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Post by steverino on Jul 12, 2009 19:44:18 GMT
In current ebay auction #290329572999 there is a curious picture, probably 1930s, of a young lady wearing what may be a gentleman's hat, a circa 1932-33 National Duolian, and not too much else. I'm not certain that she is a musician, though someone with the ability may wish to post the picture here. With the combination of elements, the southwest motif in the background and the untold story, it is quite a picture.
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Post by steverino on Jul 10, 2009 5:58:16 GMT
Frequently I have read comments on these forums that the reso shopping looks better in the USA then in the UK. Well not this time! If I was closer I would be all over that one at the Buy It Now price.
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Post by steverino on Jul 9, 2009 19:29:49 GMT
There have been a few surplus brass bodies from the old OMI company in California popping up here and there. I bought a few from an ebay seller, but these are in poor condition as they were apparently rejects in the factory that were used to teach welding and sandblasting to the workers there. These have their cone wells crudely cut out, so making guitars from them won't be easy. I value them mostly because they were pressed from the same tooling that was used to make the prewar 14 fret Nationals. A fellow named Bryan England in Kentucky has a quantity of OMI bodies that are in much better shape than the ones I bought. He occasionally offers one on ebay using his seller name "bryanengland." At least some of these appear to have a 10.5" diameter cone well. You might try contacting him at the web site of his company, Custom Inlay. BTW this is a fun site in general for guitar junkies to visit. www.custominlay.com/
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Post by steverino on Jul 8, 2009 17:41:34 GMT
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Post by steverino on Jul 3, 2009 21:21:02 GMT
I couldn't agree more, CJ. A few years ago I attended an event sponsored by the NAMM music trade show out here in southern California. It was billed as the "Acoustic Cafe" and was held in a large hotel ballroom. Though the instruments were acoustic, the sound system was huge. The levels were some of the loudest I've ever endured, almost unbearable even with foam earplugs in tight. Nuts!
As a piano technician I'm always fighting the good fight for instrumental timbre as well. In pop orchestral situations, most often the sound personnel are not concerned with an accurate piano sound. No, they just want it to "cut through" the mix, so they put the mics inches from where the hammers hit the strings and EQ up the top end. This can make a 9' piano sound like a 5', but it is usually out of my hands.
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Post by steverino on Jul 3, 2009 17:01:49 GMT
Robin, can we clone you and distribute these sound men everywhere? Your approach is so refreshing in a world that has gone mad with absurdly high, damaging sound levels. I would say that you are a superbly qualified sound guy. It is most of the currently practicing ones that need to go.
I have a 1930 book that discusses the proper use of a public address system. It is stated that the audience should not be made aware of the loudspeakers, but that the levels should be elevated just enough to ensure intelligibility for the entire audience.
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Post by steverino on Jul 3, 2009 16:40:50 GMT
As with so many things, I suppose the choice of third string boils down to personal preference. I made up some plain wire thirds after a friend mentioned that he frequently broke the wrapping on the third string of his favorite Martin Silk & Steel sets when using a metal fingerpick. When it happened to me I decided to try some plain wire.
Tark I guess "stiffness" depends on one's perspective as well. A .022" plain wire calculates about the same tension as the .023" wound third in the Martin set, 26.67 lbs. vs. 26.87 lbs. The plain wire is only at something like 25% of breaking tension, where the .011" core wire of the Martin wound third must be much closer. The plain wire can be bent more than two semitones, allowing for Robert Johnson style note bends. It is difficult to bend the wound string even a semitone, which makes it feel stiffer to me in use.
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Post by steverino on Jul 3, 2009 1:35:44 GMT
Barry you mentioned a snapping third string. I started a thread on another forum recently after experimenting with some home made plain wire third strings. I'm sold on them. I now believe that string makers use a wound third mostly to ease the transition between the bright, clear, beautiful sounding plain wire strings and the duller sounding wound strings. On the fairly light gauge Martin Silk & Steel sets, the core wire on the wound third string is only .011". It is probably pulled up within an inch of its life, and so more prone to failure. A steel fingerpick will tear through the delicate winding quickly as well. A .022" plain wire sounds better, plays easily and also allows for much easier note bending.
