Paulwp as others have said, the voltage is the same on both pairs of wires but the currents are not. To get a grasp of this think of a tiny electric motor and a really big motor hooked to a battery. Because of the impedance difference in the motors they will draw different currents from the battery. If two resistors were hooked to a battery the amount of current flowing thru the resistors would depend on their values.
In a tweeter if it was connected directly to the amp, it would try to move with the bass. It would probably quickly burn out. The crossover (the simplest is just a cap in series) acts as a high impedance at low frequencies and because little current flows in a high impedance circuit no force is generated on the cone of the tweeter at low frequncies.
In the woofer the crossover (just a coil in the simplest) as the frequency gets lower the coil passes more voltage to the woofer which causes more current to flow thru it. In other words at really low frequencies the woofer 'feels' all the voltage that the amp puts out.
To sum this up, at the crossover input terminals both high pass and low pass sections see the full voltage of the amp. At the output of the crossover (the driver terminals) only part of the full amp voltage is felt which is totally dependant upon the frequency. Since the voltages applied to the drivers terminals change with frequency so does the current. It is this change in current with frequency in the high/low pass circuits (which include the wires) that I was describing.
It should be easy to rationalize that the big currents flowing thru the woofer could not possiably flow also in the tweeter circuit or it would surely burn it out. If the speaker is connected with only a single pair of wires then both woofer & tweeter currents are combined at the amp but get seperated out in the crossover. In a bi-wire speaker the currents leave the amp together but get sepersted out at the amp terminal and only the tiny high frequency current flows into the wire connected to the tweeter crossover.
Hope this helps ... I will be out for 5 days and therefore can not respond unless I get on the net in Az. Chris |
Try it both ways and leave it the way it sounds best to you! It really dosnt matter which way is recommended or considered correct in theory, what matters is what sounds better to you in your setup. If we trust only numbers we might as well throw out all high end tube amplifiers. Anyone considering doing so please contact me for free disposal. |
It was a recommended tweak to try, by Jon Risch at AA, which I mentioned previously. Doesnt work for me. My speakers sound better to me with no jumpers. But some people report that they like it. I dont know why. |
I recall reading in another thread about the practice of using a jumber on the (-) side only in a bi-wire setup. Does anyone do this? I did not understand the explanation that was given before (and probably won't this time either if it comes up). |
Thanks to all.
My general non scietific "sense" told me that running the jumpers + my Biwire cable (kimber 8 pr) would be the same as running "standard cable" on two posts. As always though I have this FEAR of hooking something up wrong and smelling smoke! (What I like to call the bad smell) As always I appreciate the knowledge and advise I get from this site!
Best Regards |
Thanks Sndsel, that makes it a little clearer, I think. I do prefer my own speakers bi-wired and think people should just try it both ways and see if it makes any difference to them. |
Paulwp - The point, I believe, is that current is the same throughout a series circuit. The + speaker wire, the crossover and driver, and the - speaker wire comprise a series circuit. The amount of current for a given voltage applied depends on the impedance of the load - the crossover/driver, but it is the same in the entire circuit. That is; there is not a lot of current down the + wire to the post, then a little current through the load, then a lot of current back through through the - wire. (Discussion of electromagnetic field needed here, but beyond scope) The crossover is frequency sensitive and represents a high impedance to frequencies outside its bandpass. Current resulting from voltage alternating at frequencies outside its bandpass is therefore relatively small and it is so through the entire series circuit including the wires. No harm is being done by biwiring with the jumpers in place, however. It is the same as running two wires to each post of non-biwirable speakers - each "polarity" wire of the set is simply common at both ends - you are just running more wire in parallel to each post. Do your speaker wires have multiple strands? Same thing. Some may feel that it is advisable to do or not do one or the other because of different sound, but that is a different discussion. :) |
Sqjudge, I'm confused. Regardless of whether bi-wiring is or is not beneficial (and I bi-wire in my main system), I just don't understand how the signal, current or whatever can be different, coming from the same source. Doesn't the amp send the entire signal to whatever crossover is at the other end of the circuit? And isnt the circuit completed at the crossover, which sees the entire signal regardless of what it passes on to the driver?
