Hello all,
I had a fairly long conversation with Danny regarding the differences between these two designs. If y'all recall, I had written a short review of the OB-5's that I heard in Toronto with Denny's setup. I was mighty impressed, but unfortunately I can't afford the OB-5 nor the new OB-7s at this time. In addition, I would probably need a larger room. What follows below is a short summary of the differences between the O-3 and OB2X's whose crossovers are both designed by Danny. For the record, the OB2X original design is Al Wooley's of RAW acoustics.
The O-3's are an excellent overall ported 3 way omnidirectional speaker design. The drivers used in the O-3's include a pair of M-130's and the BG planar magnetic tweeter. Danny said that at the audiofest, they were difficult to discern from the larger OB-7's except in larger rooms and with louder music such as heavy metal or large orchestral pieces. In addition they employ the BG planar magnetic tweeter which have a very quick transient response and can convey the leading edge of a cymbal quite well. The speaker would be best used with a subwoofer, but it has an advantage over Danny's other designs in that the low end can be tailored to the room by altering the capacitor stack. They image a lot like the OB-5 and OB-7's which is not surprising given that the off axis responses are very smooth and similar. In other words, the O-3's carry on the advantages of an MTM design like the OB-5's and OB-7's but at a much lower cost but with lower overall acoustic output. When you stand up and walk around the room , you don't notice any dropped frequencies like you would with a regular MT. The O-3's require plenty of room around them to play well, about 3 feet all around. This can be a pitfall in some rooms.
The OB2X's are an open baffle MT ported 3 way design. They employ the higher end M-130X drivers which apply an improved XBL2 magnet structure and phenomenal X max. In addition, they use Al's custom Aurum Cantus tweeter. This ribbon tweeter is different from the BG planar magnetic in that it doesn't emphasize the leading edge of a cymbal, but more the trailing edge of a cymbal. Different strokes for different folks. It's hard to make this tweeter to sound strident or hard. In addition, it requires a little more care in crossing over as it has slightly higher distortion below 2K. This isn't really much of an issue for Danny as he tries to utilize each driver in an optimum frequency area in order to optimize the off axis response and cross the drivers while they are still in *piston*. The distortion profile of the M-130X drivers is quite a bit lower than the M-130. Danny said that one M-130X was equivalent to a pair of M-130's. This pretty much means that the midrange clarity of this speaker design should rival the OB-5's and OB-7's. The vertical off axis response of the OB2X is not as smooth as the O-3 or OB-5/7 designs. However,the OB2X can be placed closer to the side walls of a given room compared to the O-3. This can be very advantageous in smaller rooms. But, if you want to do the get up and walk around test, you will notice that the OB2X is an MT design while the O-3 is omnidirectional (great vertical and horizontal off axis response). This may or may not matter to you. Again, different strokes for different folks. The midbass of the OB2X's should also have greater clarity than the O-3 due to the M130X driver. This speaker is easily crossed over to a subwoofer. The OB2X should be able to handle greater amplifier power than the O-3's due to the XBL2 magnet structure. This should be okay as long as you don't fry the Aurum Cantus ribbon!
I hope this helps some of you who may be in the same/similar quandary as I am. If I was just a little richer, I would build the new OB-7's no doubt. In the meantime, it looks like the OB2X is the winner for me, although you can't go wrong with either design.
Best,
Anand.
