Michael F. Lazar
Luthier


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Design and Construction

Design

Over the past 12 years since returning from my learning experience with Greg Byers at the American School of Lutherie, I have tirelessly researched the art of classical guitar construction seeking out information that would enable me to achieve my objectives. One by one I have examined and incorporated innovations that "made sense" to me in terms of their potential to address commonly perceived shortcomings in the performance capabilities of the concert classical guitar. I have modified and "proved" each of these

innovations to the satisfaction of myself, my group of evaluators and my clients by building at least 6 instruments before going on to address the next challenge. The latest innovation was introduced in 2012 with the reconfiguration of the top bracing design I've been using and the results truly represent the culmination of my efforts over the past 30 years. Descriptions of the more important elements of my guitar design/features and the performance issues that they each address are set out below.

Laminated Ash Linings, Maple Harmonic Bar and Dropped Tail Block

Energy dissipation has been identified as an issue in lightly built guitars. Energy dissipation or waste occurs when the top does not rest upon a solid, dense and rigid foundation. Replacing kerfed linings or small blocks (tentellones) made from light wood with heavier laminated linings made from dense hardwood seems to help in addressing this issue. These linings coupled with a harmonic bar from dense hardwood form a solid foundation upon which the top

 (particularly the lower bout) can rest and operate from. Vibrating energy tends to follow the path of least resistance and is reflected back into the top rather than being dissipated into the sides. This increases both volume and sustain. The dropped tail block enables the linings to form an uninterrupted perimeter around the entire lower bout and this serves as a further enhancement to the design concept.  

Sloped Top and Elevated Fret Board utilizing Spanish Heel Architecture 

In 2003 I modified my design to so as to incorporate an elevated fret board. This was achieved by rotating the top using the bridge saddle as the point of a fulcrum so that, in fact, the fret board is not really elevated but rather the top is simply sloped downward. In order to maintain the plane of the bridge, the top is fully domed with the apex of the dome located at the mid point of the entire top in front of the bridge. This results in a very uniform top shape as opposed to deformation that occurs when only the lower bout is domed. 

In order to achieve the Spanish heel architecture the recess in the neck for insertion of the sides must stop at the proper distance below the fret board. In addition the top now had to be inserted into the neck and glued to the underside. The top photo details the kind of work necessary.  

The benefits I was looking for from the elevated fret board were as follows:

1. Improved sustain in the treble notes above the 12th fret due to the continuance of neck wood supporting the fret board all the way to the sound hole.

 

 

2. Improved volume and projection due to the change in the angle of pull by the strings in relation to the top. The fully domed top shape also provides more volume, projection and balance as well as increased structural stability.

 

 

3. Improved access to notes above the 12th fret as observed by most players when they experience a raised fingerboard. 

 

 

4. Improved stability in the fret board as it is now glued to a flat surface from end to end. This helps to accommodate more finely tuned action heights.

 

 

 

Scalloped Bridge

Near the end of 2010 I decided to try a new bridge design that I had been pondering for about 10 years. To the best of my information the concept was originated by John Gilbert, a well known American Luthier and a similar approach is showing up in guitars made by other important luthiers.  

Clearly the design is stronger as the weak points found in the traditional bridge where the arms meet the tie block have been addressed. The design should distribute energy into the top more evenly as the bridge arches downward toward the top from the center to the arm ends. 

I also found that the weight of the bridge is more easily controlled.

The objective I was looking to achieve was an improvement in treble response and balance so that crescendos could be more easily achieved in melodic passages, particularly those involving treble string notes going above the 12th fret. 

The results from guitars utilizing the design have been very gratifying to the extent that several of my clients have asked me to retrofit the design to their guitars.

Dual Fan Struts (Latticed)

My top strut design is based on a concept developed by Greg Byers although it is configured quite differently. While it almost appears to be a lattice design, the concept incorporates two fan strut sets. Each set is rotated about 18 degrees off center, one to the left and the other to the right. The focal point for the braces is located further out so as to achieve a full "open" tonal response. The dimensions of the struts are such that  the total mass is slightly less than that of the traditional fan system. 

