Falbo Intension Bridge

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lamanoditrento
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Falbo Intension Bridge

Post by lamanoditrento » Sat Aug 13, 2016 4:21 pm

falbo-g.jpg
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I heard Frank Falbo speaking on a podcast about his intension bridge design, which I thought sounded interesting. So I looked a youtube clip where he speaks about it and draws a simple diagram about it. He states his bridge design reduces rotation torque on the bridge to produce a louder more response guitar. From what I can gather, it does this by increasing the monopole mobility and maybe reducing the long dipole.

Anyone have any experience or thoughts on this design

http://theluthierist.podbean.com/e/frank-falbo/
https://www.youtube.com/watch?v=v0Dzxb1dZH4
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Re: Falbo Intension Bridge

Post by kiwigeo » Sat Aug 13, 2016 7:08 pm

At 4:12 in he video I don't see how he achieves a downward rotation behind the bridge.....it doesn't make sense. He needs to provide some lower bout deflection measurements to back up his claims.
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Re: Falbo Intension Bridge

Post by jeffhigh » Sun Aug 14, 2016 7:00 am

His structural analysis is very dodgy.
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Re: Falbo Intension Bridge

Post by lamanoditrento » Sun Aug 14, 2016 12:26 pm

I found his patent application for the design, but not sure if I am any the wiser
US20150243262A1.pdf
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Re: Falbo Intension Bridge

Post by kiwigeo » Sun Aug 14, 2016 12:48 pm

I can sort of see what he's getting at from the diagram in the patent document but surely the fulcrum is the forward edge of the string anchoring device rather than the saddle as he states. In his video he talks about the set up improving the tonality of the top. Having a bridge plate that extends way behind the bridge plus the added mass of the anchoring device is surely going to reduce the area of the lower bout that is free to vibrate.
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Re: Falbo Intension Bridge

Post by jeffhigh » Sun Aug 14, 2016 1:41 pm

There are no free lunches with this arrangement.
Whilst the bridge itself is free from rotational forces, the "string end receiving article" will be applying significant rotational forces to the area behind the bridge, the bridge will have significant downforce and will also be unable to transmit the first harmonic tension signal.

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Re: Falbo Intension Bridge

Post by johnparchem » Mon Aug 15, 2016 10:45 am

I see a strong upward force between the attachment and the bridge, At the saddle there is still a downward force and a force toward the nut. So I do not see why the top in front of the saddle does not dip and the back of the saddle does not rise.

If the area between the attachment point and the saddle is ridge then I just see the whole thing as a wide bridge, it may not rotate as much because the bridge is in effect wider for good or bad in terms of sound.

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Re: Falbo Intension Bridge

Post by blackalex1952 » Mon Aug 15, 2016 3:14 pm

On a practical level, the holes for the string ball ends, no matter what's underneath to secure them, are plain spruce.Give that a few years of string changing and the spruce would look pretty shoddy. To my mind, even if there is a vector force counteracting the string pull angle, the end result would still be an upward pull behind the bridge...so what's changed? The complexity and weight of the bridge and the size of the bridge plate, tying up the top movement, stiffening and thickening the soundboard in that area and increasing the mass.Ross
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Re: Falbo Intension Bridge

Post by Nick » Tue Aug 16, 2016 6:11 am

blackalex1952 wrote: To my mind, even if there is a vector force counteracting the string pull angle, the end result would still be an upward pull behind the bridge...so what's changed? The complexity and weight of the bridge and the size of the bridge plate, tying up the top movement, stiffening and thickening the soundboard in that area and increasing the mass.Ross
What he said :wink: :lol:
As you so eloquently put it Ross, it adds mass to the top, actually restricts top mobility because you have a larger bridge plate and subjects the top to a double distortion. Not to mention the loading of the glue joint at the "string end receiving article" and bridge plate interface, rotational and shear forces at this point must be up there.
Good on him for thinking outside the box but can't see it becoming the "go-to" design for future bridges.
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Re: Falbo Intension Bridge

Post by frankfalbo » Mon Oct 03, 2016 1:18 am

Greetings from the Santa Barbara Acoustic Instruments Celebration, where a couple attendees have alerted me to this fine forum's existence. I love what I've seen thus far.

I can try to make detailed answers to some of the quotes here as time permits during the show today, but prior to that are there any specific questions you'd like me to address?

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Re: Falbo Intension Bridge

Post by lamanoditrento » Mon Oct 03, 2016 8:54 am

Hi Frank,

Thanks for making yourself available for questions and I look forward to your response to the above discussion.

Do you have any frequency response curves of your design that you can share? Also do you have any deflection measurement of the monopole mobility?

