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In this Synth Secrets, we use Xenakios’ PaulXStretch sampler to employ an audio stretching technique commonly used by Bonobo to achieve haunting textures and ambiences. 

The Los Angeles-based British producer Bonobo traditionally uses sound beds, pads and other textures as the backdrop for the main elements of his tracks. In an interview from 2017, he revealed that one of his main techniques for achieving this while producing his last album Migration was PaulStretch. Developed by a software developer named Nasca Octavian Paul, the Paul’s Extreme Sound Stretch engine was later released as a free plug-in, available for both PC and Mac from the company Xenakios. (You can get the plug-in here—scroll down to the Downloads section for the download links.)

bonobo paulstretch ambience
The Original PaulStretch by Nasca Octavian Paul

It is described by Paul as, “producing high-quality extreme sound stretching. While most sound stretching software sounds bad when trying to stretch the sounds a lot, this one is optimized for extreme sound stretching. So, the stretch amount is unlimited.” 

Here is the sound we will be making using a simple Rhodes loop in PaulXStretch:

bonobo paulstretch ambience
Xenakios PaulXStretch

The way Bonobo described using audio stretching in the interview was as follows. “I took a portion of what I was working on and took it into PaulStretch and then bring it back into the track to sit low in the mix as a drone version of itself. It gives the track a good base and a haunting texture to it. I use the PaulStretch audio as a sound bed to further build the track from.”

Although this type of extreme stretching can be used creatively with all types of audio, we will make use of the concept of layering a part with a stretched-out version of itself. 

The Rhodes sample we will use can be downloaded on Splice and is called “DBM_SL_LVSG_FIND_A_WAY_RHODES1_90BPM_F-MINOR” from the Lavish BSTRDS Vol. 1 pack. However, as this trick can be applied to any instrumental loop or part, you can easily follow along with any audio of your choosing! Click any image to see an enlarged version.

Step 1

In Ableton Live, create an empty audio channel and insert the PaulXStretch plug-in. Click import audio at the top left and then select the sample you want to stretch. 

bonobo paulstretch ambience

The plug-in will immediately begin to emit audio. Pressing play or pause in your DAW does not affect it. By clicking and dragging on the audio wave in the bottom section, you can have the sampler loop only a portion of the audio. The loop will be highlighted in white. As this sample has an empty section at the end, set the loop to avoid this section. 

bonobo paulstretch ambience

Add an EQ to cut the subs and low-mids—especially the muddy 200Hz area!

bonobo paulstretch ambience

Here is our progress so far:

Step 2

Now to tweak some parameters!  The most important one is the Stretch Amount found at the top right. The plug-in’s speciality is extreme stretching but even subtle amounts are enough to introduce new textures. Set this parameter to taste—we used 3.4 in this example.

The plug-in’s internal effects provide a slew of options for further shaping your sound but we are going to focus on the Tonal vs. Noise, Spread and Filter effects. 

The effect chain is above the audio wave section at the bottom and effects are activated by clicking on the yellow boxes in the left corners. You can re-arrange the effects by dragging their black boxes left and right and you can click on the black boxes to have their parameters highlighted in yellow.

bonobo paulstretch ambience

The Tonal vs. Noise effect drastically changes the character of the overall sound so it is a great tool to experiment with and even automate. Activate Tonal vs. Noise in the effect chain, set the Tonal vs. Noise Preserve setting to 0.323 and keep the Tonal vs. Noise BW function at its default lowest value.

The Spread effect is similar to chorus but when the parameter Frequency Spread is pushed to the max it begins to turn the entire sound into white noise. Activate Spread in the effect chain and bring Frequency Spread to 0.571. 

The Filter is quite straight-forward, having both lowpass and highpass parameters but no resonance setting. Bring Filter Low to around 90Hz to prevent any low-end rumble.

bonobo paulstretch ambience

Step 3

Because there is technically no audio input on the PaulXStretch audio channel it cannot be record-armed. To record it, create an additional audio channel and select PaulXStretch’s channel as the input source.

bonobo paulstretch ambience

Record-arm the new audio track, select In from the input section and choose Post FX from the dropdown list. Mute PaulXStretch’s channel so that the audio is only coming from one channel.

bonobo paulstretch ambience

Create one more audio track and import the Rhodes sample. Add an EQ to cut the lows so that they do not clash with the lows of the PaulXStretch audio. Loop the sample so that it continues to play while its stretched-out version plays underneath it. 

Once you have everything set up, hit record to capture the output of PaulXStretch.

bonobo paulstretch ambience

The main sample’s chords will be playing at a different rate than its stretched version so many moments will not line up perfectly. To find the sweet spots, hit the record button and record a long passage. After, you can cut up the best sections and drag them around as you please.

Here is our finished sound, a combination of the Rhodes loop with its drone layer:

Author Aykan Esen
16th July, 2020

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u-he are makers of award-winning software synthesisers and effects including Diva, Repro-1, Zebra2, Hive, Bazille, Presswerk and Satin.

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