Why Bi-wiring Makes No Sense.

Status
Not open for further replies.
jonnythan

jonnythan

Audioholic Ninja
Rowdy S13 said:
Ok so then the way they had it hooked up was BS. From what I saw it was a balanced input from who knows where (I think just a CD player into a pre amp at the back of the room, I think this because thats where I was controlling volume) and then just out from there to the speaker.

Sean
It wasn't BS. It was bi-amping.

Each amp was driving a separate driver. Each driver had significantly more power available to it than in a single amp setup.
 
Seth=L

Seth=L

Audioholic Overlord
Only at high volumes would you notice any difference. Of course we are talking about McIntosh amplifiers here. I would think you would only see a 3 db increase, which is audible. I wouldn't spend double the money on amplification to see 3 more decibels, but maybe throw in active crossovers and I will consider it.:)

It is possible that purchasing a 200 watt per channel amp would be more cost effective than purchasing two 100 watt per channel amplifiers.
 
Rowdy S13

Rowdy S13

Audioholic Chief
jonnythan said:
It wasn't BS. It was bi-amping.

Each amp was driving a separate driver. Each driver had significantly more power available to it than in a single amp setup.
BUT, should they have had some kind of active crossover in there?

Sean
 
jonnythan

jonnythan

Audioholic Ninja
Rowdy S13 said:
BUT, should they have had some kind of active crossover in there?

Sean
It would probably be "better" to do it with active crossovers, sure. But I don't think it's fair to call it BS. There are clearly defined technical advantages to simply using two amplifiers. Whether it makes a difference in sound is probably debatable.. but it's just as debatable whether using an active crossover with two amps makes a difference in sound. As Seth points out, it would only really help when the amps are at full tilt and the volume is very loud. I can imagine, however, that having the extra headroom could clean up the peaks a bit at higher volumes.
 
Sheep

Sheep

Audioholic Warlord
Rowdy S13 said:
BUT, should they have had some kind of active crossover in there?

Sean
For TRUE bi-amping. Having an amp per driver is still very good. Heck, 1 2 channel amp for 2 speakers is great too!

SheepStar
 
Seth=L

Seth=L

Audioholic Overlord
Rob Babcock said:
You gotta admit biwiring looks freakin' cool!:D
"I spent some extra cash on a pointless upgrade, my wife is mad at me, and my friends think I am an idiot, but hell it looks cool, right?":D
 
no. 5

no. 5

Audioholic Field Marshall
Seth=L said:
Originally Posted by Rob Babcock
You gotta admit biwiring looks freakin' cool!:D
"I spent some extra cash on a pointless upgrade, my wife is mad at me, and my friends think I am an idiot, but hell it looks cool, right?":D
hay, if you have the money, and the wife don't mind, buy the ones that look cooler! ;)
 
J

jneutron

Senior Audioholic
jonnythan said:
When bi-wiring, you take an electrical signal traveling through one wire and split it into two wires 20 feet earlier than you normally would.

Anyone who thinks this makes a difference knows nothing whatsoever about electricity.
Perhaps you wish to rethink that statement??

Cheers, John
 
Seth=L

Seth=L

Audioholic Overlord
Me too:D

jneutron, what do you feel the benefits of Bi-wiring are?
 
J

jneutron

Senior Audioholic
jonnythan said:
Nope, I'm pretty comfortable with it.
Sigh, that is unfortunate.

Do you have a technical background? IOW, if I explain it technically, will you understand?

(sorry, don't know how to ask that without seeming condescending, that's not my intent..

Cheers, John
 
Wait for it... wait for it... lol. Seriously, there is some educating to be done here. The BEST response would be to take it as a learning opportunity (and not get offended). I think jneutron is "going to take y'all to class"... sigh...
 
J

jneutron

Senior Audioholic
Seth=L said:
Me too:D

jneutron, what do you feel the benefits of Bi-wiring are?
First, the initially quoted stuff technically is garbage, and of no use. Might as well invoke pixie dust to explain biwiring benefits..as another said, some of what was said has merit, but certainly not the technical explanation..

Biwiring changes the instantaneous losses present within the wire. What most get confused on is the fact that the RMS dissipation is constant, so biwiring does not alter the integrated, or long term, energy loss from the mono situation. What is taught in engineering curricula is the RMS average component, not the instantaneous one.

Biwiring also changes the instantaneous energy storage within the wire. This is most significant with the inductive component, as most speaker wires have very high cable impedance, and therefore the bulk of the energy storage is inductive rather than capacitive.

The inductive portion is a little more difficult to imagine, so for now I will not really go on about that. The resistive is trivial to explain in comparison, and I've posted the dissipation graphs already on this site as well as others..

