The Sennheiser Mic Modification:

The Sennheiser ME 3 microphone, unrivaled in it's accuracy and noise canceling ability when used with speech recognition software, is manufactured with a jack containing a threaded locking ring which is not compatible with standard 3.5 mm audio or microphone input jacks. As a result, in it's native state the microphone does not work reliably with the hardware typically used with speech recognition applications. Successful use of the Sennheiser ME 3 therefore requires either:

1. Use of an adapter to convert from the unique threaded connector to a standard 3.5 mm audio plug. This simple adapter is available for puchase on this site and costs about $10
2. A physical modification of the plug on the native microphone which either removes the threaded locking ring or pushes it sufficiently out of the way.

We share with you here two methods for modifying the Sennheiser ME 3 jack. Before considering modifying the Sennheiser M3 for speech recognition purposes, realize that making such modifications could lead to damage to the microphone and will, unquestionably, void any warranty on the microphone. If you decide to try the modifications described below, you are doing so with the knowledge that you alone are responsible for the result! It also essential that you have the minimal tools and skills required to accomplish the modification. Also keep in mind that an alternative to doing this modification is to construct or purchase the Sennheiser

If you don't mind paying an additional $40-$50 over the price of the ME 3 from an audio wholesaler, by all means purchase a pre-modified microphone from either emicrophone.com or KnowBrainer, along with the needed USB Pod. You'll spend a few more bucks but you'll get a microphone ready to use. Both of these venders are highly reliable and stand behind their products. Otherwise, strongly consider either modifying the microphone or using an adapter.

One additional note: in our experience this microphone does not work well (modified or not) when plugged directly into a computer sound card, apparently because it requires more voltage across the microphone element than provided by the usual sound card. It does however work superbly when used in conjunction with a USB sound card which accomplished the analog to digital conversion and plugs directly into your computer's USB port. If you decide to make this modification yourself, we would recommend that you purchase a an Andrea "USB Pod" from emicrophones or Knowbrainer.

The Problem: This microphone is designed to be used with a belt mounted wireless transmitter and contains a "locking ring" on the plug, designed to attach it firmly to the appropriate female end on the transmitter (see photo below). When plugged into computer mic input jack or USB pod, the locking ring prevents the male end from fully entering the female end and making a solid connection.

The two methods are designed either to move the ring out of the way (method 1) or to remove it altogether (method 2).

METHOD ONE: This is the simpler and undoubtedly safer method, but not quite as definitive.

1. The male end of the jack needs to be modified by pushing (forcefully) the "locking ring" out of the way (further into the base of the jack) and to allow adequate contact with the extension cable listed below.

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.

This can be done in several way, but my recommendation is to do it as follows:

Materials needed:

• wood or metal vise (or pair of vice-grip pliers)
• 1/4 or so socket from socket wrench set
• Hammer

Method:

• cover base of jack with some cloth or tape to prevent damage from either the vice or vice-grips.
• with tip of jack pointing upward, grip base of jack (the plastic portion) with vice, or vice grips, with moderate force to hold steady
• Place 1/4 inch socket over end of jack, allowing male plug to enter into the socket (ideally the plug should not extend beyond the end of the socket), with the lower end of the socket resting on the rotating locking ring.
• Tap the top of the socket several times (with increasing force if necessary) until the locking ring moves down and seats firmly against the black plastic base of the plug.

2. Temporarily (and carefully) remove the foam covering from the microphone element, identify the long, semicircular slit along the distal, rounded edge of the microphone, and carefully cover this slit with a piece of scotch or other tap. This modification is intended to lesson a reverberation or echo phenomenon. Personally, we haven't found this makes any difference, but some folks say it helps. You may want to try it both ways.

METHOD TWO (Removing the locking ring entirely) This is my preferred method although it is more difficult than "method one" and requires a bench vice and hacksaw.

1. The critical step in the modification using this method is using a hacksaw to make a series of diagonal cuts through only the locking ring (not into the meat of the jack within the ring) such that the ring is weakened and will easily break apart and therefore detach from the jack.

Materials needed:

• Metal bench vice
• Hacksaw
• Screwdriver

Method:

• Mount the microphone jack in a metal vice, grasping only the lower half of the locking ring itself with the jaws of the vice.
• Make a series of diagonal cuts through the locking ring with a hacksaw.
  
  • In order to do this without causing damage to the jack which the lock ring surrounds, I recommend that once you get the cut established you do the cutting with one hand and hold and rotate the jack by the black plastic base as you do the cutting. As soon as the blade penetrates the ring and touches the underlying jack, you will feel it with the hand rotating the jack. At this point your can alter the angle of your cut slightly, making the length of the penetrating area as long as you can without doing damage to the jack.
  • After each cut, remove the jack from the vice, rotate it slightly and re-tighten, making a diagonal cut through another area.
  • In my experience 3 or 4 cuts, generally evenly spaced along the circumference of the locking ring will do the trick.
    
• Break the locking ring free either by prying into the saw kerf with a screwdriver, or by squeezing the locking ring firmly within the vice. After sufficiently weakened by several hack saw cut, the ring with literally break apart, leaving the inner jack undisturbed. If you're having a hard time getting the ring to break off, it likely means you need to extend, deepen, or increase the number of cuts.

2. When doing the modification using method two, the jack fits very nicely into either a computer mic input jack or (preferably) the jack on your USB pod. As a result, it is not necessary to use the Radio Shack extension cord as described in method 1, unless you need the added length to reach your desktop.

3. As with "Method 1" you should carefully and temporarily remove the foam covering from the microphone element, identify the long, semicircular slit along the distal, rounded edge of the microphone, and carefully cover this slit with a piece of scotch or other tap. This modification is intended to lesson the likelihood of breathing and other locally generated sounds (other than your voice) from being recognized as words. Personally, I haven't found this makes any difference, but some folks say it helps. You may want to try it both ways.

Although it has been claimed that such a repair will allow the mic jack to penetrate too far into a USB pod or sound card (and thus do damage) as you can see from the photo above, the jack widens underneath the locking ring and absent the ring this widened area prevents excessive penetration into the female counterpart. I have never observed any tendency for an ME3 modified in this way to do such a thing.

One More Thing to Know: this microphone does not work well (modified or not) when plugged directly into a computer sound card, because of a non-standard wiring arrangment. It does however work superbly when used in conjunction with an Andrea USB sound adapter which accomplishes the analog to digital conversion and plugs directly into your computer's USB port. If you plan to use a Sennheiser ME3, either modified or with an adapter, we would recommend that you purchase an Andrea USB Sound Adapter found in our accessories area of this site.