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Loud hum from when using iconnect audio 4+, but not irig DUO with certain instruments...

I’m getting a pretty terrible hum coming from my uke bass, and Mohan veena equipped with a K&K infinity pickup, but not so much from my mandolin with a K&K mando pickup, which goes quiet if i touch the metal part of the cable jack entering the instrument. This happens using my ica4+ But not if I use my irig Duo.

I’ve spent a fairly ridiculous amount of time learning about ground/main hum issues and fixes for them, but can’t seem to identify why I’d have this issue with two of the three instruments, and on the iconnect but not the duo. But I do wonder if the fact that the iconnect is plugged into the wall and the duo is usb powered is a factor?

Wondering if a hum eliminator/suppressor and/or DI box and/or this Ebtech HumX thing I’ve also seen proposed as a solution if it’s an issue with the power supply...

Any suggestions GREATLY appreciated before i go out and buy stuff...

Brusfri does work wonders on this as a software solution but as it adds latency and adds another app in the setup it doesn’t really seem like the best solution for live play...

Comments

  • edited December 2021

    A DI box or ground loop hum eliminator usually works in these cases, but it could be another noisy device on the same line somewhere else in your house, so testing other wall outlets could find the culprit. Or see if a surge protector between the wall outlet and the iConnect helps - sometimes that's all that's required.

    In my experience, those iConnectivity interfaces are more susceptible to interference, due to all of their ports. Hum and noise can enter through MIDI cables too. And especially USB cables. So please first unplug those devices from your iConnect to narrow down the culprit(s). Then test the K&K sources again.

    What are you using for a preamp for those K&K pups? Did you mean Fishman Infinity? A decent DI for those transducers usually have the hum elimination built-in.

    If you do get a ground loop lifter, make sure it filters out the hum, rather than lift the ground, which can kill you.

    And you're correct - battery-powered devices usually don't have to deal with interference issues.

  • @ManWhoWouldBeStrings . Are you able to turn around the iConnect power connection at the wall? If it's not polarized (only goes one way), that might help.

  • @ocelot Yeah I’ve tried a few different outlets and surge protectors, and just tried without my usb midi controller...hum still as bad as ever... And yeah I don’t know where K&K “infinity” came from, it’s a “pure mini”, but I don’t have the preamp for them. But the hum is actually the worst with my Sound Smith Uke Bass which has an internal pickup system of some kind. I just tried to find out what but couldn’t find specs online, but it does have a battery, sooo, active pickup/preamp of some kind...?

    @uncledave I’m actually in Europe right now using the adaptor for euro plugs, and it goes either way...

    I have run the iconnect off a portable battery before, and I remember the hum being there as well, though perhaps not as bad...I don’t have it with me here right now to check though...

    Any suggestions for a DI box and/or ground hum eliminator? Might make a separate thread post asking for opinions on that...

  • edited December 2021

    Another piece of info that may or may not be relevant is that the hum reacts to the volume knob on the uke bass...I mean it isn’t just constant but gets louder with the volume knob up

  • So no balanced output on the uke? TRS or XLR? That'd be the best option, since it sounds like it's active. If not, and/or you're using a regular TS cable, be sure in iConfig that the input is set to line, not mic. That might be the issue here, come to think of it...

    Check that first. On the uke, not the passive K&K-equipped one.

  • Well...I get zero audio out the uke with a balanced TRS cable, so that seems like a no on the balanced output...

    Where/how in iConfig can you change input from line to mic? The manual says input jacks 1 and 2 are unbalanced high-z inputs and 3 and 4 are balanced, but I get the hum through all four jacks

  • If it goes quiet when you touch the strings or metal parts, then it’s almost certainly a grounding issue. Especially if it changes with guitar volume.

    Are you using any pedals in between the instruments and the iConnect? Their power supplies can cause trouble.

    As @uncledave says, try turning the power plugs around 180 degrees. I have to plug my guitar amp into power with the plug the right way around, or I get hum.

    Also, remove the usb cable. USB is always a pain, hum-wise. It may be causing a ground loop. Often USB connections aren’t isolated properly from the audio section.

    A few years ago I bought a Strymon Zuma power supply. Absurdly expensive, but I’ve not had one power or power-related problem since. No hum, ever.

  • Is it auto-sensing? I don't remember. I'm doing this from memory.

    The manual says input jacks 1 and 2 are unbalanced high-z inputs and 3 and 4 are balanced, but I get the hum through all four jacks

    Those are four combo mic/line inputs, for either XLR, TRS, or TS inputs, and either high-Z or low-Z sources. I'm not sure why the manual would say that they're "unbalanced high-z inputs"?

    There's another iCA4+ thread, let me see if I can find an answer, or remember....

  • Hi-z won’t make a difference to hum. It’s a manual change on the iCA4+ BTW. In the iConnect app, under the audio mixer page. There are buttons at the bottom of the input channels.

