Phoenix Carbiano Press Release April 2016
In September 2012 we showed the first grand piano ever made from carbon fibre at the Music Fare in Cremona. It was a baby grand 170 cm piano based on the scaling design of the Steingraeber Model A 170.
For more than two years prior to this we and Steingraeber had been marketing climate resistant Phoenix pianos which incorporate our carbon fibre soundboards of minimal thickness to make their sound quality and power rather better than that of traditional pianos. The sustaining of notes sounding in these pianos is outstanding and up to twice the duration of otherwise similar traditional pianos.
The Challenge of Carbon Fibre in Pianos
Building a carbon fibre piano presents a particular and massive challenge. Whilst cast iron frames and the steel strings of pianos expand or contract similarly when temperature changes, carbon fibre barely changes dimension at all with rise in temperature. Thus a piano incorporating a steel strung frame made of carbon fibre but otherwise similar in concept to that of a traditional piano with cast iron frame, will drop in pitch about a semitone with a rise in temperature of its surroundings of a little under 10 degrees Celsius. Our piano at Cremona incorporated in its frame a new concept that ensured the frame extended or contracted to compensate for change in length of the strings with rise or fall of temperature. Indeed the dimensional changes with temperature change were better matched than is achieved in conventional pianos.
We so designed this frame that its strength in terms of dimension change under string load was virtually identical to that of a traditional piano on the basis we would thereby at least match the tuning stability associated with traditional wood/cast iron pianos.
We could have attempted to develop a string metal material with minimal thermal expansion properties to match that of carbon fibre, based on invar iron/ nickel alloys with small additives such as carbon vanadium and yttrium, but the high strength requirement of piano wire would have been costly and perhaps technically impossible to match. We did not want a piano whose strings snapped or behaved plastically in service. We had learned that lesson from those who have tried to make stainless steel strings for pianos. It probably can be done but it would be is a huge project.
Lessons from Cremona
This first prototype at Cremona demonstrated that;-
- We could build a fine sounding piano of about a third of the weight of a similar sized conventional instrument.
- The use of carbon fibre with it extra stiffness, strength, and lower sound energy absorption enabled us to achieve, from a baby grand size of piano, sound power, a duration of sustained sound, and sound quality normally associated with large instruments
- We showed that the climate resistance of carbon fibre which is inert to humidity and temperature change could be exploited in pianos.
- However we did not succeed in enhancement of the bass sound sufficiently to match that of the amazing upper registers of the Cremona piano. Sound uniformity across the registers needed attention.
A New Application of Computers in Piano Design
Since Cremona we have worked intensively on further development of this “little piano with big sound.”
The main thrust of our work since Cremona has been to create a computer programme that enables us to calculate the natural frequencies (technically called “eigen” frequencies) of the whole piano system and its components, and to study how these alter with changes in design or materials of individual components. This programme uses the high power Finite Element Stressing technique. It divides our particular piano into over 6 million tiny elements and evaluates how they interact. Clearly a powerful computer was needed for this study. The work was subcontracted to Simpact Engineering in Warwick who had the necessary skills and facilities.
We demonstrated that in the upper registers of a piano there are many natural (eigen) frequencies of the instrument and that they are so close together that it is almost inevitable that any note struck will be very near to a natural frequency of the system so that resonance will occur and the note power will be optimised. However in the lower registers the incidence and proximity of eigen frequencies to the note being struck in all pianos is far less favourable. The smaller the piano the worse the situation. Indeed in our piano the lowest eigen frequency was well above the 27.5 Hz frequency of the bottom A of the piano! This is the case in most if not all baby grand pianos.
We began investigating ways to introduce more eigen frequencies in the bass registers.
- Soundboard thickness
- Soundboard fibre quality
- Soundboard mounting stiffness
- Stiffness of the edge of the soundboard parallel to the keyboard
- Bridge height
- Position shape and stiffness of sound board ribbing
The calculations from the computer programme fortunately also enabled us to show the geometrical patterns of the way the soundboard vibrates and how the ribs can be used to control the shape of the cells of vibration. Adjacent cells always move in anti-phase and the cells can be shaped by rib geometry. Using this data we were able to apply the more advanced concepts in loudspeaker design to minimise the phase cancellations occurring in pianos by creating a resonance box under the instrument. This meant we had to build a deeper case for the piano. The latest design now looks more conventional in this respect.
