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Double Bass adjustable soundpost – Anima Nova

#41
drurb said:
I believe it's been known for, at least. decades. It affects the vibrational modes on the top. IIRC, it creates a null. Look here, among many.

Check here too, and here.

Here's a fine overall source.

Oh yes, and [Invalid or Expired Link Removed]as well. There's a whole science of string instrument acoustics out there.
Click to expand...

Yes. Thanks for the link(s) to the Ph.D. thesis, (and overview source.)
I'm more interested in how the material and tension of the sound post affect the sound. These issues are not addressed in any of the above links, and I wonder how much of "violin-size" research carries over to the larger size of the double bass. I'm sure many of the fundamental(!) principles DO carry over, but I would think that the size issue would be a significant variable to consider. I guess we could use a bunch of Ph.D. Theses, dealing solely with the DB.
Chuck Traeger's book devotes a few pages citing the work of Carleen Hutchins (sp?), which substantiates some of his ideas regarding the physics involved in the DB.
I still am amazed at how little is known (at the Luthier/Player level) about the science and its application regarding the soundpost - it seems that it is still in the "trial and error" realm, despite the academic research that is ongoing.
All I know is: anytime I ask my luthier questions about the soundpost, they usually put on a feathered headdress, start chanting, and sacrifice a chicken, before saying "well, let's try this...."
Also - 35 years ago I heard Kolstein's would take a top off, generate the Chladni (sand) patterns, then re-graduate (re-carve) the top. I'm not sure that this led to any definitive, positive, repeatable results, and I've not heard much chatter about this in current building/restoration/repair.
Sound like we're still fairly early-on in having a complete understanding of the sound post, its function and variables.
Thanks for your time and interest.
 
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#42
Don Kasper said:
Yes. Thanks for the link(s) to the Ph.D. thesis, (and overview source.)
I'm more interested in how the material and tension of the sound post affect the sound. These issues are not addressed in any of the above links, and I wonder how much of "violin-size" research carries over to the larger size of the double bass. I'm sure many of the fundamental(!) principles DO carry over, but I would think that the size issue would be a significant variable to consider. I guess we could use a bunch of Ph.D. Theses, dealing solely with the DB.
Chuck Traeger's book devotes a few pages citing the work of Carleen Hutchins (sp?), which substantiates some of his ideas regarding the physics involved in the DB.
I still am amazed at how little is known (at the Luthier/Player level) about the science and its application regarding the soundpost - it seems that it is still in the "trial and error" realm, despite the academic research that is ongoing.
All I know is: anytime I ask my luthier questions about the soundpost, they usually put on a feathered headdress, start chanting, and sacrifice a chicken, before saying "well, let's try this...."
Also - 35 years ago I heard Kolstein's would take a top off, generate the Chladni (sand) patterns, then re-graduate (re-carve) the top. I'm not sure that this led to any definitive, positive, repeatable results, and I've not heard much chatter about this in current building/restoration/repair.
Sound like we're still fairly early-on in having a complete understanding of the sound post, its function and variables.
Thanks for your time and interest.
Click to expand...
You're quite welcome. Here's what you asked:

Don Kasper said:
Also - What purpose(s) does the sound post serve? Is this a knowable known? Is it solely to support the top plate against the downforce of the strings upon the top plate at the bridge foot (lacking a bass-bar)? Does it acoustically couple the top plate to the back plate?
Click to expand...

I believe all of those questions are addressed in the sources I referenced. As to the material and tension, you may wish to look at:
Fang, N. J.-J. and Rodgers, O. E. (1992). Violin soundpost elastic vibration, J. Catgut Acoust. Soc. 2d ser., 2 (1), 39-40. I was considering mentioning Carleen Hutchins work in my previous post. She did publish re the soundpost.

You may be interested in the list here as well.

I agree with you that the science as old and rich as it is, hasn't been incorporated into the working knowledge of most luthiers. FWIW, Upton has a copy of the complete works mentioned in the link above. Anyone interested can order a copy here.

I'm happy to add anything relevant to this list:
Acoustical Studies of the Double Bass and Stringed Instruments
 
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#43
drurb said:
IIRC, it creates a null.
Click to expand...
Also known as vibrational knot, in this case on a two-dimensional surface.
Similar to putting your finger with some pressure on a drum membrane.

