Low freq. from small drivers? Is it possible

Thanks for your very up-front response Karl. As fine of a speaker as you have been able to produce, your comments varify what i and several others have stated. That is, obtaining extreme low bass out of a smaller driver comes at the expense of some other area of operation. I applaud your honesty and integrity, both in your responses here and in the design attributes of your product.

As a side note, neither Mr Dartford or myself were actually making an "apples to apples" comparison between your speaker and the 901's as much as we were discussing the various manners that technology can be applied and how it is actually used in various products.

I do have one question for you though. Have you ever tried running these actively crossed? I'm curious as to what your thoughts / experiences were in this regards IF you tried that.

Other than that, i do remember you posting positively about sealed box designs in the past and contributing some excellent information / comments in various threads. I knew that i always respected your opinions and now i know why. That is, we basically agree. At least on this specific issue : ) Sean
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Sean,

When you ask if I've tried them actively crossed over, I assume you mean to a sub on the low end. The answer is that I haven't. It is my opinion, having played with this stuff for a long time, that putting any crossover on the low side of the midrange drivers, anywhere but in the low bass, causes more problems than it solves. The transition from woofer to midrange is always audible.

Many people (and I would guess that you would be in this camp) would rather run subs with active crossovers on both high and low sides, primarily for the reason we have been discussing: limiting excursion in the midrange drivers. But there is another way that is superior, in my opinion.

First of all, I will state that a subwoofer should be crossed over as low as humanly possible, for all kinds of reasons. 100Hz is way too high, and 80Hz is pushing it. Given that this is the case (and I would be very surprised to hear anyone disagree with this, if they've had experience in this area and have good ears), then it makes far more sense to let the speaker itself provide the high-pass function. In the case of the UM, its natural rolloff is essentially equivalent to a 12 dB/octave Butterworth at just under 70 Hz. Of course, this only works with a sealed-box monitor, which is self-limiting in the deep bass, but of course that is exactly what I intended from the start.

This approach is exactly equivalent to an electrical solution, but with the advantage of no added electronics and their inevitable colorations. It allows perfect compatibility with the RELs and other similar subs which are designed for exactly this approach. In my experience, this is the only way of connecting a subwoofer that actually achieves the goals of making the transition sonically invisible and causing no sonic degradation to the main monitors.

Best Regards,
Karl Schuemann
AudioMachina

Karls...As sean said, noone is comparing your speaker's sound to that of a Bose 901. (How could I...never heard yours). But, there seem to be some similarities with the design concepts of the ORIGINAL 901. Did you ever hear original Bose 901's? Not to be ridiculed, especially for 35 years ago. That's why your effort to develop the technology is of interest to us old farts.

C'mon guys, I was kidding, honest. It just struck me as funny, given the status of 901's as the reigning poster child for how not to make a high fidelity speaker.

Best Regards,
Karl Schuemann
AudioMachina

Karl: I wasn't talking about supplementing the bottom end of your design with an actively crossed sub, but about using the existing design with an active crossover and bypassing the internal series crossover. I understand that you have several different circuits ( impedance compensation, notch filters, etc... ) that would have to remain.

I also have other questions about series crossovers for you, but that is neither here nor there : ) Sean
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