  • @mistercharlie I tried turning the plug around, to no avail...and disconnected the usb midi controller...still hummin away. And no pedals between the instrument and iConnect. And wow yeah that’s an expensive power supply, definitely cheaper to go with a DI box/hum eliminator if they’d work. Also, I’m not sure how I’d plug the iConnect into the Strymon if that was your suggestion...

    @ocelot said:
    Is it auto-sensing? I don't remember. I'm doing this from memory.

    The manual says input jacks 1 and 2 are unbalanced high-z inputs and 3 and 4 are balanced, but I get the hum through all four jacks

    Those are four combo mic/line inputs, for either XLR, TRS, or TS inputs, and either high-Z or low-Z sources. I'm not sure why the manual would say that they're "unbalanced high-z inputs"?

    There's another iCA4+ thread, let me see if I can find an answer, or remember....

    I actually found different explanations for the jacks input in different places, but this screenshot is from the manual...

  • edited December 2021

    @mistercharlie said:
    Hi-z won’t make a difference to hum. It’s a manual change on the iCA4+ BTW. In the iConnect app, under the audio mixer page. There are buttons at the bottom of the input channels.

    On mine it just shows 1, 3, and 4 as Line, and 2 as Inst but no button to change anything (no changes if i tap on the text) as far as i can tell...but anyways it doesn’t seem like that’s the problem

  • Inexpensive hum eliminators - Art, Whirlwind, and Morley were decent in our experience. Not sure what the market looks like now.

    Countryman and Tech21 made good analog acoustic DIs, but won't help much with the hum.

    Or better yet, check out the recent digital acoustic DI/preamp/FX processors, as those should have decent noise suppression built in. Zoom, for one, is a bargain. Plus it does a lot more.

  • @ocelot said:

    >

    Countryman and Tech21 made good analog acoustic DIs, but won't help much with the hum.

    Or better yet, check out the recent digital acoustic DI/preamp/FX processors, as those should have decent noise suppression built in. Zoom, for one, is a bargain. Plus it does a lot more.

    I thought DI boxes can help with hum by converting unbalanced to balanced...? Or do they need the ground lift switch? What ya think about these?

    With switch:
    https://www.thomann.de/intl/behringer_ultradi_di600p.htm

    No switch, but 2 channels:
    https://www.thomann.de/intl/behringer_microhd_hd400.htm

    And is this an example of the Zoom DI/preamp/fm processor you mentioned?
    https://www.thomann.de/be/zoom_ac_2_acoustic_guitar_fx.htm?glp=1&gclid=CjwKCAiAwKyNBhBfEiwA_mrUMsaGRXqe4xEMJpxO2I1iGtDyESdFqyrptxuq9wZr1DKfW272bcNpVxoCTnUQAvD_BwE

  • edited December 2021

    Converting from unbalanced to balanced won't help. That helps with extremely long cable runs. If it has a ground lift, that'll likely help reduce the hum.

    I recommend a preamp, which will also have a DI built-in.

    Your K&K Pure Mini, without a preamp, like all passive piezo pickups, output a very high impedance signal. A preamp will not only reduce the hum, but will make it louder, more balanced, and can shape your sound with EQ. It will sound a lot better.

    Tech21 Sansamp Para Driver DI new for $230. There's an older model called the Acoustic DI.
    Behringer ADI21 new for $30. I never used this but I believe it's a clone of one of the above.
    LR Baggs Para DI used for $100. It's a classic.
    Zoom used for $10-50 - they made many different acoustic preamps/FX units, going back at least 20 years.

  • @ocelot said:
    Your K&K Pure Mini, without a preamp, like all passive piezo pickups, output a very high impedance signal. A preamp will not only reduce the hum, but will make it louder, more balanced, and can shape your sound with EQ. It will sound a lot better.

    But it’s the uke bass that is the worst culprit at the moment...I have been considering the matching K&K preamp for a while, but honestly the pure mini sounds surprisingly good and loud already, I will likely get it later but for now the hum is the main issue I’m trying to solve...you think it’d also solve the issue for the bass?

    Zoom used for $10-50 - they made many different acoustic preamps/FX units, going back at least 20 years.

    The cheapest “Zoom acoustic preamp” I can find is 180 euro...you have any links you could share?

    Sorry to keep drilling into this question but I REALLY appreciate your feedback! :) Trying to not buy something that won’t actually solve the problem...

    Ultimately there’s three separate but related things I’d like to accomplish that I was hoping one device could cover:
    1) kill the hum
    2) amplify the signal so I could use my powerful Minirig setup as a monitor/speaker (when not using the iconnect/ipad/phone setup, for easy quick simple busking, for now I can do this individually with fun little headphone amps and an aux cord...)
    3) mix multiple signals (including a mic) into the Minirig setup...

    So maybe just a mixer/preamp would do for the second two, and maybe the hum when using the iconnect is a separate issue, but I was thinking maybe one device would get me there for all three...

