by a 200watt amp into 8ohms at hi volume.

 

[Thompsonuxb]

to the op - you get what your amp can deliver to both units minor a few dbs - so if your amp at normal levels provides 30watts per channel thats more or less what each unit recieves.

note: you do not lose decibels/loudness/volume when you bi-wire when compared directly with single wire. you do get better seperation and control (stop/start of units) though

 

[busb]

Lol it's not extreme anxiety! It's engineering thought

so if the same power is scalable to each speaker, how is it split between tweeter and mids? 42.5W In each in which case bi wiring is worse when at high volume since my woofers are only getting 42.5W where as not biwiring means I let the speaker take what it needs and where it needs it for example 10W to the tweeter and 75W to the woofer

its really food for thought no? This whole biwiring thing could be limiting the output to your speakers

This is completely & utterly false logic. Instead of the Xover in the speaker being fed through one cable that has a certain resistance, the Xover is spit, fed by two cables connected at the amplifier's output terminals. Bi-wiring effectively halves the resistance of the cable compared to normal single wiring. Cables also have capacitance that increases with the length series inductance. Both are generally far less important than the loop resistance over sensible cable runs in a home Hi Fi system.

The displacement of a large cone is in mm & takes a certain amount of power to move backwards & forwards - has far greater mass than a tweeter whose displacement & mass are much much less. So the energy needed to to drive the tweeters is a fraction of what's needed to drive the bass. The upshot being that the current will never be split 50 50 (even on a single continuous tone close to the Xover frequency) any more than a three way speaker with two Xover frequencies would be 33.3, 33.3 & 33.3%.

again, is this right?

a speaker that can handle 200watts at 8ohm for example - if it has 3 drive units each unit will be able to handle 200watts into 8ohms from an amp...er...supplying 200watts into 8ohms. So if you just ran 200watts into the tweeter alone it would work fine & because it only works within a certain frequencie band a clean 200watt will make it work at its best its what its designed to do.

an amp won't discrimante it'll just provide its power the drive units operate within their range with said power.

example put a 200watt into 8ohms tweeter in a box with a 50watt into 8ohms woofer and see what happens when its driven continuously by a 200watt amp into 8ohms at hi volume.

Not exactly.

Watts is input power not the sound pressure level or loudness in the same way a light bulb's watts rating is power comsuption, not degree of illumination. There are equations that state efficiency such as with light bulbs. If a lamp was 100% efficient & a solar cell was as well, we could convert that light back to electricity without any losses but we never can. The power comsumption of a multi-driver speaker is the summed average of the drivers, Xover & damping of the cabinet itself. Some of the input power will be converted to heat & vibration instead of sound. Taking a two-way speaker, the woofer is going to take far more power than the tweeter for the same perceived loudness. So the tweeter will never draw 200W in your example.

Things get more interesting with real music which have complex waveforms that cover many frequencies simultaneously rather than spot frequencies used in testing & determining power rating & specs in general.

 

[jiggyjoe]

This is how the power is split by the crossover.

X-over Frequency (Hz)Power to Bass (%)Power to Mid+High (%)2504060350505050060401,20065353,00085155,0009010

so for a typical 2 way speaker crossed over at 3k only 15% of the amp power goes to the tweeter.

 

[jiggyjoe]

copy and paste of table did not work :wall:

 

[hoopsontoast]

The easiest way to explain (simple terms, not literally) :

Single-Wire

Car with RWD and a single engine.

Bi-Wire

Car with 4WD and a single engine

Bi-Amp

Car with 4WD and two of the same engines (One front wheels, One Back wheels)

Minus the extra weight/gearing etc, all will go at the same top speed.

Single-Wire, Bi-Wire and Passive Bi-Amp should not make any difference unless using sub-standard cable(s) or amplifier(s). IMO and IME.

 

[nopiano]

And easier still, don't worry about it!