Cheers, John
 
J

jneutron

Senior Audioholic
jonnythan said:
By all means, educate us.
You did not answer my question, so I do not know to what level I can proceed...read my previous post, and ask questions..that'll probably be the best option.

Cheers, John
 
gene

gene

Audioholics Master Chief
Administrator
Originally Posted by jonnythan
When bi-wiring, you take an electrical signal traveling through one wire and split it into two wires 20 feet earlier than you normally would.

Anyone who thinks this makes a difference knows nothing whatsoever about electricity.
There is a measurable difference in loop resistance (lower) and reactance (higher) seen at the amp. Audibility is another story however.

I will leave the star trek physics to Jneutron for now as we are still waiting for his epiphany on the wonders of exotic cables, cryo freezing and soaking your cables in kosher chicken fat ;)
 
jonnythan

jonnythan

Audioholic Ninja
I have a nuclear engineering background with a handful of electrical circuits engineering courses.

I'll eat my hat if you can demonstrate that the waveform at the crossover input is in any way whatsoever significantly different when biwiring.
 
J

jneutron

Senior Audioholic
jonnythan said:
I have a nuclear engineering background with a handful of electrical circuits engineering courses.

I'll eat my hat if you can demonstrate that the waveform at the crossover input is in any way whatsoever significantly different when biwiring.
Cool...

I will not hold you to your hat offer.

Give me a few minutes to draw up a supporting diagram..for now, here's a graph to consider, it shows the dissipation differences between a mono and a biwire configuration..

Ok..now with that to see, a little splainin...

The currents and the resistance are normalized, so the peak woof and tweet currents are 1, and the resistance of the wire is also normalized to 1.

The woof current is the blue line, the diss is (Asquared) I<sup>2</sup>R, so as you can see, it peaks at 1, and is always positive (real dissipation cannot be negative). It is your basic sine squared waveform, a direct result of the woof current flowing through a wire by itself. Note that for an ideal load, this is also exactly the same dissipation time profile scaled differently.



The tweet current is the magenta line, called Bsquared. again, I squared R...

With biwiring, the total wire dissipation is of course, the sum of the two, A squared plus B squared, and the load dissipation at the speakers is an exact scale of the wire dissipation.

The yellow line (asq plus b sq) is the summation of the wire loss in biwiring.

Now, consider both signals travelling in one wire, such as monowiring..

The equation is P = I<sup>2</sup>R, with I = A + B

(A+B)<sup>2</sup> = A<sup>2</sup> + B<sup>2</sup> + 2AB.

So, subbing A + B for I creates 3 parts of the power dissipation, the third and most interesting component being the 2AB part..

I put that on the graph, that is the brown (I think) color. Note two very important things about the 2AB component...

1. It goes NEGATIVE!! At first blush, that seems impossible..However, look at it's value compared to the yellow line which is the A<sup>2</sup> + B<sup>2</sup> part....note that if you sum them, they NEVER go negative. In other words, the 2AB component is a modulation of the expected dissipation. So, the monowire dissipation never goes negative..

2. It is a ZERO INTEGRAL power waveform...in other words, what is below zero is exactly the same area as that above zero. Since FFT algorithms cannot spot a zero integral power waveform, it isn't seen.


Think of the instant in time when the woof has 1 ampere positive and the tweet has one ampere negative...at that instant, a monowire sees zero current, therefore zero power loss within the wire... But, a biwire setup has one ampere in the bass wire with it's dissipation, the tweet wire has negative one ampere and the exact same loss as the bass wire...

The result? In a monowire setup, the current of one signal will modulate the losses that are caused by the other..when I see loop resistance recommendations at the 5% level, I cringe..

Cheers, John

sigh..I hate it when I can't wrap the explanation around the graphs..it's a pita when the graph goes off screen while you read the verbage..and I hate it even more when I forget what website supports what notation...

OK, I've finished editing my huge quantity of errors (I think)
 

Attachments

Last edited:
J

jneutron

Senior Audioholic
gene said:
I will leave the star trek physics to Jneutron for now as we are still waiting for his epiphany on the wonders of exotic cables, cryo freezing and soaking your cables in kosher chicken fat ;)
Your killing me...

It ain't rocket science..

I've not seen cryo do anything to change wires..I have seen it destroy most insulators though..I use kapton and tefzel exclusively for 77K, 4.5K and 1.88K work. Kapton because it remains flexible in liquid helium, tefzel cause it retains abrasion resistance in it.. Nomex ain't too bad either, but the form factor is not so nice..

Cheers, John

ps...no chicken fat, kosher or otherwise..you're sounding like DB now..
 
Status
Not open for further replies.
newsletter

  • RBHsound.com
  • BlueJeansCable.com
  • SVS Sound Subwoofers
  • Experience the Martin Logan Montis
Top