PreSonus Blog

So…What Does the CTC-1 Really Sound Like?

Good question, because the effect is subtle. If you play with the various controls while listening to a mix, you can tell that something is different, but you may not know exactly what. So, let’s find out what the CTC-1 actually contributes to the sound.

Bear in mind that Mix FX work across multiple buses, and the overall effect depends on the audio being sent through them, as well as the control settings. So while this tip can’t tell you what the CTC-1 will sound like under various conditions, you’ll get a sense of the character associated with each of the CTC-1’s mixer emulations. Note that the audio examples are not mixed songs, but only the effect added by the CTC-1 to mixes, and amplified so you can hear the effect clearly.

Also, it doesn’t look like PreSonus is letting up on Mix FX development any time soon (PortaCassettes and Alps, anyone?), so this tip should be handy in the future as well.

The Test Setup

  1. Load a track with a stereo mix of a song you like.
  2. Duplicate (complete) the track, and invert the copy’s polarity (phase). To invert the polarity, you can insert a Mixtool and click on the Invert Left and Invert Right buttons. Or enable the channel’s Input Controls, and flip the polarity with those (as shown in fig. 1).

Figure 1: Test setup for evaluating the CTC-1 mixer’s various characters.

  1. Insert a Bus, and assign the out-of-phase track’s output to the Bus input. The Bus output goes to the Main output, as does the in-phase track output. Make sure the Main output’s Mix FX is set to None.
  2. Set all faders to 0 dB, and start playback. With the Bus’s Mix FX set to None, you should hear nothing—the only audio sources are the original track, and the out-of-phase track playing back through the Bus. If you hear anything, then the faders are not at the same levels, the out-of-phase track is somehow getting into the Main bus, or the Main bus has a Mix FX enabled.

Now you can check out various CTC-1 mixers. Fig. 2 shows the default setting used for the tests. In the audio examples, the only changes are setting the Character control to 1.0, or to 10. 1.0 is the most faithful representation of the console being emulated, while 10 adds the equivalent of a sonic exclamation mark.

Figure 2: Default CTC-1 control settings used for these tests.

Let’s Start Testing!

Note that there’s a continuum of Character control settings between 1.0 and 10.  Settings other than those in the audio examples can make a major difference in the overall sound, and you can really hear them with this kind of nulling test.

Here’s what the Classic mixer sounds like. Its main effect is in the midrange, which a Character setting of 10 really emphasizes. Among other things, this gives a forward sound for vocals.

The Tube sound kicks up the low end, but turning up the Character control emphasizes a slightly higher midrange frequency than the Classic sound, while retaining the bass.

The Custom mixer is about adding brightness mojo and bass. Bob Marley would probably have loved this. Turning up Character emphasizes lower midrange frequencies than the other two.

Snake Oil, or the Real Deal?

I don’t have the mixers on which these settings were modeled, so I can’t say whether this is the real deal. But I can say it’s definitely not snake oil. The effect is far more nuanced then just EQ, and the audio examples confirm that Studio One owners who say the CTC-1 adds some kind of mysterious fairy dust are right…it does add some kind of mysterious fairy dust.

These audio examples should make it easier to get the sound you want. For example, if you like the way the Custom hits the bass and treble, but it’s a bit much, then simply turn up the Character control for a little more midrange. If your mix is already pretty much where you want it, but it needs to pop a bit more, the Classic is the droid you’re looking for. The Tube really does remind me of all those years I spent on tube consoles, especially if I turn up Character a little bit.

Sure, you just turn select mixer emulations, and play with controls, until something sounds “right.” But I must say that running these tests have made it much easier to zero in, quickly, on the sound I want.


  • Interesting…that could very well be the case. In any event, that would underscore that what you observed is part of the CTC-1 Tube console sound.

  • Steve Levine

    Mind-expanding stuff, but I feel like there is one oversight, here… I’m 90% certain that the bass coming out of the Tube test is because the “Tube” console gets rid of so much bass, that the original Bass was not phase-cancelled.

    I could be wrong, but that’s what a quick test with pink noise seemed to show.

  • Peter Birch

    When you go through the presets you will notice that the serial number changes. I wrote down about 12 or so and what I perceived they did. You will notice that one preset has the suffix 1984. Because the differences are just as profound as the knob twiddling (technical term 🙂 ) I think Presonus should let us know what numbers have been programmed in.
    BTW Glad you learned something new too, hope a few others do as well.

  • I had no idea that changing the serial number made a difference! Where did you find out about that? I’ve searched for a CTC-1 manual but have never been able to find anything…there are some videos, but I’m one of those people who prefers text, because videos don’t allow for random access.

  • Peter Birch

    Hi Craig, Very good article and a brilliant way to find out what the Mix FX is doing.
    So I went and tested it…
    One thing you didn’t mention was just how MUCH changing the serial numbers made. Some emphasized the bass end and some the mids and all that without changing any of the knobs.
    So I went and tested the new ones…
    I was very disappointed in the results and changing the serial numbers didn’t do very much at all.
    I hope you do test these and don’t forget the serial numbers..In the CTC 0000 is like bypass but only CTC!

  • I also plan to evaluate the new ones on a more formal basis than just listening to them in action. Please circle back if you have an opinions you want to share.

  • My pleasure, I’m really just taking the time to document things I learn as I work with Studio One. It’s a lot of fun, actually 🙂

  • Steve Watson Music

    Brilliant testing method indeed, Craig! And appreciate your contributions to the community over all of these years!

  • Jason Roberson

    Great article! I am loving the mixbus FX. As a Sphere subscriber I have them all. They all have their own special sauce. I like this experiment and will try it when I get a chance so I can get a better idea of each one. Thanks again, Craig!