Model 12 Hiss Noise

Discussion in 'Model 24/16/12' started by MRosh, Sep 14, 2020.

  1. MRosh

    MRosh New Member

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    Gear:
    Tascam Model 12
    Hello,

    I've just purchased a Model 12 to set it up for my electronic synths setup. However, once I did this, I immediately noticed a hiss noise in the Main output.

    At first I thought the Volca's were noisy and that might be causing it, but after disconnecting everything from the inputs I could still hear the same hiss noise.

    So, to be more detailed, I turn the main channel fader to 0 db or lower, I switch the channels to send input to Main by pressing the Main button next to them and then I turn up the volume for each channel (gain at 0db or lower, even turn all the way down), then I start hearing the noise gradually as I raise the volume for the channel. If i do the same for the next channel, the noise gets doubled and so on.

    It happens on the speakers and in the headphones, as well. Also, only when the input is set to live.

    To be completely sure I did all in my power and knowledge, I tested the follwing:

    1. Disconnected all synths from the inputs, Phatom power is off and all channels have INSTR off.
    2. Changed the power source from a power strip to a power outlet and disconnected the speakers from the outputs, still geting noise in the headphones (probably in the speakers if I connect them). Thought maybe there's something to do with ground noise.
    3. Tried to see if it gets better or worse by using any EQ, effects, compressor value, no difference. It gets worse by adjusting the volume to be higher, obviously.
    4. Set the channel phase to be inverted, same thing.
    5. Ok, now I wanted to see if there's an issue with only the outputs, or it affects recording as well. So, i went ahead and recorded over USB with Audition and Audacity and the hiss is present in the recordings, even if the volume from the Main or the channels is turned all the way down. Basically, every recording has an equal volume hiss no matter what I do.
    6. Now, I recorded directly with the Tascam on the SD card, I get the same hiss there as well.

    The second channel seems to have more noise than the others.

    I tried finding a solution on the internet, but I haven't found a user experiencing the same issue as I do with this product.

    Therefore, I might be doing something wrong or the product may be faulty. Can you please help me in solving this issue or if I should go back to the retailer and get it changed?

    Other equipment:
    - 2x Balanced male jack to female XLR (gold plated) to connect to the monitors
    - Ansmann Type-C USB Cable 200
    - Alessis Elevate 5 monitor speakers
    - Senheiser HD-25 headphones
    - Synths (even though irrelevant as I get the hiss even when nothing is connected): Volca beats/keys/FM, Elektron Digitakt
    - Power strip with surge protections and grounded (but also used an outlet directly).

    Thank you for your help!
  2. Blue Monster 65

    Blue Monster 65 New Member

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    Gear:
    Model 16
    What do your gain settings look like?
  3. MRosh

    MRosh New Member

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    Gear:
    Tascam Model 12
    As I use only line ins (synths), I now have them at 0, which is 11 o'clock.
  4. Blue Monster 65

    Blue Monster 65 New Member

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    Gear:
    Model 16
    Green on the lights next to the gain knobs?
  5. -mjk-

    -mjk- Moderator Staff Member

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    From:
    Hukou Township, Hsinchu County, Taiwan
    Gear:
    DP-32, | 2A Mixer, A3440
    I need to ask some questions:

    You said:

    Main channel fader to 0 dB or lower.

    "Volume for each channel" is the gain trim knob?

    Engineers typically start with the gain at minimum and we work our way up from there. If you are soloing a channel or channels with no audio then you probably can hear the noise. But, what if you have an audio input such as a keyboard (properly adjusted for gain) going to the channel?

    The manual says this on page 75:

    S/N ratio 103dB (MAIN MIX & 1Ch 0dB, 22kHz, A-weighted)

    Equivalent input noise (EIN) -128 dBu (Rs=150 Ω, MIC IN w INSERT SEND, gain knob at MAX, A-weighted)

    So you can see, this is a very quiet digital interface. If you're hearing hiss, then work on the gain structure.
  6. MRosh

    MRosh New Member

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    Gear:
    Tascam Model 12
    Hi,

    @MJK - Yes, that's one of the main reasons I picked the Model 12 to be my mixer of choice, because it is a quiet one, after many other attempts with different mixers which basically failed at doing so. However, the gain structure was not quite the reason for the noise.

    After tweaking at it all day with one of my mates, it seems we have reduced the noise substantially. Here is what changes reduced the noise:

    1. Changed the output cables that connected the mixer and the monitors from the 2x XLR to TRS to 2x XLR to RCA. Wow, what a change, which is quite unexpected, as the XLR-TRS cables are balanced and these are not. Not only the hiss noise from the monitors reduceda lot, but from the headphones (almost to no noise) and the recordings, as well. I am not sure of the logic or reason behind this, but it did the job. I'm upgrading these old Alesis montiors soon, but I would surely want to know how can the monitors affect the whole sound of the mixer.

    2. Connected ALL the instruments to the mixer. Now I have 6 instruments plugged in (synths, drum machines, sampler), when I was testing yesterday I used only two. It seems that if the all channels are empty (nothing plugged in) or only one, two used, the mixer has a natural noise, which disappears when it gets some inputs. This happens only in live mode.

    3. Cable clutter. Obsioulsy I knew this, but there's always a mess when you add something new to your setup.

    To sum up, there's still a bit of noise, especially on the 2nd channel, but it is unnoticeable when playing or recording, probably after a bit more tweaking or in time it will go away or I'll get used to it and not notice it anymore.

    If you have any more tips, feel free to give a hand, not only to me but to others who may face this situation.

    Thanks for the help!
    MR
  7. -mjk-

    -mjk- Moderator Staff Member

    Joined:
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    From:
    Hukou Township, Hsinchu County, Taiwan
    Gear:
    DP-32, | 2A Mixer, A3440
    Hi MR,

    Well, my first thought was "Whoa!" because it's not clear exactly what's going on.

    Balanced cables are supposed to improve, not degrade the audio. So, either there was a ground loop (which seems unlikely as that's one of the things those cables are designed to eliminate) or the new cables are actually preventing you from hearing the hiss that is still there. But a crucial piece of information is that you notice the difference on headphones also and not just on the monitor speakers.

    You said:

    "I would surely want to know how can the monitors affect the whole sound of the mixer."

    The main reason being that whatever is going through the mixer is being heard/judged on the monitors. So, if the monitor chain sounds bad, everything sounds bad (which is why, when you are rebuilding a console, you start with the monitor section first).

    And with any interconnect there is the possibility of introducing noise into the system. Equipment grounding is a huge issue and un/balanced interconnects can make it worse or better.

    So, I echo your sentiments and wouldn't expect that going from balanced to unbalanced would improve the noise situation either.

    I would leave all the channel gains down and not on Live mode unless recording.

    Thanks for the followup.