35Hz - 25kHz -- A Partial 'Purist'?

the sub i'm looking for HAS TO offer a seemless intergrated sound...if i "hear " the sub while listening to the music i don't want it in my system...i'll do without...howevere the brand new sub line from FOCAL the 11WX 13WX 15WX seems to be the one up to the job..i'll use my out on my JADIS to drive a sub amp, any suggestions on superior sub amps? as well should i go single 13 , 15 or dual 11's?

Tweekerman, If you've got to do it, then use a sub that has a driver with a very low Fs(resonant frequency). Usually the larger size drivers. Large phase shifts appear around the Fs, and can extend into the listening range. Fs should be about 15Hz or lower if possible. Then, actively cross out the sub as low as possible to avoid contamination of the lower mids/upper bass. If you have a closed box main speaker,the lows will roll off at about 12db/octave below the Fs of your woofer. If you have a vented enclosure, the lows will roll off rather steeply at 24db/octave. Allow the mains to roll of naturally with no cross out. Set your sub crossover point to 1 octave below the mains Fs and use a 12db slope on the sub crossover if you have sealed box mains. If you have vented mains, set the crossover point at 1/2 octave below the Fs of the PORT, and use a 24db/octave slope on the sub crossover. By matching the rolloff points at these points, the slopes will intersect halfway beween, and the additive effects of the two rolloffs intersecting will give a theoretically smooth transition. This is just a starting point and may require adjustment if you hear a hole or a peak. If you don't know the Fs, then use the 3db down point of your mains' response curve as a guide.

What happens techinically if you add a sub? And also, what is the proper way to add a sub? If I plug in the powered sub to a "regular out" on the pre-amp, does the signal somehow only send the lower frequencies to the sub, thereby reducing the "load" on the main speakers woofers?, or is the "signal strength" going out of the pre-amp to both the main amp and the sub-woofer relatively the same strength?

The situation you describe would send the same frequencies or signal strength to sub as to your mains.

In my case, my pre has RCA and XLR outs. I use XLR outs to the amp and RCA outs to the sub. The filters in sub filter out the frequencies you've desired not to have the sub reproduce.

Rwwear, your comments regarding "bass speed" are WAY off in left field.

What is typically referred to as "fast bass" is a low frequency system that suffers from minimal overhang, ringing and has excellent transient response on the whole. To achieve such, most designers typically resort to a sealed design with a Q of between .5 and .7 at the highest. Some have had very good luck with specific driver and TL combinations i.e. the Kef B139.

All of those designs tend to sound somewhat "dry" or "tight and lean" compared to other designs that have similar frequency response curves. This is due to the lack of "bloat" or "ringing" that they AREN'T introducing.

The effect that many people consider "good bass" or "meaty bottom end" is similar to what an electric guitar player looks for in his sound. This is called "sustain", which is a form of ringing distortion. It helps to fill the sound out somewhat by carrying on longer than it would naturally and / or by adding IMD ( intermodulation distortion ). Needless to say, it might sound good but it is not an "accurate" portrayal of what was recorded. The speakers contribute their signature to every recording uniformly. As such, that is a distortion or "coloration" of what one should hear.

Think of "bass weigth" and "bass speed" this way. Try looking at a physically fit, muscular atheletic person and a "slob" that are the same height and weigh the same. One carries themselves much better and efficiently but end up weighing the same in terms of "measurements" that most people can relate to. Not only that, one has a very different presentation than the other. This is true even though they look the same on paper.

I do agree that many times, people confuse lack of extension or "bass weight" for "fast bass". That is primarily just a lack of experience and something that can be corrected with time if they continue on their path to "audio nirvana". Sean
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