The AM Forum

I know that some people are much more sensitive to low frequency sounds than others. For example, Steve (WA1QIX) has told me that he really notices the absence of modulation frequencies below 50Hz in my signal when I use my Orban audio chain. [The programmable HPF in the Orban 9200 does not provide any selections that are lower than 50Hz. even though it is designed for professional broadcast AM]. He much prefers my other audio chain [Symetrix 528e].

I can hear the difference in my off-air monitor... but I don't have a preference for one or the other.

Nick (KG2IR) prefers the sound of the Orban audio chain.

So....

If I assume that audiophiles (at least those who actually have good hearing) are sensitive the low frequency qualities of the audio... then I suggest the following as a possibility

Magnostriction in composite audio cables:

As I understand it... the expensive audio cables that audiophiles favor contain numbers of wires fine wires that can move relative to one another in the radial direction.

Currents flowing in these wires will create magnetic fields that (depending on the composition of the wires and the overall cable structure) might cause the cable to expand and contract radially (by a small amount).

At low frequencies, where the cable length is comparable to the acoustic wavelength (100Hz ~ 10 feet), and where the mechanical time constants of the cable allow for more movement... the cable might act as a distributed speaker.

Furthermore... it is conceivable that a brand new cable would expand and contract more after it is "broken in" [Just like a new pair a shoes or boots can be a little stiff until you break them in]

Has anyone read any experiments to test whether magnetostrictive effects are turning these types of cables into distributed speaks that produce sound qualities that audiophiles prefer?

Stu

Years ago we went through a number of tests to see if litz wire was better in switcher transformers for shin effect. In the end the extra copper of solid conductors won due to heat transfer effects.

Stu,

Probably the best place to go to suggest this idea is http://www.diyaudio.com

I'd suggest that you post it there - you are very very unlikely to get any frivolous replies there, and there are some very smart and experienced people there...

Magnorestricition is known, but the question remains as to how this mechanism in a given cable of a geometry not prone to produce electrical variation would operate?

Wire "effects" are reported in cable geometries where in the example of speaker cables the two conductors are not physically associated with each other by mechanical connecton... so are you proposing that wires that are in parallel running the same signal would produce a magnorestrictive effect WRT each other, and that this would in turn develop signal in the conductors?

And, in addition it is generally accepted that the place where "differences" are heard is in the HF not the LF spectrum... of course that does not prevent an effect generated by LF from producing HF "distortions"...

                 _-_-bear

If you are suggesting that the mechanical expansion and contraction of the cables is generating acoustical sound that might affect what you hear from the speakers, it should be a simple matter of replacing the speakers with an equivalent resistive load to see if you hear any sound coming from the cables.

Don

Yes... the effect I am speculating about would be easily observed (at least with test equipment: microphone + amplifier + oscilloscope scope) if the speakers were replaced with a dummy load.

Bear

"...so are you proposing that wires that are in parallel running the same signal would produce a magnorestrictive effect WRT each other, and that this would in turn develop signal in the conductors?"


While I wasn't thinking of the phenomenon you mentioned above (quote)... I believe it is worth some further thought (on my part). I'll get back to you on that.


Stu

wheeeeeewwwwww uuuuuuuuuuwwwwwwwwww wwwwwwwwwweeeeeeeeee "Jed Clampit" 1960somthing

Stu with all due respect I think your time, talents, and intellect are far too important to squander on such research.  Please devote more time to quantum mechanics, Gnome research or  .... wait for it.... which came first the chicken or the egg.

All kidding aside Stu most of the group hear suffer from a condition known as   C.H.S anyway.  Its probably not that critical.
besides that they probably cant even pronounce Magnumerctionism anyway