SPRUCE SOUNDBOARD?

It is generally assumed, published and stated that spruce is the ultimate soundboard to have for the harp. Technically there is much truth to this conclusion. However, there are many items of practical fact that should be considered, regarding the sound board question.

Unfortunately, it is often assumed that the sound of any harp is almost totally dependent on the sound board material. Many believe that ONLY harps with a spruce soundboard are capable of producing a great sound. Such conclusions are closer to myth, rather than that which can be demonstrated by the proof of scientific fact.

To be fair, it is generally accepted that if we make two harps of identical construction, putting a laminated sound board one, and a tapered spruce sound board on the other, in most cases, we would generally find the harp with the spruce sound board delivering a superior sound, once sufficiently aged in. However, it is a given with musical instruments that spruce can require up 15 years to arrive at peak performance. The question becomes, how much superior is the sound of spruce, compared to other, more economical choices? Lets try to explain.

While it is true that spruce is among the best of sound board materials, its value of advantage, compared to other possibilites has been much exaggerated, especially when the question of practical isssues are thrown into the mix. While spruce is the wood of choice for the sound board of a violin, please remember that a harp is not a violin, and there are some very good logical reasons why other types of wood are often used for the harp face, typically referred to as the sound board.

In general terms, every wood species can have different sound characteristics, and even two harps of identical design, made of the same wood, played side by side, will usually have detectable differences in sound. This is just a given fact for any musical instrument. So, while it is probably correct to say that other sound board materials, compared to spruce, produce a different sound, it is entirely not true that a different sound is always inferior. As with vision, the beauty of sound is often in the ear of the beholder.

While the sound produced by spruce and similar wood species, such as cedar and redwood, is said to be techically superior, for most of us, the comparative margin, when attained, does not warrant the extra expense of production, in a practical sense. This diminishing curve of realized sound improvement per doller spent is why you will find many harpmakers using alternatives like the European birch laminates. The durability and cost savings of the laminated birch, as an alternative to spruce, makes it quite attractive as a sound board material.

Because tapered spruce and sound boards of similar woods are fairly expensive to manufacture, and because spruce, in particular is more vulnerable to cracking and splitting, and because harp sound boards must carry a huge, constant stress load throughout the life of the harp, laminated or other alternative wood species are often used, and deemed more practical in the long run for harp players whose harps will be subjected to enviroments of sudden humidity and/or temperature changes.

Laminated woods are stronger and more durable, compared to spruce of the same thickness. The thicker the wood, regardless of species, the less ability it has to respond to the plucked string vibrations. Any wood, regardless of the type, has greater ability to produce sweet, open tones, when kept light and thin. However, the stress load on the sound board can be in the realm of 1,000 pounds or more, depending on the size of the harp. Hence, when we consider that a wood like spruce or cedar, more fragile by nature, must then be made thicker in order to withstand the stess resulting from the constant pull of the harp strings, we can begin to see why a thinner, but durable laminate can have a noteable advantage, thus reducing the gap of comparison between spruce and the birch ply. Without question, spruce at a given thickness has better acoustical properties, but when we can maintain a durable sound board structure with birch ply at half the thickness of spruce, it is not difficult to see that laminated woods can have a definite advantage in this regard. The European birch laminate is mass produced and shipped in large sheets, making it able to be worked at only a fraction of the cost of tapered spruce.

In addition, when spruce or a similar soft wood is used, an additonal hardwood rib must be added to the exterior face of the harp sound board. All harps typically have a string rib on the back side of the sound board face. This is part of the skeletal framework employed to support the stress load of the harp strings. However, with spruce, being too soft and fragile to hold the metal string eyelets in place, a second hardwood rib must also be added to the outside face of the harp to prevent the eyelets from pulling out of the sound board. This additional rigidity and weight of hardwood, to some degree, will retard the ability of the soundboard to respond to the plucked strings, thus we are further diminishing the ability of the spruce to breathe or respond to string activity.

Some will rightly argue that when this additonal rib is added, an equal amount of wood may be subtracted from the inside rib, thus neutralizing the negative effect. This statement, in theory is true, but the practical matter is that much of the time, such care, because of time and expense, may not taken during construction, thus resulting in the fact that a spruce sound board more often than not, has more bulk of hardwood weight and density attached to the face of the harp, reducing its freedom to respond and transmit the release of string energy. This is just one more detail, which to a degree, defeats the very purpose for which spruce is employed. Hence, a laminated birch soundboard, NOT requiring this additional rib on the harp face, is left more free and open to be activated when the strings are pulled. The string rib, when employed, automatically interjects a degree of resistance to the transfer of energy from the strings to the sound board and sound box cavity. Remember, the only reason for the string rib on the face of the sound board is to provide a hard surface for the string eyelets. Hence, it should be no wider and thicker than necessary to perform this function, when used on a spruce sound board.

So, there is a crossover concept where any comparative acoutical advantage of the fragile spruce, needing to be kept relatively thick to withstand the stress load, plus requiring the addition of an extra hardwood rib, results in a reduction of the product of any total sound advantage it may provide.

While it is true that lamination (use of wood plys) also retards the ability of any wood to resonate, the overall negative effect of laminating is minimal compared to the other positive advantages mentioned. The cumulative result of all these comparisons yield a statement of truth, which is simply that the oft used European birch laminate produces a greater yield of sound and durability per dollar spent. Since the difference in sound quality between the various options discussed is fairly subjective, and since the difference in cost between a tapered spruce and laminate birch soundboard can be as much as 20 to 25% of the total harp price, the cost issue, for many buyers, becomes the more important weight of decision.

Like most harpmakers, we at Blevins are happy to produce your harp, with the sound board of your choice, at the stated price. The point of this discussion is to provide the customer with more facts on which to base a practical decision, as it is obvious to us, being clearly indicated by the number of questions we receive on a daily basis about harp sound boards, there is much misunderstanding of the harp sound board issue, with about as many myths as facts floating about in the seas of the harp adventure.

It is our belief that you should be made aware that paying 25% more for a harp just because it has a traditional spruce soundboard, does NOT guarantee that you are buying a harp with a 25% improvement in sound quality, any more than paying $4,000 guarantees a harp will have twice the quality of sound and function, compared to one of similar range, costing only $2,000. The price yardstick is not always linear in this regard.

In conclusion, is it true that spruce should produce a better sound? The general accepted answer is yes, but to what degree and how much it is worth in terms of value received for dollars spent is something each of us must decide individually. There is no clear cut answer on this. It depends on many factors, including the intended use of the harp, budget available, and also the sound desired, which varies greatly from person to person.

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