biwire trick

Thanks very much for the nice words, gentlemen.

Rcrerar, no, what Tholt is describing is a conventional biwire arrangement but with the + conductors of the two cables interchanged at the speaker terminals. It may not have been clear to you that the statement he quoted from the MD site is addressing something different, a non-biwire arrangement in which jumpers are used but the connections of the + and - conductors of the single speaker cable are made to "diagonal" speaker terminals, rather than adjacent speaker terminals. I have no idea, btw, why the latter would make a difference sonically, although a number of people have claimed in past threads that it did for them.

Shadorne, neat calculator that you linked to. I agree that if the two sets of cables are within the same jacket, the effects I described would probably be reduced to insignificance. However, if they are physically separated by some number of inches or feet over a significant fraction of their run length, I think that the following factors would make those effects more significant than the calculator would seem to indicate:

1)The calculator assumes the speaker is purely resistive. Dynamic speakers will tend to have an impedance at high frequencies that is somewhat inductive, due to tweeter voicecoil inductance. Cable inductance will have a greater effect on bandwidth when it is connected to an inductive impedance than when it is connected to a resistive impedance of the same magnitude.

2)The speaker impedance at high frequencies may be less than the 8 ohms that is assumed in the calculator.

3)While the effect may amount to only a db or less at 20kHz, which I agree is insignificant in terms of steady-state frequency response, as you certainly know our hearing mechanisms give increased emphasis to the leading edges of rapidly changing transients. Fast leading edges, of course, correspond to high frequency spectral components.

The bottom line is that I'm not asserting that the effects I've described are necessarily the explanation of what Tholt perceived, but that there is technical rationale that is sufficiently plausible for this tweak to not be dismissed as placebo effect.

Best regards,
-- Al

Al,

The majority of tweeters are above 6 to 8 Ohms in the 10 KHz to 20 Khz range - rising with frequency due to the inductance. So the applet formula in the link is a pretty good approximation for the 10 KHz to 20 KHz range.

I think we can all agree that below 10 KHz we can pretty much ignore the effects of cable inductance.

In the applet I used 5 meters of speaker cable with + and - leads separated by 1 meter in order to get a 0.25 dB drop at 20 KHz compared to 200 Hz. I deliberately used an "extreme example" to show that the effect is very small in all situations.

However, the effect does exist and you are absolutely right that it might be audible in some situations. I stand corrected.

I would argue that this "trick" is definitely the wrong way to bi-wire speakers - at the very least it goes against normal way to make electrical connections which is in general to use either two wires side by side in close proximity for low frequencies (audio) or a coaxial cable for ultra HF applications.

Yes, the MD description I used/quoted is not the same as what I'm describing (single cable + jumper arrangement), but it led me to think of what I've described here. I stand by my first statement -- I hear more air, more dimensionality, larger staging, more natural and full sound. Unless there is a downside electrically, which I haven't read yet (Almarg...assuming you would have brought it up?) I'm hearing positive differences and don't have a good reason to revert back to the conventional hook up method.

Unless there is a downside electrically, which I haven't read yet ....

I think that the only conceivable downside would be a philosophical one, along the lines of Shadorne's last comment. It could be argued that you are raising the effective cable inductance to compensate for an imperfection elsewhere in the system or the room. But given that nothing is perfect, and that the adjustment is extremely small in electrical terms, as a practical matter I don't see any issues. I would think of it simply as fine tuning the system.

Best regards,
-- Al