 

[BigH]

Here is an article about biwiring:

http://www.achievum.eu/bi-wiring.html

Even some WHF reviews say that biwiring some speakers is not recommended.

I think some people misunderstand biwirig and think that only the high frequencies go along to the cable to the tweeters and the lower notes to the woofer, this is not so, all the frequencies to both and then is split by the crossover. The main problem is the crossover that is why active speakers canbe better than passives.

 

[MajorFubar]

Is that right?

Taking your example if you run the 2nd bulb in parrallel - you will see a 'dip' in the brightness in both bulbs

No, that's if you wire them in series and therefore halve the voltage. You might see a dip in brightness if the battery can't deliver enough current to illuminate both lamps at full brightness, but it wouldn't depend on whether you took a feed from the battery for each lamp or whether you fed the second lamp in parallel to the first. The load on the battery would be more-or-less the same in each instance, which was my point. Hence my analogy was correct from an illustrative perspective, albeit not from a technical perspective, as obviously I accept that lamps/batteries and speakers/amps are completely different things.

 

[RobinKidderminster]

Believable BigH, this article.until one reads ..... biwire (biamp) ...., suggesting in its only reference to biamping that they are the same. No opinion either way but disappointing that this 'scientific' explaination is flawed

 

[Andrew Everard]

I skimmed that article linked above, so may have missed it, but AFAICS nowhere does it make the point that part of the advantage is that the signal for each leg of the speaker only goes through half of the crossover when biwiring (assuming the crossover is properly split internally). And fewer passive components (or indeed any kind of components) in a given signal path can only be a good thing.

 

[hoopsontoast]

I skimmed that article linked above, so may have missed it, but AFAICS nowhere does it make the point that part of the advantage is that the signal for each leg of the speaker only goes through half of the crossover when biwiring (assuming the crossover is properly split internally). And less passive components (or indeed any kind of components) in a given signal path can only be a good thing.

But it doesnt, most crossovers are parallel crossovers, so the only difference is the HF signal (for example) is coming from a seperate speaker terminal. So whether its single wired or bi-wired it makes no difference other than an extra pair of terminals.

It would have to be a parallel crossover anyway if you had the option to Bi-Wire as the series crossover would not work if you did.

For example, the single wired version of my old ATC SCM10:

Instead of the second terminal for the tweeter section, they are just run parallel of the lower terminals.

Bi-Wired ATC SCM20

http://www.mhennessy1.f9.co.uk/atc/index.htm

This same crossover board is used for the single wired SCM10 and Bi-Wired SCM20.

 

[BenLaw]

less passive components

Sorry to pick up on grammar, but would that make them a bit more active?

 

[BigH]

I skimmed that article linked above, so may have missed it, but AFAICS nowhere does it make the point that part of the advantage is that the signal for each leg of the speaker only goes through half of the crossover when biwiring (assuming the crossover is properly split internally). And less passive components (or indeed any kind of components) in a given signal path can only be a good thing.

Why does it only go through half the crossover?

If so why do you say that some speakers are better single wired?

 

[Andrew Everard]

But it doesnt, most crossovers are parallel crossovers, so the only difference is the HF signal (for example) is coming from a seperate speaker terminal. So whether its single wired or bi-wired it makes no difference other than an extra pair of terminals.

In a speaker designed for biwiring/biamping, the crossover should be split into two separate sections, one with a high-pass filter to feed the treble section, the other with a LPF for the md/bass driver (in a simple two-way system). The two sections of the crossover aren't connected at the speaker end, but only right the way back at the amplifier end of the speaker cables. What you seem to be suggesting is that the crossover is unchanged, and that the two sets of terminals are really only there for show, which – at least in a properly-designed biwirable/biampable speaker – isn't the case. If it were, pulling the jumper bars and just connecting one set of cables would result in the speaker still playing normally, which doesn't happen.

But as with all things, the advice is to try it for yourself and/or – if a retailer is suggesting biwiring would be beneficial – ask them to prove it by demonstration.