[Scott Dorsey]

wrote:

I have a pair of oktava mk319s which i have modded as per the scot
dorsey article. Oddly though since modding one of the grills has
caused whichever mic it is attached to, to suffer from severe ground
hum.

It's probably not ground hum. It's probably some kind of RF noise.

I have checked grounding continuity between pin 1, the earth track on
the board, and the the grill basket and in any combination of mic and
grill all appears to be in order.

What if you cover the grille with aluminum foil? Does the noise go away?

when you apply the good grill to either mic it sounds lovely and the
hum goes away, apply the bad grill to either mic and the problem rears
its ugly head again.

Something is not connected to something else, somewhere. What did you do
to the grille?
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[[email protected]]

On Oct 12, 6:19*pm, (Scott Dorsey) wrote:
wrote:

I have a pair of oktava mk319s which i have modded as per the scot
dorsey article. Oddly though since modding one of the grills has
caused whichever mic it is attached to, to suffer from severe ground
hum.

It's probably not ground hum. *It's probably some kind of RF noise.

I have checked grounding continuity between pin 1, the earth track on
the board, and the the grill basket and in any combination of mic and
grill all appears to be in order.

What if you cover the grille with aluminum foil? *Does the noise go away?

when you apply the good grill to either mic it sounds lovely and the
hum goes away, apply the bad grill to either mic and the problem rears
its ugly head again.

Something is not connected to something else, somewhere. *What did you do
to the grille?
--scott

--
"C'est un Nagra. *C'est suisse, et tres, tres precis."

Cheers for the replies

I'll try the aluminium foil idea when i get back at the weekend,

"What did you do to the grille?"-hehe, exactly my thoughts! ruined it
i think may be the answer! I've obviously done something wrong but
what exactly?

I have removed 1 layer of mesh from the top and sides of the baskets
and taken out the side bars of the grill cases. Effectively leaving 2
rings holding the grills in place.

The reason for thinking that it is a grounding issue is that the hum
is constant, loud, around 60hz and reduces when you handle any part of
the mic.

Thanks in advance for suggestions

Ben

[Scott Dorsey]

wrote:

The reason for thinking that it is a grounding issue is that the hum
is constant, loud, around 60hz and reduces when you handle any part of
the mic.

The giveaway is that it reduces when you handle any part of the mike.
There is not solid connection being made between pin 1 and the case.
If it were a problem with the grille itself, touching the mike would not
change the noise.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Bill Ruys]

Keep in mind that the capsule and anything before the FET is supa-dupa high
impedance (we're talking giga-ohms) and requires the grill as part of the
faraday shield to stop it inducting noise. You need to ensure it's well
bonded to the body of the mic.

Bill.

wrote in message
...
On Oct 12, 6:19 pm, (Scott Dorsey) wrote:
wrote:

I have a pair of oktava mk319s which i have modded as per the scot
dorsey article. Oddly though since modding one of the grills has
caused whichever mic it is attached to, to suffer from severe ground
hum.

It's probably not ground hum. It's probably some kind of RF noise.

I have checked grounding continuity between pin 1, the earth track on
the board, and the the grill basket and in any combination of mic and
grill all appears to be in order.

What if you cover the grille with aluminum foil? Does the noise go away?

when you apply the good grill to either mic it sounds lovely and the
hum goes away, apply the bad grill to either mic and the problem rears
its ugly head again.

Something is not connected to something else, somewhere. What did you do
to the grille?
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Cheers for the replies

I'll try the aluminium foil idea when i get back at the weekend,

"What did you do to the grille?"-hehe, exactly my thoughts! ruined it
i think may be the answer! I've obviously done something wrong but
what exactly?

I have removed 1 layer of mesh from the top and sides of the baskets
and taken out the side bars of the grill cases. Effectively leaving 2
rings holding the grills in place.

The reason for thinking that it is a grounding issue is that the hum
is constant, loud, around 60hz and reduces when you handle any part of
the mic.

Thanks in advance for suggestions

Ben


** Posted from http://www.teranews.com **