I need help connecting outboard, please!

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This topic contains 6 replies, has 2 voices, and was last updated by Profile photo of ljefe ljefe 3 weeks, 2 days ago.

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    Profile photo of ljefe

    HELP! I am very confused trying to connect an elysia xfilter eq. I have the old qu-16 (original version). I am trying to send a vocal from my Macbook through the qu-16 to an elysia xfilter via the Mix Outputs then back to the computer.

    These are the specs from the A&H manuals:
    qu mixer input: +18dBu = 0dBFS
    qu mixer output on xlr: +22dBu = 0dBFS (I can’t seem to re-find where I read this)

    from the qu-16 data sheet:
    nominal Mix Outputs: +4dBu = 0dBFS

    If I send a -10dBFS signal from the computer into the qu, it should read +8dBu on the qu mixer?
    Then what is the dBu of the signal at the send?

    the elysia xfilter- max input +21dBu, max output +21dBu

    I’d like to leave about 8dBu of headroom for clean eq adjustments, what output signal should I send from the Mix Outputs to the elysia?

    Please help if you can, understand I am not good at math. Thanks!

    Profile photo of Chris

    To assist you in connecting your vocal setup from your MacBook through the QU-16 to the elysia xfilter and back to the computer, let’s break down the process and calculations step by step. We’ll make sure to keep the math simple and straightforward:

    ### Understanding dBu and dBFS
    – **dBu** is a measure of voltage. +4 dBu is considered a “professional” line level, standard in most pro audio gear.
    – **dBFS** stands for “decibels relative to full scale.” It’s a digital standard, where 0 dBFS is the maximum peak level in digital systems.

    ### Signal Path
    1. **MacBook to QU-16**: The signal comes from your MacBook and goes into the QU-16 mixer.
    2. **QU-16 to elysia xfilter**: You’re sending the signal from the mixer’s Mix Output to the elysia xfilter for EQ adjustments.
    3. **elysia xfilter back to QU-16**: The processed signal returns to the QU-16.
    4. **QU-16 back to MacBook**: Finally, the signal goes back to the computer for recording or further processing.

    ### Levels and Conversion
    – **From MacBook to QU-16**:
    – You’re sending a -10 dBFS signal from the computer.
    – According to QU mixer specs, +18 dBu = 0 dBFS.
    – So, -10 dBFS would be roughly 8 dBu lower, which equals +10 dBu at the mixer.

    – **QU-16 Output Level to elysia xfilter**:
    – Nominal Mix Output of QU-16: +4 dBu = 0 dBFS.
    – However, for headroom, you want to send a lower level to the xfilter.
    – Assuming you need 8 dB of headroom, and the xfilter can handle up to +21 dBu, you should aim to send a level that peaks around +13 dBu to the xfilter. This provides headroom while staying within the xfilter’s capability.

    ### Setting Up the QU-16
    – Adjust the output level of the Mix Output channel on your QU-16 to ensure that the signal peaking around +13 dBu is sent to the xfilter.
    – Use the QU-16’s meters to monitor the output level.
    – Be cautious not to exceed the max input level of the xfilter (+21 dBu) to avoid distortion.

    ### Returning to the QU-16 and MacBook
    – After EQ adjustment in the xfilter, send the signal back to QU-16.
    – Ensure the return level on QU-16 is not clipping. Adjust the input gain if necessary.
    – Finally, route the signal back to your MacBook for recording or further processing.

    ### Additional Tips
    – Always start with lower levels and gradually increase to find the sweet spot, monitoring for any distortion or clipping.
    – Use the QU-16’s metering to ensure levels are consistent and within the desired range at each stage.

    By following these steps and keeping an eye on your levels, you should be able to integrate the elysia xfilter into your setup effectively while maintaining clean sound quality.

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    Profile photo of ljefe

    Wow! Thank you so much! That reply is above and beyond, I appreciate it!!!
    I am going to do some reading today, I have some learing to do, I want to get the most out of this gear. You made my week.

    Profile photo of Chris

    Legit copy and pasted your question into a chatgpt bot I made to help with my own questions. ChatGpt is the new life hack my friend. Happy I could help!


    Profile photo of ljefe

    That is very cool!
    Can I trouble you to ask it one more question?
    I am sending audio through the qu-16 to the Mix Output. The qu-16 input is calibrated at +18dBu = 0dBFS. The Mix Output, however, is calibrated at +22dBu = 0dBFS. Am I gaining or losing headroom when I send audio through the Mix Output?

    Thank you!

    Profile photo of Chris

    In this scenario, you’re sending audio through the Qu-16 mixer, and the input is calibrated at +18dBu = 0dBFS, while the Mix Output is calibrated at +22dBu = 0dBFS.

    When you send audio from the +18dBu input to the +22dBu Mix Output, you are actually gaining headroom. Here’s why:

    The input is calibrated at +18dBu, which means that 0dBFS (digital full scale) corresponds to an analog signal level of +18dBu.

    The Mix Output is calibrated at +22dBu, which means that 0dBFS corresponds to a higher analog signal level of +22dBu.

    So, when you send audio through this path, the signal level is being increased from +18dBu to +22dBu, which results in a gain of 4dB of headroom.

    Profile photo of ljefe

    You’re a hero.
    Thank you!

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