[Vintage-Audio] Stylus Feedback? Why?

Wed Jun 24 17:33:09 EDT 2009

Couple possibilities.

One is location of the speaker with respect to the turntable, but the most 
probable is that the Lansings are flat. Typically mediocre or poorly 
designed bass reflex speakers try to get some modicum of performance out of 
the low end by resonating the box at some frequency below the natural 
resonace of the speaker itself and thus drag the whole thing to do something 
at the lower frquencies. Usually it makes a hump of several dB in the 
response and maybe your "weaker" speakers have this hump up around 60 Hz. 
I'll wager that the JBLs are flat to 40 Hz within a dB in spite of being of 
the bass reflex genre. Lots of bass is good only if it is coming from the 
music and not from the system.

Another bad habit of bass reflex systems is that they tend to cause the 
woofer to double or tend to enhance the second harmonics of the bass notes. 
This too makes sound that is not in the music. This is one habit not enjoyed 
by the acoustic loaded speakers.

Along these same lines, the masteringers of the music also tends to either 
remove the very low notes as they cause overloads in the vinyl by making the 
grooves run into the next groove (so the variable groove recordings were 
invented) or in analog tape, the bias saturation is more obvious. Now in the 
modern "music" they enhance the bass to be sure to get the approriate amount 
of distortion as that is what makes the car windows break and the teenagers 
to have a unique identitiy in the nighborhood. Pain is more important than 
fidelity.

WBob

----- Original Message ----- 
From: "Duane Fischer, W8DBF" <dfischer at usol.com>
To: <vintage-audio at mailman.qth.net>
Sent: Wednesday, June 24, 2009 2:05 PM
Subject: [Vintage-Audio] Stylus Feedback? Why?

>
>
> Hi All,
>
> Several days ago while I was experimenting with different bass, midrange 
> and
> treble settings for my B&W 630 three way monitor speakers, that I 
> sometimes
> blend in with my James B. Lansing Century L-100 ceiling mounted mains, I
> thought that I heard a rumble coming from a source other then my stomach!
>
> Hark! Was that an electronic Harpsacord or just another harmonic caused by 
> a
> Gamma Ray rebounding off that atom smashing thing in the Ann Arbor, MI 
> home
> of the University of Michigan Physics lab where someone got their 
> doctorite
> by discovering that "Wilson-Phillips" could not sing! No! It was coming 
> from
> the eight inch active poly ... some kind of thing woof woof wanna be cone
> three feet to my right.
>
> I got up off the carpeted floor where I had been squatted down doing the 
> IHF
> +/-2 Db adjustment procedure and switched over to the ceiling mounted JBL
> Century L-100's. No rumble, Rumba or other residual reverberations. So 
> just
> what was giving the B&W 630 high frequency bi-wired monitors that rhythmic
> distress?
>
> The Shure diamond stylus was picking up a rumble from the Sony/Marantz 
> 5520
> turntable, amplifying it and causing audio distortion. Frankly, it sounded
> to me as if I had somehow enhanced a turntable drive mechanism rumble
> feedback loop, but only in the one set of speakers. It seemed to me that I
> should have had the rhumba rumble in both sets of speakers.
>
> As Maxwell Smart used to say; "Missed it by that much!" Which explains why
> Secret Agent #99 never became pregnant! (LOL!) It scares me to ponder what
> might have happened if old Max might have hit the target!
>
> I did a little reading in my previously created audio research note file
> circa 1999 and found out that the James B. Lansing Century L-100 speakers
> were low efficiency and that the B&W 630 speakers were high efficiency. A
> concept that I am still not sure I fully comprehend yet today! One of 
> those
> "low" is really high and "high" is actually low cosmic time space
> dimensional shifting event horizon things where one is correct if the
> velocity of light is positively accelerated by the density of a Black Hole
> that is not a hole, but a round sphere that is invisible because of the
> Black On Black optical principal or negatively accelerated if the universe
> is truly infinite and time never ends! No wonder our children can not tell
> what time it is on a watch or wrist watch having moving hands!
>
> So more continuous RMS (What the Hell is Root Mean Square all about 
> anyhow?)
> is going to the B&W 630 speakers and less to the JBL Century L-100's? But 
> if
> the volume control knob is in the same position for both speakers at the
> same moment in time, how can that be? Maybe it has something to do with 
> the
> Metric System! I've always been suspicious about people who called money a
> "pound", when a pound equals sixteen ounces, unless it is a prescious 
> metal
> pound and then is has only twelve ounces! Then they call a "meter" 39.2
> inches and the car windshield a "windscreen"! Someday someone is going to
> make a lot of Yen, Yuro's, Pesos or Ben Franklin's by announcing that the
> real secret hidden in the King James Bible, U.S. Declaration Of
> Independence, ceiling where that famous inventor - painter of nude women -
> gear reduction thing with a big spring that kept time, the day of the 
> week,
> the month of whatever year system was then in use, predicted famines and
> plagues and wars and plagues of Turtles with an image of Susan B. Ugly
> Anthony on their backs ...Discover that it is really the Metric System 
> that
> killed off the Dinosaurs, wiped out the Inca's before the Spanish did and
> tried to cheat the Mayan Indians out of leap year was not the Da Vinci 
> Code,
> but that damn Metric System!
>
> Sorry about that. I just hate it when the deserving person, be it for good
> or evil, fails to get his or her dues because some so called Greek 
> Scholar,
> American archieologist, Soothsayer, cosmic visionary who causes Bald 
> Eagles
> to grow hair on the sixth Thursday of any month with three full Moons etc.
> All because they can not spell on a stone tablet, parchment scroll, chalk
> board, mechanical typewriter or word processing computer program where 
> they
> click the mouse and it fixes all of their flaws!
>
> So tell me, please! Why do I get a sixty cycle hum from the B&W 630 
> speakers
> when the Shure stylus tracking at 1.25 grams is playing what is hiding in
> those deep dark vinyl grooves and only the sound of silence from the JBL
> Century L-100's? Is it the Simon and Garfunkle effect?
>
>
>
>
> Duane Fischer, W8DBF - WPE8CXO
> E-Mail: dfischer at usol.com
> Hallicrafters web site: www.w9wze.net
> HHRP web site: hhrp.w9wze.net
>
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