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Fodera Club Part XIV

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#401
jsbarber said:
Mike,

The reason I said "if" is because the only time I'd ever heard of this (longitudinal mode in the context of a bass) was in a previous post of yours a couple of years ago, so I wasn't sure if it was your own theory or accepted science. I just read the article in the link from nuwavedc's post quoting your post, which I originally missed. It's a very interesting article. The fundamental of the longitudinal is comparatively high in pitch, as I had indicated would be the case in my post the other day. But what's puzzling me is whether the longitudinal wave is in the core or the winding. At first I figured must be the core, because we're calling it a longitudinal (pressure) wave, but it could be some kind of slinky-like effect in the winding/wrapping. (the article says it can be tuned by altering the speaking length, or the ratio of winding mass to core mass. I would not expect the latter to affect the tuning if was a pressure wave in the core...)

If it's in the core, then the pressure wave in the core wouldn't directly affect the magnetic field to the pickup (as I indicated above, and especially with the winding shielding it) - but what it could do is cause an oscillating force on the tuning peg and bridge saddle that cause the instrument itself to vibrate, hence the pickup to vibrate relative to the string, and then the string's magnetic field responding, and thus the pickup detecting the strings response. Anyway, enough hypothesizing. Are you aware of more literature on this? I'd be interested to read more.

Jim
Click to expand...

After doing a quick experiment, in which I put the B string on the B tuner and played through an amp loudly (so I could be sure I wasn't hearing the acoustic sound) and plucking in precisely the same way and same location with both pickups is single coil mode, I found that the longitudinal mode is most definitely audible. You can hear it as the string is dying, as it seems the longitudinal mode sustains longer. Very much like a piano, with the string on the E tuner, it is roughly a minor 7th above the octave (plus a couple/few octaves). With the string on the B tuner, it is around a maj 6th above the octave (plus a couple/few octaves).

I'll make a recording tomorrow. It is definitely telling, though. I'll do one version with the relatively dead string that's on there now, and then again with a brand new string. That way we can hear the longi pitch pretty clear on it's own, and then hear how it interacts with the natural upper harmonics of the string.
 
#403
jsbarber said:
Mike,

The reason I said "if" is because the only time I'd ever heard of this (longitudinal mode in the context of a bass) was in a previous post of yours a couple of years ago, so I wasn't sure if it was your own theory or accepted science. I just read the article in the link from nuwavedc's post quoting your post, which I originally missed. It's a very interesting article. The fundamental of the longitudinal is comparatively high in pitch, as I had suggested would be the case in my post the other day. But what's puzzling me is whether the longitudinal wave is in the core or the winding. At first I figured must be the core, because we're calling it a longitudinal (pressure) wave, but it could be some kind of slinky-like effect in the winding/wrapping. (the article says it can be tuned by altering the speaking length, or the ratio of winding mass to core mass. I would not expect the latter to affect the tuning if was a pressure wave in the core...)

If it's in the core, then the pressure wave in the core wouldn't directly affect the magnetic field to the pickup (as I suggested above, and especially with the winding shielding it) - but what it could do is cause an oscillating force on the tuning peg and bridge that cause the instrument itself to vibrate, hence the pickup to vibrate relative to the string, and then the string's magnetic field responding, and thus the pickup detecting the strings response. Anyway, enough hypothesizing. Are you aware of more literature on this? I'd be interested to read more.

Jim
Click to expand...

I don't have any additional literature on it. I'm sure there's some out there. Conklins patent drawings for his string winding machines (pretty run of the mill today) are on the US patent office's website somewhere. And I am personal freinds with a guy who was Conklins design tech at Baldwin, and I own the 9' piano conklin designed. But that's all I have at the moment. The guy who makes fodera's strings is quite knowledgeable on the subject as well.
 
#409
OliveFodera said:
One of the very few basses to come out of the Fodera shop with a Koa body I'm guessing( other than the LG Signature model).



http://www.fodera.com/Main/NewBornDetails.aspx?FeaturedItemID=465

I have an old Kramer aluminum neck Koa body bass that sounds awesome. Looking forward to the comments on this one.

And look... it has an Extended B headstock.
Click to expand...

It looks good and the birdseye board is amazing. Wonder if birdseye would look good with a bolivian top :smug: I believe a have picture somewhere
 
#411
Here it is. I believe it has Bolivian rosewood top

FoderaBeez5.jpg
 
#414
thepontif said:
I don't have any additional literature on it. I'm sure there's some out there. ...
Click to expand...

Mike - I came across a 2006 Ph.D. thesis by Balazs Bank that you might find interesting. He uses physics models to develop synthesized sounds for instruments; and includes longitudinal waves, nonlinear behavior, and instrument body behavior. It's interesting because instead of starting with an instrument, then listening and trying to attribute the acoustic effects to causes, he incorporates different causes into his models and demonstrates the effect on the synthesized sound with sound files.

Invalid Link Removed


Jim
 
#415
jsbarber said:
Mike - I came across a 2006 Ph.D. thesis by Balazs Bank that you might find interesting. He uses physics models to develop synthesized sounds for instruments; and includes longitudinal waves, nonlinear behavior, and instrument body behavior. It's interesting because instead of starting with an instrument, then listening and trying to attribute the acoustic effects to causes, he incorporates different causes into his models and demonstrates the effect on the synthesized sound with sound files.

Invalid Link Removed

Jim
Click to expand...

That's some nice light bathroom reading there ; - )

good stuff
 
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