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In Reply to: RE: Need some bi-wire counseling and opinions posted by Pat D on July 13, 2015 at 19:02:54
Thanks for posting the link to that article by Russell, There was a later article by Dunlavy reporting similar results in their auditioning rooms; where they used several different tests. One was pretending to switch cables to a much more exotic looking cable, at which point the observers "heard" a difference. Auto-suggestion (AKA, self hypnosis) is a powerful influence, and we've all been caught by it at one time or another.
To avoid auto-suggestion I used to get my daughters to listen while I made changes. It was interesting that when they said they couldn't hear any difference; suddenly, I couldn't anymore either.
In regard to the 5% rule mentioned by Russell, I do use that; but prefer to use 5% of the speaker's minimum impedance, rather than the nominal.
I have personally tried bi-wiring; but gave up on it after I found it made no difference.
I have found that contact resistance does make a difference, and so all my end terminations are gold plated, and are both clamped and soldered to the wire itself. Amplifier and speaker connections are also gold plated. The point behind the gold is that it does not oxidize.
Jerry
Follow Ups:
I consider a speaker's minimum impedance to be it's impedance, as a rule. My speakers are really 4 ohm speakers, and the lengths are nowhere near enough to cause a change in the frequency response by 0.1 dB or more.
I would think contact resistance could easily be more significant than the resistance of the wires.
I remember the Dunlavy story.
http://www.verber.com/mark/ce/cables.html
The major effect of buywiring I experienced was in a store when I was auditioning the old PSB Stratus Minis, where they demonstrated the speakers I was auditioning with some tri-wire speaker cable. Unfortunately, they were careless with the extra wire, which shorted out across the speaker terminals and blew the amplifier. Just blew the fuse, I trust. THAT made a definite audible difference because the amplifier no longer worked! They had to hook up another amp.
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"A fool and his money are soon parted." --- Thomas Tusser
My experience with contact resistance was when I was trying to match up pairs of Advent tweeters by listening to a pair of speakers. The Advents were out in the middle of the room, side by side, and I had no consistency of results among the 3 pairs of Kloss tweeters I had. It turned out to be contact issues at the studs on the back of the speakers. After I solved that problem, the tweeters matched up much more easily.
Earlier, I had some contact issues when comparing two pair of speaker cables. Two different brands of 12 gauge with different jackets, 32 feet long, and matched for length. Fixing the contact issues made them sound identical. I should have remembered that experience when trying to match the tweeter pairs.
Because of my room, I have long cable runs; but I try for no more than 0.25 dB frequency response change due to series resistance in the amplifier source impedance, plus cable impedance. That works for frequencies up to 1-3 kHz; but inductance in the amp and cables causes a rise in total series impedance at higher frequencies. So if you're being really rigorous, that needs to be considered as well. Nelson Pass published some good data on cable impedance a good while ago. Bose also pointed out the 5% rule in a brochure about the 1801 power amp in the mid 70's, and included amplifier source impedance in their criteria. Bryston has also mentioned 5% in one of their papers.
Jerry
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