    1. Kill the Hum - This is the difficult part. You'll need to find the noise source(s). Keep searching! Read below.
    2. Amplify acoustic signal for your Minirig system - Get one of the preamp/DIs that I listed above+below.
    3. Mix mic+line signals - Get an inexpensive Behringer or Mackie mixer. Or search Amazon for 'sound mixer', 'mic line mixer', etc.

    Discontinued Zoom Acoustic Preamps + FX Processors -
    504 (PDF Manual)
    504 MKII (PDF Manual)
    A2 (PDF Manual)
    A2.1U (PDF Manual)
    A3 (PDF Manual)

    Years ago, I used the Zoom 504 and later the A2 with piezo and soundhole pickups on acoustic guitars, both passive and active.

    Valuewise, Zoom couldn't be beat, since they packed an entire rig into a tiny box. They can be noisy, and they aren't considered 'professional', but for small gigs, they were invaluable. I don't think they have balanced outputs, but could be wrong.

    I loved the Tech21 and LR Baggs preamp/DIs with rack effects even more.

    The Zooms are like all-in-one BOSS multi-effect pedalboards for acoustics, the others are 'pro' front ends for acoustics.

    As for finding the noise source(s) - you'll need to learn how to do this, especially if you gig. I also spent many years as a stagehand and this was what I spent the most time on. Every dive is different - each has their own special noise problems. You just get used to it, but you must be patient and learn it. And you'll need to eventually buy other DI boxes, thousands of kilometers of cables, bags full of adapters, etc.

    Ask any questions - I'm happy to help.

  • @ocelot Cool thanks for the rec’s...but do you think there’s something that can do all three as one device? A mixer with a suitable preamp that would kill the hum? I move around a lot without a steady base so portability and limiting the amount of devices is a priority for me...

    Also, any idea why the hum would be significantly worse with the pure mini on my Mohan Veena than with the Mandolin twin internal on my Mando? But again, worst of all on the uke bass...

  • The hum level varies with pickup type, impedance, shielding (from PU to plug).
    High impedance (piezo) is generally more sensitive to noise, while coil based PUs react to magnetic fields in the first place.
    (humbucking PUs use an inverse coil to suppress hum, with single coil types you can only alter your position relative to the magnetic source).

    As @ocelot mentioned it‘s often tricky to sort out the ground based parts of the noise.
    Use a single outlet with proper ground connection for your personal island supply.
    (often you may not even know about the ground quality at the location)
    But you need the ground to get rid of the noise part from PU/mic to preamp.

    Then check the „ground level“ between amp/processing/monitoring devices on your island.
    (that‘s your local part)
    If that‘s hard to get clean with proper connectors, USB isolators are likely to sort it out.
    But it helps to understand which noise/hum parts are from outside and which are from inside your processing chain.

  • Could be that the active electronics on the uke bass need servicing. Dirty battery terminals, rust, frayed wires, parts going bad, re-soldering required, not-shielded, dirt/dust/smoke/moisture-buildup, etc. (Is it a budget model? Often the no-name electronics in budget gear is...shite.)

    And as @Telefunky recommended, or as a start, get your entire studio (including PC/iPad) connected to a single, good-quality, powerful surge protector. Keep audio cables as short as possible, and away from power sources. Turn off TVs, florescent lights, wired and wireless transmitting devices, etc. (Of course you cannot do that in a bar, so that's why you'll need to become a 'noise detective'.)

    As for the kill 3 birds with 1 stone mixer/hi-Z preamp/hum-killer, I bet compact models exist nowadays (for ie-coffeeshop gigs), but I don't know them.

  • Cool thanks guys. The thing is though that I was getting the hum before too when plugged into a portable battery, so not an issue with the wall outlet...

    The uke bass is a cheaper model, and I assume yes it has no-name shit electronics inside...so could be the issue, still I was hoping for a cheaper hum fix than buying a new one as it’s in no way a major part of my arsenal.

    I think I’ll make another thread asking for rec’s for the mixer/hi-z preamp/hum-killer combo that seems to be the holy grail for me right now...

  • @ManWhoWouldBeStrings said:

    I thought DI boxes can help with hum by converting unbalanced to balanced...? Or do they need the ground lift switch? What ya think about these?

    With switch:
    https://www.thomann.de/intl/behringer_ultradi_di600p.htm

    No switch, but 2 channels:
    https://www.thomann.de/intl/behringer_microhd_hd400.htm

    Okay, I re-read the entire thread. 😉 The details were a bit unclear.

    There's also this one for $10; you'd need to use the XLR output -
    https://www.thomannmusic.com/millenium_die_dibox_passiv.htm

    But I'd definitely try the Behringer HD400 first.

    Even if they don't help (which I believe they will), you'll be gigging soon, and I guarantee that they'll come in handy down the road at some point.

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