I've worked with them on two occasions. Bear in mind that Jeff was more or less replicating a classic design, not starting from scratch with a design that he considered optimized in an absolute sense. They sound very different from most of the Salk speakers, and quite different from another Jeff Bagby design I recently worked with, which used SB acoustic drivers. The Continuum has considerably less baffle step compensation (being true to the original BBC design). I found that a problem on heavily orchestrated material, but not on simple vocals and small jazz. BTW, I also had a Diamond in hand for a couple of weeks. There were many renditions of this design, and I'm not sure which one I had. But I do have to say that this particular Diamond wasn't my idea of an accurate speaker. Perhaps you had a more recent variation, or it's also possible that we have different tastes when it comes to midrange presentation. A lot of my listening is to symphonic classical material.
Dennis,
I’d like to make a couple of comments.
Although it appears like the Continuum doesn’t have enough baffle step compensation implemented in its response, it actually uses a 3mH inductor in the crossover that yields 8dB of compensation (enough to handle the step and the 2dB baffle diffraction peak above the step). The dip that you see in the response that is centered around 350Hz is intentional and part of the design of the LS3/5a loudspeaker, and you will see it in all versions of that speaker. It was designed this way by the BBC engineers to remove any thickness or muddiness from vocals that could come from full baffle step compensation and boundary reinforcement when placed near a boundary like a table-top or near a wall. The benefit of this approach is not just a reduction in artificial thickness in the lower vocal range but an apparent improved extension in the bass range as well. As you noted already, the little speakers put out much more bass response than you would expect them to.
I must say, that I still love my set and in their near-wall placement measure very flat, with a very even polar response due to the lower in-phase crossover point. I would argue that their in-room response when used as designed is very flat and accurate. On the other hand, well out away from the wall it is possible that the lower mids may sometimes sound thin, but I don’t seem to notice much change. That being said, they were selected as the best small speaker at two different audio gatherings I took them to against quite few contenders. So the consensus on them was very positive. In fact, one of the people present, after hearing the Continuum, commissioned the SB Acoustics kits you made reference to.
The second comment is that I’m not sure if you have really heard this speaker yet or not. I know you listened to, and measured the pair Del built. Only his were not true Continuums as the woofer was front mounted with a different offset and changes in the crossover – changes I have never actually heard. When I saw the measurements you took of his speakers I noticed that something didn’t look right. It appeared that the entire tweeter level was elevated about 2dB above my reference response for my pair. Jim sent me the response plot he took of a pair he built and it matched my plot very well with a much flatter balance. After discussing this with Del, I figured out what happened and the crossover was redone to produce a response that had a better balance. I am sure with the 2dB elevation in the tweeter level combined with the dip at 350Hz, mounted on stand away from the walls, the speaker probably did sound bright. You mentioned the SB Acoustics design I did, in my listening room that speaker and the Continuum sound much more alike than different, just as a reference.
I believe if the original poster is looking for a small speaker for a bedroom that will be near the wall or sitting on a desk or table then he will find these to be very clean and balanced with remarkable bass for such a small speaker.
Jeff
