noisy preamps

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This topic contains 8 replies, has 5 voices, and was last updated by Profile photo of cAPSLOCK cAPSLOCK 7 years ago.

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  • #38946
    Profile photo of AudioplusAB
    AudioplusAB
    Participant

    Hi, a costumer of ours needed to replace their range of 01v96v2 and bought one Qu-16 to see if it fit in the production.
    They ended up sending the Qu-16 back and reverted to their yamaha desk, i havent got the desk back so that I can try the desk but here are their comments.

    *noisy gainstructure, apperently there is a big difference comparing to a 01v96 in terms of noise, nothing connected on the input, normal gain and turning up the faders.

    *not possible to choose compression pre eq.

    *not possible to send to aux after compression.

    *not possible to double route channels so that you can run a separate FOH mix and a monitor mix.

    any comments

    //
    Daniel

    #38956
    Profile photo of SteffenR
    SteffenR
    Participant

    They have no plan what they do… ???

    The gain structure with open circuits is not the one that counts…

    #38985
    Profile photo of AudioplusAB
    AudioplusAB
    Participant

    Correction, they didnt buy the device but fieldtested it, accordning to the costumer all preamps were set with the material they use on a day to day basis, then all cables were unplugged to see what might be an issue and they found the desk to be noisy. could it be like the CL1-5 consoles, different stages in the preamp? Any others experience this issue? Sounds strange to me but I know the costumer knows what hes talking about.

    #38986
    Profile photo of mervaka
    mervaka
    Participant

    * Mix sources can be post preamp, pre PEQ, post PEQ, and post delay. All of which can be pre or post fader.

    * Yes, the PEQ/compression order is fixed. What’s a use case for wanting to compress PRE-EQ?

    * Yes, the input patch is fixed.

    Have you tried looking at the block diagram in the user manual? It’s all there.

    On the subject of preamps, steffenromeiss is absolutely right. You can’t evaluate a preamp based on an open circuit input. It’s high impedance, and of course will be subject to noise. A fair test would be to short circuit the hot and cold pins.

    #38993
    Profile photo of AudioplusAB
    AudioplusAB
    Participant

    *whats the use of compressing pre eq? isnt that obvious? if compressing hard post eq you end up equalizing whatever changes you have done in the PEQ setting.

    *reg. the preamps, I havent seen my clients setup but hey, a quick googling and I found another thread http://community.allen-heath.com/forums/topic/noisy-preamps

    #38994
    Profile photo of mervaka
    mervaka
    Participant

    What I mean is, why would you ever not want to EQ first? Horses for courses, I guess. Personally I like to compress an equalised signal, not a dry one.

    Regarding the preamps, I’m struggling to understand your point beyond fishing for someone to tell you they’re noisy. In the thread you linked, steffenromeiss suggested putting a test tone through both desks. You could then directly compare the noise floor against a known signal reference level.

    #39030
    Profile photo of AudioplusAB
    AudioplusAB
    Participant

    I for one never eq first, unless I have to because of hardware imitations 🙂
    testtones and measuring devices are ofcourse very good, or you could test the two desks with the same material at pretty much the same level in a room, and experience one of the desks as more noisy, with an as my client describes as -a good gainstructure on the mix. nevermind this discussion, i just had a humble question if someone else has experienced the desk as noisy.

    BR

    #39037
    Profile photo of TheProcon
    TheProcon
    Participant

    I’ve been through several of these comparison tests and never tested with an open circuit. Test with program audio such as recorded voice or music. Then test with a vocal mic. Turn all processing off or at 0.

    Now make a small EQ change on one, then the same on the other. Listen to the difference.

    Use your ears. Now multiply this result by however many channels they might have running at one time on either mixer.

    #39144
    Profile photo of cAPSLOCK
    cAPSLOCK
    Participant

    One of the reasons I bought the Qu over competing mixers was the quality and quietness of the preamps. I have done a few remote recordings with it and have been very pleased with the virtually nonexistant noise floor via the XLR channels. I have a pair of ECM8000s I may use from time to time in a pinch (usually for room mics), but in the past noise has been an issue with these mics. With the QU I have found they are far more quiet than my previous remote rig. I have not found an explanation for this beyond the quietness and quality of the pres. I was marveling last night at the cleanness and clarity I was experiencing when using a sampler connected to the mixer with an old pair of HOSA 1/4in cables I should have thrown away years ago. I was noticing when playing large arpeggios with the pedal down on a piano sample (On a Korg Kronos) I would eventually hear the cumulative noise on the SAMPLES(!) but there was never the faintest whisper of hiss from the mixer.

    I feel your client has either poorly performed his tests, had something else noisy in the signal chain, or had a defective unit.

    I feel the order of likelihood is from first to last in that list.

    Their method of testing seems odd. I generally keep channels with nothing in them muted or at least turned down. 😉

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