The network of struts with its numerous intersections provides both great strength and protection against the development  of cracks. In addition the shape of the top holds up extremely well under tension and there is much less deformation than that which occurs with the single fan system. 

Tonally, the guitars are virtually indistinguishable from my guitars utilizing standard fan strut design. On the other hand response elements such as volume, projection, clarity, and sustain are notably improved. In particular I found the treble response to be further improved in the higher registers.  

 

I'm sure most would agree that the top of a guitar will govern its performance characteristics more than any of the other components. While  the manner in which the other components are designed and constructed can make an important contribution to a guitar's response, their role is primarily to support what the top is sonically capable of producing. 

The principles governing the manner in which a top operates are extremely complex. Essentially they revolve around two opposing characteristics that govern its ability to vibrate in response to applied energy. The first is "impedance"  (the extent to which the top resists vibration) and the second is "admittance" (the extent to which it responds to vibration). Tops with too much built in impedance will not produce much volume or projection. Tops with too much admittance can be loud and projective but may sound unpleasant as they respond excessively to a wide range of harmonic partials (overtones). So the apparent challenge seems to be finding the balance between impedance and admittance that will produce the desired guitar like sonority and tone along with the needed volume. But its far more complicated than that.....

Read More..

Construction

I build my guitars in components, ie; top, neck, sides, back and bridge. When the components are complete the top is attached to the neck and then the sides are affixed to both the top and the neck at the same time. The top resonance will change as a result and it is again measured. The top may then be thinned further around the edges to reduce the resonant frequency if necessary. The guitar is now ready to receive the back.  The back braces are a little heavier than usual for additional mass.  

When the back is on, the box is now closed and a cavity resonance can be determined. If adjustments are needed, the back perimeter can be thinned as well as the perimeter of the top if not already done.  If all has gone well, both the top and cavity resonance will be where I want them to be.

Finally I decide upon the weight of the bridge. If the resonance is on the high side of my targets, the bridge may be made a little heavier if lower, it may be lighter. 

Before gluing on the bridge, the bindings and purflings are put in. When the bridge is glued on,  the resonance of both the top and cavity are checked one last time. If, at this point the perimeter of the top still has not been thinned in order to achieve a desired response, there is one last opportunity to do so.

I then fashion the compensated nut and saddle, install the tuners,  string the guitar, adjust the action and play it for a few days until it fully "wakes up". If deemed desirable I may make further adjustments by thinning the top closer to the center, removing wood from the bridge to lighten it etc. When I'm satisfied that the guitar is the best 

that it can be, I then remove the strings and tuners and  weigh the completed guitar. Finally, I french polish the instrument and the work is done.  

So, to summarize the decision making or "voicing" part of construction process, tapping and feeling are replaced by measuring resonance and stiffness with specific instruments. A laboratory scale is used to calculate density and measure the weights of the braced top and back to ensure that they fall within predetermined parameters. Stiffness and elasticity are measured by placing the top in a special frame and measuring the amount of deflection and return when a specific amount of weight (force) is applied to the top and removed. Resonance is measured by applying variant frequencies to the top with a tone generator until it reaches its maximum vibration amplitude. The top is thinned until the target resonance is achieved.  In order to work this way, one must know what the density, stiffness and resonance targets should be and this is part of what  I learned during the master class with Greg Byers. 

At the completion of each stage of the voicing process using measuring instruments (most of which were not in existence during the time when Torres built guitars) I then "tap and feel" so that my hands also get an education. This is important to me as I believe that the hands can be incredibly sensitive measuring devices and that my tactile senses are becoming "calibrated" in this way. 

Greg also teaches that records should be kept regarding the final measurements for each guitar made along with comments covering a subjective assessment of the guitars characteristics when it has been completed. These records begin to form a collection of empirical data upon which to base further evolution.