Sean, some speaker makers include bi-wiring terminals because the retail market demands it, even though the designer/maker doesnt think it does any good. Some people just won't take a speaker seriously unless its bi-wireable and some people have already invested in the cables they want to use with their new speakers. I wouldnt call it an afterthought or marketing gimmick. |
I used to teach basic electronics at a Vo-tech. I feel a need to clarify the bi-wire issue because I believe that some do not understand the electrical circuit. As Sean describes above a true bi-wireable speaker has a electrically separate crossover for each driver. Most speakers have separate crossovers for each driver but they are not electrically separate because the input to both of the crossovers (in a two-way speaker; one a high pass to tweeter, the other a low pass to the woofer) are tied together to the single pair of input jacks on the back of the speaker. In a bi-wireable speaker, if the jumper is removed between the two pairs of inputs and only one of the pairs has hooked up, then only one speaker will produce sound. This is a sure fire way to see if the crossover sections are independent.
Sdcampbell you are partially correct that you are feeding the same VOLTAGE to both sections of the crossover. Both pairs of wires connect to the same + & - terminals on the amp and then each pair of wires is connected to the drivers thru the crossovers. This is like connecting two toy DC motors to a single battery, both motors will 'see' the voltage and both motors will turn.
A speaker is a current driven device. The current flowing thru the voice coil reacts with the magnet to produce movement of the cone. (yes, I am sure you all know this but I am only trying to be complete) It is the job of the crossover to direct the appropriate audio current into each driver. This is done by what is called the voltage divider principle. This principle is based on Ohm's law that states the current flowing thru a circuit is proportional to the voltage applied and inversely proportional to the resistance. If you were to take two 6 ohm resistors and connect them in series and place them across a 12 volt battery, 1 amp of current would flow. (ohm's law) If the resistors were doubled in value then the current would be cut in half. Now, lets look at the voltage. The voltage across one of the resistors is determined by taking the current thru it (1 amp) and multiplying it by it's resistance (6 ohms) to arrive at a voltage of 6 volts. The 12 volt battery has been 'divided' down to six volts. The crossover in series with the speaker works the same way, only it is frequency selective. In the case of the woofer crossover, it only 'passes' the low frequency voltage to the woofer and blocks the high frequencies.
The major advantage to stretching separate wires to the woofer and tweeter is the separation of the audio frequency currents in the wires. Even though the voltage is the same on both pair of wires, the currents are not. If speaker cables were perfect, then we would hear no differences in cables. If they were perfect, it would not make any difference if both high and low frequency currents flow in the wires. It is the separation of the currents in the cables that does the most to affect the sound. Does it not seem possible that the large woofer currents could affect the small tweeter current while it traveled down the wire? It is the fact that the currents are different that makes me think one could 'tune' their speakers by using different cables on the top and bottom.
A manufacturer might not recommend bi-wire because he has voiced his speaker to take into account the interaction inside the single cable. (I am not sure how this could be done, but it always possible) If everyone were to follow recommendations, why would anyone try a different cable than the one recommended. I believe the answer is found within the context of taste. I like my 'sound' to be a certain way. I position my speakers and use 'xyz' brand equipment to make them sound the way I want. Just because a manufacturer doesn't recommend bi-wiring, does that automatically mean that I won't like it that way? It is a personal choice and I feel strongly about the option to make that choice! If I feel a speaker sounds better upside down, what is wrong with me using it that way?
I want to thank all of the Audiogon posters for their comments about the sound of equipment in this and other posts. I reside in the middle of no audio land. I really like to read the opinions of others on equipment. I believe our motives for saying something good or bad about a piece of gear is at least NOT ruled by our paychecks!
I really hope this dissertation sheds light on the bi-wire topic and will help guide all in the pursuit of good sound. |
Try reading Jon Risch's website regarding the "technicalese" on bi-wiring.
As to bi-wiring feeding the same signal to both sets of terminals, that is not necessarily so. On a speaker that is TRULY designed to be bi-wired, the two sections are completely independent of each other. Using the factory supplied jumpers simply ties the whole circuit together. Once the jumpers are removed, you now have two seperate frequency selective paths for the signal to take. While this is the type of "bi-wiring" that MAY result in sonic benefits, it would be negated by using an "all in one" type of bi-wired speaker cable. You would literally need a seperate run of cables for the lows and a seperate run for the highs to achieve optimum results.