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Post by steverino on Jun 30, 2009 4:14:31 GMT
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Post by steverino on Jun 29, 2009 6:46:32 GMT
Barry I think you are mistaking the spinning marks on the foil surface with the look of a coil wound from wire of some sort. The marks do form a spiral, but the material was in sheet form before being spun into shape. I thought for decades that cymbals were made from wound brass wire, but it turns out they are also formed from flat stock and turned on a lathe.
The spinning process is fairly easy (and fun) once the tooling is done. Spinning compression driver loudspeaker diaphragms is very similar to spinning resonator cones. Jim Lansing pioneered the process for loudspeakers, and his factory was next door to the Dopyera brothers' at the time. Wonder where he learned to spin aluminum?
In the case of loudsppeakers, the aluminum foil sheet is clamped about the perimeter of a female tool. The assembly is spun in a lathe and a shaping tool, often a rounded stick dipped in kerosene, is applied to the outer edge of the aluminum. As the operator slowly moves toward the center, the aluminum stretches and assumes the shape of the tool. There needs to be a tiny hole in either the aluminum or the tool to let the trapped air escape. When the center is reached the aluminum is now shaped like the tool. After some finishing operations such as trimming the outside edge the piece is done. In the case of tri-cone and biscuit cones, the spirals are impressed using a two part tool after the spinning operation.
Many reso cones and most loudspeaker diaphragms these days are pressed or stamped rather than spun. One method involves a two part tool (male and female) with the foil trapped between while the tools are brought together in a stamp press. Another method involves a single female tool and a soft butyl rubber bladder filled with liquid and backed with something solid. The aluminum is placed between tool and bladder and WHAM!, the worker hits the assembly with a hammer. This is the way the shiny aluminum center domes on JBL cone speakers were made, at least in the early days.
Some shapes of cone can be either spun or pressed, while others with irregular features must be pressed. The spider bridge cones with raised lugs are an example of the latter. I believe that John Dopyera said that either process should result in an equally good sounding cone. However, in his patent on the spider bridge resonator he states that the outer suspension compliance of the cone could be thinned to increase the resiliency. This could be done by a skilled operator in the spinning process, but would be difficult to achieve with a stamped cone. I have one 1930s lugged cone and it has a very stiff outer suspension compared to most of the spun cones on hand.
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Post by steverino on Jun 27, 2009 21:49:14 GMT
Pete, I like your thinking. Is it too much to hope for that you might be located in southern California?
I did make one attempt at a floating bridge resonator. I put a fairly strong coil spring behind a spider cone, with a screw tension adjustment threaded through the back of the (cheapo) guitar body. That way the spring tension could be adjusted after the guitar was assembled. Then I trimmed the perimeter of a cone and installed a masking tape outer suspension between cone and guitar top. As the string tension came up the spring was tensioned to offset the pressure on the bridge. When it was up to pitch I had a guitar with really great throbbing bass but little else; the lossy outer suspension sucked away almost every trace of the cone's lively middle and upper frequencies.
So we have a basic dilemma. The cone needs to have a clean pivot termination at its outer edge that doesn't bleed off cone energy yet seals the guitar cavity. It is hard to imagine how to achieve this without applying an amount of string pressure to the bridge that is sufficient to stifle the movement of the cone at low frequencies. Ideas anyone?
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Post by steverino on Jun 27, 2009 20:52:00 GMT
I had spider bridge reso sound holes on my mind, probably because of continuing discussions about the effects of their mesh grills on the sound. Melp's original question was in regard to the cover plate vents on a tri-cone. In this case the holes exist to let the wide-band sound from the cones out, and my assumption is that they were covered with wire mesh to protect the delicate cones from damage.
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Post by steverino on Jun 27, 2009 2:57:36 GMT
Acoustically the mesh screens could be modeled as a momentary partial obstruction to a transmission path, which would have the effect of a low pass filter. In other words, high frequencies above some threshold would be progressively attenuated. I would expect the effect to be very minor due to the small percentage of obstruction, and I have a hard time hearing any difference at all.
Tark the sound holes will allow all frequencies to pass through to a great extent, though their output seems to be all bass due to the broad peak at resonance.
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Post by steverino on Jun 24, 2009 18:07:40 GMT
Another vote here for Scott Ainslie's DVD. Also, several of his performances of RJ songs are up on YouTube. Here's one:
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Post by steverino on Jun 20, 2009 20:04:48 GMT
You might like Ry Cooder's version of "Vigilante Man." I sure do.
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