Bi-Wire Tuning


I'm wondering if anyone has experience tuning bi-wired loudspeakers with different sized wires in the high frequency and low frequency inputs. Does it work? If so, what sizes would you recommend switching to?

Basically, I'm trying to improve bass accuracy and overall soundstage/imaging on a recently acquired pair of towers that have four binding posts each for low frequency and high frequency inputs.

Here is the system:

* An older, high end Sony CD player
* Arcam A75 integrated solid state amp
* Nordost interconnects
* DIY speaker cables: Belden 5000UP 12 AWG with gold plated BFA and banana plugs
* Paradigm Reference Studio 100 V.2 towers

At first I used my old Nordost Flatline cables in single pair with the jumpers that came with the speakers. I liked the way they sounded but, partly owing to the room dynamics and partly to the two 8.5" woofers that handle the lows, found that the bass could overwhelm and subsume the mids and highs, especially in ensemble jazz and rock. To remedy the excessive bass, I experimented with speaker placement and decoupling the speaker feet from the floor with aluminum receiving cups, to which I later attached furniture floor sliders -- which to my surprise *dramatically* improved instrument separation and imaging. But the bass could still be overpowering at times, so I decided to try bi-wiring to see if I could improve accuracy and sound stage.

I made two 6' pairs of cables with Belden 5000UP 12 AWG wire. The Paradigms have separate crossovers for the high and low frequencies. The Arcam has two output pairs per channel that operate in parallel, so one pair in a channel goes to the high frequency binding posts on the speaker, while the other pair goes to the low frequency binding posts.

I do think the bi-wiring led to subtle improvements in sound stage, instrument separation, and bass accuracy, but I want even more. What if I went down to a 16 AWG (or something else) for the low frequency inputs, or even used 4-conductor wire from one of the amp outputs to the two speaker inputs? Is that likely to have a noticeable effect? Are there any rules of thumb for figuring out optimal wire thickness?

Thanks,

Jeff
jdrouin
I haven't tried different gauges but different brands. A long time ago I used Linn speaker cable for the highs and Naim for the lows and had pretty good success. If I switched them the bass diminished and the highs developed a harsher tone. I forget the models of the cables but they were the bulk cables available at most Linn and Naim dealers.
Jeff, Belden 5000UP is a stranded bare copper cable - the worse to use in my opinion. According to Audioquest thick cables produce skin effect that changes impedance of the cable with frequency. Skin effect starts at gauge 18 (@20kHz). In stranded cable current jumps from strand to strand to stay on the outside (skin effect) crossing surface of each strand where copper oxides are. Splitting cable into insulated strands will be the better choice but when strands are in magnetic field of each other skin effect is still the problem. For that reason cable companies use flat tape, flat wound wire or hellical twist on oversized hollow tube. Flat tape is thin defeating skin effect. Flat wound strands are only in magnetic field of neighboring strands. Twisting each wire with with GND (return) wire also reduces inductance. Hellical twist on oversized hollow tube is pretty much the same in different form factor.

I'm not sure if skin effect is audible, especially since tweeter's impedance goes up at high frequencies, but cable companies engineers know more on the subject while different manufacturers use exotic configuration to achieve the same.

Mixing thinner and thicker wires is often done in biwired cables (Audioquest), but thinner wires also have higher inductance. My Acoustic Zen Satori Shotgun have separate cables for Woofer and Midrange/Tweeter - both gauge 10. Hellical twist on hollow tube makes them almost an inch thick. Insulation of the cable is Teflon to reduce dielectric absorption. It uses 6N zero crystal copper.

Biwiring supposed to reduce effect of EMF from one speaker to another that still exists in spite of crossover filters. Some speakers show great improvement with biwiring while others show none.
Have you experimented thoroughly with speaker positioning? You'll get more noticeable results by moving the speakers a few inches than you will by varying cables. Especially for a speaker with the bass output of the Paradigm Studio 100.
Jdrouin, I'm using cables that have 2 different thickness on my Apogee Slant 6s in bi-wired form (as spec'd from my provider), and yes they made a difference and I have done a bit of what you've also said. The biggest way I have found to help is with room treatments as opposed to making wire changes. Right now I'm using 6 Room Tune floor standers, 4 corner Tunes and will be continuing to experiment with more (possibly), this has made a HUGE Difference! I've invested hundreds of hours moving and listening but the results have been more than worth the time and investment, so you may want to consider that. I continue to read of fourm members that have had great success in doing this, of course this is my subjective opinion and I hope that what I offer is of help.