MIT cables: the details - excerpts from Brisson interview on Dagogo

I'd like to throw in some more technical details on MIT cables. Below are two links of Bruce Brisson's interview on Dagogo, where you will find some juicy details.

Part 1 http://www.dagogo.com/the-bruce-brisson-interview-part-1 and
Part 2 http://www.dagogo.com/the-bruce-brisson-interview-part-2

Points of interest:

1) I've said a number of times in the past that, based on the patents, they attempt to keep the voltage/current phase relationship at various frequencies as close to ideal (-90 degrees) as possible:

Q: It has been said, “There is no free lunch.” The same would apply to a system which stores and releases current and voltage. Have you determined a measurement of inefficiency of the networks, i.e. loss of power through the storage and releasing of current and voltage? If so, what is that relationship and your thoughts about it?

Brisson: All electronic systems or networks store voltage in their capacitance and current in their inductance. Measurements such as the ‘Q’ or quality, the DF or dissipation factor, or the loss tangent of the component are used to quantify electronic parts such as capacitors and inductors. The loss tangent, as an example, is the tangent of the phase angle relationship between the capacitor voltage and capacitor current as the angle departs from the anticipated, or the theoretical 90 degree value.

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Brisson: MIT simply installs networks that store Voltage and Current linearly, over a definable or preset range of frequencies. This way, when the cable is stimulated with a complex tone that contains a wide range of frequency components, the cable will ‘articulate’ the ‘same’. Why? Because it is delivering back to the cable, the ‘same’ amount of energy from the network to the load that was delivered to the networks from the source. This energy is now called a pole of in-phase power, and it can now be transported to the load to perform work.

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2) How are the "poles" connected:

Brisson: The interconnects and the speaker cables employ an array of networks in parallel to the cable’s unbroken conductor, or hot to hot legs, that store and release energy from the capacitors and inductors as in-phase power. We have technical papers on both of these applications on our MIT web site that your readers can download and print out and read if they wish.

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I think I am reading that correctly, the networks are in parallel with the individual conductors, not the hot and return.

Contrast this to how the power cords (or even my Z-Strip) are constructed:

Brisson: The AC power cords, which are actually poles of attenuation, simply employ an array of low impedance filter poles in parallel, across the hot and cold legs that first absorb, and then turn undesirable noise into thermal heat.

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On the Poles:

Brisson: In summary I found that I could now measure a ‘Pole’ of power at some ‘arbitrary’ frequency within every cable. We also found that by adding specially engineered networks we could add additional poles of power at ‘other’ frequencies. Adding additional poles of in-phase power allowed us to achieve a ‘flat’ In-Phase power curve and the cable would then ‘articulate’ the same at any frequency.

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3) Can the networks add noise? Why do we consider the SL line inferior?

Brisson: If the power factor compensation network was built using inferior parts, with poor phase angles, and the power factor was just about 1, then you would certainly degrade the performance of the audio system by injecting back into the system another form of noise.

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The key here is the highlighted section: inferior parts (as suspected in the SL line) will add their own V/I issues, effectively not correcting what they attempt to correct as well as superior parts would.

4) What does the impedance switch in the interconnects do?

Brisson: Generally speaking regarding interconnects Doug, impedances that are too high for a given cable will roll off the highs and diminish transients, while impedances that are too low for a given cable will emphasize the highs as well as their associated transients. Audiophiles would be much better off using short interconnects and long speaker cables, particularly when interfacing components with high impedance balanced inputs.

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And is the underlined claim audiophile anathema?

More on impedance:

Brisson: The loss of overall system bandwidth, and associated transient response, along with a skewed articulation response are most commonly found in high impedance applications. The input and output impedances associated with an audio systems front end are much, much, higher than the impedances commonly found between the output impedance of an amplifier and the input impedance of speakers. Low impedances allow one to manage the system bandwidth, transient response and articulation response much easier than via high impedance front ends.

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5) Does input/output impedance matching matter (and he refuses to actually say how they implement it):

Q: I have heard and seen discussion of Impedance matching (output/input) being the “last (foreseeable) frontier” in component design, that being the still existing need to match impedance between components, i.e. preamp and amp, for best results. Is MIT claiming that the impedance of a component’s signal output can be effectively changed through the use of the Impedance Selectable IC’s?

Brisson: Properly matching impedances between the outputs of a component to the input of the next component of any audio system is very important, Doug. I believe that MIT has been doing this for well over ten years now, maybe fifteen?

I think what we are claiming is that the outputs and inputs of the associated hardware being interfaced into a system can be ‘optimized’ to reduce various forms of audible distortions as I discussed in my answer to your last question.

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6) But is impedance matching really that important?

Q: Please rank: Articulation response, conductor material, geometry, impedance.

Brisson: Since the articulation is linked to the ‘systems’ impedance found with every interconnection, I would then have to rank Impedance number one (1) and articulation number two . However, since they are linked together, and function as one, then I will rank them together as number one (1). I would then rank the quality off the capacitance number two (2). We spec a Dielectric Constant (DK) of under three (3) for low to moderate priced cables, and a DK of around 2.1 – 2.3 for high end cables, and our reference cables use DK’s well under 2.0.

I would then rank conductor geometry and conductor material as four and five

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7) What? No 6- or 7-nines copper?

Brisson: I will categorically state that 3 – 5 nines are all that is required for high end audio. I am not stating that you can’t hear the differences in a purer conductor; I am simply stating that it is more optimal, more accurate and much easier to correct for those distortions using other much more practical methods that also happen to be more reliable and accurate.

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8) Can we explain this Articulation in every-day terms?

Brisson: take my Audi RS6, which is equipped with a twin turbo charged V8 that puts out approximately 450 horsepower and 415 lb-ft of Torque. If we divide the torque by the horsepower, we get a drivability factor of 92.2%. In addition, the torque is pretty much a flat curve from around 1,950 RPM to just about 5,500 RPM. If the drivability factor is 92.2%, at each and every RPM between 1,950 RPM and 5,600 RPM’s, then the car will respond the same way each and every time I depress the accelerator pedal.

Simply put, I have done the same thing with our cables. Our best cables will deliver around 50% articulation over a very, very broad range of frequencies, from somewhere around a fractional Hertz (less than 1Hz) up to around 150 kHz. This means that whenever the cable is stimulated by a complex tone containing a wide range of frequencies, the cable will deliver all of the frequencies contained within that tone with the same articulation... There are reasons for the 50% reference line, but I am not able to go into those reasons yet as I still have other patents pending.

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Please refer to the original full interview for further information.

And finally, MIT's video (cross posted in another thread):

It is becoming even clearer to me that the MIT cabling requirement for Spectral - well beyond the stability they bring to these unfiltered designs - is that, most likely, they want to preserve the extreme linearity found in Spectral products (and for which they work so hard to achieve) in the cables. As such, a number of other cables can probably provide stability, however, they will not make Spectral sound right. It has been said a number of times over the years that a lot of people have tried other cables, and their Spectral just don't sound as good as with MIT; yet others, disagree. The data, though, favors the Spectral/MIT approach. I would say, not worth fighting it.