In a single dimension, bass-related, it is like a flageolet, but not neccessarily at a small number fraction of the string length. But since in two dimensions this is more complex, moving the position of the soundpost influences the frequencies of the vibrational modes (which are the resonances of top and back) as well as the damping of that modes. So this influences sound coloring and responsiveness of the instrument.
And since the soundpost is close to one of the drivers (the treble bridge leg), the position also influences which resonance mode gets how much energy from the driver.
And finally it also determines how much energy of the top vibration is coupled to the back. Since there are (at least) three coupled vibrating systems, analyzing the total vibrational behavior can get really complicated (think of three coupled pendulums, that have a mathematically chaotic behavior). But this might also be the reason why we like the sound which is produced by these kind of instruments.
 
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#44
Don:

I've tried to find information on soundposts over the years looking for the same answers. I concluded soundposts are like strings, bridges and tailpieces. You have to try them on your bass. Science can only take you so far.
Borrow or buy this new carbon fibre soundpost ....or a plain carbon fibre soundpost...or one made from various kinds of woods. Become an expert and let rest of us know your conclusions and why. But as soon as you add a mic or a pickup, any benefits from your experimentation could be lost.:(
 
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#45
DoubleMIDI said:
Also known as vibrational knot, in this case on a two-dimensional surface.
Similar to putting your finger with some pressure on a drum membrane.

In a single dimension, bass-related, it is like a flageolet, but not neccessarily at a small number fraction of the string length. But since in two dimensions this is more complex, moving the position of the soundpost influences the frequencies of the vibrational modes (which are the resonances of top and back) as well as the damping of that modes. So this influences sound coloring and responsiveness of the instrument.
And since the soundpost is close to one of the drivers (the treble bridge leg), the position also influences which resonance mode gets how much energy from the driver.
And finally it also determines how much energy of the top vibration is coupled to the back. Since there are (at least) three coupled vibrating systems, analyzing the total vibrational behavior can get really complicated (think of three coupled pendulums, that have a mathematically chaotic behavior). But this might also be the reason why we like the sound which is produced by these kind of instruments.
Click to expand...
Yes, I'm quite familiar with vibrational modes and chose to keep things simple in my posts. Thanks for the extra detail.
 
#48
I have been out of town and off the grid for a week; hence the delayed response.....but this one is of more concern than most replies to me.

Martin:

Its great that you had tea with Edmond Hillary and got a chance to hear an old man revel in his legacy. It is important to our oral history and I would cherish the opportunity more than most. For about a fifteen year span I worked as an expeditionary mountaineering guide and leader all over the world. During the mid 1990s, there was a six year window where I spend the summers in North America and then wintered in Nepal and spent 100s of days at a time in the Himmalaya, including a couple of stints in the peaks and valleys surrounding the Everest basecamp. I have a ton of direct firsthand exposure with how the entire mountaineering scene works over there and got to know dozens of locals that I considered great friends and was in surroundings where we all depended upon every man to survive the conditions.

Every day I saw the same thing on the big mountains: expedition after expedition loaded with pastey white guys who would be near death WAYYYYYYYYYYY beyond the level of being able to take care of themselves and useless literally being dragged up the mountain by the locals just for a summit selfie and "bragging rights". After being subsequently dragged back down the mountain in the same condition and the expedition was over, the Nepali guys would get a few hundred dollars as a tip and go back up again in a few weeks and then spend half the year back in their family's village leading a very modest and humble life before going back up again another dozen seasons while all of the doughboyz who got dragged up the hill tripping on hypoxia and supplimental oxygen would go back to the US or Europe or Japan and start a new career as a corporate motivational speaker who had "summitted" Everest charging $25k per event. Most of the Nepali folks I met on the mountains were unbelievably amazing people who possessed superhuman strength and endurance yet were treated like a disposable commodity. Without them, none of it would have been possible, yet they go down in our skewed history as unknown B side player baggage handlers, along with the other approximately 350 (!!!!!!!!!) porters carrying equipment used on the 1953 expedition. So yes, I'll comfortably restate my claim again that without him, Hillary would be another unsuccessful adventurer lost to history and that Tenzing carried his a$$!
 
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#49
martinc said:
Become an expert
Click to expand...

I'd really like a second (or third) bass, that could be used for "research".
I'd really like to experiment with (radical) placement of a traditional wood soundpost, just to see what effect it might have.
Also, to try varying diameters/shapes of different wood species to, again, try and hear the difference(s).
I understand and appreciate why most luthiers are a bit hesitant to wander out of the mainstream, as their livelihoods (like ours) are based upon their abilities to use tried-and-true methods, NOT to use a client's instrument for experimentation.
I wouldn't want someone to use my bass as a guinea pig, but it would be interesting to see what might be uncovered/discovered if there was a bit more thinking that was "out of the box".
I think this adjustable CF soundpost, for instance, is admirable just for attempting to get people to "...make people think in a different way"... about the bass, as Chuck Traeger has written.
Thanks.
 
