Limiting a full range driver

Hi Koestner. You are right on the money. The level of distortion and volume limitation low bass causes in full range drivers is unacceptable. It is the single most significant thing you can do. Room control is important but it will do you no good if your system is volume limited and distorting. I have made this AB comparison for other people many times. I use full range ESLs. By themselves they are big polite loudspeakers, good at Jazz and classical. Crossing to subwoofers at 100 Hz is like putting a turbocharger in a 911. Hold on to your hat.

There are several obstacles, finding a decent subwoofer and a good active crossover. For subs I suggest the Martin Logan Balanced force series and the KEF KC 92 also a balanced force subwoofer. This is an extremely important design feature, it helps to limit distortion by keeping the enclosure from shaking. 

The best crossovers are digital. However, now you need four DAC channels instead of two. The inexpensive MiniDSP is a fine crossover, but the DACs are not so hot. The MiniDSP SHD Studio gives you a fine crossover and room control and you use your own DACs. Benchmark Media Systems uses this set up with their own DACs. That is a $6000 bill. Preamps such as the DEQX Pre 4, the Trinnov Amethyst and the Anthem STR have everything built in. The STR is under $4000.

I have no doubt that if you do this right you will be THRILLED with the results. Don't punt, take a full swing or you will just waste money. If you want to discuss this more please message me.

I still don’t  understand why a single driver to handle all of the frequencies would be a desirable thing given the potential problems that arise. Is the lack of a cross over the only reason? It seems like a well built 3 way would be the way to go. 
 

Happy listening all! 

Interesting speakers.

Dual 8’s are the equivilant of an (approximate) single 11" woofer. That’s a fair amount of "meat" and should produce a reasonable amount of bass at moderate levels without getting too "weird" in the midrange. Having dual motors and smaller cones (dual 8" vs 11") gives you advantages in control and resolution. I think this is a valid design that should yield very good sonic results. (Some reviewers agree). I’d make sure your vertical listening position height (ears) are dead on with the tweeter location. Otherwise, the "point source" benefit of the speaker will be compromised

To high pass, or not to high pass, may be a product of experimentation. There’s credible sub manufacturers out there that INSIST that you run the mains full range. I’ve experimented with this a bit, and can’t disagree with their recommendations. I think it’s speaker dependent, and volume dependent. And, yes, room dependent.

Before you start throwing money at fancy crossover schemes, you might want to just toss a quality sub (or, two, or three...) in the room and see/hear what happens. You may also find that the additional sound pressure created in the room by the powered sub(s) negates, to some degree, the need to put the pedal to the metal on the volume control, which will reduce some stress on the mains, thus cleaning up everything.

Nice speakers by the way. Well done.

Thank you for the recent posts, but deeper in this thread I did say that I am using subs. They are Velodyne DD15's that both broke (electronics problems) so I ran drivers to banana plugs that I installed on the plate amps. Now I use a stereo Crown Class D amp to power them. The amp is about 750 WPC into 4 Ohm in each channel. The amp has a built in low pass that I have set at 24 db/oct. and at 74 Hz.

"but deeper in this thread I did say that I am using subs."

Yep, there it is.  Got me.