Dear Mr. Bogantz,
Very interesting.
Wouldn't lowering the mass of an acoustic soundbox reduce the lateral
inertia and cause the whole tone arm to vibrate with lower frequencies
rather than transmitting them to the diaphragm?
The low frequency response of the Actuelle is impaired because there is no
baffle to prevent the air compression from behind its cone canceling that
from in front & the mass of its long vibratory link limits high frequency
response.
Am enjoying this discussion since I want to obtain optimum sound quality
from my vintage phonographs. Many thanks!
Very truly yours,
Jim Cartwright
[email protected]
EarthLink Revolves Around You.
> [Original Message]
> From: Greg Bogantz <[email protected]>
> To: Antique Phonograph List <[email protected]>
> Date: 2/8/2008 9:13:35 PM
> Subject: Re: [Phono-L] Victor versus Columbia big guns
>
> Hi Robert,
>
> To answer your general curiosity, yes, I
> have tried many of the things you suggest. I have designed and made a
> complete "New Orthophonic" (with apologies to RCA who couldn't care less
at
> this point since they're owned by the Chinese) reproducer to fit Victor
> ortho tonearms out of lathe-turned aluminum - none of the parts are
recycled
> from old designs. The aluminum model weighs about half of the potmetal
> design. I don't want to divulge too much more of the design in case I
> eventually want to make and market it. But it really isn't ready for that
> yet. Even so, I don't know how much market there would be for a toy like
> this. Most phono collectors don't obsess about the audio performance of
> their acoustic machines like you and I do. Their attitude is that
anything
> that isn't an original 100 year old design constitutes a "frankenphone"
and
> they don't want anything to do with it. So I'm not encouraged that there
> are more than a dozen of us with this interest.
>
> As an adjunct to this design, I also have been making for some time
now
> my own tungsten needles. This started out because I needed durable
needles
> to use in my oldest record changers that are designed for steel needles.
> Steel needles are no good for these changers because they wear out
> completely after two record sides are played. So, what's the point of
> having a record changer if you have to change the needle every two record
> sides? Victor recommended their Tungstones for this purpose, and indeed,
> they were the best choice for this application at the time. But I didn't
> want to use up expensive, original, antique Tungstones so I designed my
own.
> What I found out was that the original tungsten wire used by Victor is
.007
> inch (7 mils) in diameter. This is really too big for the typical groove
> which is around 5 to 5.5 mils in width. But they used it because anything
> smaller is too delicate and bends too easily. Also, the heavy tracking
> force of the early reproducers, both the acoustic and the early horseshoe
> magnet electric types was sufficient to mash the fat wire into the record
> groove and keep it working even though it was wearing "shoulders" on the
> sides of the too-big wire. So when I tried to use these 7 mil tungstens
in
> my new reproducer which tracked at half the force of the Victor (about 80
> grams versus 135 grams), the wire didn't wear down properly on the
shoulders
> and stay in contact with the groove walls. This caused audible
mistracking.
> I have since gone to 6 mil wire which works pretty well. I would rather
use
> 5 mil wire, but I've tried it and it's just too fragile and bends too
> easily. So this is yet another problem that requires some compromise.
>
> To address your suggestions about using large diaphragms: you are
faced
> with a tradeoff between diaphragm compliance, resonance, and application
> requirements. If you want to try a "Lumiere" type of very large
diaphragm,
> or direct radiator cone really, then you can't effectively horn load it,
and
> you probably don't want to anyway. You can simply let such a large
> vibrating surface radiate directly into the surrounding acoustic space as
is
> done with the Lumiere and Pathe Actuelle designs. Such a design can sound
> pretty good in the midrange of audio, but it is inherently limited in how
> much bass it can reproduce - there just isn't efficient coupling with the
> air mass at very long wavelengths of audio (bass frequencies) to get good
> bass response. To load a large diaphragm into a horn would require a
large
> horn throat to accommodate it. Which would require a VERY large horn to
> work into to keep the compression horn acoustic principle working
properly.
> Improper mismatches in sizes here result in vastly reduced efficiency.
>
> Long story short(er), the approximate sizes of the diaphragm,
reproducer
> throat, and horn length and flare are just about optimum as realized in
the
> Victor designs for the application of playing 78rpm records with 5 mil
wide
> grooves. Bigger systems would require bigger records and bigger grooves
to
> keep the mechanical couplings and impedance transformations working
> correctly. Loading a typical 78rpm groove with a correctly-designed large
> diaphragm compression horn system would simply cause too much mechanical
> loading on the needle. This would result in very low compliance at the
> needle tip which would result in severe mistracking. Furthermore, the
> extreme mass of the entire system would be difficult to track with a
pivoted
> tonearm under groove power, as you suggest. But lateral-cut records do
not
> lend themselves to feedscrew-type tonearm assist systems because most
> records are not cut at a constant groove pitch which cylinders are. Then
> there's the problem of record eccentricity that must also be accommodated.
