The Talking Machine Forum — For All Antique Phonographs & Recordings

larryh wrote:I have never been a fan of seeing the lid up when the records are in play due to the distortions that generally come from the diaphragm or reproducers, or so I thought. But as I have played though many records now I am finding that with the lid up I get very little of that feedback effect. Maybe someone will have a different view but I am only guessing that since the stylus is now reading the grooves well it is transmitting a clean sound it isn't producing that odd feedback to the reproducer? I know that its clearer because I always would shut the lid so as to not hear that feedback sound. Now there is very little of it. Only places I have heard it was on a record that simply was too worn to play totally clearly which would seem to go along with that theory?

Larry

I suppose that is possible. I would generally close the lids on my phonographs in order to block some of the surface noise and the sound coming from the other side of the reproducer (like a two speakers playing out of phase). Of course, I didn't get to experiment too much with my c 250 before the Expert stylus failed, so maybe you were hearing something that I don't remmeber. Either way, it is good news that the sound has improved!

Well Larry, your observtion makes sense
considering that these new Bruce diamonds
are close to exact copies of the Edison
orginals, not some cheesy modification made
as was done on the "brand X" imitations which we all know and love so well.

Which brings to mind a question I have for
the forum, which has been bugging me now
for a long time about these DD styli.

Diamond is by far the hardest, toughest
substance known to man. Indeed, in a machine
shop, a diamond tipped tool is used to dress
grinding wheels to keep them flat and true
for sharpening cutting tools for the various
machines. One of these diamond-tipped
grinding wheel dressing tools can serve for
a very long time without having the diamond
get wrecked.

So, how can it possibly be then, that a diamond riding over a smooth, soft, phenolic
resin disc turning at a slow, slow 80 RPM
can be damaging any diamond?

Something just does not add up there, to me,
at all. Can anyone explain why in one situation a diamond works so well under
extremely harsh conditions, and then there's
a much less severe case (the DD situation)
which seems to produce damaged diamonds at
the slightest little flaw in a record.

Something is missing there, and I would like
to know what it is.

Any ideas?

Chuck

Chuck,

I believe that this came up recently on the board. The way I recall the answer was something to the effect that although diamonds are the hardest material, that doesn't mean that they won't split or chip under a blow. It was pointed out that is how they make diamond rings to have all those shiny facets. A blow in the right place and you have a clean break. Also the tendency of some arms to fall on their own due to a worn lifting rod support can also possibly cause damage. So when the diamond plays on a smooth undisturbed surface of a good record a good quality stylus should last a long time. Although they too will wear over time and have. But a split in the lead in or scratches more than mere surface types or dimples or holes from stylus being dropped on the record can cause the diamond to have a blow to it that can chip it. If you think about it isn't mica a form of split hard material that breaks along a seam in the material?

I may be somewhat off in my idea but I tend to think that its close to what I have read.

larry

Well Larry, that is certainly a partial
explanation. However, as was explained to
me by a jeweler, diamond is the only
substance which will cut diamond, so they
use diamond-dust impregnated stones and
polishing tools to cut the facets on
jewelry diamonds.

Mica is a whole different story. It is formed
in many, many extremely thin layers which are
weakly bonded, hence it can be easily split.

If diamond were so weak as to be easily
knocked to bits by the slightest blow, then
those machine-shop diamond-tipped grinding
wheel dressing tools would not last 2 seconds.

But the fact is they last for many years
and they are being ground upon by a carborundum grinding wheel!!!!

So, we have a smooth, soft, phenolic resin
disc turning at a slow, slow 80 rpm, which
damages diamonds at the slightest provocation,
and then we have diamonds which stand up
to a grinding wheel!!

Again, some critical piece or pieces of
information are missing from this puzzle
and I would very much like to have the
explanation. It defies logic, without much
much more information. It simply does not
add up.

Chuck

Diamonds are hard, but brittle.