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#50
James: can't disgree with your assessment of latter day mountaineering in Nepal.
However my post was about that first successful expedition. I did mention that nothing I wrote was meant to take away the incredible accomplishment of Sherpa Tenzing.
Your conclusion flies in the face of the reporter who was with the team ...and accounts by both Hillary and Tenzing. There is a lot more information available, all of which was first hand and paints a far different assessment than yours. I prefer to stick with that.
And as for my 'having tea and listen to an old man revel in his legacy".....there you go again making another snarky and denigrating comment about something you know nothing about. Why do you do this? I interviewed him as a CBC reporter and I can assure you I was no starry-eyed groupie. And Hillary was certainly not "revelling in his legacy". That was not his style and not what I was looking for. Too bad you have never spoken to him...about anything. You would have learned the true meaning of humility.

Anyway ...back to the topic at hand which is something I will gladly admit is an area where you are an expert.
Cheers.
 
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#51
As a "Root and a 5th" plywood Kay guy, I shouldn't even be messing around this bass forum but I just can't help keeping quiet when I read something so off the track----the Everest climbing thing, on a bass repair and set-up thread no less.
"I interviewed him as a CBC reporter"-----hardly lends support to Martin's credence, I'm not too big a fan of the various media folk. For what's it worth (Most likely nothing) I'm throwing in with James, who dragged himself around the area with the locals, talking, maybe drinking, and generally getting a pretty good grip on "the climb". I'm sure the Sherpa crowd has kicked around this exact subject matter. Each season, I'm amazed at the various teams, with their massive amount of gear and supplies with all the various logos exposed, don't forget the high altitude helicopters, $25,000 sounds low. Anyway, it has been really interesting and gives me something to bring up at the coffee table down at McDonalds this morning.

Fog
 
#52
Fogducker said:
As a "Root and a 5th" plywood Kay guy, I shouldn't even be messing around this bass forum but I just can't help keeping quiet when I read something so off the track----the Everest climbing thing, on a bass repair and set-up thread no less.
"I interviewed him as a CBC reporter"-----hardly lends support to Martin's credence, I'm not too big a fan of the various media folk. For what's it worth (Most likely nothing) I'm throwing in with James, who dragged himself around the area with the locals, talking, maybe drinking, and generally getting a pretty good grip on "the climb". I'm sure the Sherpa crowd has kicked around this exact subject matter. Each season, I'm amazed at the various teams, with their massive amount of gear and supplies with all the various logos exposed, don't forget the high altitude helicopters, $25,000 sounds low. Anyway, it has been really interesting and gives me something to bring up at the coffee table down at McDonalds this morning.

Fog
Click to expand...

Fog: I'll ignore the uncalled-for personal insult. There's been enough unsupported speculation on this already by James. Unless you have any concrete, new information I'd say the coffee table at McDonalds sounds like a much better place to add your own cynical and unsupported views than this forum.

Cheers.
 
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#53
Martin, For you to assume my comment as a "personal insult" is amazing to me! When me and ALL the people I know think of Peter Jennings, Dan Rather, Andrea Mitchell, Rachel Maddow, Brit McHenry (ESPN sideline babe who tore into the parking garage lady claiming "She is on TV and you are nothing!"), et al, a bevy of media folk from the left and right who are all legends in their own minds, attractive but empty suits none the less. With hind sight, editing(Censoring?) sometimes lying, I'd hardly call them infallible. Sorry if I caused you angst,-------I still think I'll lend more credence to James' and his local Asian group of Sherpas' "unsupported views" on this! No question, Hillary and Tenzing were the 1st to get up there even though all we have are them relating their stories.

Fog
 
#54
Fogducker said:
Martin, For you to assume my comment as a "personal insult" is amazing to me! When me and ALL the people I know think of Peter Jennings, Dan Rather, Andrea Mitchell, Rachel Maddow, Brit McHenry (ESPN sideline babe who tore into the parking garage lady claiming "She is on TV and you are nothing!"), et al, a bevy of media folk from the left and right who are all legends in their own minds, attractive but empty suits none the less. With hind sight, editing(Censoring?) sometimes lying, I'd hardly call them infallible. Sorry if I caused you angst,-------I still think I'll lend more credence to James' and his local Asian group of Sherpas' "unsupported views" on this! No question, Hillary and Tenzing were the 1st to get up there even though all we have are them relating their stories.

Fog
Click to expand...


Fog: Wrong assumption again!
I was in radio...not TV. Better have another coffee. ;)
 
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