Login / Register
 
Sennheiser MD421 Strange Noise
New Reply
Subscribe
leoguiders
Thread Starter
#1
26th March 2013
Old 26th March 2013
  #1
Gear interested
 
Joined: Sep 2010
Location: Karlsruhe, Germany
Posts: 28

Thread Starter
leoguiders is offline
Sennheiser MD421 Strange Noise

#2
26th March 2013
Old 26th March 2013
  #2
Gear addict
 
Studerfreak's Avatar
 
Joined: Nov 2009
Location: the Netherlands
Posts: 428

Studerfreak is offline
Sounds like you did something wrong with the ground wire (shield).
Shield has to go to pin 1 of the XLR connector (assuming the connector IS an XLR...)
leoguiders
Thread Starter
#3
26th March 2013
Old 26th March 2013
  #3
Gear interested
 
Joined: Sep 2010
Location: Karlsruhe, Germany
Posts: 28

Thread Starter
leoguiders is offline
Quote:
Originally Posted by Studerfreak View Post
Sounds like you did something wrong with the ground wire (shield).
Shield has to go to pin 1 of the XLR connector (assuming the connector IS an XLR...)
OK, so how do I determine which wire is the shield?
I read something about using a multimeter and look for 200 Ohms resistance between two wires to determine hot and cold, so the remaining wire must be the shield/ground?

Regards
leoguiders
leoguiders
Thread Starter
#4
27th March 2013
Old 27th March 2013
  #4
Gear interested
 
Joined: Sep 2010
Location: Karlsruhe, Germany
Posts: 28

Thread Starter
leoguiders is offline
I checked the connector and measured the 200 Ohms resistance between Pin 1 and Pin 2 on the bad mic, so this seems to be the problem. On the working Mic the resistance is measured between Pin 2 and Pin 3.
Should be correct if i swap Pin 1 and Pin 3.
Is there any easy way to determine which Pin is Signal + and which is Signal - ?
#5
27th March 2013
Old 27th March 2013
  #5
Lives for gear
 
Richard Crowley's Avatar
 
Joined: Sep 2006
Location: Portland OR USA
Posts: 3,213

Richard Crowley is offline
Quote:
Originally Posted by leoguiders View Post
I checked the connector and measured the 200 Ohms resistance between Pin 1 and Pin 2 on the bad mic, so this seems to be the problem. On the working Mic the resistance is measured between Pin 2 and Pin 3.
Should be correct if i swap Pin 1 and Pin 3.
Yes, that sounds right.

Quote:
Is there any easy way to determine which Pin is Signal + and which is Signal - ?
If you had the proper test equipment you could determine it empirically. However it would probably be easier to trace the wires from inside the microphone. Aren't the wires the same colors in both microphones?

Search Google for other discussions of 421 wiring. For example, in this very forum...
sennheiser md441 bad soldering repair?
leoguiders
Thread Starter
#6
27th March 2013
Old 27th March 2013
  #6
Gear interested
 
Joined: Sep 2010
Location: Karlsruhe, Germany
Posts: 28

Thread Starter
leoguiders is offline
Quote:
Originally Posted by Richard Crowley View Post
Aren't the wires the same colors in both microphones?
Sadly no, they seem to be from different production years or they have been serviced at some point in time.

Quote:
Originally Posted by Richard Crowley View Post
Search Google for other discussions of 421 wiring. For example, in this very forum...
sennheiser md441 bad soldering repair?
I already did an extensive google search and I found several threads with different pin connections.

Has swapping + and - the same effect as a phase invert button? Or, in other words, when recording with these mics, can I fix it when mixing the tracks?

Thanks for your help
leoguiders
#7
27th March 2013
Old 27th March 2013
  #7
Lives for gear
 
Ike Zimbel's Avatar
 
Joined: Oct 2006
Location: Toronto, Canada
Posts: 1,029

Ike Zimbel is offline
Quote:
Originally Posted by leoguiders View Post
I checked the connector and measured the 200 Ohms resistance between Pin 1 and Pin 2 on the bad mic, so this seems to be the problem. On the working Mic the resistance is measured between Pin 2 and Pin 3.
Should be correct if i swap Pin 1 and Pin 3.
Is there any easy way to determine which Pin is Signal + and which is Signal - ?
Hi,
Put both mics in front of a speaker that is playing a steady tone. Match the levels of the mics and sum them together. If the signal increases, the polarity of the mics is correct. If it cancels, it's reversed. This is not something to fix in the mix every time you use these mics.
Best,
Ike
__________________
--
Ike Zimbel,
Zimbel Audio Productions
Toronto
416-720-0887

"Studio House Calls". Authorized Warranty service for Allen & Heath, Clear-Com, Drawmer, Soundcraft, SPL and Yamaha. Repairs and upgrades to analog audio equipment including: AMEK, dbx, Neve, Neotek, MCI, Soundcraft and more. Ask about our RF frequency co-ordination services!
www.zimbelaudio.com
#8
27th March 2013
Old 27th March 2013
  #8
Gear addict
 
Studerfreak's Avatar
 
Joined: Nov 2009
Location: the Netherlands
Posts: 428

Studerfreak is offline
Checked with my own MD421's:

There is a red wire, a blue wire and a black wire.
The black wire is the ground and goes to pin 1 of the XLR
The red wire goes to pin 3, and the blue wire goes to pin 2 of the XLR.

Sennheiser must have used different wire colors, as my other MD421 has a green wire instead of a blue wire.
In that MD421 black to pin 1
Red to pin 3
Green to pin 2

Checking the phase of the two microphones indeed is the easiest way to do with the "Ike Zimbel method".
Before changing the internal wiring of the microphone, doublecheck with another microphone.
Saves you from reversing the phase of the wrong microphone....
Quote
1
leoguiders
Thread Starter
#9
27th March 2013
Old 27th March 2013
  #9
Gear interested
 
Joined: Sep 2010
Location: Karlsruhe, Germany
Posts: 28

Thread Starter
leoguiders is offline
Thank you so much, this was a great help!
#10
27th March 2013
Old 27th March 2013
  #10
Gear addict
 
Studerfreak's Avatar
 
Joined: Nov 2009
Location: the Netherlands
Posts: 428

Studerfreak is offline
Quote:
Originally Posted by leoguiders View Post
Thank you so much, this was a great help!
Does that mean that your "noisy" MD421 is working correctly and quiet now and is in phase with your other MD421 ?
leoguiders
Thread Starter
#11
30th March 2013
Old 30th March 2013
  #11
Gear interested
 
Joined: Sep 2010
Location: Karlsruhe, Germany
Posts: 28

Thread Starter
leoguiders is offline
Yes, it's usable now. I did not have the time to check for phase issues yet but since the red wire is connected to pin 3 in both mics I suppose they should be correct.
New Reply Submit Thread to Facebook Facebook  Submit Thread to Twitter Twitter  Submit Thread to LinkedIn LinkedIn  Submit Thread to Google+ Google+ 
 
Topic:
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Similar Threads
Thread
Thread Starter / Forum
Replies
jahtao / Music Computers
175
fifthcircle / Music Computers
11
matucha / So much gear, so little time!
3
AlexLakis / So much gear, so little time!
7
bodaciouscowboy / Music Computers
2

Forum Jump

SEO by vBSEO ©2011, Crawlability, Inc.