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 ARCHIVED TOPIC: Resonator? Trapdoor? Ideas?


Please note this is an archived topic, so it is locked and unable to be replied to. You may, however, start a new topic and refer to this topic with a link: http://www.banjohangout.org/archive/360013

darryl k. - Posted - 01/02/2020:  09:47:35


I have a 1923 open back Gibson style 0. The lower truss rod has a flattened section and a threaded hole at the centre span.
It has a Frank Neat neck.
I would like to add something close to the original back to this banjo not as a perfect restoration but in order to get a bit more tonal punch.
I play mostly pickless 2 and 3 finger style.
Ideas?

maneckep - Posted - 01/02/2020:  10:48:31


I don't beleive that threaded hole was ever used to hold a resonater. I think it was used to hold the rod in place while the nuts were turned to tighten the neck.

I have owned a few of those old Gibsons with the trap doors. The two mounting options that I remember were 1. just screws into the back of the pot and 2. a special hook that went around the single rod and then went thru the resonator and a nut was connected on the outside of the resonator to hold the hook/reso tight. The trap door portion that opened had a special swivel nut that either went behind the rod to hold it closed or pushed into the rod to hold it open.




G Edward Porgie - Posted - 01/02/2020:  14:03:20


I own a trapdoor PB 3, and in my opinion, the trapdoor makes no discernable difference in "tonal punch." What type of resonator might help is debateable.



Perhaps some experimenting would be in order. You might devise a way to attach a more conventional style resonator, at least temporarily, with magnets or clips or something. I would leave that hole in the lower rod alone; it was not intended to hold any style of resonator, and it may not even be centered in the pot; mine isn't.

darryl k. - Posted - 01/02/2020:  14:36:38


Thank you both. This is very helpful. Maybe no resonator. I was actually curious whether the trapdoor would make much difference.

maneckep - Posted - 01/03/2020:  08:54:13


I agree with George. The trap door resonator does not make much difference in the tone versus no resonator.

The only difference I noticed was if the door was open, the person playing the banjo might be able to hear it a little better. From the front of the banjo - very little if any difference.

Helix - Posted - 01/04/2020:  13:36:56


Nope, no ideas neither.



I think they were made to bounce off of an orchestra pit's floor, wide bout acoustic guitars were taking over.



All Fiddles, Violas, Basses use an Ossicle under the top below the bridge to connect with the back of the instrument.  Otherwise they don't play.



 



Only Wetzel in Eugene, Oregon does that here on the hangout with banjos.  



I think I'm seeing an external Ossicle connecting the heel to the bridge in a direct path.  I never thought of anything like the use of an Ossicle before.  I think a simple bamboo chopstick would suffice, maybe try it.  I build with Bamboo.


Edited by - Helix on 01/04/2020 13:41:37






G Edward Porgie - Posted - 01/04/2020:  18:27:03


Trapdoor banjos predated the guitar boom, and the Gibson trapdoor aimed toward the player's face, not the floor. It was just one of about a billion banjo "improvements" that didn't go anywhere.



I'm not sure when "ossicle"-- defined in my dictionary as "a small bone or calcareous body part" became synonymous with "violin sound post."

 

Helix - Posted - 01/06/2020:  04:53:09


In good humour, an Ossicle is not frozen water hanging from my gutter.



In my opinion, hyperbole is good, but maybe your dictionary is not deep enough.



Take another look, there's a lyre shaped piece in there. There is no provenance on this collectible neither, but I know of the band that played this instrument up in Washington in the Olympia area.



I would like to add something close to the original back to this banjo not as a perfect restoration but in order to get a bit more tonal punch.

I play mostly pickless 2 and 3 finger style.

Ideas?



My other idea has already been done on  the hangout.  But, I hope you might enjoy trying this.



Cut a disc out of Birch Plywood  and insert it into your resonator on top of a 1" post about 3/8" high.  Attach the post in the center of your REZ and then attach the disc to it and let it float there like a circular spring.  It will flex with playing and spring back to help ratchet sound out of  the banjo.  That way it's a useable change that is invisible to the eye, but not the ear.



If I was changing rims, I would also use Fresnel ledges which gives 3 different sized chambers inside the rim like a working amphitheater.  I've been using those since 2006, but who's counting.  



Ledges inside the rim can also be made from installing binding with a top edge beveled, they work internally without altering your old rim. Two pieces of binding to make 3 chambers. 



So there's about 3 new ideas, I'm glad to confer off forum..  We all want what works,  I don't care to read someone's philosophy about banjo building from a book. I don't like it when specifications become law,  



Take a look at the Lange Challenger with the adjustable apertures on the Resonator and the 3-point bayonet mount,  That's innovation. 



 


Edited by - Helix on 01/06/2020 04:56:18

G Edward Porgie - Posted - 01/06/2020:  06:21:20


I can imagine "ossicle" as being usurped as a term for bone and used instead as a term for a connection between two sounding surfaces, the most obvious examples of this being the three tiny bones in the ear--ossicles for sure--that serve as a conduit for vibrations between the eardrum and the cochlea. There are many such terms which are borrowed from dictionaries to serve as descriptive jargon in unrelated fields, which are subsequently overlooked in formal dictionary definitions. I was merely having a little fun with the word, yet I still haven't encountered anything but "sound post" in reading about violin family instruments.



In case you missed it, I did earlier make a suggestion that th OP experiment with attaching other types of resonators, perhaps using magnets to attach them; something that I believe you have talked about in the past, and it's a good idea.



If the OP ever does decide on a resonator of some sort, the birch disc you suggest might be a way to get even further amplification. 