As to speakers that were designed for bi-wiring as an afterthought or as a marketing gimmick, you might not gain anything other than the lower resistance of using more wire as a conductor. In itself, this is not a bad thing but hardly worth the extra money. Sean
> |
In response to your question, you are not hurting your speakers in the current setup, but you might be hurting your amplifier. Your amp sends out power over two cables to the + terminal, and the wire is shorted out when it gets there, its like connecting two wires together at the end. Could cause some type of mismatch or something if the wires are not exactly the same or whatever. Not a big risk so don't worry too much. |
In response to Sdcampbell and KennyT, as a matter of fact you DON'T feed a full range signal to both terminals in a bi-wire configuration. Through some unexplained phenomenon (I'm being serious), the crossovers somehow limit the frequencies being transmitted through the cable. The effects have been measured, it's a interesting occurance. The only frequency being delivered at the same level to both terminals is the frequency point between the crossovers between the terminals themselves. |
No harm to leaving the jumpers in (unless as some people say, you will benefit from replacing them with a small length of speaker wire). I doubt seriously that you need to reterminate your cables. If your speakers are bi-wireable (because thats what the market wants), it cant hurt to take the jumpers out and use them that way. You may even find you like them better bi-wired. But if you prefer the sound with the jumpers in and all four cable ends attached (belts and suspenders), use them that way and dont worry about it. |
I was told by the distributor that the biwire posts were added due to market pressure. From what I understand the manufacturer does not recommend biwiring. ( Their new models can not be bi wired.) I guess I need to reterminate my cables however I thought with the jumpers+the biwire cable I was essentialy doing the same thing.
Thanks |
Bi-wire or not depends on how your speaker crossover is designed. A well designed speaker crossover does not benefit from bi-wiring.
A not so well designed crossover feeds back EMF to the amplifier thus splitting the crossover into 2 or more sections REDUCES this effect. A well design gets this phenomena correct thus bi-wiring mokes little or NO difference.
Just an example, Dunlavy does not recommend bi-wiring but puts 2 sets of binding posts on his speakers so not to piss his customers away.
On the other hand if you open up a Thiel speaker, there are 2 or 3 boards inside, one for each of the low, mid, high frequencies and still the speaker is not bi/tri wireble.
I have personally had experienced on certain speakers, bi-wiring DOES make a hell lot of difference and on some hardly any.
One word of advice.....get rid of those jumpers. Make your own using the cable of your choice. Jumpers they provide are usually crappy. Bi-wire or not, you have to deceide. I have not much experience on SF speakers but heard that they are not recommended (correct me if I'm wrong) for bi-wiring.
Hope it helps. |
KennyT is right. I mis-stated what I meant to say: bi-wiring feeds full-range signals to both crossovers, but having 2 X-overs allows the X-over design to be optimized: 1 for the low freq's, and 1 for the mid and upper freq's. |
Vandersteen 2Ces, 3As, and 3A sigs. all sound better bi-wired, and Richard Vandersteen recommends bi-wiring. His speakers were designed for bi-wiring. Cheers. Craig |
I do not agree with you bluesman. I always had better results with bi-wiring (with 6 sets of different speaker brands). |
Most manufacturers put bi-wire options in because it's good marketing. I've talked to many top engineers at speaker companies and most agree biwiring is just a gimick. If you analyze the circuit, biwiring just makes the sound worse. |
There was a post here at the Gon about a particular speaker equiped for bi-wiring, but not recommended by the manufacturer. They had equiped so just to please the French market, if memory serves. Anyone remember the post I'm refering to? |
Sccampbell,
Regardless of whether or not you use a jumper or not on biwired speakers, you ARE feeding a full-range signal to both crossovers! I agree with the rest, just correcting the oversight.... |
As Argent said, the manufacturer would not have installed bi-wire posts unless it was a good idea. Speakers that have bi-wire posts have two crossovers in each speaker. The purpose is to have one crossover handle the low frequencies, and the other handle the mid's and upper frequencies. As a rule, bi-wiring produces better transients and cleaner, more transparent sound. If you use a jumper plug on your bi-wire posts, you are feeding a full-range signal into BOTH crossovers, and the chances are good that you are not getting the best audio quality from your speakers. You will NOT damage them this way, but you are also probably not getting their top performance. I am curious who told you not to use the speakers in a bi-wire mode. Unless it was the dealer, I'd question the advice you were given. You might want to contact the US distributor for Sonus Faber and ask their advice. |
If the speakers have bi-wire posts, then the manufacturer obviously thinks it is okay to bi-wire. I say take the jumpers out. Let me know how it sounds. |
