OK I'm convinced, switched lex mc-1 to Outlaw (1 Viewer)

[John Tompkins]

Switched lex to ICBM for side bass enhance that is
A while back somebody had mentioned that you could use the icbm in a 4th order fashion by hooking up from one icbm output to another icbm input, thereby using two channels of the icbm (stacked) together.
In other words, you would run from pre out to the icbm input and then icbm output to another icbm input and out again, effectively giving you a 4th order bypass for each channel that has been doubled up. Is there anything to be gained by doing this ?

 

[Chris Zell]

John,

I think that was me that suggested cascading ICBM inputs. I have mentioned that in a couple of different posts in the last few weeks.

What do you have to gain? More flexibility in crossover types/slopes. ICBM has only 2nd order Butterworth HP, and 2nd or 6th order lowpass (the switch on the back). What if you want 4th order? Two cascaded second order Butterworths is by definition a 4th order (24 dB) Linkwitz Riley (LR) crossover. These are considered the best by a number of very respected designers (Kevin Voecks of Revel for one). I think 2nd order can be a little shallow, particularly if you are trying to relieve some monitors of the low bass. I have had great luck with 4th order LR crossovers, and use them as a first try whenever I am first setting up a new system, integrating a new component, or setting up in a new environment (either new room, or radically different speaker/sub placement).

When I get my 950, I will be setting the mains to bypass, and the main outs will go to cascaded ICBM inputs to achieve 4th order LR high pass. I'll also be sending a full range split mains signal directly to the sub and use it's integral crossover for low pass. Almost always I achieve better results when I can vary the HP and LP crossover frequency independently (rather than being tied to both being at exactly the same point). As an example, a while back I set up an SVS 16-46 with Revel M20 mains with the HP set at 80 Hz, the LP at about 70 Hz. The LP level was slightly elevated (house curve), and the frequency gap blended the level smoothly between the two. Sounded great.

I have also heard this technique work very well with Paradigm Studio 100s, Revel Studios and various Snells integrated with Paradigm Servo 15, Bag End, Sunfire and Stryke subs. When setting up a system, the more flexibility the better!!!

Cheers,

Chris

 

[John Tompkins]

Thanks Chris,

That does seem to make perfect sense. I will give this a try when I set the icbm up as I would only be using two channels anyway, so I have nothing to lose by cascading 4 channels other then it takes two more cables.