Can you assess this?

[Darryl Young]

I like the fact that he develops a model, then compares the model to measurements from real guitars to judge the model. Anyone else doing this? Here is an example.


The modelled frequency response of a guitar with heavy sides (blue line) vs. the measured frequency response to 500Hz of the same guitar

[Jim_H]

But what does that translate to in terms of 'good' or 'bad' from a guitars standpoint?

[johnnparchem]

But what does that translate to in terms of 'good' or 'bad' from a guitars standpoint?

They do not talk in terms of good or bad as people look for different things from their guitars. The chart is a frequency response curve. They use it to map where the guitars resonances are from tapping or some other broad frequency input. Predictably moving the resonance peaks to shape the voice of the guitar and help tunability is the point of the graph. The do describe what each peak is and where it comes from. They also describe how the graphs relate to sound ie. Low or high frequency response.

[tippie53]

too much whilttlin for Wayne . I can see the structural advantage of this but I am a traditionalist . I hope to hear one of these at Woodstock in a few weeks

[Darryl Young]

Interesting that Trevor uses additional mass in the sides to improve sustain. John P., do you know where he adds the mass? Also interesting that he uses a very lightweight bridge so he doesn't use traditional bridge materials. He even uses carbon fiber to get the stiffness he wants from the bridge material he chooses. So he is at half the weight of a normal bridge. Apparently, heavier sides help add back some of the sustain lost from using the lightweight bridge (if I understand correctly). He discusses it some here:

http://collingsforum.com/eve/forums/a/t ... 020426/p/2

I've got to admit that I lean toward traditional as John stated. However, I always want to know more about how the guitar works and how I can use that to tweak traditional designs to get the most from them. But, never say never! It would be interesting to have identical guitars (which they never are) and hear the difference between a normal weight bridge with lightweight sides and a lightweight bridge with heavy sides. These type changes could be done using traditional bracing.

[johnnparchem]

Interesting that Trevor uses additional mass in the sides to improve sustain. John P., do you know where he adds the mass? Also interesting that he uses a very lightweight bridge so he doesn't use traditional bridge materials. He even uses carbon fiber to get the stiffness he wants from the bridge material he chooses. So he is at half the weight of a normal bridge. Apparently, heavier sides help add back some of the sustain lost from using the lightweight bridge (if I understand correctly). He discusses it some here:

http://collingsforum.com/eve/forums/a/t ... 020426/p/2

He adds "overgrown side splints" with T-Bolts onto the the sides about in the center of the lower bout. He does this when he wants to acheive the effect of a very stiff frame. The effect on the guitar is to use more of the top as the node line as shown in chaldni patterns at low frequencies moves toward the edge of the guitar. (more of the top is moving for low frequencies).

He says the it gives the guitar more of a solid weighty sound increasing the general volume but favouring the lower frequency.

I think a part of his design consideration is to produce a concert volume guitar. He clearly describes the tradoff between volume and tone in his discussion.

[Tony_in_NYC]

The more I learn about guitar building "theory" the more I realize that there is more than one way to make an excellent guitar. I also know I dont make enough guitars each year to experiment to any great degree. The cedar topped dread I just finished has one finger brace per side and only one tone bar below the X. I can tell you it sounds great to my ear. I also know I still need to build lighter. The top on this guitar could have been thinner based on its stiffness. I am going to get to build a very close copy of it this winter though and I think I will make it with a thinner cedar top and similar bracing. When I feel I have done all that I can with a traditional X-brace(never going to happen at my pace), I will move on to another type of bracing. Or, if another style of bracing is proven to be significantly better, I will give it a try. Otherwise, I am very happy with how my guitars are turning out so I see no reason to change, and again, I don't have time to experiment. This winter I have two commissions to build and my one and only experimental guitar, the all cedar guitar. That is going to be X-braced as well. The only real experiment is that it will have cedar for the back, sides, bracing, kerfing, and neck. I'll prolly use mahogany for the neck and tail blocks. If anyone does try another bracing style, I would love to see and hear it!

[Darryl Young]

He adds "overgrown side spints" with T-Bolts onto the the sides about in the center of the lower bout. He does this when he wants to acheive the effect of a very stiff frame. The effectt on the guitar is to use more of the top as the node line as shown in chaldni patterns at low frequencies moves toward the edge of the guitar. (more of the top is moving for low frequencies).

He says the it gives the guitar more of a solid weighty sound increasing the general volume but favouring the lower frequency.

I think a part of his design consideration is to produce a concert volume guitar. He clearly describes the tradoff between volume and tone in his discussion.

John, when you say "about in the center of the lower bout" when describing the location of the additional mass on the sides, does that mean in the tail block?.....or on each side of the lower bout....meaning roughly at the ends of an imaginary line extending along the rear of the bridge?

A question was asked earlier about how this applies to guitar construction. I guess everyone over time develops a model in their mind of how a guitar works/functions. And if you want to improve the way your guitar sounds (tone, volume, etc.), how do you decide what you will change? Likely you think about how the guitar functions (the model in your head) and come up with ideas how you change/alter something to help get the tone you desire (choose a differnt wood, different body style, different bridge, wider X brace angle, etc.). But what if the model in your head isn't exactly right? What if your assumption on how things work isn't correct? So my thinking is the better one understands how a guitar actually functions, the better decisions you will make resulting in better sounding guitars.

So how many have actually tested their theory on how the guitar works? Trevor is an engineer that has based his model on physics concepts. He spends a lot of time developing his model and describes it in detail. He then compares the model to measurements from real guitars to see if the model proves itself. I can't think of anyone else that has done this.....can anyone else? It's one thing for someone like me to "speculate" on how I guess the guitar works and postulate how this or that change will affect tone (I enjoy these discussions but hopefully everyone here knows you must take the speculation with a lot of skepticism) but it's something else to develop a model based on scientific principles then test to see if the theorys prove correct!

So Trevor took things one step further and developed (or refined, not sure) the falcate bracing using the model to test the design, and produced more of what he wanted in his guitars. Now likely I'll never experiment with falcate bracing.......but I still think I would greatly benefit from understanding more about how a guitar works to get the most I can from traditional X bracing.

[deadedith]

I just exchanged emails with Brian Burns re: Trevor Gore. Gore spent 10 days with Brian in Ft. Bragg and they became friends, covering a lot of ground concerning voicing and all other manner of guitar building procedures.
One thing Gore said, and I quote Brian here : "As for his bracing system, he said that most any conventional bracing system would work, and that the main thing was to get the resonances in the right places."

[kencierp]

I am not going into detail -- but I'll Ditto Rick -- data that proves or disproves then concludes -- must be investigated and validated by a third uninterested party. Shiminoff had a data pool now it seems Gore disagrees and likes his own data pool better. Someone will no doubt come along and disagree with Gore --- which is exactly what happened to Kasha. Not to mention that construction principles which were "proven sound" did not work in a repetitive manner -- yes Gibson most likely screwed it up to some extent.

Its all great fun -- but some may remember I posted long ago that I built two guitars almost identical but one was tap tuned per Shiminoff's theories using an original Peterson Strobe tuner -- in the end no one could hear any difference between the two guitars. So I personally tend to use guitar engineering data with a grain of salt.

Are there a forums where guys and gals talk about redesigning pianos or saxophones? Just kidding -- it would be nice to be able to predict the "exact" characteristics of a guitar before we make one. It just seems to me the easiest way to do that is to copy one we've heard in person.