> You could address these issues with a sophisticated servo-controlled
> tracking system. But it all adds up to swatting a fly with a sledge
hammer.
> So it turns out that the approximate sizing of the playback elements as
seen
> in the Victor (and others) designs is probably about optimal for real
world
> use. But that doesn't mean that you can't put a considerably larger horn
on
> a Victor-sized system. To do so would extend the bass reproduction
> frequencies down lower. Victor themselves did that in their theater-sized
> horn designs. But the efficiency tends to degrade with increasing horn
> size, so even the biggest theatrical Victors used electrical horn drivers
> and electronic amplifiers.
>
> You mention the excesses of the Archeophone design: True, this is
> pretty much overkill, too. But there really aren't any modern cylinder
> player designs that offer highly accurate record speed and vanishingly low
> flutter, so these are two design criteria that are purposefully addressed
in
> the Archeophone. However, the basic business of turning a disc record and
> holding a reproducing means in the groove have been developed for years
past
> the acoustic technology as embodied in all modern disc record players.
All
> that really needs to be done if you want to extract the most from a disc
> record is to use a modern hifi pickup equipped with the proper size and
> shape stylus. Done deal. It doesn't need re-inventing.
>
> But I DO understand that you are trying to "squeeze the turnip" and
see
> how much blood can be extracted from pure acoustic playback technology.
But
> I CAN tell you that it is NOT possible to make the "perfect" acoustic
> reproducer - you can't get fully wideband frequency response AND
> low tracking force AND good efficiency (loudness) from an acoustic design.
> It's just not in the physics. Unlike the situation with modern hifi
> pickups, the physical requirements of an acoustic reproducer are vastly
> different. The modern record player does not require anything more of the
> record than to merely "instruct" the player on how to direct its
electrical
> energy to the loudspeaker. This requires an infinitesimal amount of power
> from the groove. By contrast, an acoustic player extracts ALL its sound
> power from the record groove (assuming you aren't using a mechanical
> amplifier such as the Higham friction amplifier or compressed air schemes
> such as on the Auxetophone). This makes all the difference in the world.
> Acoustic playback requires that all the audio power must be extracted by
> making the record groove do the actual work. The more work the groove
must
> do, the more wear is likely to be exhibited as the needle scrubs along the
> groove walls. You quickly get to the point where you can't get any more
> blood out of it. The Victor design is close to the optimum, in my
> estimation. I've been able to improve upon it, but I don't expect that
too
> much more can be had from what I'm getting now. But I'd love to be proved
> wrong, if someone wants to have a go at it.
>
> Greg Bogantz
>
>
>
> ----- Original Message -----
> From: "Robert Wright" <[email protected]>
> To: "Antique Phonograph List" <[email protected]>
> Sent: Tuesday, February 05, 2008 10:16 PM
> Subject: Re: [Phono-L] Victor versus Columbia big guns
>
>
> > Wow, thanks for all the great information, Greg, and thanks for taking
the
> > time to type/copy&paste it all! I'm wondering additionally about using
> > space-age materials and creating something using a Victor horn that's
> > beyond comparison with any antique products of any kind. I'd like to
see,
> > for starters, what a larger diaphragm suspended by a rubber surround in
a
> > milled aluminum soundbox with a titanium stylus bar and razor blade
pivot
> > point would do mounted to a Credenza tonearm. With a larger diaphragm
and
> > soundbox, some counterbalancing (a la Ultona) might be necessary, but
with
> > aluminum instead of brass, maybe not.
> >
> > That's just for starters. I'd also be interested in creating an even
> > larger soundbox, say 10" or so, with similar materials (think modern
HMV
> > Lumiere), mounted rigidly (laterally speaking) to a large, non-folded
> > exponential horn (a la Nimbus Records'), with a modern direct drive
> > turntable mounted to a feedscrew stand so that the disc moves laterally
> > under the stylus (think Wizard or other moving-mandrel cylinder
phonos).
> > Maybe a titanium diaphragm to keep moving mass to a minimum...
Granted,
> > this would be truckloads of cash to build, but I figure if they can
build
> > the Archeophone...
> >
> > continuing to dream,
> > Robert
> >
> >
> >
> > ----- Original Message -----
> > From: "Greg Bogantz" <[email protected]>
> > To: "Antique Phonograph List" <[email protected]>
> > Sent: Tuesday, February 05, 2008 8:34 PM
> > Subject: Re: [Phono-L] Victor versus Columbia big guns
> >
> >
> >> Well, Robert, I think I agree with you that the Credenza is the
> >> standard of excellence in American acoustic reproduction. I have an
> >> early 2-door Credenza as well as a Victor 10-50, 9-40, and 10-35 as
well
> >> as a Columbia 810 which has the biggest horn that Columbia put in
their
> >> Viva-Tonals. I don't hear too much difference among the big Victors,
but
> >> each has subtle differences from one to another. All are GREAT
machines,
> >> and any owner should be proud and pleased to listen to them. The
reason
> >> that I put that caveat about American acoustic reproduction is that I
> >> haven't had the pleasure of hearing any of the really good English
> >> machines such as the biggest re-entrant HMVs or the biggest EMGs.
