Re: Don, Noons: TIF v. JPG. More samples.

Recently, Colin D <ColinD@xxxxxxxxxxxxxxxxxx> posted:

Neil Gould wrote:

Recently, Colin D <ColinD@xxxxxxxxxxxxxxxxxx> posted:

Neil Gould wrote:

Recently, Colin D <ColinD@xxxxxxxxxxxxxxxxxx> posted:

For your >40 years of experience, you don't come across as knowing
much about amplifiers.

Having designed and built many "good amplifiers" over the years,
I'm comfortable with what I know about them.

Yes, you probably are. But I see from another post of yours in this
thread that you are a long-time guitar player/musician. That's
fine, but that's the field where you can claim to be professional,
not electronics.

Rather than toss insults, perhaps it would be better if you spoke of
something you know of? From the period of roughly 1968 through 1990,
I earned my living designing, building, and selling pro audio,
video, and sound reinforcement systems. During that time, I was also
a dealer for EV, Altec, JBL, BGW, and other high-end products and
over that period also owned two recording studios. From your
childish need to insult and present multiple erroneous yet
obfuscating conclusions, my guess is that you haven't been alive as
long as I've been in business, so your opinion about my
"professional involvements" and/or education are fairly irrelevant.

You are as wrong there as anywhere, Neil. My para. above was a
deduction from one of your other posts.

Another *incorrect* deduction, Colin.

It is not, and was not
intended to be, an 'insult'. Musicianship does not confer electronic
qualifications. Neither does being a dealer in numerous makes of
gear.

I agree, and an EE doesn't make one proficient in pro audio, even though
the basic electronics should be well understood.

A direct question: have you any formal qualification, trade or
tertiary training in electronics?

Why, yes, I do.

I have both trade and tertiary
qualifications in electronics, gained when it was normal to work down
to component level, not board changers and chip users as many are
these days.

Well, as I started in the late '50s with short wave radio, it wasn't

Also, your guess as to how long I have been alive is wildly astray as
well, and for that matter bears no relevance at all to my opinion.
Going by your dates of 1968 - 1990, you are likely a bit younger than
me. I won't see sixty-odd again, so you can work out how much
experience I have.

So, I'm wrong about that, and would appreciate the courtesy that your age
should bring. A valid point of view does not require insults or
presumptions.

Apparently, you think that 25A @
120V = 25A @ 12V. Since you're into "experiments", here's an easy
one for you: for which one would you let your body complete the
circuit? Try them both, and decide. ;-)

Of course I don't think that 25A @ 120V = 25A @ 12V, and that isn't
what I said. Reading your last paragraph, I get the feeling you
aren't too familiar with Ohm's law.

It is what you implied with your statement about power (W) that
ignored voltage.

It is *unnecessary* to know the voltage. See below.

The simple fact is that YOU brought up the power handling
capability of lamp cord as a reason not to use it as speaker cable,

That was a secondary reason. The primary reason, which started this
discussion, was the resistance of speaker cable compromising the
amplifier's ability to control the speakers.

Except for two things:
* The ability to control speakers _accurately_ is a matter of being able
to deliver the necessary _voltage_ to the speaker.

* The ability to deliver the necessary voltage depends more on the
efficiency of the speaker than the damping factor of the amplifier. Most
decent audio amps will have a sufficiently low output impedance to provide
adequate voltage to control a reasonably efficient speaker, but that is
only one factor, and while the damping factor may be somewhat useful to
compare amps "on the shelf" if comparative data is also supplied, it's not
a very useful one in determining the performance of a system because
speakers are not pure resistive loads and vary widely due to many factors,
including the type of enclosure used.

so
that was germain to the point I was addressing, while Ohms law is
not. As watts can be computed more directly by W=V*A, doing so might
have exposed your erroneous thinking sooner and saved you from
making yet another incorrect assertion.

That 'assertion' was a mistake that I realized, acknowledged,
corrected, and apologized for. For your part, you simply accepted my
figure of 25 amperes without realizing it must be wrong.

I simply didn't throw it in your face before, as it didn't affect the
point at hand, which was your statement about the power handling ability
of lamp cord in an audio application.

Throughout this discussion, your assertion has remained that speaker
runs typical of home audio -- e.g. those of less than 20' -- can
result in an audible impact due to cable resistance of >=18 Ga.
lampcord, which is an absurdity.

It is measurable on an oscilloscope. Considering the lengths
designers go to to minimize distortion in amplifiers, usually
achieving less than
0.1% THD at full power *into a dummy load*, why would they overlook
measurable distortion from a speaker?

Well, that says a lot about your perspective, anyway. Typically, a dummy
load is simply a resistor capable of handling the power from the
amplifier. Surely, you realize that this in no way emulates the
characteristics of a speaker; that a speaker's impedance can vary widely
depending on such things as where the cone is and where it has to be next
to represent a waveform accurately?

The performance of a particular speaker/amp combination can certainly be
plotted, but it won't provide much useful information about other speakers
with that amp, or other amps with that speaker. IMO, the impact of short
runs of lampcord is so far below those variables as to be a non-issue. On
that last point, we may agree to disagree.

Neil


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