Speech Recognition
Solutions

4 Spencer Rd.
Hanover, NH 03755

603-643-3145

Modification of the Sennheiser ME 3 Microphone

Many view the Sennheiser ME 3 to be the ideal microphone for use with speech recognition software. Its reputation results from two outstanding qualities:

1. High Accuracy
2. Excellent noise canceling abilities

The Problem:

Unfortunately, the Sennheiser ME 3 - as manufactured - suffers from several shortcomings which require action before it can be practically used with a personal computer and speech recognition software. The issues are these:

• The jack or plug is non-standard and does not interface properly with standard audio equipment
• The wiring of the plug is non-standard and when plugged directly into most computer sound cards, it simply doesn't work.
• A final although controversial issue has do do with a small slit in the microphone element that may cause a reverberation or echo effect which may reduce the accuracy of the microphone
  

  	The Non-Standard ME 3 Plug with Associated Locking Ring

The Solution:

There are, then, several steps which need to be followed in order to bring this microphone to its full exceptional potential:

1. The simplest method of dealing with the non-standard jack is to purchase a small adapter which accepts the non-standard male jack on the Sennheiser ME3 and converts it to a standard 1/8 inch (3.5 mm) audio plug. This adapter (pictured at right) is sold exclusively at Speech Recognition Solutions (see accessories)

2. The Non-standard Jack: the must be dealt with in one of several ways.

• First, the locking ring can simply be pushed back far enough to prevent it from interfering with adequate contact with a female microphone input jack.
  
  Please note: Sennheiser ME3 microphones manufactured in September of 2006 and onward have utilized a new jack design that does not allow the ring to be pushed back using this method. The key to knowing whether your ME 3 has an adapter which can be modified in this way is to try pushing it back manually - if you noticice the ring can be pushed back a bit and the ability to rotate it becomes limited, you are dealing with an old one and can use this modification technique. If you have no ability to push it back and it does not bind when pushing it back, you are likely holding a newly manufacutured jack and do not attempt the "push-back" method of modification.
  
  
• Pushing back the locking ring requires a bit of force and is the method of specialty microphone dealers since it is quick and easy. It can be done individually as described elsewhere on this site, or in a mass production style using a "modification jig", also described on this site. The main disadvantage of this method is that physical manipulation of the jack in this manner may void the warrantee from Sennheiser. Also, if you're not adept with manipulation of this kind, or don't have the few required tools, it may not be practical for you.
  
  

  Individual method of pushing back locking ring.	Quick modification using a "jig"

  
  
• Second, the locking ring can be physically removed by clamping the jack in a bench vice and using a hacksaw to make a series of cuts through the ring and thereby allowing it to fall free of the plug. This method is a bit more time consuming and demanding than using the above method, but has the advantage of fully removing the culprit locking ring. The disadvantage of this method is the need for a bench vice and hack saw, and the potential for doing damage to the underlying jack if the hack saw cuts are done carelessly. Needless to say this is the most invasive method of modifying the jack and would not be looked upon favorably by Sennheiser if the microphone developed problems.
  
  

  Figure: Locking ring mounted in bench vice and being cut with hack saw.	Figure: Completed locking ring removal after hack saw method.

  
  
  

3. Incompatibility with standard sound cards: Although the cause for this is often attributed to a lack of sufficient voltage being applied to the microphone, this is unlikely to be true and the true reason appears to be the non-standard wiring of the microphone and the reversal of the standard means of providing voltage to the microphone element. The bottom line is that the options are either 1) to use an adapter sold by Andrea which switches the polarity between the base and tip of the adapter, or 2) to use the microphone in conjunction with an external USB sound adapter, such as those sold by Andrea or VXI. The adapters are readily available, either directly from the manufacturers or through microphone dealers. Another advantage of using an external sound card such as this is avoiding electrical interference experienced by internal sound cards, particularly in laptop computers.

	Andrea USB Adapter

4. The "Echo" issue is one which we consider a non-issue. Although it has been said that the performance of the microphone can be improved by covering the small semicircular opening on the side of the microphone element (exposed by carefully removing the foam wind screen), we have yet to see evidence that this truly makes a difference. Try it if you like! The modification requires nothing more than removing the foam windscreen, covering the slit with some transparent tape and then returning the foam windscreen to its original position. See detailed instructions for this modification.

For details on modifying the Sennheiser ME 3 using any of the above methods, please view the following pages:

Using "the jig" to modify the Sennheiser ME3
Detailed instructions for modifying the Sennheiser ME3
Instructions for modifying the Sennheiser Mic Element