When looking at acoustic pianos, the types of woods used within the piano are imperative to the tonal quality it creates. However it’s often overlooked why these certain types of wood cost so much to produce, and the process that they go through to create some of the best sounding instruments in the world.
Today we’ll briefly outline the processes that most manufacturers use, give you some insight into the types of woods to consider when buying a piano and explain the process that gives the piano it’s wonderful tone.
Read More: What do tone, voice and timbre mean on a piano?
Understanding Sound
Before we begin looking at the types of wood, it’s important to understand both why and how the wood interacts with the piano. The best way to do this is actually to compare the instrument to a common digital speaker that we all have in our homes.
In it’s most basic form, a speaker works by passing an e-signal through a circuit, sending that through a magnet, which then in turn moves a speaker cone up and down, producing high and low pressure that then in turn amplifies and creates sound.
This is the same for acoustic pianos, however instead of an e signal, we have the input action (pressing a key), transferring this through the instrument (via the action), creating a vibration in the strings (similar to the magnet), transferring this via the bridge into the soundboard (which acts like a speaker cone) which then produces a sound.
Now whilst that may seem straightforward, there is an awful lot going on here and every single part matters in creating the perfect sound. Unlike a speaker that is largely directional, a soundboard produces a sound that travels both up, down and every way imaginable, producing a more powerful, direct sound.
Types Of Wood
Now we understand why the wood is needed, let’s move onto the types of wood you’ll most commonly find on pianos.
Woods can be largely split into two types - Hard and soft. Each type of wood has it’s own unique specific tonal quality that makes is great for one particular job. For example oak sounds VERY different to spruce.
Firstly lets look at the softwoods. Soft wood is far better for transmitting sound than hard woods, because of this, they usually make up the soundboards on pianos and are rather sensitive and more fragile woods. This is why if a soundboard becomes cracked or damp, it’ll sound VERY different to how it should.
Ultimately softwoods need to have a fantastic vibrational resonance and need to be able to cope with that level of pressure whilst playing. Great materials for this that are used in a whole host of instruments are spruce, cedar, ash and alder. Most quality pianos primarily use spruce as their soundboards.
Next we have hardwoods. These are primarily used for the body and framing of the piano as they are hard wearing, smooth but also so not compromise the sound quality. Some examples here may be: Maple, mahogany, rosewoods, Brazil woods or ebony woods. Many of these materials also make for great fingerboards on instruments such as violins or guitars as they’re smooth and long lasting. Walnut is also a great example of a hardwood with a very particular tonal purpose in pianos. Due to it’s density and durability, walnut is a premium wood for creating the hammers within a piano.
Read More: Acoustic Vs Digital Pianos
Sourcing Material & Preparation
Now that we know which woods we’re looking for, we actually have to go and find them. This is such an important step that some premium piano manufacturers hire what are known as ‘wood scouts’ - people who travel the world and the best trees in the world, knock on them to listen to the ‘sound’ that the tree creates they then select the trees on an individual basis as to whether or not they want them to be used in manufacturing.
The density of wood is based on how quickly the tree grows, when a tree grows slowly, the rings within are packed tighter together, when a tree grows quickly, the rings are further apart. As you can imagine, trees grow at different rates based on: The weather, the temperature, the soil and no end of other external factors that might affect them. For the common everyday tree, this creates a variation in the size of rings within the tree, meaning that from a sound perspective, the tree will ‘sound’ inconsistent.
In order to avoid this, piano manufacturers look for trees that grow in extremely controlled and consistent conditions. These locations are in interesting areas where there is little seasonal change and usually...are very high up on mountains - The swiss and French alps in particular are known for producing this type of wood.
The manufacturers are then faced with a few more challenges, obviously it’s rather difficult getting a tree down from the side of a mountain, and also because of their slow growth rates, these trees are incredibly premium and so there is a very finite amount of them available. This is why certain wood types can inherently cost more to produce.
There are of course other sources where manufacturers will get their wood from. Some use reclamation woods from Alaksa, Asia/Africa, whilst others will use various wood types and ‘stick’ them together (known as laminate).
Laminate wood is it’s own complete tangent and deserves a guide in itself! However on the whole, laminate woods are generally considered below natural spruce as they are essentially thin pieces of woods that are stuck together with glue. The glue has a very different sound quality to that of natural woods and the variations in the strips will mean there are large inconsistencies within, creating a ‘less perfect sound’.
Cutting the Wood
Now we’re getting into the real fun stuff!
It may be easy to overlook, but the way the wood is cut will have a significant impact on it’s tonal properties. There are 3 main ways to cut piano woods.
Plainsawn - This way of cutting is inconsistent, but incredibly cheap and cost effective.
Quartersawn - A nice middle use of woods with a little wastage and better consistency.
Riftsawn - A lot of waste but incredibly consistent (Many manufacturers use the spare wood for other uses.
As you can see, the way in which the wood is cut, produces very different results in how the rings appear on the wood and thus determine the quality of sound produced.
Preparing The Wood:
Now we have our wood and we’ve got it cut, it then needs drying. This period can take anywhere from 2 weeks to over 18 months...as you can imagine, if you’re having to naturally wait for the wood to dry, it puts up the price dramatically, what it does do however is minimise any potential inconsistencies within the wood. For pianos that need to be produced in larger quantities, many manufacturers use kilns to heat the wood. However this does lead to potential knots, cracks or inconsistencies within.
This process is incredibly secretive and one of the main factors that makes each manufacturer so different in achieving their overall sound quality. If the wood is left too ‘stiff’ then it will create a ‘tinny’ sound that won’t transmit properly, if it is left too ‘flexible’, it won’t resonate properly and will lose a lot of it’s tone. This is why cheaper instruments generally ring for less time.
Manufacturing:
Again, every manufacturer has a very different approach to creating their pianos and it would be impossible to cover them all in one place. Essentially however, they will use the wood that has been cut, dried and treated and will then move onto the manufacturing process and assemble the piano. These will include combining the soft and hardwoods together to create an instrument that sounds impeccable. A few key areas to pull out here that all impact the tonal quality of the piano are:
The soundboard
The body of the piano
The bridges
The backposts
All of these woods come together with the various other actions, metals, strings, keys and intricate pieces to create that sound we all know and love! We will be exploring the manufacturing processes in a later article, but hope for now this has given you just a small insight into the level of details and perfectionism that can go into one of these incredible instruments! Next time you read ‘spruce’ or ‘laminate’ soundboard, we hope you’ll know what you’re looking for!