I also do not like it when specifications become law, but I have to say that quite a few mistaken directions can be avoided by reading a few banjo building books. There may be some questionable philosophy in spots, but there are also viable construction methods. The funny part is that the Gibson trapdoor is one banjo that didn't follow the law; the rim is too small, the resonator (although it doesn't actually do much) is unconventional, and the neck attachment was an innovation. Coordinator rods! Where did that come from?!


Edited by - G Edward Porgie on 01/06/2020 06:24:11

Helix - Posted - 01/06/2020:  07:52:08


Back to the topic I didn’t miss anything.  The Banjo builder himself used the term ossicle



Comment on the flexible disc, maybe. It’s a lot more interesting



strips are pretty simple, too. 


Edited by - Helix on 01/06/2020 07:55:42

G Edward Porgie - Posted - 01/06/2020:  10:05:09


"I think I'm seeing an external Ossicle connecting the heel to the bridge in a direct path. I never thought of anything like the use of an Ossicle before. I think a simple bamboo chopstick would suffice, maybe try it. I build with Bamboo."



I think that connecting the heel to the bridge with any kind of strut would seriously inhibit the movement of the bridge. It could have a muting effect, exactly the opposite of what the OP desires.



I think the best answer is most likely some sort of resonator, but not the flush-fitting enclosure of the trapdoor design, but more along the lines of what most other companies use: a wooden bowl-like structure with a space between it and the rim and of a larger diameter than the rim. How it can be attached is the issue, due to the "O" lacking any kind of mounting point. Screw eyes could be installed, magnets might work, or something like the Weymann pop-off models. Beyond that, there are other tone enhancers such as the birch disk mentioned. Spoons could also be experimented with, or a tone ring or tube could be installed, although the latter option would require some heavy modifications, and the fact that these early Gibsons had a non-standard rim size would make fitting a tone ring even less viable.



If I were to be perfectly frank, I really don't believe resonators do all that much concerning volume; they do project the sound forward, which helps the audience here the darned thing, and they modify the tone, but I've never noticed much change at all in loudness. With its relatively small head area and consequently smaller air chamber there's only so much volume that will be available from an early Gibson.

mike gregory - Posted - 01/06/2020:  12:48:00


My guess is that trapdoors are only of interest to collectors of trapdoor banjos, and must or should be original.



Banjo picker named Art Thieme played a banjo which was originally an open back, and simply added a cake pan to the back, with a notch cut where needed to fit past the dowel stick.

He said it was a cheap but effective way to overcome the dampening effect of  what he referred to as his "home-grown Tummy Mute!"

G Edward Porgie - Posted - 01/06/2020:  14:27:17


quote:

Originally posted by mike gregory

My guess is that trapdoors are only of interest to collectors of trapdoor banjos, and must or should be original.



Banjo picker named Art Thieme played a banjo which was originally an open back, and simply added a cake pan to the back, with a notch cut where needed to fit past the dowel stick.

He said it was a cheap but effective way to overcome the dampening effect of  what he referred to as his "home-grown Tummy Mute!"






I have experimented with pie plates, colanders, pot lids, etc. and found that the only thing that really changed was the tone color. (I liked the lid well enough to buy one of those old spin-on metal Eltons because it was the closest I could find to the pot lid. Gave a nice tone to my old Slingerland tenor, but didn't make it any louder.



I'd mention the lack of a dowelstick on most of the trapdoor era Gibsons. but I would think it obvious that notches could be cut to fit past a coordinator rod. I seems quite possible that a layer of body fat (I have very little of that) could be absorbing some sound, so it might be worth a try and might have a greater effect than when I stuck all those contraptions on my banjo. I'm certainly not going to overeat a for a few months so I can experiment some more!

steen - Posted - 01/06/2020:  15:37:23


About trapdoors: Many experiments have been made during the early banjo-making days, and the trap door system is one of them, I see the banjo as a kind of a loud speaker (have made loudspeakers myself). It has a membrane and a cabinet and the menbrane is powered from a point on this (the bridge) like a loud speaker is powered from the coil in the middle of the membrane.
I think you can compare a trapdoor banjo to a loudspeaker with an adjustable bass-port, by which you can manipulate and tune the basic resonance of the banjo (the tap tone) and maybe help the deep tones of the banjo a little or change the colour of the sound a little as it is already suggested. Doesn´t it make sense? Steen

Helix - Posted - 01/06/2020:  19:07:36


Thank you, steen, yes it does

Bobby Burns - Posted - 01/13/2020:  09:48:36


The flattened threaded rod was used with the “pyrolyn” resonator. It had a knob that screwed into that hole to hold the resonator on. After years of celluloid shrinkage, the resonator either cracks, or doesn’t fit, or both. That threaded hole could be used to fasten a more standard type resonator. Similar to the way many slingerlands, Vegas and others were fastened

G Edward Porgie - Posted - 01/14/2020:  05:57:19


quote:

Originally posted by Bobby Burns

The flattened threaded rod was used with the “pyrolyn” resonator. It had a knob that screwed into that hole to hold the resonator on. After years of celluloid shrinkage, the resonator either cracks, or doesn’t fit, or both. That threaded hole could be used to fasten a more standard type resonator. Similar to the way many slingerlands, Vegas and others were fastened






It won't always work. That hole in the flattened rod in many cases is off center, so a center mounted resonator, no matter what it's made of, would also be off center.



Although the trapdoor might be similar in some ways to an adjustable port on a loudspeaker, in my opinion, it simply doesn't work

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