Generations of piano makers have been constantly attempting to improve the quality of their instruments. Julius Blüthner made an important contribution with the development of the Aliquot System. Patented for the first time in 1872, it was one more step that provided Blüthner’s well known warm and romantic sound. The patented Blüthner Aliquot System consists of an additional fourth string in the treble section which is not struck by the hammer. The fourth string vibrates by resonance, and introduces additional overtones which enrich the dynamic sound.
Does it work?
Many people are skeptical, but it is easy to test. Simply play a note alternately muting and then leaving the fourth string to vibrate.
It is surprising how loud the Aliquot string is even though it has not been struck by the hammer. Currently, the Patented Aliquot System employs an additional fourth string in the treble section attached directly to the bridge that is not struck by the hammers.
The fourth string is stimulated to vibrate through sympathetic resonance when the other three strings are struck, which results in an acoustical system enriching the overtone spectrum. It produces a very dynamic sound, which is audible over a wide range. This unique effect conveys the resonant treble of the Blüthner piano. As an example, it is possible to experience this special effect in many piano compositions giving an added dimension in tone colour and dynamics. Another factor that is that all Blüthner strings are individually hitched. For optimum effect, precise tuning is essential. In today’s instruments the ‘aliquot strings’ are tuned in unison with the trichords.
The Blüthner Aliquot System was born out of Julius Blüthner’s drive to enrich the piano’s tonal palette during the golden age of piano innovation in the 19th century. Here’s how it came about:
Historical Context
By the mid-1800s, piano makers across Europe were competing to create instruments with greater power, resonance, and expressive range.
Julius Blüthner, who founded his company in Leipzig in 1853, was especially interested in producing a warmer, more lyrical sound than his rivals.
His idea was to add a fourth string to the treble section of the piano.
Unlike the three main strings, this fourth string was not struck by the hammer.
Instead, it was tuned in unison and placed slightly higher, so it would vibrate sympathetically when the other strings were played.
The Effect
This sympathetic vibration introduced additional overtones, broadening the vibrational energy across the soundboard.
The result was a richer, more colorful, and romantic tone that became the hallmark of Blüthner pianos.
The system was especially effective in lyrical passages, where the sound seemed to “float” with extra resonance.
Legacy
The Aliquot System was one of several 19th-century innovations (like Steinway’s duplex scaling) that pushed piano design forward.
While not universally adopted, it gave Blüthner a unique tonal identity that distinguished it from Steinway, Bösendorfer, and Bechstein.
Even today, Blüthner grands continue to feature this system, making them instantly recognizable to pianists and technicians.
Why It Matters
The system broadens the vibrational energy across the piano, creating a more colorful and layered tone.
It’s especially noticeable in lyrical passages, where the sound seems to “float” with added depth.
Some pianists and technicians debate its effectiveness, but many agree it contributes to the unique Blüthner sound that sets these instruments apart from Steinway, Bösendorfer, or Bechstein.
Fun Fact
If you want to hear the effect yourself, pianists sometimes demonstrate it by playing a note while alternately muting and unmuting the aliquot string—the difference in resonance is surprisingly audible.
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