Number one and number two are incorrect. Full range is transmitted on both lines. If the wire had the capability to distinguish between HF and LF then there would be no need for a crossover.
Number three is correct and the only reason that the phenomenon of bi wiring from a single amp exists.
Full range voltage, yes, full range current, no. Remember what the crossover on the other end of the cable does.
When doing the comparisons, have you adjusted for the difference is resistance between 2 wires and one? Basically, you have one AC source ( it should be modeled with impedance, not perfect) driving two cables to two filters. The only difference is if the cables are tied together at the source or at the filters.
.1 Ohm is large for the cable, but trivial compared to the resistance in the crossover coils and caps. A more complete model may make the differences diminish. What currents are flowing in the cables are not revelant, is there a diference in the VOLTAGE as applied to each driver?
Been too busy to do this myself. Just finished off a new pair of surrounds built on the Dayton RS135 and Vifa xt25 first order. Not bad. Not great. Probably OK for surrounds. Can't really get a smooth in-room responce with such a simple 3 part crossover ( coil, cap, resistor). They will do until I come up with another idea to play with.
.1 Ohm is large for the cable, but trivial compared to the resistance in the crossover coils and caps. A more complete model may make the differences diminish. What currents are flowing in the cables are not revelant, is there a diference in the VOLTAGE as applied to each driver?
Been too busy to do this myself. Just finished off a new pair of surrounds built on the Dayton RS135 and Vifa xt25 first order. Not bad. Not great. Probably OK for surrounds. Can't really get a smooth in-room responce with such a simple 3 part crossover ( coil, cap, resistor). They will do until I come up with another idea to play with.
If the cable has a resistance of .1 ohm and the woofer draws 1amp at some lower frequency, the cable will drop .1V which may represent something perhaps 40dB down.
It's probably not the full story. This might explain the tweeter being fed less signal but maybe the woofer currents are out of phase with the driving voltage.
It's probably not the full story. This might explain the tweeter being fed less signal but maybe the woofer currents are out of phase with the driving voltage.
Ref; Post 166
To make this test valid, you need a third test, where you use two cables just doubled up.
One cable to both crossovers
Two cables to both crossovers
Two cables, one to each crossover
Currents in the cables will differ. Sure. The impedance across the spectrum seen by each cable from the amp end is different. The question is if the current through the drivers differs. Does the current through the amp differ?
This test is also includes the real world problem of the amplifier output. As that could be different with every user and any change in the load will effect it, might I suggest a "perfect" voltage source with some chosen output impedance.
The AV guys, having boxes with 7 or 9 amplifiers in them, have taken to using 2 of the extra amps to "biamp" as in different amps for woofers and tweeters driven full range, but still the passive crossovers. They are claiming great sonic benefits. If the power supplies, or even the filter bank were dedicated to each amp pair, this would make sense at higher power levels, but as receivers share the one way too small power supply for all amps, I am rather skeptical if the benefits are as much as is described. Don't know. Maybe the amps are so bad, every little thing helps.
To make this test valid, you need a third test, where you use two cables just doubled up.
One cable to both crossovers
Two cables to both crossovers
Two cables, one to each crossover
Currents in the cables will differ. Sure. The impedance across the spectrum seen by each cable from the amp end is different. The question is if the current through the drivers differs. Does the current through the amp differ?
This test is also includes the real world problem of the amplifier output. As that could be different with every user and any change in the load will effect it, might I suggest a "perfect" voltage source with some chosen output impedance.
The AV guys, having boxes with 7 or 9 amplifiers in them, have taken to using 2 of the extra amps to "biamp" as in different amps for woofers and tweeters driven full range, but still the passive crossovers. They are claiming great sonic benefits. If the power supplies, or even the filter bank were dedicated to each amp pair, this would make sense at higher power levels, but as receivers share the one way too small power supply for all amps, I am rather skeptical if the benefits are as much as is described. Don't know. Maybe the amps are so bad, every little thing helps.
Vandersteen said
Now of course, if the speaker already had a peak of the right shape then the biwire dip will improve it by making it flatter. Of course, it is quite possible that the dip is too small to be audible but it will definitely be there - circuit theory requires it.
Why should we be interested in his unsubstantiated beliefs?
I have, a few months ago - I forget which thread. Assuming the speaker has a flat response with single wiring then biwiring is likely to introduce a small dip at the crossover frequency. This is because the crossover is likely to present inductive and capacitive reactances in each half, which may roughly cancel at the speaker terminals for normal wiring but at the amplifier output for biwiring. This means that for biwiring the actual cable current is increased near the crossover region as the cables now carry more reactive current. Unless the cable has zero resistance (in which case it can't do anything at all to affect the sound) this means more voltage drop so a drop in sound.gootee said:
Now of course, if the speaker already had a peak of the right shape then the biwire dip will improve it by making it flatter. Of course, it is quite possible that the dip is too small to be audible but it will definitely be there - circuit theory requires it.
