Feedback Shift II

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Feedback Shift (2011) was written for Julia Werntz's Microtonal Composition and Performance II Course at the New England Conservatory and premiered by cellist Sebastian Baverstam at Jordan Hall (Boston, MA). The composition began with an idea of creating a single instrumental thread that would hold otherwise dense or complicated music together. I determined that a perpetually oscillating pitch would make for a fascinating thread. From that I recorded and looped myself playing an acoustic guitar, using a coin held diagonally as a pick for more timbral color. Next, I began to find public domain audio samples of electric guitar feedback. In searching through the plethora of samples I looked for recordings which sounded unique and not overly abrasive the ears. The best samples exhibited an inviting opening envelope, a nice sound profile, and a longer decay period. I edited and arranged these clips like a mosaic to create a rich sonic texture of sustain. Once the pre-recored sound part was completed I began to flesh out material for the cello. Here I tried to work in a mindset of restraint, beginning with one note in one range and slowly adding new pitches to the palate. In terms of form, I focused on avoiding clear sections and aimed to let the music gradually develop in a way that felt natural. The role of the cello in Feedback Shift is to provide balance to the pre-recorded sounds; sometimes complementary, but often reactionary.

Premier recording

Original score

Feedback Shift extended (pre-recorded sounds only)

Solo viola version (summer 2014)

Feedback Shift II was composed in the fall of 2014 for cellist Séverine Ballon's January 2015 residency at Stanford University. While planning the structure of the work I initially conceived of 8 sections, each lasting exactly 1'15" and episodic in character. The role of the electronics was to be a rhythmic canon of the cello material, offset by 2 sections (2'30") and realized through extended distorted guitar techniques, a nod back to Feedback Shift I. The goal of this long rhythmic delay (constituting the playback) was to provide an odd sense of similarity to the cello solo, but stripped of any real likeness (such as pitch and timbre). The extreme duration of the delay was also imagined as a way to have listeners question their own perception/memory: what is the relationship between these two seemingly disparate elements?

The cello material was faithfully written according to the 8 section plan. However, due to the pressing schedule I was unable to simultaneously work on the electronic part if I was to send the score to the soloist on time. After finishing the cello part I had winter break to independently realize the fixed electronic concept. For this I designed a Max/MSP patch that would take the MIDI playback rhythms from the Sibelius 6 score of the cello line and use them drive a sampler pulling various non-traditional electric guitar sounds I had recorded. Though the results were fascinating and in line with my initial vision of the work, having lived with the cello writing for months already, I felt this outcome to be competing with the soloist for attention and therefore obscuring much of the carefully composed nuances for the live instrument.

I still felt the piece needed an electronic component, however, due to the limited time to rehearse with the performer I choose to focus on crafting the specifics of the live part rather than rushing into a sloppy electronic placeholder for the premier. After the premier I listened carefully to the recording and decided that the 8 section form relied on the presence and activity that a canonic fixed electronic part would provide. Now that I determined such a part would be too much competition for focus with the soloist, the 8 sections could be edited down (particularly in the latter half of the work). For this 220C project I am aiming to use the premier recording as source material to then revise and process. I hope to have the electronic component of the piece as more visceral than previously thought, highlighting and extending the timbral palate of the solo cello instead of covering it up.

Pre-compositional sketches

2014 December 14 score

2015 January 15 premier recording (CCRMA Stage)

First Edits / Picking Found Sounds (April 02-14, 2015)

In an effort to make the form more concise I cut a few segments out of the latter sections. I feel this is stronger dramatically with a tighter, more efficient structuring of material.

Score edits1

Recording edti1

Score edits2

The experience of recording strange electric guitar extended techniques over the winter break and creating a draft which sampled them through the cello rhythms was not lost on me. Spending time dealing with these sounds was encouraging to continue delving into that sonic space. For the fix electronics I wanted so see if I could find comparable recordings from public domain sources via Here, I intuitively selected tracks that I thought had a character in some way similar to the cello line's timbral gestures.


Guitar Sample Heavy Effects wav.wav

The remains of Mr Bamf :: Weird guitar noise.wav

Feedbacking System :: Feedback-System-with-distortion_18-Jul-2010.wav

baker hall feedback experiment sample

Creaking Metal Desk

Spaghetti-Western Guitar :: western-danger-stab-03.wav

In treating these found recordings I layered them in Audacity and then performed a number of transformations to each. In order to not make the same mistake again with competing sororities, these tracks were temporally stretched multiple times, creating a macro texture to support the cello rather than a series of micro events to obstruct it. The harmonic spectrum of each track was also filtered and the dynamic envelope shaped accordingly. The process felt akin to traditional orchestration, crafting both the additive sound quality of track pairings and the distinct places where specific excerpts should be brought to the forefront.

Tape part (version1)

Re-recording and Gain Map (April 22-23, 2015)

For the next stage of revisions I decided on a live electronics element to the piece. The cello would be amplified and the microphone signal would be passed through a digital effects pedal. Throughout the performance the distortion level or gain knob (not to be confused with the volume parameter) would be continually adjusted. This timbral saturation is intrinsically tied to the musical gestures in the cello writing, particularly the reoccurring motion first seen in the opening where the player transitions from ordinario to scratch tone to scratch tone behind the bridge. The function of the increased saturation is to then extend the extreme point of "noise" on the instrument past what is usually possible acoustically. From a practical standpoint, and for the sake of this project, I used the CCRMA Stage premier recording as the "live" input. The digital effects processor used is my old DigiTech RP100, modified with an Arduino to stream the gain knob position data.

Before re-recording the cello part with the new gain settings I went through the working score draft and mapped out the transitions on a 0-100 scale-- page 1 example with gain markups.




Recording mix with processed cello, first page example

Scaled Data and Proportional Score (May 03-27, 2015)

During the re-recording of the cello line I had the data from the gain knob position streaming from the Arduino to my laptop. The data was sampled at a rate of once every 10 milliseconds. The values of the gain are usually displayed digitally on the effects processor interface as 000-100, however, the Arduino was sending values scaled from 000-691. For the purposes of my score revisions I wanted to maintain the 000-100 incrementation. To re-scale the values I first exported these long lists into a spreadsheet. Here I noticed that there was an error in the beginning values from the knob. The digital readout on the processor would say 000 even when the knob position was not at the extreme counter-clockwise setting. Upon further investigation it turns out that the Arduino values 000-100 are all within the digital effects processor readout 000. After removing this set the new range becomes 000-591. Lastly, I scaled this to 000-100 and charted each page values with 20 point increments on the y-axis.







The next stage of score edits require the cello notation to be converted from standard notation to proportional notation. This is necessary because of the juxtaposition of real-time temporal events in the form of the gain knob position graphs. In order to create proportional spacing in Sibelius 6 software I inserted another instrumental line and filled each measure of this new line with constant "high" note values. For instance, filling each measure with straight 32nd or 64th notes. Afterwards I hid the music as well as this line, enabling the formatting to stay without having to see the unnecessary extra part.

Proportional score

Presentation Materials (June 07, 2015)

Full Recording

Recording (tape only)

Feedback Shift II Youtube Video