Strange ground noise????

[FZfile]

Hello?

Last night I went and saw a local band (the Erftones, who whooped the horses ass) and recorded the show.

My modest setup was a Rode NT3 with a fresh battery to a Marantz 201 deck.

When I was checking the room levels vs the pad(s) I noticed that there was a BUZZZING sound.

Not loud, but there and constant.

As soon as I touched the transfomer adapter (to bring the XLR to a 1/4" TRS with an 1/8" adapter) the buzz went away.

Is it possible for mis matched impedences somewhere in the chain to cause a grounding type of noise like that???????

The transformer itself is "like new". I am fairly anal about taking care of even the accessory stuff but is it possible that the tranformer might have been damaged??????

I know its not the mic or the cord because I checked when i got home.

Any thoughts would be appreciated.
The show still sounded good and the performance was good enough to make the noise very much un-noticable.

........OH YEAH ......the funny thing is the noise recorded at about half of the volume relative to the room sound (crowd sound) that it seemed to be when I monitored with the head phones.......
BUT then for the second set I changed the mic angle a little bit and the buzz recorded louder, but still not as loud (relative to the crowd) as I seemed to be monitoring.

HMMMMMM>>>>>>?????
I don't know. Wadda ya think????

-mike

 

[MONTE]

If the input to the Marantz is TRS as you say, you shouldn't need a transformer...just an adaptor to get from XLR to TRS 1/8". I checked the Marantz web site to find out just exactly what this input is, and the online manual is pretty vague about it except to say that it is low impedance. They do not say whether it is balanced or not. I suspect you may be jacking into the deck with improper connections, although I do not know for sure. Possibly the input is not being properly grounded because of this. Of course this is only speculation without knowing for sure what your setup is. The point is, you may want to find out EXACTLY what type of input it is and reconfigure your "adaptor" accordingly.

 

[FZfile]

Thanks Monte.

I talked to a guy in one of my local shops and he said that inside of the transformer capsule there a couple of possible places to check for loose ground connections.

I did check my Marantz manual and it is very vague in a lot of ways.

But i guess now that you've mentioned it I realize that I have always assumed that in order to go from an XLR to a TRS(mono) connection, you needed to use a transformer adapter.

I had always used one with my Porta 2 and Porta 7 4 tracks.

But I guess that doesn't really make sense because you only need to connect ground pin to sleeve and the other 2 pins to tip to make the connection work, right??

So....am I right in saying that the tranformer adapter is only really needed for impedence matching??????
.....and that you are saying that I need to find out if the impedences of the mic and deck are or are not compatible with out the transformer adapter?????

Thanks for your help.
-mike

 

[CGDA]

I would ask the question, "Where was the Marantz getting it's ground?" I think when you can answer that you will also know the source of the hum. I suspect the answer is nowhere. But I am just guessing.

Peter

 

[MONTE]

I'm not sure, but some of the problem here might be due to misunderstanding of terminology and/or inputs. TRS= tip, ring, sleeve. These connectors (if you look at a plug for instance) have 3 connections. Generally they are ground, hot, and neutral with the exception of insert jacks and some other special connections. Most mic inputs of the unbalanced variety are only a two conductor input whether it be 1/8" or 1/4". You need to find out which type of input you have (3 conductor or 2). The issue I believe is not impedance, but rather connection to the unit. If your connecting any of the pins on a condenser mic together, you are also screwing with the phantom power because the phantom power will get grounded out through a lot of transformers. You MUST know what type of input connector you have in order to properly connect the mic.