[RFI] NOISE GADGETS

[EDWARDS, EDDIE J]

After thinking this through after hitting send, the equation Z = sqr
root of (R-sqrd + X-sqrd) comes to mind so the DC resistance does
influence Z.  And changes in Z could impact frequency response.

However, would changing from 16 gauge to 12 gauge for short runs be a
significant enough change in DC resistance to affect the bass in an
appreciable way?  Particularly if Z is 8 ohms?  I guess I'll have to run
the numbers later sometime to see for myself.  

This could explain the "mushy" sounding bass range at a Chicago (the
group) concert back in the 80s.  All this time I blamed it on the fact
that the sound person was a woman and wasn't able to hear low freqs the
way I was hearing it.  

Thanks for the discussion Jim.

73, de ed -K0iL

-----Original Message-----
From: rfi-bounces at contesting.com 

On Wed, 10 Nov 2004 09:32:08 -0600, EDWARDS, EDDIE J wrote:

>So my question is:
>How does the change in DC resistance due to beefier cables affect the
>bass frequencies?
>
>First your saying there's no transmission line behavior due to the low
>frequencies used, then you're talking about damping factor which
implies
>an impedance characteristic is in play.
>
>I always thought that as long as you had a large enough conductor to
>handle the power levels (with some safety margin) you were OK (thus the
>Monster Cable guys are full of it).  But you're saying there is some
>sort of impact to low frequency response based on the DC resistance?  
>
>Again, I'm no audio guy, but I'm having trouble putting this altogether
>in my head.  Thanks.

Read the parts of my original post about the woofer "flopping around" if
there is too 
much resistance between it and the power amp. It is NOT transmission
line behavior at 
all, but it IS a simple, lumped parameter, analog circuit excited by a
(very) complex 
waveform.  The power amplifier can be thought of as a constant voltage
source having a 
VERY low output impedance (a tenth of an ohm is typical). And the woofer
has rather 
complex electrical equivalent circuit that relates to its mechanical
properties and 
includes L's, C's, and R's both in series and parallel. It can be
analyzed as a simple 
transient problem -- you excite the woofer with an impulse through the
resistance of that 
wire. If the resistance is large, it will ring (flop around), but if it
small it won't, because the 
low source resistance will damp it.  

There are many excellent engineering texts on loudspeakers if you want
to learn more.

Jim

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