Sorry everybody. I didn't realize it was a 3 yr old thread. There it was on the first page of topics. :) Anyhow - I agree inductance and even the total impedance which includes capacitance as well, but given the level of discussion and the incorrect statements being made - I figured I'd keep it simple. Again mea culpa! |
IMO bi-wiring is one of the few contentious issues in audio that there is no point in analyzing or debating theoretically. There are many subtle technical effects that can come into play to a small degree, a lot of them having been mentioned above and in the links that were provided, and their net result will, as I see it, undoubtedly be system and listener dependent. Regards, -- Al P.S: Kijanki, don't forget the 2pi factor for inductive reactance (which your post 4 years ago correctly reflected). 35 milliohms should be 220 milliohms, and Z = 222 milliohms. |
Jkorten, since you opened the can of worms, here is something else for you to read that talks about more than just the intermodulation issue. Bi-wire, not only an advantage If you like bi-wire, great, I'm happy for you. In reference to the OP, I prefer single wire with jumpers of the same wire. |
I'm reading a bunch of stuff in these posts that doesn't make sense. The reason bi-wiring works is due to the finite but definite level of resistance a wire has. If you send a current to the tweeter and woofer and the crossover splits it and then the signal returns via the "ground" speaker wire. That return post from the crossover will develop a voltage. Because the current is flowing through the wire that has a resistance. Bi-wiring improves the sound because the tweeter return path is on it's own wire and therefore the voltage at the crossover is due only to the tweeter current and you will not get intermodulation with the current flowing through the bass wire (the voltages sum when using one wire for both). The net result is that the larger currents that flow through the bass network do not affect the amplitude of the tweeter signal. |
Musicnoise - This is just hypothesis and changes are so miniscule that it's difficult to make sense of it. My speakers show slightly more air in the sound when bi-wired but now I'm not so sure if I made right decision buying shotgun cable. It costs practically twice and I could get better cable for the same money. Another strange thing that somebody mentioned is leaving one of the jumper brackets in-place (one on the ground side). For some reason it made sound with my previous amp slightly more coherent/focused. It worked only when jumper was on the ground side and since I have right now class D full Mosfet bridge driving my speakers there is no ground side and I haven't tried it again. From engineering point of view it doesn't make sense at all. |
Not every HF circuit has resistor in series - it depend on speaker design (many have L-PAD). I didn't say that impedance of the cable is comparable to speaker's impedance - it is in order of 50-100x lower. What I'm saying is that it might be still audible since our hearing is logarithmic and ratio of 100x is only -20dB of power. Crossover attenuates - but is far from perfect especially around crossover frequency. Resistor in series (often in L-Pad), that you mentioned, might have something to do with the fact that some speakers show improvement (usually more air) when bi-wired but other don't. It might also depend on the inductance of the cable. Inductance of straight wire is in order of 0.2-0.3uH/ft (depend on gauge) but my interconnects have only 40nH/ft (I don't know how they do it) Even if you divide mentioned effect by another 100x it will be -40dB of power and far from being inaudible. Remember we're talking slight difference. |
How do you figure the emf of the LF driver (essentially a source at that point) sees a Z of the cable and amp that is less than the Z of the HF circuit? It is not even close. HF circuits typically have a resistor in series with the driver ( 2 or 2.5 ohms usually), that series resistance plus the R and L of the HF coil swamps the Z of the cable and amp. Additionally, the frequencies supplied by the LF driver that will fall in the passband of the HF crossover are attenuated by the passive components in the crossover of the LF circuit, particularly if that crossover is higher than first order as part of that crossover will have a low Z path that shunts the higher frequencies. |
EMF interaction between speakers is aided by the fact that output of an amp is separated from the speakers by inductance of the cable. Typical wire has inductance in order of 0.3uH/ft - equivalent to 0.188 ohm at 5kHz (counting 10ft both ways). It is 43x less then speaker's impedance but it is only -16dB of power. (our hearing is logarithmic). In addition amplifier's output impedance is in the similar order at 5kHz (or even worse). |
Flashunlock "The 2-4 design is a bit waste of time and might as well use single wired with jumpers instead." That couldn't be any further from the truth. There will of course be systems where conventional bi-wiring results in no audible improvement, but it's generally (in mid-fi & better systems) a very effective and impressive tweak. To expand on what I explained earlier, 2-4 bi-wiring has the same effect as putting the crossover at the speaker terminals, rather than in the speaker, thus greatly reducing the distance traveled by the combined high & low frequencies. Basic electronics will tell you that once any kind of filter exists in a circuit (eg a high-pass frequency audio filter as in a crossover), then the ENTIRE CIRCUIT is only capable of carrying what that filter allows. As an analogy; if you put a 100 ohm resistor in line with 0.01 ohm/metre cable, the entire cable will have a resistance of about 100 ohms; the resistor dictates what that cable can carry. Removing the jumpers and bi-wiring means the low-pass filter (for the woofer) acts on the entire LF cable right back to the speaker terminals, and same for the HF cable. |
Bi wiring will not always give you a better sound. It really depends on the speakers and it's cross over design. If you really want to go the bi wiring route then you need to go what I call true bi wiring meaning 4 seperate runs to each speaker. The 2-4 design is a bit waste of time and might as well use single wired with jumpers instead. Hope this helps. |