Using all the above listed parameters we extended the incidence of eigen frequencies in the bass registers of our piano to well below the bottom A and also increased their number many fold and thus their proximity to the notes being sounded. The bass power now matches the upper register power so there is excellent uniformity of sound power across all the registers.
The piano on display in Frankfurt incorporates most of these changes. Its power and sound quality from such a small instrument are truly amazing and can be heard on our website, www.phoenixpianos.co.uk . Several professional pianists have remarked that it is difficult to realise that playing this baby grand, they are not sitting at the keyboard of a full sized concert instrument.
A Carbon Fibre Bridge
The piano at Cremona was fitted with a conventional wooden bridge because we did not want to confuse interpretation of the results by incorporating too many new and perhaps critical ideas in one experiment. Since Cremona we have designed and fitted a carbon fibre bridge to the prototype piano. This material offers ideal high stiffness and low acoustic energy absorption in the material of the bridge and it thus improves the efficiency of string vibrational energy transfer to the sound board. The piano at Frankfurt has this new carbon fibre bridge. A problem of firm and controlled insertion of bridge pins into carbon fibre, which has poor bearing stress capability was tackled and overcome. The pin angles and side draught angles have been increased to reduce to a negligible level the need for down bearing on the upper registers of the bridge and thus free up the board for better vibration response.
Studies of the Type of Fibre in the Soundboard
Other changes have been using a new specification of fibre in three of the five layers of the soundboard. The three functional inner layers are now encapsulated in two sacrificial surface layers of woven carbon fibre whose main purpose is cosmetic. This change has increased the stiffness and strength of the soundboard while reducing the sound absorption losses in the material. It has thus enabled us to make the board thinner and thereby substantially increase the number of eigen frequencies in the bass registers of the piano.
Our soundboards are now manufactured using a new technology to produce both sides fair and smooth without recourse to potentially damaging subsequent surface dressing of the board to make it flat and of uniform thickness.
The Carbon Fibre Piano in Production
We have now completed design of a production instrument that is between two and three times stiffer and stronger than a conventional piano in terms of dimension change under string load. This will go into commercial production after tooling has been manufactured. Initially we will build a batch of ten pianos in a limited edition. Each instrument will be hand finished to the ultimate standards of manufacture possible and will be allotted the name of a classical composer.
The first high quality finish “limited edition” pianos, being largely handmade, will not be cheap, but cost studies for production in larger numbers when full tooling is available confirm that our carbon fibre pianos, despite the high cost of carbon fibre material compared with timber and cast iron, can be manufactured for less than a comparable size of craftsman built traditional piano.
Recording and Performance Reproduction Facility
Our first ten “limited edition” carbon fibre pianos are designed to accommodate easy installation of a brand new reproduction and recording system fashioned specially for the Carbiano.
Our company has long owned and operated a recording studio based on recording with a Bosendorfer SE imperial piano designed by Wayne Stahnke. This records and replays to the highest standard ever achieved in player pianos. The SE system is expensive and in consequence has never been widely used or developed. Together with Stahnke and others more skilled in electronics than ourselves, we have brought the hardware of the original SE system up to date and miniaturised it so it is not visible in the piano. Whilst others have sought to cheapen the system– in our opinion at the cost of its performance– we have retained and enhanced all the key features of the original Stahnke SE system that ensure the extreme authenticity of its reproduction regardless of cost. We have however managed some cost saving. In recognition of its origins we call this revised system the Stahnke Electronics 2 or”SE2.” Our new production carbon fibre piano is designed to accept the SE2 kit by simple attachment which requires only a screwdriver and spanner as tools. The costly and difficult modification of the tuning pin block thickness and need to cut holes in the key bed for the original system have been eliminated. The lyre contains invisibly, all the pedal reproduction equipment.
In our studio we have already played Rachmaninoff’s piano concerti as performed by the composer himself, with adapted orchestral accompaniment from other sources, on a simulated prototype SE2 system.