The ability to change the tempo of an audio recording, without affecting the pitch, was one of the great advantages of the DAW revolution. Many of us, from bedrooms musicians through to Grammy winning producers, rely on having the ability to ‘stretch’ the tempo of an audio recording. This tutorial will focus on some of the ways in which we can manipulate the tempo of audio in Steinberg’s Cubase SX.
The ‘Old Fashioned’ Way
People who came to SX via VST will remember, with frustration in some cases, this manner of time-stretching an audio file.
You can access this method by left clicking on the audio event/clip you wish to alter and then going to ‘Audio->Process->Time Stretch’
Unlike the other methods of changing tempo in Cubase SX, this method is more ‘mathematical’ and requires you to give information about the source file (such as tempo or number of bars/beats/16th notes etc) This method is not the quickest or easiest way of going about changing the tempo of an audio file, but it does have advantages over the more intuitive methods. You can achieve a greater degree of accuracy for starters, and you can also time stretch to a tempo independent of your current project tempo quickly. This is also a good method for batch processing a number of audio files from one tempo to another.
This method also gives you a number of algorithm options such as MPEX 2, Standard, Drum and Realtime. The MPEX 2 algorithm in particular can produce very good results on both monophonic and polyphonic sources.
The Quick Way
Probably the quickest and easiest way to change the tempo of an audio file in Cubase is to use the ‘Sizing applies Time Stretch’ option when using the Object Selection tool (i.e. the arrow). You can access this tool in 2 ways, either click on the arrow tool twice – once if it’s already selected – as shown in the image on the right, or press the number 1 key on your keyboard (not on the Num Pad) to scroll through until you see a little clock appear next to the arrow, again seen on the right.
Once you have selected this tool you can now change the length, and therefore the tempo, of an audio file by dragging the ends of it, much like you would change the length of a MIDI part by dragging the ends. If you have ‘Snap’ enabled then the length will automatically snap to whatever Grid Type and value you have defined – if you are working with ready made drum loops then setting the grid to ‘Bar’ will probably make most sense as then the event will snap to exact bar lengths as seen below.
The quality of this time stretch is dependent on the algorthim that you choose – to choose the default mode go to File->Preferences->Editing->Audio and choose the required algorithm under the ‘Time Stretch Tool’ heading.
One thing to remember which catches many people out is to remember to reset the Object Selection tool back to ‘Normal Sizing’ after you have finished stretching your audio file.
The ‘Musical Mode’ Way (SX 3 only)
‘Musical Mode’ is a feature new to SX 3 and gives Cubase some of the real time time-stretching that users of ACID and Ableton Live are used to without resorting to changing the file format a la .REX files.
To use Musical Mode you must first use the Audio Tempo Definition Tool to specify the length of the clip in bars and beats, or specify the tempo of the source file. To do this you must open the Sample Editor by double clicking the event that you wish to time stretch. Once in the Sample Editor you need to turn on the Audio Tempo Definition Tool by clicking on the relevant button on the toolbar as seen on the right.
Once this tool is selected, you should be able to enter information into the ‘Musical Controls’ area of the toolbar, such as Signature, Audio Tempo, Bars and Beats. If these options aren’t available then check they are selected by right-clicking on the toolbar and ensuring there is a tick next to ‘Musical Controls’. In a simi liar way to the Time stretch dialog box you should enter the tempo or the length of the loop in bars and beats. If you are working with a loop from a commercial library then often the tempo of the loop will be included in the file name. If the tempo of the loop is not known then you can simply count the number of bars and beats in the loop and enter them into the relevant box and the tempo will automatically be calculated for you.
Once you have correctly inserted this information you can enable Musical Mode by clicking on the ‘Musical Mode’ button which is shown below.
If you are working with a low screen resolution then sometimes the ‘Musical Mode’ button is not visible on the screen. If this is the case then it is easiest to right-click on the toolbar and temporarily remove some of the toolbar options you are not using. Alternatively you can drag the corners of the sample editor to make it larger then your screen and then move the sample editor so you can see the options – this is quite a messy method however.
Once you have turned on musical mode you can choose an appropriate ‘Warp Setting’ from the drop down box – these are self-explanatory so just choose the one that is nearest to the audio file you are stretching.
Upon closing the Sample Editor you should see that your audio event has now changed in length to fit the tempo of your song. Even more impressive is that if you now change the tempo of your song your loop(s) will automatically change in tempo to match the project tempo – this even works when using the tempo map to define ‘on the fly’ tempo changes!
The eagle-eyed amongst you may have noticed that I’ve not included the Hitpoint/Slice method of loop manipulation in this tutorial. It is fair to say that for most users the methods mentioned above should be suitable for most applications – we will cover the Slicing method in a future tutorial however.
Anyhow, stop reading this and get stretching!