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Thread: Wow, the C3 is AWESOME..... but ....

  1. #1

    Question Wow, the C3 is AWESOME..... but ....

    But whyyyyyyy is the audio cut off frequency so DAMN low ?
    (The same goes for the demo board and the El Jugador as well)

    If the R and C values are correct in the C3 manual, it gives:
    f3db = 1 / (2 * pi * 1k * 0.1uF) = 1591 Hz

    I tried to run a new audio driver (I'm currently working on) at a sample rate of ~80kHz and it sounded very muffled and Lo-fi. On my modified "El Jugador", which now has got a cut off frequency of ~20kHz, it sounds MARVELOUS.

    I DO understand that audio drivers with low mixing frequencies (like 22kHz or lower) produces a lot of audible aliasing distortion and probably sounds better with a cut off frequency lower than 20kHz. But C'MON 1.5kHz ????

    Of course, I'm going to modify my C3 to sound better, but to be honest it should sound better from factory.

    Lastly, I just want to thank André LaMothe for this feature rich and excellent piece of hardware. The design with the spi interface is just CLEVER.

    / Johannes
    Last edited by Ahle2; 01-22-2011 at 05:45 PM.

  2. #2

    Default Re: Wow, the C3 is a AWESOME..... but ....

    @Ahle2

    I think there is a minor revision in the works, perhaps this could be brought to Parallax's attention.

    Either way, please post your mod.

    OBC
    Visit PROPELLERPOWERED.COM -:- Micromite Companion available now!
    After you are done here, wander over to our Friendly Forums.
    Online Chat Saturday Nights 9pm EST -:- Projects, not Platforms -:- Follow me on Twitter.

  3. #3

    Default Re: Wow, the C3 is a AWESOME..... but ....

    We used that values on the HYDRA I think, so that's why I picked them, just so things would sound the same. But, on the next revision of people want me to bump the resistor a bit, that's obviously easy. However, you are going to make one group happy or another group, and one sad So, since 99% of all the initial games used the hydra and that has a .1 and 1K for that RC filter, I stuck with that. But, try changing the resistor and see if you can find something that works good for EVERYTHING and email the value and I will switch it next rev. Just make sure all the games sound good, etc.

    Andre'

  4. #4

    Default Re: Wow, the C3 is a AWESOME..... but ....

    @OBC
    I will post information on the mod soon.

    @André
    To be honest I think even a 22 or 11kHz driver sounds better with a 20kHz cut off frequency.

    I have included a little comparison mp3.

    Description:
    - 3 tunes are played; each with a different sound driver
    - The sound is recorded straight from the C3 to a reference studio audio-card in 44.1kHz
    - First each tune is played with a cut off frequency of ~20kHz
    - Then the same tune is played with the normal C3 cut off frequency of ~1.5kHz
    - The cut off frequency changes after the beep


    Tunes and driver information

    Tune 1: "Mega Twins"
    Driver: AYcog by Ahle2
    Mixing freq: 125kHz
    Origin: Atari ST register dump

    Tune 2: "Funk Junk"
    Driver: SIDcog by Ahle2
    Mixing freq: 31kHz
    Origin: C64 register dump

    Tune 3: "Dire Straits - Money for nothing"
    Driver: Wav-player by Raymond Allen
    Mixing freq: 44.1kHz
    Origin: My private collection.

    / Ahle2
    Attached Files Attached Files

  5. #5

    Default Re: Wow, the C3 is a AWESOME..... but ....

    Wow..

    Yeah, that's a big deal..

    I'll be looking for your mods.

    OBC
    Visit PROPELLERPOWERED.COM -:- Micromite Companion available now!
    After you are done here, wander over to our Friendly Forums.
    Online Chat Saturday Nights 9pm EST -:- Projects, not Platforms -:- Follow me on Twitter.

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