Has anyone else experienced this?

[Mr.Si]

Hi all,

 

It's been a while since I've been on here (I've been on HERE instead, I'm longing for snow and my Austria trip)

 

Anyway, I've recently, this morning infact, used a MixWizard 16:2 (not the latest version, the one before) and had a very odd thing happen:

 

Mixer on, phantom (global) on, main faders up, all channels muted, faders down gains down etc. Plug in a mic, *pop* goes the FOH, plug in another mic *pop!* goes the FOH.

Why in any world, would a mixer do this? (apart from needing fixing) - channels are off!!!

 

Only when I pulled down the main faders did this stop the popping of the FOH.

 

 

I haven't tried it with Phantom off, but I always like to use it for my Active DIs and Condensers etc. so if during a gig I need to add a mic or a DI to an unused channel, it would pop and be a bad thing.

 

 

Has anyone else had this issue? I'm probably just gonna get it looked at (dur) but I'd be interested to hear your views, stories etc

 

 

Thanks,

 

Si

[Rob_Beech]

Snow, dont like snow,

 

anyway, onto the board.

 

First of all as you have thought yourself, testing without phantom is a good choice, there may be some ground issue there, also (carefully) check what happens when you switch phantom on and off (with the channels muted etc <current state>).

 

Tests :

Test without phantom

When you get the pop, do you get a meter reading on either the channel and/or the masters?

Test the Aux outs (remember the channels are muted anyway, and faders down so the channel aux sends dont need to be up, but the aux masters will).

Plug a XLR cable into a channel, you get the pop. Do you get another pop if you plug a mic on the end? what about an active DI?

 

Could it be some internal connection issue (ribbon etc) when you physically push on the board (when plugging the XLR in) it is creating some problem to the left and right outputs, in its basic form this could be on the output connectors (meaning no signal would show).

 

 

Rob

[Mr.Si]

Ta Rob,

 

Will try some of those in my "private test facility" (read, bedroom)

 

(Probably will take a different desk in the meantime! maybe a little overkill, but GL2800 would work well.)

[Carey D]

Mixer on, phantom (global) on, main faders up, all channels muted, faders down gains down etc. Plug in a mic, *pop* goes the FOH, plug in another mic *pop!* goes the FOH.

Why in any world, would a mixer do this? (apart from needing fixing) - channels are off!!!

Only when I pulled down the main faders did this stop the popping of the FOH.

 

Hi Si.

Some of the previous version 2 MixWizards suffered a problem with this. It has been documented on the A&H site. The operational cure is simply to select the PAD switch while you switch phantom power or plug in powered mics. (strange, but it works!) If you want a more permanent fix there is a circuit modification which involves soldering a few diodes to each input card. For more info please contact A&H tech support mailto:support@allen-heath.com.

Hope that helps,

Carey (A&H)

[Mr.Si]

Thanks Carey, yes it does.

 

Being the Allen and Heath man, Do you know if it is just when phantom is on? or if it happened on a variety of scenarios?

[Carey D]

Thanks Carey, yes it does. Being the Allen and Heath man, Do you know if it is just when phantom is on? or if it happened on a variety of scenarios?

 

The pop happens only when you switch on or switch off the phantom power, or when you plug or unplug a mic from an input that has phantom power turned on. It is normal for a preamp to make this popping sound which is why you should always mute the channel when switching or plugging the 48V. The problem with some of the earlier MixWiz models is that muting the channel still lets some of the pop through to the main output (a design quirk). This can be avoided by pressing the PAD switch, or fixed with the card modification.

Hope that makes sense,

Regards,

Carey

[Mr.Si]

Totally. :(

[Ben Lawrance]

A band I work with have a mixwizard and the same thing happens. A massive pop throught the PA. When you have a 6KW PA, it can be quite a pop.

 

The only fix I have found it to have the masters down when plugging/un-plugging into the phantom'd (sp?) mic channels.

 

Slightily :( but channels 8 & 10 keep going open circuit. The desk has been back to A&H numerous times. Any ideas?

 

 

Ben

[Carey D]

A band I work with have a mixwizard and the same thing happens. A massive pop throught the PA. When you have a 6KW PA, it can be quite a pop. The only fix I have found it to have the masters down when plugging/un-plugging into the phantom'd (sp?) mic channels.

Slightily :( but channels 8 & 10 keep going open circuit. The desk has been back to A&H numerous times. Any ideas?

 

Hi Ben.

Please note the work around I mentioned in my post above - press PAD while changing phantom power status or plugging the mics.

 

Regarding your intermittent channels, it may be that a connection somewhere has gone bad, for example the switching contact in the channel insert jack may have become corroded over time and need cleaning or the jack replacing. You can test for this by bypassing the jack contact using a TRS plug with its tip shorted to its ring contact, and nothing connected to the sleeve. If this cures the problem try cleaning the insert socket by plugging a jack in and out several times, or spraying a suitable contact cleaner.

 

If you still have problems then it is worth getting the console checked by a service agent. The starting point would be to remove the base and rear cover and inspect the internal connections and wiring for displaced or bad connections. There were some early problems with the fader wiring which can be easily inspected and resoldered if needed.

 

If you need further advice please contact our (A&H) tech support team mailto:support@allen-heath.com.

Let me know if I can help further.

Regards,

Carey (A&H design)