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My Gallo's should be here soon and I know I want the Bass to perform down to 25k
The superimposed in-line low-pass filter is an FMod by Harrison Laboratory and spec'd as 50Hz @ 12dB/octave. Gracias to Kalman Rubinson of Stereophile for sharing the Crutchfield connection from whence I purchased this little $29 gizmo. I'd experiment with bi-amping the side-firing woofers' second voice coils...Dedicating two eVo 4 GenII channels to the Gallos' regular full-range inputs as you would any ordinary speaker, the two others were preceded by the 50Hz networks to power the woofers directly in parallel. While I was ready to take notes, I was not entirely prepared for what was to follow. In a nutshell, 'unassisted' and despite their brute appearance, these woofers began their roll-off around 40Hz. Some of this is clearly a slightly variable function of boundary reinforcement which was sorely lacking in my case. It will enter the picture in a regular, fully enclosed room of more common dimensions. However, with the twin-drive scheme in my unusually open environment, the drivers' roll-off was distinctly retarded. Response now extended fully audible to a shockingly taut 25Hz. How do I know? Look at the Avantgarde woofers above. Ask me how I wouldn't know!...However, when I bi-amped the Gallos for 'active woofer drive', the only thing missing vis-a-vis the German monster subs was raw air displacement. That's no surprise. Any child would see that four sealed woofers driven from 250-watt dedicated high-current amps couldn't help but move more air. The Gallos also lacked the last word in infrasonic shudder on certain synth pedals of Trance/Ambient fare. However, the word 'lack' in this context is really a very feeble $2,500 joke. For all sane intents and purposes, the bi-amped Reference III is a bona fide full-range speaker that reaches to 25Hz in honest fashion. For obvious reasons, I cannot comment on the relative need for bi-amp augmentation in spaces smaller than my own. What I can stress unequivocally is to not use a higher low-pass filter value. You merely want to augment the woofers from the point at which they begin their natural roll-off. The next filter value in the FMod line is 70Hz. This will likely be a little higher than ideal and cause minor midbass fattening. That could be great shakes for movies -- and indeed was the case with the 80Hz THX-style sub-out from my modest T 751 NAD home-theater receiver -- but is far less desirable for linear 2-channel music with the greatest possible transparency.
