Play-In Service

Play-In Service

Play-In Service

The most advanced instrument play-in technology in the world.

Every note on your instrument actually played 24/7, at fortissimo volume.
In just two weeks on the Krentzer, my instrument was nearly indistinguishable from a played-in instrument. Within about 3 months the transformation is complete and my recording engineer can’t believe it was made only 4 months ago!
Jon Michel, Professor of Cello, Central Washington University


Dr. Krentz’s first invention in this field began development when he received his first new modern cello in 2001. His background in the sciences and impatience for waiting for his new instrument to sound its best pushed him to the string-driving radiant field technology used today. Though there are many urban myths about methods of playing an instrument in, none of them are capable of driving each string to play every pitch on the instrument at fortissimo volume and non-stop for a week at a time. None of them can produce the results that the Krentz String Works technology does.

His first attempt used an electric hair trimmer motor attached to the bridge like a product currently on the market. Feeling that the instrument was not changing and was so different from an instrument actually playing, he continued to experiment. He wanted to find a method that would be able to play the actual strings of the instrument and different pitches with the instrument free to vibrate in all its complexity.

Though many assume that the technology consists of a bow connected to some sort of bowing machine, that idea also proved to be very difficult to operate continuously and without possible mechanical failures of various types that could result in damage to an instrument. In fact, The Krentzer, as it has affectionately become known, is elegantly efficient, powerful and will result in no damage to the instrument.


It is not really known why playing an instrument in makes the instrument mature though many theories abound. However, we might assume that doing it at fortissimo, the instruments greatest level of activity bending and vibrating, will be necessary to activate the entire instrument.

How much of the time are you playing at fortissimo in one year?

Normal, Serious Player,
Playing 2 Hours Each Day

1250 minutes of playing fortissimo per year =
20 hours / 71 notes of cellos range =
minutes per pitch
Approximately 5 minutes a day of fortissimo playing, playing 5 days a week, and approximately 50 of the 52 weeks in a year.

In 2 Weeks
on the Krentzer

2 weeks = 24 hours x 14 days =
hours of playing fortissimo
336 hours / 71 notes in cellos range =
minutes per pitch


The standard method for testing the acoustic signature of instruments in the violin acoustics field is the ‘velocity hammer’. By tapping a small hammer on the side of the bridge and recording the sound, instruments can really be compared as apples to apples. However, for the non-acoustician, the resulting charts are not very helpful beyond the ability to see that something is different.

Below, you have the next best thing. Every possible variable has been controlled for, except that we wanted the instrument to actually make sounds that listeners could hear and evaluate.

A special apparatus was built to hold each instrument and the recording microphone in exactly the same way. Since a bow had to be used to make sound, the three bow variables were tightly controlled for: The speed of the bow was set by metronome, the weight of the bow was controlled by allowing only the bows own weight, and the placement of the bow was marked on the strings and tightly controlled. The recording equipment was not changed in any way and even the strings were removed after the first recording and replaced after the play-in. The bow itself also was not played or rosined between recordings.



A Viola by Abraham Fairfax

A Violin by Brian Madsen


We accept play-in orders in either one or two week increments generally. The cost is $300 per week.

Please contact us directly to discuss your particular situation and your instrument. Playing-in an instrument does wonders for new or newly restored instruments. However, many players who are not happy with their instruments ask about playing them in further in hopes that they will improve. If your instrument is already a year old or more, play-in will likely not be worth the effort of sending the instrument to us.

Further, Dr. Krentz can also offer other services if he believes they may help your instrument including soundpost adjustment, a new bridge designed and voiced to solve your instrument’s issues or even something as simple as string, endpin, or tailpiece choice.

Contact Us