HZ.....How low for full range music???

electric bass goes down to 41 hz. organ can go down into the 20's. it depends what you listen to. blues , rock, jazz and most music are happy with 40 hz performance. pro sound PA and bass gear is built to go down to 40 hz, so other than organ and home theater we don't get to hear much music below 40 hz, live or recorded.

I feel that 30hz and below could safely be called full range...not a lot going on down this low but still low enough to give the heft that full range has over speakers that can't go below 35hz or so.

Bass slam never takes place at these low freq's...I would say 35-40hz limited speakers will provide plenty of slam if thats what you are after. At around 30hz things like room-shudder (thats what I call it anyway) can set in...this can be very pleasing if your room is built well enough to have also achieved room-lock and of course is part of the music (new age comes to mind).

Dave

The lowest fundamental tone a string bass plays is at 41hz per second.

The treatment of overtones is not relevant to your question but remember the difference tones. A difference tone could be called an "undertone". A fundadmental of 41 will generate a difference tone of 20.5,which will generate a difference tone of 10.25 and so forth. These later tones are felt as much as heard and are responsible for the visceral ambience in a live performace that is(for me) outrageously expensive to recreate.

A poster above mentions an elaborate array of subwoofers and based upon the quality of his posts,I believe he has recreated that ambience.

I'm not a subwoofer guy(which is my problem,of course) and am happy if enough of the fundamentalsin the forties and fifties are present to represent the harmonies involved.

Hope your friend finds speakers he likes.

One issue that never gets mentioned is the SPL (loudness) at which the LF extension is measured. At very low volume I can get close to 20 Hz with some small Dynaudio speakers which I have. But, as you turn the volume up, the bass volume stays the same, so that at normal listening level the 20 Hz capability is for all practical purposes, zero.

IMHO, frequency response should be spec'd at some SPL. Perhaps the same level used for the sensitivity spec.

You may want to conduct a simple test. Go to an audio salon, and listen to whichever speakers you like, both with and without a subwoofer. You may notice quite a discernable difference when the subwoofer plays.
I heard a REL subwoofer in such a demonstration, and was amazed at how much "fuller" even quiet passages with vocals sounded with the sub!
I also owned Maggie 1.6's for a while, and was content with their bass, for a while. However, after adding a Vandersteen sub, found that it improved the entire listening experience dramatically. It's strange, but having those lower frequencies seems to take some of the edge off the highs...
It was recommended to me by an owner of a high end audio store that I should run a pair of subs, since there's plenty of low freq. information sent to each channel. I ended up buying his own pair of Vandersteen 2W subs. It's true, especially if listinging to such music as smooth jazz, synthesized, etc., two subs do make a stereo image of the low end. With one sub, you hear the boom, with two, you hear which side the boom is coming from!
Now I'm running tiwn pairs of Eminent Technology LFT-8a's with tiwn Vandersteen subs. That's a total of 10 eight inch drivers for bass. It's incredible! Powerful, precise bass, without distortion. It doesn't have to play loud to sound authoritative.
Once you familiarize yourself with good, clean lower frequencies, you'll know when you're missing it listening to other speakers/systems.
Two times I have tried monitors with subs, and both times I went back to floor standing full range speakers. If you want good bass representation in your system, do full range floor standers, and subs. But as previous posters have said, better quality with a couple less hz than boomy boxes with distortion.
You may want to read reviews of speakers on audioreview.com

Some good affordable speakers I have used with clean bass are Vandersteens, Magnepans, Eminent Technology (I switched from Vandys, to Maggies to Eminents).
For economy you can even go with a setup like a pair of Wharfedale Diamond 8.3's coupled with a sub. I had a pair of them in my system and was amazed how good they sounded for an economical speaker. Great bass. Biwire them or biamp them and you'll have nice sound. It's all how many $ you want to throw at the issue.