Archived from groups: rec.audio.tech (
More info?)
In article <1112394887.468090.248090@l41g2000cwc.googlegroups.com>,
dpierce@cartchunk.org says...
>
>No. because, as I said there is no one "expression."
Sorry, but you are wrong. Mechanical power factor is simply the
ratio of mechanical resistance to mechanical impedance, i.e.
PFmec=Rmec/Zmec. This is made clear in chapter one of
"Fundamentals of Acoustics" by Kinsler et al.
>It all depends upon the specific details of the model.
*All* worthwhile models should have a derivable mechanical
resistance and mechanical impedance.
>Instead, I provided you with almost the entire means of getting
>the frequency-dependent mechanical power factor.
Thank you, but details were not clear, and you clipped them out this
time around. My interest was in expressions for PFmec using parameters
other than resistance and impedance.
>If you want to take a given model and dervice an expression from it,
>go for it. It's not a trivial excercise given the complexity of the
>model. Essentially, you have to dervice the complex transfer function
>for the mechanical portion of the model, and solve it for phase vs
>freuqency.
>
>If you're looking for a single number that says "the mechanical power
>factor is x", forget it. There is no such single number. It is, in the
>simplest of models, a co,pex frequency-dependent function. You can get
>a single number.
>
>Now, when I asked why you wanted to know this, being told that
>you're writing an article doesn't tell me much. The question is, why
>do you think this information is important, in the sense that there
?might be a better way of trying to understand what you're doing.
>
>In other words, what use is having a numver, frequency dependent as it
>is of mechanical power factor?
Having PFmec makes the derivation of many other parameters simple
and intuitive. Sometimes an angel resides in the details as well
as the devil.