Adding subwoofer to Full-Ragne Speakers question

I don't have any engineering or electrical background, but here's my experience:

I had Maggie 3.6's and a REL sub. I sold the Maggies and bought Aerial 9's. They are rated to 30hz, down 6 db at 27hz. They aren't at all bass shy.

I still had the REL....just hadn't gotten around to selling it. So, for kicks, I hooked it up with the Aerials. I ran the REL straight off the amp, driving the Aerials full range.

AND>>>>WOW. It made the whole system sound better, top to bottom. I found that I was setting the volume lower and the room was still pressurized. It seemed to me that the treble was clearer and the midrange more spacious.

I don't have a clue why this was the case, but I hooked it up and unhooked it, and I've done this with friends present, and they all agree. So don't look for my REL for sale any time soon.

Of course, YMMV.

Rich

Me no electrical engineer either, but think of it this way -- folks bi-amp speakers, right? And the point is both to increase the power to each individual set of drivers and to put correspondingly less demand on each amplifier in order (which is why folks presumably do it) to improve the sound. Depending on how, where in the signal path (and if) you've got a crossover dividing things up, the addition of a powered sub could work in exactly the same manner. As long as there is some sort of crossover in the chain before the signal gets to the speakers, the speakers should never see the low frequency demand (nor place the power requirement demand on the amp in order to reproduce it) as those low frequencies would be sent to the sub (with its own, private amplifier). The functional equivalent of bi-amping by proxy. Thing is, while they could be, I bet most subs simply aren't set up this way (which is only right an proper, when you're talking about a full range speaker in the first place). Rather, they are simply put on top of the existing setup: the amp and the speakers continue doing exactly what they were doing before the sub got there and the sub just provides "extra," instead of redistributing the signal, or power demands or responsibility for makeing certain sounds. Sure, this might make "everything" sound better for a whole number of reasons, real or imagined, I just have a lot more trouble coming up with a rational, electrical explanation for the improvement in the second scenario.

Take the speaker grill off, and play a record with lots of bass, best of all an LP with a bit of a warp, and watch the antics of the woofer cone. I think you will agree that it is a wonder that the poor woofer reproduces midrange at all.

Also, some folk think that the slightest movement of the speaker "blurs" the midrange, and they go to great expense to immobilize their speakers. Well, with the midrange emminating from a cone that moves back and forth 3/4 inch or more, what does that do to the midrange?

I think that the main reason to have a subwoofer is to get that LF which requires long cone excursions, out of the woofer. Oh, and it helps the HF power amp too.

I have two ways (w/12"PHL 4530 midbass drivers) plus stereo subs, and use a DEQX with both 2 and 3 way digital crossover ability. My initial plan was to implement a 3 way crossover to lessen the bottom end burden on my PHL midbasses (decrease intermodulation distortion). Philippe Lesage, head speaker designer of PHL, graciously answered an email inquiry on this topic with the following. He said, in essence, that the deleterious effects of a high pass filter on the midbasses outweighed the benefit of chopping off their low end duty, and that letting the midbasses naturally roll off while "dialing in" the subs to supplement the bottom octave was far preferable.

Another factor to consider is the low end capability of your 2 ways. My 2 ways are -3dB at 44 Hz and there is precious little musical content below this frequency in the music I listen to (example: the lowest electric bass note is still above 40 Hz). In truth, my stereo subs are a costly luxury, basically musical slackers for the vast majority of my listening with much potential to overly excite room modes and detract from enjoyment. "Dialing-in" is far from a simple task, even with stereo subs.

My 2 cents, to be taken ONLY for what it's worth, is to find two way loudspeakers that are capable of playing down to 40-50 Hz at adequate SPLs for your taste. It's all about choosing the best compromise among the imperfect solutions. A single full range point source reproducer exists only in theory. For me, no single driver stereo loudspeaker system will truly "rock" to the SPLs I like. I've never heard the big 2 way line array loudspeakers so can't comment. For me, 2 ways with large cone midbass drivers, actively biamped, provide the best combination of imaging, soundstaging, dynamics and SPL ability.

Just some grist for the mill - nothing more, nothing less.

Rbirke,

I don't know how many times I've heard other REL owners say the same thing as you, and that's why I intend to buy one myself to improve the already great sound I'm getting from my ProAc 2.5s.

I guess when a sub bass system is well designed and set up correctly it can yield improvements in the main speakers even if the sub is completely separate from it. The point you make about the REL pressurizing the room and being able to back off the volume to the mains may be the key.