I think biwiring works if you can filter the HF and LF before the speaker cables, or even before your power amp. The ideal would be according to me: LF-power amp- speaker cable-tweeter pre amp < HF-power amp- speaker cable-woofer This being 1 channel, if you have 3 way or more then repeat for each. I don't understand why some 3 way speakers have bi-wire option shouldn't they have a tri-wire set up. |
While the back emf from the LF driver does create a signal that beats with the higher frequency components to produce distortion in the range of the HF circuit, I question the extent of that signal. Thevenizing the respective circuits (with a signal sources from the amp and signal source from the LF driver) results in a large disparity in loads. Unless the output Z of the amp and cable are significant in comparison with the Z of the HF circuit the amount of IMD should be extremely small. Most decent amplifiers and just about any cable at length less than say 20 feet present a Z orders of magnitude less than the HF circuit. While biwiring will affect the IMD caused by the LF driver signal, it is unlikely that the IMD thus generated is of any practical signficance in most instances. |
There's a very sound reason why bi-wiring works. Remember that your crossover is basically a filter that splits the signal inside your speaker and sends the highs to the tweeter and the lows to the woofer. Up until that point, all frequencies travel together along the single speaker cable. By removing the jumpers and using bi-wired cables, the high and low pass filters become part of each loop right back to your amp terminals, meaning that the high frequencies can't travel along the woofer cables and vice versa. This helps to reduce distortion and smearing of the sound. It's very similar to the way S-video cables separate the luminance and chrominance signals to improve picture quality over composite cables. But as Shadorne said, if your speakers/system isn't truly suited to bi-wiring, you may hear little or no difference. At the very least, you've doubled your wire gauge! |
If you have speakers that are designed for it then you can reduce distortion. (TYhis requires a speaker with crossover sections that can be separated) See this article If you don't hear a subtle difference then perhaps... 1) Your speakers are not designed for proper bi-wire 2) Your amp is not doing enough to control the output (output impedance may be too high) 3) The speaker crossover is of high order and it dominates or something else is masking the IMD distortion reduction 4) Your bass woofer is super linear and creates only inaudible harmonic/IMD distortion/breakup outside of its intended band (unlikely). |
I've once tested my biwire Analysis Plus cables in a configuration where I've connected both HF and LF spades together to a single binding post on the speaker side, and use jumper wires from HF to LF. I couldn't tell any difference between that and the proper biwire setup. I did hear differences when I went from Analysis Plus to Cardas to Kimber. But not when I used the biwire cables in such configuration. |
In my comparisons of the same exact cable in a Bi-wire vs shotgun with jumpers, the Bi-wire wins out for a more pleasing musical experience. I find the soundstage to be larger, bass is better defined with a better sense of pace. Treble is sweeter and cleaner. Of course, the cable has to be one of quality and more importantly, it must be synergistic with your amp/speakers as well. |
Bi-wire by a mile here.....your results may vary. Maybe my supplied jumpers were inferior,I don't know. My "theory" is the LF and HF present two different loads in terms of impedance and frequency and having two sets of cables to carry these separately is better. Also besides my system I have never heard a system that didn't improve from bi-wire and I set up many when I was a dealer both on the display floor and in customer systems. For these comparisons the same type of cable was always used for LF and HF within a setup although the experience overall represented several types/brands of cables and speakers. ET |
At the end of the day, it all comes together at the amp. Vandersteen as noted above, and DIY'er Jon Risch over at AudioAsylum recommend bi-wiring when the HF/LF crossover boards are totally separated, and they each give reasons why bi-wiring is a better approach in that case. My monos have dual binding posts as do my speakers, and I have taken advantage of that to try two totally separate (single)runs of a high quality cable. However, that set-up was bested by a more conventional bi-wire cable, but one in which there are two separate and equal awg runs connected only at a single amp binding post. I can see that there would be a camp that advocates (for a given purchase price) purchasing the highest quality single run cables you can afford then using jumpers, instead of a lesser quality bi-wire cable. BTW, jumpers can be inexpensively constructed using high quality wire obtained through places like Partsconnexion. IMO, instead of using jumpers, the best way would be to solder the speaker lead wires inside your speaker to a single binding post. Few absolutes in this hobby when matching different equipment and wires, so I doubt there will ever be consensus on this question. |
I have talked to Richard Vandersteen about this very thing. He says that bi-wiring is the best for any speaker that is designed for it..that has an input for the lows and another for the highs. The cables have to be separate runs for each input...that is, you can't have a single cable that splits at the speaker end for bi-wire. I have done that setup as he recommends, and can definitely hear the difference. In addition, I like seperate + and -wires as well. All can view the technical reasons on the Vandersteen website. |
you will get a million opinions on this subject, the view that it is very system dependant is accurate IMO. Unfortunetly a pair of jumpers can be quite expensive so it ruins some of the advantage of using a single run of better wire buy used try for yourself and sell at a minimal loss the wire you don't want. fwiw: a nice way to hook up a single run of wire to a speaker with two sets of terminals is to hook up the + to the tweeter + and the - to the woofer - then use the jumpers as normal. this evens out any favoring of the drivers a normal hookup (both wires to the tweeter for instance) would bring. |
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