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Radial DM1 mic switch clicking noise

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Radial DM1 mic switch clicking noise

Postby forumuser637535 » Sun Mar 03, 2019 6:05 pm

Hi all. Long time no see :)
I'm trying to figure out why my radial Hotshot DM1 mic switcher is giving a big nasty click when I press or release it - even when using a dynamic (beta 58) mic.

The click comes out of both outputs.

I emailed Radial, they suggested it was a DC offset in the system, so try using an isolating transformer on one or both outputs (bought one from ART for this purpose, that's another £50 I'll never see back!). I used it on both, still the same problem.

I'm connecting to an X32 rack or an x18 unit. Phantom is off. Can't figure it out. I'm thinking it must be the switch itself - but I thought Radial made pretty good stuff?!
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Re: Radial DM1 mic switch clicking noise

Postby blinddrew » Sun Mar 03, 2019 6:44 pm

forumuser637535 wrote: Phantom is off.
That would have been my starting point!
Try a bit of Deoxit on the switch?
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Re: Radial DM1 mic switch clicking noise

Postby Hugh Robjohns » Sun Mar 03, 2019 8:00 pm

Radial do make good products, and although it is possible that the switch has become faulty, I doubt it. I suspect the problem is external to the DM1.

For a click to become audible there has to be a step change in the signal voltage, which means there has to be some sort of signal present at the time of switching. That could indeed be a DC signal from an imbalanced phantom supply -- I'd have made the same suggestion as Radial! -- or it could be normal audible background sound (such as an aircon rumble or aomething else constant but overlooked). Equally it could well be something well above or below the normal audible range, such as RF or EM interference. It's also vaguely possible that the clicks are an indication that your preamp's common-mode rejecting properties are below par, or that ground-loops could be playing an evil part in this!

It sounds like you've tried isolating transformers in the output lines, which is a good idea. That would negate the possibility of DC on the output connections, but did you try each line separately, or both together? I'm not sure from your earlier post exactly what you did, but you need to isolate both lines simultaneously to be sure.

Also, did the ground-lift switch make any difference at all (without the transformers)?

The other thing that might be worthntrying is to make up a muting plug (male XLR3 with a shorting strap wired between pins 2&3) and plug that in to the DM1 instead of the mic. If you hear no clicks when operating the switch with that connected, the problem is with the mic and/or the mic cable (picking up some form of interference).

Oh, and regarding the ART isolation box; I'm sure you'll find that an invaluable problem solving investment in the years to come. :-D I have amassed five ART DTI boxes over the years and they get used all the time for fixing ground-loops, providing signal distribution, signal combining, converting between balanced and unbalanced connections, converting between different connector types, and more besides...

H
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Re: Radial DM1 mic switch clicking noise

Postby forumuser637535 » Mon Mar 04, 2019 10:55 am

Hi Hugh, thanks for the reply! (and for the reassurance re: the art box!)
I isolated both channels. I've definitely used it with different cables, and I can try it with different mics too. The same issue has happened in a variety of venues, where there has been no other rumble or earth issue. I've tried switching the lift switch, but it made no difference.
Could it be something to do with the x32 rack or the x18 mixers I'm plugging into, or can I rule those out? The gains are set pretty normal for dynamic mics, maybe 20/30db gain at the desk preamp.

A friend has a cheaper mic switcher box that works in the same way. It has a slight click, but far less pronounced than mine. I'd be OK with a small click, but this feels like a full range stab that's very difficult to even EQ out, and too fast for a compressor to shut down.
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Re: Radial DM1 mic switch clicking noise

Postby Wonks » Mon Mar 04, 2019 11:31 am

As its unpowered, there can't be much more than a switch inside (though I'm probably wrong), so I'd suspect a dodgy switch, myself.

If it's out of warranty I'd open it up and have a look inside. If in warranty, I'd take it back and see if a new one cures the problem.
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Re: Radial DM1 mic switch clicking noise

Postby forumuser637535 » Fri Mar 15, 2019 2:03 pm

I've tested this in my studio, plugged into my prism Orpheus it doesn't replicate the problem. There is a negligible click, audible at high volume, (e.g. over 35db gain) but very acceptable, and only clicks in the channel which is coming on - it mutes silently.

This suggests to me that the issue is the Behringer digital desks I'm plugging into - both the X32 rack and the X18.

Do they have some kind of digital protection circuitry that detects signal and switches an input on/off? Is there something in their preamps which is causing this clicking?
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Re: Radial DM1 mic switch clicking noise

Postby Hugh Robjohns » Fri Mar 15, 2019 2:09 pm

Have you tried it with a behringer desk at home? If it's an interference problem you may not have the same level at home as on location.

The Orpheus is probably a lot better protected against RF than the Behringer too, and will undoubtedly have better common-mode rejection figures.

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Re: Radial DM1 mic switch clicking noise

Postby forumuser637535 » Fri Mar 15, 2019 2:22 pm

Hi Hugh -

can you explain where the interference is likely to play a part - is it in internal electronics? I don't understand things at that level. Is it related to e.g. a bad/inconsistent power supply? Does it mean that there is a current coming back to the mic from the desk, and this current is interfering with the circuitry of the pedal? And should the ART box not have eliminated that?

What I've discovered is that the ART box makes the problem worse - the clicks are much louder even on the Orpheus, with the ART box in between the Radial pedal and the Orpheus. (or between the mic and the radial pedal, for that matter).
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Re: Radial DM1 mic switch clicking noise

Postby Hugh Robjohns » Fri Mar 15, 2019 4:36 pm

forumuser637535 wrote:can you explain where the interference is likely to play a part...

I did in my earlier post. If -- and at this stage of the investigation it is an if -- there is some sort of interference getting into the mic/cables/DM1, then the action of the mute switch will result in a step-change of voltage voltage which may well become audible as a click -- especially if the common-mode rejection of the mixer is poor -- and even if the interference signal itself remains inaudible (possibly because it is outside the audible range).

And should the ART box not have eliminated that?

No, it can't prevent interference getting into the mic/cables/DM1

What I've discovered is that the ART box makes the problem worse - the clicks are much louder even on the Orpheus.

Ooh. That's interesting... I'll need to have a think about that... Is it the same with different mics, and did you try the shorting plug I mentioned earlier?
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