Low freq. from small drivers? Is it possible

Sean,
I haven't tried active crossovers, no. It's not really designed for this, because as you probably know, series crossovers only use one set of binding posts. There's no such thing as biamping. So there's only one set of posts on the speaker, and no way to easily add another one.

One of the interesting things about series crossovers is that they work like sh** unless you have everything, and I mean everything, exactly right. This means both drivers flat in frequency response, impedance, and phase, along with perfect time alignment. But once you accomplish this, it's simply a matter of punching the numbers on a calculator to get the correct values for C and L, and it will work perfectly every time. This was a revelation the first time it actually happened, but it makes perfect sense when you think about it. That, in a nutshell, is why almost everyone uses parallel crossovers. They're easy to "fudge" if you haven't done your homework. Not so with a series.

This is a long way of saying that the "other stuff" is by far the most important, not the primary C and L. And as such, there isn't much benefit to making them active. All the usual problems with passive crossovers, such as impedance and phase anomalies, have already been dealt with, and since it is only a two-way with a high crossover point, it can use small, high quality C and L, which effectively eliminates (or at least minimizes) the other argument for active crossovers.

Eldartford,
The marketing side of this project really hasn't started in earnest, but hopefully next year. So there are no dealers yet, but we do make demo systems available to people if they're interested enough to pay the shipping, and offer very good pricing on the demo systems if they decide to keep them.

Best Regards,
Karl Schuemann
AudioMachina

Karl: My experience with even very high grade "passive parts" placed smack dab between the amp and drivers is that they drastically reduce sound quality. One can use even a lower grade electronic crossover and get better results than if one used very simple passive crossovers of the highest quality. At least that's been my experience.

My Brother argued with me about this for quite some time. That is, until i gave him an old electronic crossover that i hadn't used in years and he tried it out. Pulling even a single cap from his tweeters made a HUGE difference in terms of sonics. Why one can get away with running a MUCH more complex circuit at line level without near as much sonic degradation is beyond me, but i'm guessing it has something to do with the current levels involved.

After studying the circuit lay-out of a series crossover, i've often wondered how much more "low frequency leakage" there is into the tweeter as compared to a standard 1st order "parallel" crossover? I've also wondered about the differences in power handling between the two. Have you ever compared the two with identical designs? Sean
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PS... Thanks again for your taking the time to clarify your comments and respond to further comments / questions.

Sean,

I'm aware of the advantages of actives, but again it becomes an issue of the overall design compromise. As few people would be interested in a $15k/pr monitor, only a tiny fraction of them would even take a glance if it required biamping. Besides, using really high quality parts makes a huge difference, and keeping it simple helps perhaps even more.

The tweeter power handling (from LF leakage) in a series crossover is a function of the DCR of the woofer inductor. The tweeter attenuation "shelves" at some point, and the lower the DCR, the lower that point is.

The power handling in our case isn't even close to being an issue. The inductor is small with very low DCR, the crossover point is fairly high, the tweeter is padded down, and on top of all that, the response is designed to fall like a brick below the tweeter resonance, which is more than two octaves below the crossover point. So in this particular case, it is more than bombproof. But that isn't always the case.

Best Regards,
Karl Schuemann
AudioMachina

Karls...In a SERIES crossover, a WOOFER inductor? You need to explain this.

El: Series crossovers consist of the opposite components one would use in a parallel crossover.

While "common" crossovers are called "parallel" designs, they really are closer to a series circuit by their very nature. Some newer speakers ( and old ones like Fried and Koss ) use what is called a "series" crossover, which is really like a parallel circuit. You can see a diagram of a basic "series" crossover here at Karl's website. The terminology is quite confusing and i can understand why this baffles people.

As a side note, i was doing a search and ran across Clement Perry's comments about Karl's speakers. You can read it by clicking on the link to Stereotimes CES coverage. Sean
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