Cheers
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Re: Falbo Intension Bridge

Post by kiwigeo » Mon Oct 03, 2016 10:59 am

frankfalbo wrote:Greetings from the Santa Barbara Acoustic Instruments Celebration, where a couple attendees have alerted me to this fine forum's existence. I love what I've seen thus far.

I can try to make detailed answers to some of the quotes here as time permits during the show today, but prior to that are there any specific questions you'd like me to address?
Hi Frank and welcome to the forum.

Thanks for popping in and making yourself available for discussion/questions about your bridge system.
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Re: Falbo Intension Bridge

Post by johnparchem » Mon Oct 03, 2016 11:46 am

I have seen a bridge a little like this; it is like a pinless bridge but the strings run to a tail piece. Falbo's design has a deeper anchor. It seems to me as the anchor is pulled toward the nut it will rotate allowing the bridge to rotate. I admit I could be missing a lot. I am just trying to make it work in my mind.

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Re: Falbo Intension Bridge

Post by frankfalbo » Tue Oct 04, 2016 3:24 am

Thanks guys. Forgive me in advance, I am very open and sharing with any and all general luthierie subjects, but sometimes have to tighten my lip with regard to the patent, not to put things in print that "teach" the design. There are several other patents that will follow this first one.

I'll be more specific with quotes when I'm at a desktop. From my phone here I can give a few quick generalities. The pivot points are very nuanced, and slight movements in the way I build the guitar; small differences as little as .050" are enough to visibly change the outcome.

The principle is simple, and the patent drawings are painfully rudimentary on purpose, so as to protect all of the iterations. So no, the inside of the guitar does not look like the patent drawing :lol:

I cannot give deflection numbers because first, they are meaningless without a benchmark. The top is already in a slight compound dome arrangement, with the bulk of the pre-stress at the neck area to lift the top to better match the fretboard angle, and to protect from neck cave. Then, the X brace flattens out to produce a "flat top" from the X brace to the end of the guitar, but all this while the kerfing/sides have been dished for a 50' radius. This is because when torque moments cancel, the force left is "up". This means my flat top is "pre-hung" a little. It is pulled up into a ready state, a small part of what makes the guitar sensitive to very light touch.

I'm sorry that was so long, but it is to say that, when you catch the top in the light, you can see the X brace locations, and you can see that (depending on now I have implemented the string end receiving article) that the top area behind the bridge is either slightly positive, neutral, or yes, slightly negative of the X braces. I can negate torque to the point that the top dips negative in relation to the X brace.

Holes in the spruce: I make those after the guitar is painted, and then I soak the area with the thin cyanoacrylate. It penetrates the wood fibers, draws its way in, and "plasticizes" the wood in that area. So what looks like painted spruce is actually reinforced. The bridge plate is underneath of course. If I ever feel like wear is an issue I can recess little Ebony or phenolic inserts into the top, or even shell but no complaints yet, so maybe we'll save that for the really expensive ones :)

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Re: Falbo Intension Bridge

Post by routout » Tue Oct 04, 2016 9:21 am

I like Innovative design and you sure have given that a go great work I like and get the concept :D .
John ,of way too many things to do.

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Re: Falbo Intension Bridge

Post by frankfalbo » Wed Oct 05, 2016 11:25 am

kiwigeo wrote:I can sort of see what he's getting at from the diagram in the patent document but surely the fulcrum is the forward edge of the string anchoring device rather than the saddle as he states...
In a normal pinned bridge, there are still multiple torque moments, but they are all in the same forward direction. With this, just imagine that the way things are configured, the top of the guitar and the fact there's a bridge plate laminated underneath, plus the fact there's a bridge on the outside (which is a brace unto itself) that the positive and negative torque moments are working together to cancel. They don't behave as individual moments that put a "bend" into the top between them.
kiwigeo wrote:Having a bridge plate that extends way behind the bridge plus the added mass of the anchoring device is surely going to reduce the area of the lower bout that is free to vibrate.
The lower bout has zero bracing at all. No transverse braces, it's clean behind the X brace. Cumulatively, there's less mass overall. If you add up the rest of the "stuff" that's in the guitar it still equals less mass than if two sizeable transverse braces were there. But the other thing to consider is that the mass that is there, is concentrated around the bridge, near the center of the top. This makes a very effective motor with a lot of horsepower. The top is driven very efficiently, from the center more like a speaker motor, or like hitting a drum with a larger drumstick.

I hope that makes sense, in relation to what you're saying here. If not let me know.

