I measured the wire of a tungstone needle and found it to be in the 5-6 mil range. Hmmm. I have SEMs of a Tungstone tip before and after one play if anyone is interested.
Ron L -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Walt Sent: Saturday, February 09, 2008 4:09 AM To: 'Antique Phonograph List' Subject: RE: [Phono-L] Victor versus Columbia big guns Greg, This is a good general axiom (although I would not word it the same way): "an acoustic player extracts ALL its sound power from the record groove" Jim Cartwright had also asked a question about the effect of decreasing the mass of an acoustic soundbox and if it would result in what he called a "decrease of lateral inertia and therefore a tendency for the entire tone arm to vibrate with lower frequencies rather than transmitting them to the diaphragm". Applying the axiom as previously stated, one possible short answer to Jim's question is yes, decreasing the mass of a given acoustic soundbox can result in a decrease of lateral inertia. I don't think that the decreased mass would necessarily result in a tendency of the entire tone arm to vibrate with lower frequencies, but there would definitely be a tendency of the tone arm to try to swivel (minutely) at all frequencies. Maybe Jim is saying the same thing in principal and I am being a bit semantic. BUT, Greg made some other points along the way that must be considered and I will try to harness a few of them here for focus' sake. This means that the other not-so-short answer to the question would be, no, decreasing the mass of an acoustic soundbox will not necessarily result in a decrease of lateral inertia. How so? Theoretically, if the reduction in mass is compensated for by way of compliance, and if the tone arm pivot friction (not the tone arm weight) is not a factor (which I believe it would probably be in actuality, and even more so as the soundbox is made lighter and lighter) then the needle movement of the soundbox would not suffer from decreased mass. It's a neat theory. In referring to your (Greg's) description of the results of using your homebrew 7 mil tungsten stylus and your prototype reproducer, you mention that your reproducer tracks at about half (approx 80 grams) that of Victor (135 grams). You go on to mention that in your test result(s?) the 7 mil wire didn't wear down properly on the shoulders and neither did it stay in contact with the groove walls, the result of which was what you termed "audible mistracking". Going back to the axiom that "an acoustic player extracts ALL its sound power from the record groove" I would fully have expected to hear audible tracking issues using the lighter soundbox - no question about it, especially at 80 grams. I have calculated the average weight of a Victor soundbox to be 140 grams, so your 135 gram figure seems consistent with my data. But this figure is not really an accurate measure of tracking force because it does not take into consideration the mass of the gooseneck if a machine has one, and even when they do, they vary in mass depending on the model. A more realistic tracking force is probably 160 to 170 grams (and even higher on a Victor Orthophonic portable like the 2-55). I would love to hear the "audible mistracking" you mention because I am inclined to think that what you are hearing is something that phonograph makers during the acoustic Victrola days knew would be a problem, and they therefore engineered the mass of soundbox/gooseneck combinations to stay away from it altogether. That 135 to 140 gram figure representing soundbox weight is somewhat of a magic number. We tend to not think of tone arm "skating" in regard to an early acoustic machine. But, as the tracking force is decreased then the issue of skating (among others) arises. Food for thought: As the motor drives the turntable it rotates and develops momentum. When the stylus is in the groove of a record, the momentum will tend to pull the soundbox in the direction of the spindle. On a modern stereo skating problems are pretty easy to hear and compensate for. But once the magic number of 140 is lowered on an acoustic machine, things start to happen. This is why I would have fully anticipated hearing some kind of audible mistracking before I ever left the drawing board. But the mistracking also opens the door for groove damage. A brand new Tungstone needle actually has a rounded tip. Greg, how do you cut your tungsten filaments and then round the ends? Cutting is a simple matter of a carbide-jawed cutter. I can tumble tungsten filaments in carbide and ceramic grit to achieve the radius. I also have a few other ideas of my own to electrically form the tips using low voltage - high current DC and carbon rods to briefly raise the temperature of the tungsten tip above its melting point (which is REAL dangerous) to round the end, and then cool it quickly to harden it [again], but I am curious as to how you are forming the tip. Also, I am assuming that your tungsten is NOT annealed, correct? Annealed tungsten wire on a roll is more abundant out there, but it is not rigid enough for use as a stylus. And...yeah... Lighter tone arms and lower friction pivots. More later...It's 4:00AM... Walt p.s. I think you will find more than a dozen "of us". We are they who are called "nerds" at MIT <wink>. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Greg Bogantz Sent: Friday, February 08, 2008 10:11 PM To: Antique Phonograph List 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 > > _______________________________________________ > Phono-L mailing list > http://phono-l.oldcrank.org _______________________________________________ Phono-L mailing list http://phono-l.oldcrank.org No virus found in this incoming message. Checked by AVG Free Edition. 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