bi-wire theory

[onplane]

Not really, since the resistance provided to each crossover section is still that of one set of wire.

Stuart, for just a minute assume we have our bi-wire in place and now we reconnect the straps on the speakers.

Is the NET resistance of the speaker wires (compared to a single wire):

1. the same
2. higher
3. LOWER

Regards,
Jerry

 

[Dougr33]

Stuart, for just a minute assume we have our bi-wire in place and now we reconnect the straps on the speakers.

Is the NET resistance of the speaker wires (compared to a single wire):

1. the same
2. higher
3. LOWER

Regards,
Jerry

PLEASE MAKE SURE YOU DON'T ACTUALLY DO THIS!!!! IT'S A LOT LOWER...IT'S A SHORT.

 

[Lefty]

PLEASE MAKE SURE YOU DON'T ACTUALLY DO THIS!!!! IT'S A LOT LOWER...IT'S A SHORT.

Not a short, just two pairs of wires, wired in parallel at both ends. If equal size wires and original wire resistance was .1 ohms then the pair will be .05 ohms.
Biwiring, but leaving the speaker crossover jumper on will not cause a short circuit.

That's why biwiring is so suspect, all that is really being accomblished is a oh so slight decrease in total load resistance (say 8.01 to 8.005 ohms) as seen from the amp. All the other explainations are new wave feel good, hear good, subjective opinions. If there was something to it, it would be measurable and repeatable to all.


Lefty

 

[stuartk]

PLEASE MAKE SURE YOU DON'T ACTUALLY DO THIS!!!! IT'S A LOT LOWER...IT'S A SHORT.

No, it isn't a short.

It would also be lower resistance than single wires, but that's because both ends are connected to the same place.

With each wire pair attached from the amp to half of the x-over, each x-over filter sees the resistance of a single wire pair, not of both pairs.

 

[stuartk]

Not a short, just two pairs of wires, wired in parallel at both ends. If equal size wires and original wire resistance was .1 ohms then the pair will be .05 ohms.
Biwiring, but leaving the speaker crossover jumper on will not cause a short circuit.

Lefty

Bi-wiring as it is supposed to be done doesn't have both ends connected in parallel. Both wires are connected to the amp, but at the speaker end one pair gets attached to the highpass filter and one to the lowpass filter in the x-over. This is also why it will only work with parallel x-over networks and not series ones.

 

[Clmrt]

Wet hair, lather, rinse.

- Or -

Wet hair, lather, rinse, repeat.

A good way to sell more product.

With bi-wiring, aren't we just adding really long, fat traces to the XO board? If I ever get my shiznit together, I'll jump right into bi-amp.

 

[Lefty]

Bi-wiring as it is supposed to be done doesn't have both ends connected in parallel. Both wires are connected to the amp, but at the speaker end one pair gets attached to the highpass filter and one to the lowpass filter in the x-over. This is also why it will only work with parallel x-over networks and not series ones.

I certainly know that, I was just carrying through on Onplane's question of what if.........

The fundamental question of this thread is:

When driving two parallel wired filters (high and low pass), what is the difference if the parallel connection is done at the speaker terminals or at the amp's speaker terminals via separate wires?

Lefty

 

[onplane]

Not a short, just two pairs of wires, wired in parallel at both ends. If equal size wires and original wire resistance was .1 ohms then the pair will be .05 ohms.

That's why biwiring is so suspect, all that is really being accomblished is a oh so slight decrease in total load resistance (say 8.01 to 8.005 ohms) as seen from the amp. All the other explainations are new wave feel good, hear good, subjective opinions. If there was something to it, it would be measurable and repeatable to all.

Lefty

Lefty, that's the way I look at it as well. The current handling capability has increased very SLIGHTLY with the dual set of wires.

The more interesting argument is that bi-wiring only achieves anything on speaker systems with high woofer back EMF (usually low efficiency systems) and poor xover rejection. What this guy is counting on is the resistance in the speaker wires!

He says that back EMF in a bi-wire is NO longer immediately available to the mids/tweeters. It has to travel all the way back to the amp (resistance in the speaker wire) and once there is dissipated in the amp, which has a "near zero" output impedance. In other words, the "path of least resistance" is dissipation in the amp rather than traveling again down the speaker cables to the mids/tweeters. Further, this constitutes a 30db reduction!

My problem with this argument is no real amp has a zero or "near zero" output impedance. I think back EMF will still travel to the mids/tweeters, but with a very, very slight reduction. Now whether you can actually hear this difference is another matter. I would bet that some people can.