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Re: Falbo Intension Bridge

Post by DarwinStrings » Wed Oct 05, 2016 10:53 pm

Any chance of seeing inside the Guitar Frank, surely it will only be a matter of time before someone buys one and puts a image on the www. Do you string up from the outside? Like do you just poke the ball end through those holes and hook it into something?
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Re: Falbo Intension Bridge

Post by frankfalbo » Thu Oct 06, 2016 1:34 am

I apologize, I can't do photos of the inside, maybe someday. I can't stop someone from buying one to destroy, but its an expensive experiment. So it is cheaper for a company to just contact me, to discuss licensing under NDA. And lucky for me, sawing the guitar in half doesn't tell the whole story, much like on an arched surface, it would be difficult to tell if a brace was pre-arched or if both were straight but glued under an arched caul.

But yes the strings just slip into the holes and catch, simple like some electric guitar bridges. That's another reason the holes in the spruce don't really take any abuse. It's easy to "aim well" and the ball doesn't even contact the area. But if it does, there is no weight behind it. It's just the ball on the end of the (flexible) string. Not like the Takamine/Taylor/Ovation style top loading bridges that snap the string ball down against the top as it gets closer to position.

I can say that the piece inside is mostly a wooden block with certain grain orientations (different for different guitars I make) and the other parts are pulp-based, like phenolic or vulcanized fiber. So they have the same temp coefficient as the rest of the guitar. No aluminum in there to sweat and get cold, etc. The string ball contact is a 65,000psi crush strength material, so it's a "lifetime" part. Strings (even heavies tuned high) can't really dent the part. Even if they did the part would still perform its function just fine.

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Re: Falbo Intension Bridge

Post by DarwinStrings » Thu Oct 06, 2016 10:31 am

Hmmm if sawing the guitar in half won't help someone to work out what you are doing then how could a photo? I guess I don't understand how patents work as I had assumed they were to stop someone copying what you do.
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Re: Falbo Intension Bridge

Post by DarwinStrings » Thu Oct 06, 2016 11:04 am

Frank,Trent asks "Do you have any frequency response curves of your design that you can share? Also do you have any deflection measurement of the monopole mobility?"

You answer in part with this "I cannot give deflection numbers because first, they are meaningless without a benchmark"

Trent is referring to Trevor Gore's "monopole mobility" calculation. Trevor has published benchmarks for this measurement.

I watched a few Youtubes featuring you and I am pretty sure I understand exactly what you are talking about when you refer to parlour guitars as sounding like AM radio (nice expression/description) I use a conventional bridge on my parlour guitars (13 inch lower bout) and do not get that sound that I recognise from some factory parlours. I get the feeling that that sound you are talking about comes from relatively high main air response frequency as well as relatively high main monopole frequency response.
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Re: Falbo Intension Bridge

Post by frankfalbo » Thu Oct 06, 2016 12:15 pm

DarwinStrings wrote:Hmmm if sawing the guitar in half won't help someone to work out what you are doing then how could a photo? I guess I don't understand how patents work as I had assumed they were to stop someone copying what you do.
It's primarily about deviant behavior. If you have data out in public, that could teach someone how to do something similar, it also teaches them how to come in right behind you as a patent troll with something slightly different that will, for all purposes, just ruin your life and cost you unnecessary money. This is not the only patent that I will have issued on this subject either.

As for sawing in half vs. photos, both would teach a good portion, but neither (nor both) would teach all the secrets. As I said though the internet is a permanent and global place. Consider the fact I was alerted of this thread on the other side of the globe in Santa Barbara, California by someone who lives in the US!
DarwinStrings wrote:Frank,Trent asks "Do you have any frequency response curves of your design that you can share? Also do you have any deflection measurement of the monopole mobility?"

You answer in part with this "I cannot give deflection numbers because first, they are meaningless without a benchmark"

Trent is referring to Trevor Gore's "monopole mobility" calculation. Trevor has published benchmarks for this measurement.
Ok understood. I was taking the simpler language from kiwigeo just referring to "lower bout deflection". So it's Trent's first post that is correct, in that my long dipole is reduced/cancelled in favor of the monopole. With this in mind, this is where I start to talk about phase linearity and the comb filtering present within an acoustic top driven by torque. Amplitude, frequency density, and projection are now (in my experience) no longer directly tied to pure excursion data. In simpler terms, there are some speakers that have a longer excursion delta, that still are not the "loudest" nor have the longest throw in a group of their peers. When comparing two tops that are torque-driven, Trevor's numbers are what I mean by a benchmark. They are relevant because each is torque-driven.

