Discrete Comb

The Discrete Comb is the invention of Winslow Yerxa.  It is essentially a thick comb (about 50% thicker than a normal comb) with a partition in each chamber to isolate the blow and draw reeds into discrete cells.  Discrete combs are available for the Hohner MS (Modular Series) harps and for Lee Oskars.  Prices are $25 for MS compatible combs and $35 for Lee Oskar compatible combs, plus $5 shipping and handling.  To order one, write cheques (must be drawn on a U.S. Bank) to Harmonica Information Press and mail to:

Discrete Comb
203 14th Avenue
San Francisco CA 94118-1007
By the way, standard disclaimers apply here.. I have no financial or other interest in HIP or the Discrete Comb.  It's a great invention, full of possibilities, and I just want to help inform everyone of its existance and capabilities.

By covering both the upper and lower cells with the embouchure at the same time, a harp built on the discrete comb responds like a normal diatonic harp with the normal 2-reed bends.  But, by tilting the harp a little up or down you can select a discrete chamber containing either a blow or a draw reed.  By isolating reeds in this fashion, any reed can be played as a closing reed or an opening reed.

What this means is that

The overblows and overdraws are much easier to produce than on a normal comb, and are more stable.  Overbends can be bent in pitch and vibrato applied when played on the discrete comb.  These effects can be achieved on a very well set up normal harp, but they are more difficult to get.  No gap adjustment is needed to get overbends on the discrete comb, though adjustments can help optimize the response based on your own style.

Normally, valves are used to isolate the blow reeds to allow single reed closing bends--and valves prevent overblows. The discrete comb allows both overblows and single reed closing bends.

The downside of the discrete comb is its thickness.  The thicker comb is less comfortable to play, for me anyway, than a normal harp.  The added thickness means you have to be more accurate with your embouchure to get clean single notes, since a more wide open lip/mouth position tends to let in more of the adjacent holes.  However, these drawbacks are most likely due to limited playing experience with the discrete comb.  The more you play on a discrete comb the more comfortable you are likely to get with its size and playing characteristics.  You'll have to determine for yourself if the numerous benefits are worth the drawbacks.