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   P 135 K1 Upright Piano


Color Available

Black High Polish


PETROF P135 K1 upright piano is ranked in to the highest, master built upright piano series. These master built upright pianos have a concert character; their sound stays delightful, tender and cultivated in spite of big sound volume. They have a harmonically rich sound that has often been compared with a small grand piano. These magnificent instruments radiate energy and earn respect from musicians and crowds alike. Often a favourite of demanding professional pianists, these Series are suited not only to apartment interiors and music schools, but also piano recitals within an orchestra or any public stage. The Petrof P135 K1 piano provides wider possibilities for a player to control the sound and comes equipped with 3 foot pedals and a hand lever.


The function of pedals of the PETROF 135 K1 upright piano

  • Right pedal works standard as a forte pedal. It lifts up all the dampers. That means when the right pedal is pushed down, all the played tones sound till the pedal is released.

  • Left pedal works standard as a piano pedal. When it is pushed down, all the hammers are moved closely to the strings. Playing the tone, the way of hammer is shorter and hammer strikes the string with smaller energy. The tones are weaker.

  • Middle pedal controls the prolongement rail. When one or more tones is played and held (pressed keys) and the middle (prolongement) pedal is depressed, then the lifted dampers are captured and held up, even when these keys are released. That means these dampers do not dampen the strings played before and the tones still sound, even when these keys are released. When the middle pedal is pushed, it is possible to play other tones, which behave standard. When the pedal is released, the captured dampers move back to the strings and dampen the prolonged tones.

  • Function of moderator is controlled by hand lever, placed left on lower side of key bed. When you move this lever by hand, the moderator rail moves down and weakens the sound and change the color of tone.


Piano Size

a 606 mm
b 1341 mm
Width 1446 mm
Weight 243 kg


Model Specification

Technical Description

PETROF 135 K1 upright pianos are designed by and produced in PETROF company in the Czech Republic. P 135 K1 upright piano is the highest upright piano model with the greatest equipment and is fits for demanding players, for professional use, for specialized music schools. As with all PETROF upright pianos, the P 135 K1 is marked a "European Excellence“ label, which guarantees the European origin of the instrument.


Technical Parameter


  • Robust construction from spruce, 5 vertical posts, made in PETROF company.
  • The solid stable rim supports the tuning stability of the instrument and ensures its total stability. The special constructive modification of soundboard moldings enable clear and long-lasting tone of upright piano.


Iron Plate

  • PETROF construction, harp shape, agraffe construction, robust,  made from grey cast iron in the Czech Republic.
  • Plate working is done in PETROF factory on special CNC machines.
  • Top finish is consistent with surfacing of grand piano plates.
  • Agraffe construction of the iron plate enables exact scale of strings and is the sign of the most advanced upright piano construction.


Hardware Fittings

  • Massive polished brass, lacquered. Made in the Czech Republic.
  • Hardware fittings are lacquered, corrosion resistant and do not require any maintenance.



  • Special beech plywood type Multiplex. Original veneer thickness 2 mm compressed to the density 800 – 850 kg/m3 (= 6 veneer layers/cm). High moisture resistant glue.
  • The pinblock is highly resistant to atmospheric changes (e.g. humidity). It guarantees high stability of tuning.


Sound Board

  • The soundboard is made from solid spruce wood in PETROF company. It is shaped into wedge block. Its active surface is 1,2222 m2.
  • PETROF sound boards have to go through a special long term moisture conditioning and care during the whole production process which guarantee their exact and equal moisture content. This process increases its resistance to cracking due to climate changes. Surface treatment with PUR lacquer raises its resistivity against climate changes.



  • The ribs are circular shaped and are made from European spruce wood in the Czech Republic. The cross rib is produced from beech wood. The board is enforced by 10 ribs.
  • The ribs from European spruce supports a crown stability of the sound board.



  • The bridges are made from solid beech wood in PETROF company.



  • Agraffe construction in the whole range of 88 tones.
  • The agraffe construction enables the exact scale of strings and is the sign of the most advanced upright piano construction.


Tuning Pins

  • Steel, nickeled. The pins are produced with high exactness in the Czech Republic.
  • The tuning pins are corrosion resistant.




  • Steel wire Mapes USA, Röslau Germany.
  • Copper winding Degen Germany.
  • Made in PETROF factory.
  • Longest string 1135 mm.
  • The strings are made from string wire of the world´s finest quality.


Hammer Heads

  • There are used top German hammers Renner or Abel in the P 135 K1 upright pianos.
  • Hammer heads are voiced for romantic rounded tones, characteristic for PETROF instruments.



  • Renner original action.
  • PETROF moderator.
  • Action is installed and regulated in PETROF factory.
  • Prolongement function controlled by a middle pedal.
  • Moderator controlled by a level (left, underside of key bed).
  • Renner action is very quick, with good repetition, enable good control in creating tones, provide great feeling from play. It is rated as the world wide best.



  • PETROF original dampers.
  • High quality special French felt (Laoureux).
  • 70 dampers.



  • Keys are produced from the finest spruce wood in PETROF factory.
  • White and black acrylic tops - Polyplex Sweden.
  • The keys are carefully individually balanced for 48 - 52 g. The keyboard provides very good feeling from play.


Key Bed

  • Robust spruce sandwich board, two-sided covered by thin chipboard and counter veneer.
  • Key bed is fixed to cheeks from below by analogy to grand piano key bed.



  • Pedals are made from solid brass, produced in the Czech Republic.
  • The upright piano is equipped with 3 pedals: the right (forte pedal) lifts the dampers, left (piano pedal) draws the hammers near to the strings, the middle controls prolongement.
  • Moderator is controlled by hand lever, placed left underside of key bed.


Assembly, Regulation, Voicing

  • Whole production and assembly of the P 135 K1 upright piano is held in PETROF factory in the Czech Republic.
  • Mechanism of the upright piano is carefully and repeatedly regulated for standard values so that regulation is stable in the long term, upright action provides good feeling during play, characteristic for European upright pianos.
  • Hammers are voiced for soft romantic tone, characteristic for PETROF upright pianos.


Other Technical Information about PETROF Pianos.




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