So here again is where I unfortunately will go anecdotal: If you play my guitar(s) very softly, they still have a very wide frequency response, and are very responsive. BUT taken a step further (literally) if you are 10-20 feet (3-6 meters?) away from the instrument, the sound of the guitar is still almost the same. The distance does not degrade the signal. This is in part due to the phase linearity. The dipole vibration puts out-of-phase information into the top, resulting in comb filtering. This can be why a close-mic'd guitar goes from boomy to thin and tinny with only small mic or body movements. It's the comb filtering, not just that the guitar produces different sounds in different areas. So the maximum excursion only tells part of the story. Much like I could have a deep excursion on two speakers, but if they're wired out of phase the speaker cabinet will sound quiet and distant.
DarwinStrings wrote:I watched a few Youtubes featuring you and I am pretty sure I understand exactly what you are talking about when you refer to parlour guitars as sounding like AM radio (nice expression/description) I use a conventional bridge on my parlour guitars (13 inch lower bout) and do not get that sound that I recognise from some factory parlours. I get the feeling that that sound you are talking about comes from relatively high main air response frequency as well as relatively high main monopole frequency response.
The dipole still cancels out information. Even in the small box, there is a loss of extended frequency response as the top is in argument with itself. That said, there are MANY fine parlo(u)r guitars that achieve a full sound, and there are ways to expand the dynamic range of a parlo(u)r without my bridge and bracing design. But when a small top is more phase linear, its surprising how much frequency density is made available. Nothing I say in my marketing or social media is intended to speak less of other methods or luthier's products.

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Re: Falbo Intension Bridge

Post by DarwinStrings » Thu Oct 06, 2016 1:21 pm

frankfalbo wrote: parlo(u)r
It's okay to type American here we can translate.

Unfortunately I can't hear projection in a sound clip but the one Teja played sounded okay on Youtube.
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Re: Falbo Intension Bridge

Post by DarwinStrings » Thu Oct 06, 2016 1:39 pm

One other thing Frank if one of your guitars makes it to Darwin which only has two commercial guitar outlets (so it may be a long time coming) I will borrow it to get a spectrum graph and a photo to satisfy my own curiosity, is there anything that stops me from publishing that on the www?
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Re: Falbo Intension Bridge

Post by frankfalbo » Thu Oct 06, 2016 2:33 pm

I think it would be alright, but I would appreciate if you reach out to make me aware.

There are two things I can reference regarding frequency response that may be beneficial. First, is that one thing that is consistent from guitar-to-guitar is that if my guitars are compared to other same-size guitars with traditional construction, my resonance is about a whole step to a step and a half lower in pitch. So all things equal if a guitar body resonates in G then mine is E or F. This is true across other brands, but the repeated confirmation came over the first few years when I made my guitars inside the Larrivee factory. I didn't work for them, I just used their space and sourced some materials through Jean. So whether it was their standard parabolic bracing or their Martin styles, my self resonance was deeper.

Just recently at the Santa Barbara festival I was talking to Brian Gallop about it. Curious, he came to my booth and started reading tap tones with an analyzer on his iPhone. He says "you're right, this one resonates at [about] 80Hz."

A looonger time ago, before I made the first of what you see as Falbo Guitars' Alpha series, I also made two otherwise equal guitars, and recorded passages with both. I sent them to my friend Joe Gore for differential EQ analysis (as well as subjective feedback) and I didn't tell him any of the details. Only "here are two guitars that are different in some way, tell me what you hear".

His EQ curve matched mine. What became the Falbo Alpha had a deeper, tighter bass. Lower in frequency, more present in softer passages, more controlled when played harder. Doesn't get muddy. More brilliance above 10kHz too. More full frequency information when played softly, and the same or more total dB when played hard. There are guitars that are louder than Falbos when played hard, but there are also some that sound louder and under analysis prove it just seems that way because of an abundance of narrow-banded mids with truncated highs and lows. The Falbo is producing more dB, spread out.

Subjectively, Joe's response was that they sounded like they could be the same guitar, just recorded differently. The second guitar was "right". It was all the things you would do to the first guitar to "fix" it, although nothing you did to the first guitar actually worked to match it to the second, though both were unprocessed. This speaks to phase linearity, frequency density, things of that nature.

As for parlor/parlour and ft/meter forgive me if that sounded patronizing, but let's be clear, Australia and New Zealand are LITERALLY the first words of this forum! I am a humble guest here and thank you for the hospitality and candor thus far.

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Re: Falbo Intension Bridge

Post by DarwinStrings » Thu Oct 06, 2016 2:55 pm

frankfalbo wrote:I think it would be alright, but I would appreciate if you reach out to make me aware.
Sure will, I would post them in this thread. Shame you can't post a spectrum graph it is easy stuff to do and many of the members here relate well to that rather than words.
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