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River Cable Flexygy 8 Overview and Metrics


It is refreshing to discover esoteric cable companies such as River Cable that don’t promote snake oils or nonsense. Sure, their products are pricier than the cables you will typically find at your local home appliance store, but then again, the Home Depot 10AWG Zip cord doesn’t come dressed up in such nice clothing nor sport compression banana terminations.

In “straight” configuration, the Flexygy 8 is an 8 conductor (4 paralleled hot and return wires) with an aggregate gauge of 7AWG and effective gauge of 10AWG. You can also opt for bi-wire configurations where each pair has an effective gauge at each speaker terminal of 13AWG. I prefer to use a high quality single wired solution as opposed to a bi-wired one. Bi-wiring offers very few advantages over single wired solutions, but typically several disadvantages such as doubling of pair to pair capacitance seen by the amplifier, increasing cable costs, and furthering cable clutter by doubling up on your cables to each speaker. Personally I don’t subscribe to the bi-wire craze that some audiophiles tend to, but then again, I also don’t believe in magical CD mats or soaking your cables in kosher chicken fat blessed by a Rabbi before hooking them up to your stereo system. Thus I elected for my review samples to be “straight” single wired runs. River Cable offers the choice of banana or spade connectors. My preference is for banana assuming they are of good design.

Finding a banana plug to snugly mate with my beloved Status Acoustics Decimos has always been a challenge to say the least. The binding posts Status Acoustics choose on this product tends to cause lesser designed banana plugs to slide off or connect loosely to the speakers. River Cable has the perfect solution for all of their speaker cables. Their adaptable banana plug can accommodate pretty much any binding post out there. All you have to do is keep twisting the terminal until the banana plug firmly connects to your amp/speakers binding posts. Once tightened, I was unable to pull the cables off of my speakers or amp. Having a solid termination is critical to minimizing contact resistance. I have seen far too many poorly designed spade/banana plug terminations used by exotic cable vendors that simply added more series resistance to the product then they were allegedly trying to minimize in their cable design. I consider this counterproductive and it appears River Cable is in agreement as evidenced by their adaptable banana plug termination which is now popularized by many of the better cable manufacturers out there.

Birth Certificates Aren't Just for Babies!

birth certificateWhile some may think it’s a bit quaint to include a birth certificate along with the cables, I felt it was a nice touch - especially considering so few esoteric cable companies actually bother to measure, let alone test, their products. In contrast River Cable does this with all of their cables. Many cable companies simply don’t have the proper equipment or know-how to do so. Even more of them place very little weight on measurements and perpetuate the philosophy that you can’t measure performance. We often refer to these people as cable soothsayers. Regarding cables, they couldn’t be more wrong.

Most of the specs on the back of this birth certificate validate continuity and physical condition. It appears they were mostly taken for quality control to ensure continuity. Their website does list the following cable metrics which are essential in gauging cable performance.

River Cable Flexygy 8 Published Metrics:

  • Capacitance: 10 pF/ft
  • DC Resistance: 0.003 ohms/ft
  • Velocity Factor: 0.87
  • Inductance: 300 nHy/ft or .300 uH/ft

The capacitance specification is unusually low and the thought of high inductance immediately popped in my head before reading the rest of their specifications. As we learned in our article Calculating Cable Inductance in Speaker Cables and Dielectric Absorption in Cables Debunked, inductance and capacitance values are interrelated and based on the dielectric and conductor spacing between the (+) and (-) conductors.

Though the inductance is a bit higher than I’d like to see in cables, there is merit in producing ultra low capacitance and low resistance cables. These are the type of cables best suited for long runs to minimize resistive losses and amplifier stability issues of marginally stable amplifier designs. It’s particularly important to use low capacitance cables when powering ESL type speakers on tube amps. In this instance, the Flexygy seem to be the most appropriate cable design I have seen commercially produced.


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