Regards,
Jerry

 

[wineslob]

I certainly know that, I was just carrying through on Onplane's question of what if.........

The fundamental question of this thread is:

When driving two parallel wired filters (high and low pass), what is the difference if the parallel connection is done at the speaker terminals or at the amp's speaker terminals via separate wires?

Lefty

Honestly I dont know. But I can take a guess at it.

1. The back EMF lowered
2. Current transfer to two separate filters might be better with a speaker designed to be bi-wired.

I can hear it in my system, so, who knows? :scratch2:

 

[Dougr33]

No, it isn't a short.

It would also be lower resistance than single wires, but that's because both ends are connected to the same place.

With each wire pair attached from the amp to half of the x-over, each x-over filter sees the resistance of a single wire pair, not of both pairs.

I may have misunderstood what he meant by 'strap', but all my bi-wireable speakers' manuals SCREAMED to remove the connecting strap (that ran between the 4 posts on back of speakers) before using biwire.

 

[Lefty]

I may have misunderstood what he meant by 'strap', but all my bi-wireable speakers' manuals SCREAMED to remove the connecting strap (that ran between the 4 posts on back of speakers) before using biwire.

Oh course they would scream, it wouldn't be biwiring if the straps were left on. It would just be the equivelent of going with a larger gauge wire pair with the straps on.

Lefty

 

[Grainger49]

I can't tell you the theory, I have had it explained, but it didn't make any sense to me.

But . . . one day, I noticed how long my speaker wire was, i.e. too long. I cut it in half, removed the speaker jumpers and hooked it up bi-wired. It sounded a little better.

So I left it.

Whatever!

 

[justw]

The theory is good but whether you can hear the diff or not 'prolly depends on a bunch of variables. My Large Advents are tri-wired for that reason. I would not want the counter EMF from one woofer to affect the signal to any of the others.

 

[onplane]

The theory is good but whether you can hear the diff or not 'prolly depends on a bunch of variables. My Large Advents are tri-wired for that reason. I would not want the counter EMF from one woofer to affect the signal to any of the others.

W, what do you mean by tri-wired?? Your large Advents are a two way system .... right??


Where is the 3rd set of wires going??


Regards,
Jerry

 

[Raphael]

Never done it but isn't it a two pair connection to source with one pairs + high-pass filtered before connecting to a speaker's high side and the other pair low-passed to the woof?).

Raphael- I think you are confusing bi-amping with bi-wiring

Bi-amping uses a line level crossover to feed individual amps for low and high ends, or in the case of tri-amping low/mid/high signals.

Uhhh yea . . but not if you are using power level filters or the ones in your crossover (in many cases requiring modification to separate the woof). This is what was meant.

Bi-wiring removes the physical connection between the woofer/tweeter at the speaker and replaces it with 2 sets of wires that connect at the amp ouput.

Uhhh yea . . exactly what I said . . "two pair connection at source" usually just crimped/twisted together to the two terminals).

Also isn't this something you would only want to do with speakers that have unsophisticated or no x-overs?).

This is also why it will only work with parallel x-over networks

unsophisticated.

and not series ones.

Unless the series x-overs are modified--as many people do.

 

[Scuzzer]

Since you have modified your post my reply doesn't seem to make as much sense. Noob mistake, I guess I need to remember to use the quote function.

 

[stuartk]

Unless the series x-overs are modified--as many people do.

I've never see this kind of mod. Examples?

Series crossovers cannot be bi-wired the same way parallel ones can. It's inherent in the way they work. It isn't a multi-part network like a parallel crossover, it's all one circuit, with all parts acting together. (This is actually one of the advantages of them.)

 

[Gibsonian]

Tri-wiring

If Bi-wiring is beneficial, what about tri-wiring of three way speakers? More benefit??

 

[Grainger49]

I would guess. yes, but my speakers are three way, and bi-wired (set up for BI only, not TRI).

 

[Raphael]

I've never see this kind of mod. Examples?

Series crossovers cannot be bi-wired the same way parallel ones can. It's inherent in the way they work. It isn't a multi-part network like a parallel crossover, it's all one circuit, with all parts acting together. (This is actually one of the advantages of them.)

The gist of it is to separate the x-over into it's hi and lo components--essentially making a parallel x-over that's bi-wirable. This--of course--would be different for many x-over designs and requires new component values so should only be accomplished by those who feel comfortable with x-over modifications and knows or can accurately extrapulate his/her x-over points based on speaker/cabinet design. Basically . . I know enough not to try it!