PreSonus Blog

Mid-Side Meets the CTC-1

I’ve often said it’s more fun to ask “what if I…?” than “how do I?” “What-if” is about trying something new, while “how do I” is about re-creating something that already exists. Well, I couldn’t help but wonder “what if” you combined the CTC-1 with mid-side processing, and sprinkled on a little of that CTC-1 magic? Let’s find out. (For more information on mid-side processing, check out my blog post Mid-Side Processing Made Easy. Also, note that only Studio One Professional allows using Mix Engine FX.)


One stumbling block is that the CTC-1 is designed to be inserted in a bus,  and the Mid-Side Transform FX chain won’t allow inserting Mix Engine FX. Fortunately, there’s a simple workaround (see Fig. 1).


  1. Copy the stereo track you want to process, so you have two tracks with the same stereo audio. One will provide the Mid audio, and the other, the Sides audio.
  2. Insert an MS-Transform FX Chain into each track (you’ll find this FX Chain in the Browser’s Mixing folder, under FX Chains)
  3. Create a bus for each track.
  4. Assign each track output to its own bus (not the main out). However, the bus outputs should go to the Main out.
  5. Add a CTC-1 Mix Engine FX in each bus.

Figure 1: Setup for adding mid-side processing with the CTC-1 to a mixed stereo file.


  1. To dedicate one bus to the mid audio, and the other to the sides, open up the Splitters in the MS-Transform FX Chains.
  2. Mute the sides output for the Mid track (top of Fig. 2, outlined in orange). Then, mute the mid output for the Sides track (bottom of Fig. 2, also outlined in orange).

Figure 2: One bus is Mid only, the other is Sides only.


Now you can add the desired amount of CTC-1 goodness to the mids and sides. And of course, you can vary the bus levels to choose the desired proportion of mid and sides audio.


Audition Time!


The following example is an excerpt from the original file, without the CTC-1.




Next up, CTC-1 with the Custom option on the Mid, and the Tube option on the Sides. Fig. 3 shows their settings—a fair amount of Character, and a little bit of Drive.

Figure 3: CTC-1 settings for the audio example.




If you didn’t hear much difference, trying playing Audio Example 1 again after playing Audio Example 2. Sometimes it’s easier to tell when something’s missing, compared to when something’s been added.


The more you know about the CTC-1, the more effectively you can use it. The bottom line is I now know the answer to my “what if” question: get some buses into the picture, and the CTC-1 can be hella good for processing mid and sides!


  • I’d like to thank all of you for your comments. For these Friday tips, I encourage anyone who has questions, additions, or complaints to comment – it helps me figure out which tips get the most traction, and generate the most interest. For example, anything based on the CTC-1 seems to get a positive response, so now I’m going to run some experiments and see if I can come up with anything else that’s useful. Thanks!

  • The split mode needs to be a channel split, because the Mixtool that encodes into mid and side signals outputs the mid on the left channel, and the sides on the right channel. Both mid and side cover the full frequency range, so there’s no need to restrict them to particular frequencies. However, the idea of splitting into mid and sides, and further splitting each one into frequency bands for more selective processing, is intriguing…

  • It’s available for $79.99 in the PreSonus shop.

  • Is CTC-1 Pro Console Shaper only available in Sphere!?

  • Stephen John

    Hi Craig. It may be obvious to some or maybe I’m doing something extra for the effect, but…Doesn’t the Splitter need to have the Split Mode changed from “Channel Split” to “Frequency Split”, then adjust the frequency of the mid and side busses to reflect those frequencies one wants to process?

  • The Splitter is needed for both the M-S encoder AND the M-S decoder. Also remember that the goal was to process the mid and sides separately. I used the Custom option on the Mid, and the Tube on the Sides. No particular strategy in that, it’s just what sounded best 🙂

  • It already is, according to PreSonus:

  • Malcolm Middleton

    When will the CTC-1 be available in Sphere?

  • Malcolm Middleton

    Why do you need to use the splitter? Why can’t you just run them in series if the first one is only affecting ‘mid’ and the second one is only affecting ‘side’. What’s the difference?

  • You’re very welcome! The question I asked myself today is “What if I could take my legacy projects from Sony Acid and convert them into Studio One projects?” We’ll see what happens…

  • David Groeneveld

    I totally agree with your first sentence! “What if” is definitely the most fun! Thanks for this tip 😀