The durability of a piece of diamond in a particular application depends on the orientation of its grain structure. Edison clearly was aware of this because his styli have proven to be pretty durable for 100 years. But I suspect that Expert has not figured this out, or they don't know how to determine the grain orientation of their diamond blanks before they are ground. I would expect that Bruce is quite aware of this issue since they make diamond-tipped scribes which are intended to be durable when used for deliberately scratching on hard surfaces.

The ability of a phenolic DD record to chip a diamond is no mystery. It's not the phenolic of the record that is likely the culprit. All it takes is a minute particle of hard grit imbedded in the record surface to chip the diamond, especially if the diamond is not properly grain oriented. Tiny particles of hard grit are present all around us and are pretty likely to get mashed into the surface of a DD record with just one playing by the intense tracking force at the tip of the stylus. So a typical wiping off of the record surface with a record duster won't remove this imbedded grit particle. Then all it takes is the particular placement of the grit hitting the particular orientation of the diamond to cleave the diamond along its grain and chip it. And incorrectly oriented diamond tips are much more likely to suffer this breakage than properly oriented ones. Hopefully, Bruce knows how to orient the grain properly.

Thank you Gregbogantz, for that
explanation! It makes perfect sense, and
it explains everything.

Of course Edison would have done all the
experiments and figured this out.

Maybe the "Brand X" guys do not know
about this grain orientation at all.
I would bet money that they do not know
about it, and I would also bet money that
Bruce does know about it.

This explains everything.

Chuck

Another difference that may crop up between hobbyist/aftermarket diamond styli and the original Edison product may be in the original larger company's ability to throw out more unsuccessful attempts. Proper quality control is easier if you can afford to absorb the loss of bad ones spread over a large number of sellable styli. I've heard it said that the quality of the justly revered Leica lenses are due in a large part to the company's willingness to throw out any lens that isn't near perfect.

Trying to manufacture a stylus on a small scale is daunting in that each failed attempt kills one's cash flow and makes each subsequent one that much more expensive. That anybody would try do this at all is a testament to dedication and tenacity. Thank goodness that people like that exist!

- Martin

And now for something completely different.

Those of us who are perhaps too familiar with old Monty Python episodes are going to do a double-take when seeing the phrase "new Bruce" (viz. the episode when a fellow from England named Michael joins an Aussy philosophy department and has to change his name to Bruce "to avoid confusion" as all the other chaps in the department are named Bruce).

But seriously...

...the announcement of a new stylus has the Diamond Disc machine community celebrating. My guess is that an initial bunch will get their orders in quickly, while many of the rest of us will wait it out and then (if the positive reports continue to flow in) constitute a second wave of orders.

Remember the "Saturday Night Live" sketch some years ago, in which Dr. George Washington Carver died insane while trying to develop a phonograph needle from a peanut? I wonder why some folks on this forum haven't tried that...(and what am I implying here about their mental health?)

Ralph

Well my take on this new Bruce DD stylus is
this:

It is a brand new, "just released" product
which has not been tested yet. There are a few samples in the hands of competent fellows such as Larry H., who will be testing them.

Only by playing a few thousand Diamond Disc
Recreations, will the true, actual, real results be known. After those several thousand plays, then I will be very curious to
know what it does in a runoff test, and also
what it looks like under very high magnification.

In addition to this very stringent field-testing, my own personal take on it is that
all of the technical documentation and
engineering information should be released
for public review by Bruce and by those who
have been working on it.

I want to see all of the technical details
of this, along with engineering drawings
of the profile, and a complete explanation
of how the diamond is mounted, how the grain
is oriented, how it is polished, what the
surface finish is in microns, etc.

Only by releasing this info for public review
can anyone make a fair comparison with the
"brand X" ones which are now out there.

It would be great to have comparitive technical documentation of "Brand X's"
methods versus Bruce's methods.

Because, as I see it, if this new deal
is really any good, then the makers will be
so proud of it, that they will be more than
happy to release their data to show off
and brag about how fantastically great it actually is.

Consider for a bit, how the Shure company
provides such technical data. They put it
all out there to show people what they do,
and how they do it. Because, unsurpassed
quality is worth talking about.

Chuck