Maybe
> >> one of them can claim the prize as best acoustic machine, but I just
> >> can't say. I must opine, however, that I can't imagine the EMGs
having
> >> as good bass as the biggest exponential horn machines simply because
EMG
> >> didn't use as big a horn!
> >>
> >> Now, with all due respect to Anthony Sinclair, and I truly do mean
> >> that I respect and applaud his efforts to document the performance of
> >> orthophonic and other machines in his writings in ITG, I must beg to
> >> disagree with some of his opinions. By the way, we've recently had
some
> >> of these very same discussions on the Old Time Victrola Music Message
> >> Board (OTVMMB), but I'll repeat here what I've written there for those
of
> >> you who aren't also members there. I encourage you folks to go there
and
> >> see what else has been said recently about this topic. I don't
presently
> >> have the proper instrumentation to back up my claims, but I've
listened
> >> extensively to the big horn Victors and compared them to the Columbia.
I
> >> have made an adapter that allows me to listen to the Columbia #15
> >> Viva-Tonal reproducer played thru the Victors, and also allows me to
use
> >> the Victor orthophonic reproducer on the Columbia. I was particularly
> >> interested in whether the horns or the reproducers were the limiting
> >> factor in acoustic reproduction on these machines.
> >>
> >> In my opinion, the Columbia horn is not as good as the Victor.
The
> >> Columbia horn is not as accurately tapered because it is constructed
in a
> >> piecewise-linear-curved sectional fashion rather than having a
smoother,
> >> more uniform and proper exponentially increasing cross section which
is
> >> required of the exponential design. There should be NO cross-sections
in
> >> a proper exponential horn which are linear taper. This, in
particular,
> >> causes the treble to be noticeably weaker than the Victor. But the
bass
> >> is also less extended as well. And, overall, the efficiency isn't as
> >> good as the Victor (it doesn't play as loudly) - all these attributes
are
> >> symptomatic of an incorrect horn taper. At first blush, the Columbia
> >> strikes the casual listener as having more bass, but this is due to
it's
> >> having substantially less treble than the Victor.
> >>
> >> Another finding indicates that the big Victor horns are better than
> >> people realize because the Victor reproducer isn't as good as the big
> >> horns. More on this later. The Victor ortho reproducer has several
> >> compromises included in its design to make it more robust and more
> >> user-friendly that, unfortunately, detract from the best acoustical
> >> performance that could have been had. The bass could be a little
better
> >> if the compliance was higher, and the treble could be a little better
if
> >> the moving mass was lower. That said, the Columbia #15 is no match
for
> >> the Victor ortho. It has a more massive diaphragm which further
degrades
> >> the treble, and the compliance is even lower (stiffer) which further
> >> degrades the bass, compared with the Victor. The Columbia has the
very
> >> big advantage that it is all made of brass and is easily rebuilt, but
it
> >> still can't match the performance of a Victor ortho in good condition.
> >>
> >> The reason that I know the Victor horn is capable of more than most
> >> people realize is that I have designed a better reproducer than the
> >> Victor. My design has a MUCH lower moving mass and quite a lot higher
> >> compliance than any other reproducer that was sold to the public.
> >> Incidentally, I was particularly interested to see if this could have
> >> been done "back in the day" by trying to use only materials that would
> >> have been readily available in 1927 or so - no modern space-age
> >> materials. And I discovered that it could have been done - the
materials
> >> are aluminum, leather, and paper with a few screws and glue thrown in
to
> >> hold it together. I guess the reason why a design like this wasn't
> >> marketed is related to the delicacy of a proper design. The low
moving
> >> mass and high compliance both make the reproducer delicate and
difficult
> >> to perform needle changes. I'm sure my design would never have been
> >> suitable for mass consumption, but I like to use it because it makes
the
> >> Victor horn really shine! Reproduction on this system sounds like
that
> >> of a large table radio or small radio console - I estimate that it has
> >> about an extra octave of useful output, some above and some below the
> >> range of the Victor ortho. The bass is not window-rattling, but it's
> >> uncommonly good and the sound is well-balanced and wide-range without
> >> peakiness, and most listeners can't believe that they're hearing
acoustic
> >> reproduction. So, yes, the big Victor horns are the best acoustic
horns
> >> that I know of and are damn fine at that.
> >>
> >> Greg Bogantz
> >
> > _______________________________________________
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> > http://phono-l.oldcrank.org
>
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