I have not made adjustments, no. I want to see any differences. Yes, the only difference is that the crossover sections are tied together with a very short wire, or a 2M wire x 2. It's the only difference, but an important one. It may not matter, tho.
Because he has designed and sold many more good quality speakers than you or I have. That does not make him right, but at least he knows "something" about good speakers. His experience and knowledge make what he says worthy of interest.
Yes, and when you consider the resistance of the crossover coils, connectors, lead wires etc, the .1 Ohm difference seems rather insignificant.
Why listen to Vanderstein? Well on one hand they have to compete in the same snake oil market as every one else. On the other hand, they make some darn fine speakers. Ugly, but fine.
This reminds me of results I was getting when I was trying to quantify coupling between coils of the tweeter and woofer crossover. I was measuring considerably more coupling at particular frequencies with a signal probe that I was with near field microphone measurement. Using a reference probe at the input to the crossovers helped some. After much head scratching the discrepancy was tracked down to ground currents contaminating the signal probe measurement. Once I built a differential probe, the "phantom" coupling between the coils disappeared.
Are you using a differential probe?
If not, are you using a reference probe in addition to the signal probe?
Well I was, and still want to. But for some reason it got noise, so I switched to single ended. Will revisit. I do suspect the same ground problem you were having.
Based on only one configuration's simulation results, some of which are attached, it looks like the differences between single-cable and bi-wiring would usually be small but not necessarily inaudible.
Attachments
The heart of the matter, what stops one achieving subjectively satisfying sound, has been discerned many times by a number of individuals over the years, and various methods have been devised to resolve the issues. However, that knowledge and understanding seems to largely ignored, pushed to one side as being largely irrelevant - meaning that everyone else keeps thrashing away in a vast porridge of other "issues" - which never really get to that heart, and resolve it ... IMO,
Interesting results from a good bit of simulation effort.
Is the *.asc circuit file available for sharing?
If I understand your plots correctly the maximum difference in tweeter voltage is < 0.1dB?
You should probably double up the runs of wire on the normal configuration to have a proper comparison(ie equal total wire impedance) with bi-wire, right? Or, were you intentionally NOT doing this to show what possible differences might be there for people to hear if they simply added another cable to bi-wire and compared with a single cable of the same type/gauge.
Sure. I will attach the .asc et al.
The third plot, and the top and bottom plots of the fourth one, are not in dB. But yeah, I think that the maximum difference was about 0.068 dB, at about 230 Hz. Attached is the same plot, but in dB instead of linear.
The cables were configured the way they were in order to compare a "normal" single-cable scheme to a bi-wiring scheme. And anyway, I think that the impedances are already the same. Note that the bi-wired cables are not in parallel, except at the amplifier end.
The third plot, and the top and bottom plots of the fourth one, are not in dB. But yeah, I think that the maximum difference was about 0.068 dB, at about 230 Hz. Attached is the same plot, but in dB instead of linear.
The cables were configured the way they were in order to compare a "normal" single-cable scheme to a bi-wiring scheme. And anyway, I think that the impedances are already the same. Note that the bi-wired cables are not in parallel, except at the amplifier end.
Attachments
In the old time, whether a capacitor is "in" the signal path or not was a big issue. And I think it always start with an observation of a unique phenomenon. Some observe the phenomenon, some does not. And then probably from those who observe they try to find explanation, starting from basic Physics to unsubstantiated logic. But for me, there are "things" I don't need to find the answer for before taking actions
BTW, there are a lot of things that I can observe related to crossover. Basic Physics that I know cannot explain. It is similar to cable issue. And I don't have sufficient time to waste. But I have guessed that it relates to very high frequency that most people think is inaudible (but I think it IS audible, directly or indirectly). Something like inter-modulation, interference, stray capacitance/inductance, etc.
A solution which is generally ignored because it sounds too glib - but that doesn't stop it being vitally important - everything matters ...
How do you know whether you've covered ... "everything"? Simple: if it always sounds 'right', like music should - always, every time you put on a track, no matter when, what mood you're in, then the bases have been covered. Otherwise ... there's still work to do ...
How do you know whether you've covered ... "everything"? Simple: if it always sounds 'right', like music should - always, every time you put on a track, no matter when, what mood you're in, then the bases have been covered. Otherwise ... there's still work to do ...
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