microphone jack half way out

[dfinn]

Hi,

 

Just rigged our sound kit up at school and plugged in a mic using XLR - jack lead using the jack to go into the desk (A&H GL2200). I got nowt out of it. I pulled the lead out a bit and it works fine. I am presuming this is because I was using a mono jack (1 black band) into the desk input which I presume must be mono? I may be wrong. Why is this?

 

Thanks

 

Daniel

[Chris_R]

This may be because you plugged the mic in to the Insert socket instead of the Line in socket (the insert is the top one, the line in is the bottom one on a GL2200) The Line In's should be mono, so that wont matter.

When using microphones you should use the XLR line ins as these have a mic preamp which will increase the signal to a processable one. The line input expects a higher signal IIRC.

Hope this helps.

 

EDIT: This post may help.

[dfinn]

Nope I was definately using the Line ins not the inserts

 

what do inserts do anyway?

 

Daniel

[nickb12345]

The line input is for something outputting a signal at a LINE level (cd player, MD etc). A mic signal needs a pre-amp before it can be processed, this is usually on the XLR input to the desk.

 

If a mic is plugged into a line in you will probably get a signal but very very quiet!

 

Plug it into the XLR socket and you should be away.

 

 

The Insert socket contains a direct output and input into the channel signal which can be used to put an effects processor on that channel alone... for the wiring diagram see the desk manual.

 

 

Regards

 

Nick

[Bobbsy]

Actually, the GL2200 can accept mic or line on either the XLR or Jack input...but in either case it is expecting a BALANCED signal....and by using a mono (tip/sleeve) jack you were converted you nice, balanced mic out to unbalanced. Convention is certainly to use the XLR input for microphones...and sticking to balanced will prevent a lot of problems with noise etc.

 

Depending on how the XLR to jack cable was wired, it's quite possible that the common mode rejection on the balanced input was receiving the same signal on both legs inverting the phase of one channel and cancelling it as it would with noise.

 

Failing that, did you by any chance have phantom power turned on? I've seen this sort of loss of signal when the 48V phantom power is accidentally fed via a mono jack....and the half insertion would stop this happening.

 

Bob

[dfinn]

Hi,

 

Thanks for that. I will use XLR as much as possible from now on. I ensured phantom was turned off.

 

Ill change the lead to XLR and then it should be fine.

 

Cheers for the help

 

Daniel

[RichH]

Thanks for that. I will use XLR as much as possible from now on. I ensured phantom was turned off.

 

If you use fully wired XLR it shouldn't matter if Phantom is on or off. I sometimes leave it on incase I have to swap out a passive device (dynamic Mic or DI) with an pwered one (condenser, different type of DI)

[dfinn]

Hi,

 

I also have a VIRTUALIZER PRO DSP2024P effects unit which I run from th aux1 output into the virtualiser and then out into a line in an a free channel. Should I run this back into an insert on the channel or should I run if off the line in like I currently am. ATM I am having the same jack problem with this as it has to be half way out to work.

 

Daniel

[Mr.Si]

you're returning it correctly.

 

although Ideally, you should have some Aux Returns and so if you return it through one of them, then it will free up your free channels for other instruments.

 

If you use the insert for effects, you would have an insert lead, which is a stereo jack to two mono jacks. This would act as a send and return in one, but this would only work for that particular channel. Basically, how you'd normally use a compressor on a vocal or a bass guitar, etc.

 

So using the aux send method is much more flexible.

 

Si

[dfinn]

Ah rite,

 

yeh I use the aux outputs to output the sound from any channel on the board.

 

I have a pair fo stereo returns on the Gl, could I use these for the fx unit which would free up a spare channel?

 

Daniel

[Mr.Si]

Yep yep,

 

That's exactly right.

 

Si

 

P.S. Just a question now regarding the probs you've been having regarding the jack being half way out being the only way you can get a signal. Does this happen on all channels? or just one? cause if it's just one then it could be a fault on the console.

[dfinn]

Nope it happens on every one.

 

Daniel

[minty]

I had a similar fault on a Soundtracks MRX32 a while back. Turned out to be a faulty ribbon cable running to the master section which inadvertently caused the same problem across every line input across the desk.

I realise this is not likely to ooccur but it can happen!

[audio]

Just try using a stereo jack, and see if it still needs to be half way out to work.... an old inkel desk I used to use was like that, I have tried to figure the logic behind it (and failed ) but using stereo jacks cured the problem.

 

Talking about the fx unit, I like having mine running through a channel on the desk, just so you can vary the level easily with a fader, rather than using the rotary fader on the AUX channel. Normally fx units output a stereo signal (even if only fed a mono source) so it would be a good idea to return it through a stereo channel.

[Bobbsy]

To repeat a couple of things I said previously:

 

1. This doesn't sound like a "fault". It sound like a perfectly normal result of taking a balanced mic output, running it through a cable terminated in an unbalanced quarter inch jack, then plugging this into an input on a decent mixer expecting a BALANCED feed on a TRS jack.

 

2. Don't "just try using a 'stereo' jack". First off, in this case "Stereo" is the wrong terminology. The mic is a single channel, the mixer input is a single channel. Nothing here is stereo. It is a BALANCED signal and the jack is generally known as a "TRS" (standing for Tip/Ring/Sleeve). Second, although this Allen & Heath happens to let you use the TRS input for mic level, the vast majority of mixers will not. XLR is for mics, TRS is for line level. It's worth getting used to working with normal industry standards where possible, otherwise things will come unstuck at some point in the future, usually when you're under max pressure.

 

Cheers,

 

Bob

(in maximum pedantry mode...but trying to be helpful!)