Well one last reply now that this has become somewhat interesting. Here's
what I do in modding a speaker:

I usually replace areas of the electrical pathway that I would deem possibly
significant in reducing series resistance. Unless the internal wire is say
18 or 20 guage alloy wire, I don't worry about it too much although when in
doubt my standard 14 guage OFC is always more than good enough. PCB's and
high Rdc inductors I remove/replace as policy. The difference heard in
overall bass tightness at low frequencies is always significant and usually
very pronounced. Customers tend to love this difference especially if the
overall series resistance to the VC is cut by 40% or more. Obviously I don't
do this blindly without response compensation as previously stated. For
example, the Joseph Audio infinite slope filter models (at least from 3
years ago) have close to 2 ohms of series resistance and in one experience
benefited greatly from a complete simpler filter redesign with much less
series resistance. Tweeters, particularly older un-chambered high fs models,
seem to respond to beefing up the ground if it appears to be lacking and if
the corner freq is not on the high side. (you see this often in KEF and
B&W's from the 80's and early 90's) which I believe is the same principle at
work.

Replacing series electrolytic cap's with an appropiate film type,
particularly the older rough foils ones in any HP circuit, is subtle but
usually absolutely worthwhile. This is particularly audible when listening
to high frequency transient signals in mono. (Yup mono, IMO the center image
in mono is a great addition to evaluate overall imaging properties, but
maybe this is general knowledge, I don't know) I also really like MOF
resistors. As a rule I replace the whole crossover and give the complete old
unit back as a back out guarantee but usually ends up as a souvenier. The
new hardwired filter is in general overall improved even if fundamentally
unchanged in total response. Impedance compensation to a near resistive load
has been proven to be interesting to tube amp owners who have low power or
little to no negative feedback.

Then there is the cabinet and low frequency system itself. Often there is
alot which can be improved on the inside and outside and if desired you can
sometimes grant a wish to the owner to change the tuning profile of a vented
system to help aleve a deficiency or problem, often in combination in their
listening environment. I pay attention to many details here which
cumulatively can become extensive. Increasing Qp and Qb in vented systems if
possible is usually worthwhile especially if highly lossy to begin with. A
very over diffractive acoustic field in and around the front baffle
(including a highly diffractive grill) is usually also worth tending to and
if replacing the baffle anyway for this, improves cabinet mechanical
stability. All of which can be done without changing any fundamental tuning
parameters by compensation if the preservation of the personality of the
loudspeaker is an objective. Obviously a bit of the character will always
change somewhat in the process but not to its detriment overall.

"Dick Pierce" wrote in message
...
Stewart Pinkerton wrote in message
news:WitYb.51895$uV3.103980@attbi_s51...
On Mon, 16 Feb 2004 18:18:27 GMT, "Wessel Dirksen"
wrote:


This is what I was referring to with the "ask an amp guy" line. And may
perhaps explain why beefing up the ground connections to a loudspeaker
driver tends to improve overall damping properties.

This is not true - I'm an amp guy......... :-). Electrical damping is
only of relevance *below* the fundamental resonance of the system,

No, this is most certainly not true. Damping is most significant
AT fundamental resonance. Why? Because this is the point where
the system is storing the most energy, it is the frequency at
which the total system losses are most significant, since it is
those losses (all of them) that determine damping. Above resonance,
the system is mass-controlled. Below resonance, the system is
stiffness-controlled. At resonance, it's resistance controlled.

Now, that being said. the notion that "beefing up the ground
connections tends to improve overall damping properties" simply
does not hold at all under scrutiny, UNLESS the ground connections
are som abysmally bad as to be a significant source of the total
system loop resistance to begin with. And, if that's the case, the
system is broken.

TO explore this requires us, once again, to dispell the myth of
"damping factor." The damping of the system is essentially a
measure of the energy stored to energy dissipated through loss
mechanism. That energy storage is greatest at resonance.
Remember that the energy stored in the moving mass goes as
velocity squared which goes directly as frequency below
resonance, and as the inverse of frequency above resonance,
and in a stiffness, it goes as excursion squared, which is
constant below resonance, and goes as in inverse square above
resonance: combine the two, and we find that energy stored is
maximum AT resonance.

There are three basic means of dissipating this energy, removing
it from the resonant system and thus damping the system: energy
can be removed through the resistive part of the radiation
impedance, i.e., we do work on the air and it makes sound. It can
be removed through mechanical friction in the surround and spider,
or it can be dissipated in the effective total series electrical
resistance. I state these in increasing order of importance: by
far, the LEAST amount of energy is dissipated by producing sound,
typically less than 1% in direct-radiator loudspeakers. The
mechanical damping comes next, and is on the order 5-25% of the
total damping. By far, the largest portion of the energy dissipation,
or damping, in speaker that have any pretentions is electrical.

Now, that may SEEM to be arguing FOR "beefing up the ground
connections" and rewiring the two feet of wire between the
crossover and the driver, BUT, such notions ignore the fact
that BY FAR, the single LARGEST resistance in the ENTIRE loop,
by an order of magnitude and most often much greater, is the
simple DC resistance of all that wire in the voice coil.

Unless those whimpy ground connections and that awful ordinary
wire from the crossover to the drivers has a total loop resistance
that is significant compared to the DC resistance of the voice
coil, beefing them ground connections and replacing that awful
wire, WILL NOT change the system damping in ANY significant fashion.

I now realize that I had given the wrong impression in this thread in
that I
never intended to imply that there was any kind of voo-doo involved,
only
that electrical conduction is more that just connecting the dots and
measuring the impedance factors between those dots. I was not under the
impression that electrical conduction was actually measureable at this
level
yet.

Actually, it's been measurable at this level for more than 30 years.

Try twice that long!