Quality Strings designs and fabricates bespoke bass strings for upright and grand pianos
Additionally the plain wire unisons can be improved by rescaling
Our proprietary method brings the entire scale into balance, producing a homogeneous sound
This page explains how and why our philosophy sets us apart
Two steps
There are two steps to rescaling a piano. The first and most important of these is to determine the string diameters. This is followed by choosing the best materials
Dimensions
Before there were any formulas for calculating the properties of strings, other methods were used to determine their dimensions
The following illustration is taken from the Lehrbuch des Pianofortebaues - by Blüthner en Gretschel published in 1872
String makers used to vary the speaking length of the string, test its strength with weights and listen to the sound it produced. That was obviously time-consuming and expensive, and generally only the major manufacturers could afford to do it. They accordingly achieved the best results, which were then copied by smaller firms
The initial calculations
Formulas relating to sound, and in particular inharmonicity, only started being used after 1940. Inharmonicity is the degree to which the frequencies of the overtones that are actually produced differ from those of the harmonic overtones. Harmonic overtones are frequencies that are multiples of the fundamental
The lower the inharmonicity of a string, the cleaner it sounds and the easier it is to tune
Performing calculations in advance made it possible to predict certain sound qualities. Those calculations were based on the new inharmonicity formulas. Even today, most scaling software focuses largely on this aspect of inharmonicity
Our method is slightly different
Proprietary software
One of the major lessons that experience has taught us is that keeping inharmonicity to a minimum does not produce the best result. The purest possible bass is not in balance with a treble that is by definition much less pure. This means that the sound of the instrument becomes uneven, and problems with damping, the intensity and the body of the sound can also arise
The importance of inharmonicity is overrated
ADSR envelope
Putting the emphasis on inharmonicity has other adverse effects as well, the most important of which concerns the development of volume, better known as the ADSR envelope
Attack
The time taken from pressing the key to the sound reaching its peak level
Decay
The time taken for the sound to reach its sustain level
Sustain
The level at which the sound remains audible until the string is damped. Not only its volume but also its duration is important
Release
The time taken for the volume to decay to zero after the key is released
Envelope
The entire development of the volume (ADSR) from the moment the key is pressed until the sound dies away
Release is not simply a matter of damping and its regulation. A string with the wrong dimensions can also cause damping problems
We consider the even progression of Attack, Decay, Sustain and Release (ADSR) to be extremely important because this has a major impact on the playability of an instrument
Playability is more important than tunability
In a nutshell, we aim for a smooth ADSR progression rather than minimum inharmonicity
This serves as the basis for calculating the diameters of the strings
Smooth ADSR progression is paramount
Materials
After determining the string diameters, we then proceed to the second part of rescaling the piano, which is deciding on the materials to be used
For both the core wire and the winding material, which is wound around the core of bass strings, we can choose from various materials, each with its own properties
Core materials
Inox
Also known as stainless steel or Pure Sound, Inox is used less and less frequently because it is fairly brittle and therefore breaks relatively easily
Röslau
Röslau, or Röslau Blue in particular, has been the industry standard for some considerable time. It makes a pleasing sound and is a reliable product
Paulello
According to Paulello, the stress rate of a string is the most important factor in the sound it produces
Paulello wire is available in five strengths, progressively influencing the stress rate and thus the clarity of the sound
Click here for a more detailed explanation about Paulello wire
According to Paulello, the stress rate of a string is the most important factor influencing its sound properties and, in particular, its clarity
The percentage of a string's practical breaking load must be within a certain bandwidth in order to obtain a good sound. For modern instruments, this bandwidth begins at about 50% in the bass and goes up to about 80% in the uppermost treble register
Altering the diameter of a plain string has practically no effect on its stress rate. If a larger diameter is used in an attempt to lower this percentage, the string will be able to withstand more tension but this tension will also increase due to the greater diameter and, accordingly, the string's stress rate will barely be altered
To exert a greater influence on this, one could alter the speaking length of the string. It would be far easier, however, to change the composition of the material. Using a weaker material with a lower breaking load, for instance, would increase the stress rate of a string with the same diameter
This is why Paulello has developed five different strengths, known as types
Using a weaker material then makes it possible to reduce the well-known dip in clarity at the break above the bass. The lower breaking load increases the stress rate as well as the clarity of the sound, so that it is more in balance with the bass
It is quite possible to combine the various Paulello types with Röslau within a scale, this is known as hybrid scaling
The regular progression of the stress rate is more important than considerations of inharmonicity, but it is not more important than a smooth ADSR progression. Both these factors have to be brought into balance in order to achieve an ideal result
Winding materials
Apart from the choice of core wire, a decision also has to be made about which winding material to use
Brass
Brass as a winding material was widely used in the past and is still being drawn in the traditional way by Malcolm Rose in Sussex, UK
We still use brass wire regularly when restoring old instruments and also, for example, for the straight-strung concert grand piano that Chris Maene built for Daniel Barenboim
Click here for a photo
photo Chris Maene
Copper
However, bass strings for modern instruments are almost always copper-wound
The differences in sound properties between brass-wound and copper-wound strings is a topic on its own. In a nutshell, brass gives a cleaner, calmer sound with somewhat less depth. Copper, however, sounds a little woollier and less well-defined than brass
Based on this knowledge, we decide which materials to use where
We can then make the necessary calculations to obtain the best possible scale that has both a smooth ADSR progression and balanced clarity
These two factors together produce a homogeneous sound
Achieving the best result depends not only on proper scaling but, for bass strings in particular, also on ensuring the correct manufacturing process
