Adding subwoofer to Full-Ragne Speakers question

I'm no EE, but I'm gotten different answers to this. There are a number of different factors at work.
1. The bass waveform places a significant demand on your amplifier. If you use a powered sub and cut off the low bass with some kind of crossover, then the main amp does not have the same demands placed on it and has more current reserve available.
2. Reproducing low bass can also place a significant demand on the main woofer. If it does not have to go as low, there is a good likelihood that there will be less distortion in the bandwidth it is producing.
3. Most (but not all) full range speakers cannot produce the bass in the lowest octave at the same volume. In other words, they roll-off the lowest frequency. Or another way to look at is "how low can they go". A good subwoofer can usually provide useful, undistorted output down to 20 hz; few "full range" speakers go that low.

I'm sure there are others with more technical know-how, but that's my understanding.

i added a pair of 2wq subs to my 3a sigs and it really cleaned up the mid/upper bass. mids and highs also improved. the setup utilizes a 6db/octave highpass filter which is sampled then boosted by the sub. whether the improvement is due to less strain on the 3a's woofer or increased amplifier headroom, i'm not sure. probably both. but the systems performance did improve noticably.

aloha keith

Swampwalker gave a good answer. In addition to the amp issues he explained, I believe his #2 comments have to do with the main bass driver not trying to move as much air if the LF is cut off. Therefore, the excursion of the bass driver will be less and the inherent distortion will be less when that driver is trying to also reproduce lower mids and upper low frequencies (above your cut off). However, like most things audiophile, there are trade-offs, which in this case include very careful matching of the sub with your main speakers, meaning the actual type of sub speaker(e.g., size/ported/sealed/servo-type/power, etc.), as well as the phase, crossover level, and boost/volume. You have to be careful because many/most subs are actually designed for the loud impact of HT, and not particularly for music. Your success will also depend on where your LF driver is crossed over. If it acts mainly as a subwoofer already, e.g. crossed over under about 150 Hz, or has its own internal amp, then your benefit may only be the adding of the very low bass below what your main speakers can do. However, if your LF driver is crossed over high, up into the midbass range, then you start to get the other benefits discussed by swampwalker. Many folks with high quality full range or almost full range speakers (that go down into the mid 30's to 20's) believe their speakers sound better without the issues associated with trying to integrate a sub. Then there is the type of music you listen to, your room size and characteristics, WAF, and on, and on, and on....Good luck.

I agree with Mitch. At present I am using a Loft active crossover in my signal path. I did this more from for as amplification relief for my tube amps as Swampwalker outlined in his first comments. The other reason I experimented with this was the fact that what money I had invested in it initially, I knew I could recover if the experiment did not yield the results I wanted. I actually would have made a profit since some one offered me his present crossover + the $400 I paid for mine and a second person offered me $700. As for the Adcom I got on E-Bay to run the lows I would more or less broke even if I decided to sell. External active crossover use is pretty rare and many will argue that an added component with an added interconnect in the signal path may produce more ailments that outweigh the symptoms that are cured. So if you are willing to invest the time in trying which may be considerable since you can experiment with different crossover points and if the crossover has a gain control (My Loft does)it will only add to the possibilities. Remember if you decide to try this and once you have it tuned to your liking, pull it out and see if you are still happy without it. When I pulled mine out my music lost some of the dynamics and lower midrange clarity. I did get tiny, tiny bit of smoothness on the upper highs on some recordings so I basically choose my poison.

Good Luck James