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Extension or ELSE!!!

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  • Extension or ELSE!!!

    When I am designing a speaker, I rarely put bass extension at the top of the list, or anywhere near it for that matter. I am a believer in subwoofers to fill in the bottom end and tame the room effects. I used to look at ways to maximize bass extension, then I heard my first multiple in-room subwoofer system and I no longer really contemplate it beyond "Will it be flat to 80 or 90 Hz or not?".

    I have noticed a lot of designers tend to talk about bass extension of a certain driver in a certain application. I am not convinced that a driver should ever be discounted because it will "only hit 90 Hz in a vented application, you should go with <insert other driver here>". What plays through my mind most these days is Mr. Hoffman's eloquent axiom and after tinkering the last few weeks with a driver boasting 84db sensitivity, it has taken on keen new meaning... A bookshelf with 78-80 db sensitivity after full BSC has been applied is not a really good bargain when you look at amplification required to drive it to "loud" levels.

    I am seeing a lot of people offering designs anchored by 3" and 4" drivers and while it is pretty neat to see a small woofer like that hit 40 Hz, you have to wonder if the volume dedicated to that wouldn't be better put to use housing a nicer 5" midbass with higher sensitivity and let a subwoofer do the grunt work. Unfortunately, many designers and contributors will take the route of dedicating 0.2 or 0.3 cubic feet of real estate for a single small driver in a vented alignment in order to milk out every last Hz, and IMHO are doing themselves a disservice by doing so. A sealed alignment in the same space housing a 5" midbass will, in all likelihood, still extend low enough to cross comfortably over to a subwoofer and the entire system will benefit as a result. We often talk about using drivers within their comfort zone - how comfortable is a 4" driver playing 40 Hz, even with some extra Xmax like the ND series?

    Almost every design I have done in the last year or so has been a sealed system, with an F3 anywhere from 80 to 150 Hz. Depending on target application, yes I will go as high as 150 Hz and still consider a design to be adequate. When you place a little subwoofer under the desk, 150Hz is actually quite a happy place for a little driver to be. My Driscoll are actually the exception to the rule, since they prefer a small vented cabinet, which yields an F3 in the mid 60 Hz range. Sealed just didn't quite dig as deep as I wanted for my application. I could have done an even bigger cabinet and gotten into the upper 40's - but at some point you should begin to question of the real estate would be better suited to something else. They are 0.3 cubic feet or so right now and are pushing the limit for a desktop speaker.

    What is everyones thoughts on the obsession with pushing small drivers to lower and lower extensions? I heard the nano neps a Iowa last year, and while I thought there were some crossover issues (self imposed budget limitations from Chris - I do the same thing ), the bass response just wasn't... right. The cones were definitely moving some air, but they mirrored my own experiments with milking a small driver. Relatively largish enclosure with a bass response that was somewhat artificial. The driver set in the nano neos is capable of quite a bit more and I think Chris' revised crossover will go a long ways to bringing them out.

    My own experimentation with small drivers was the TB 4" subwoofer sold by PE a while back. Compared to even its 5" brother (in my HTiB subwoofer project) it came up pretty short. Maybe it is the lack of tactile feedback from the smaller cone, or maybe it is increasing distortion but even the modest increase in swept volume going from 4" to 5" is a marked increase in subjective realism of the bass. No replacement for displacement.

    My own Driscoll suffer in the bass department, but that is primarily by design. I have a lovely 10" subwoofer to take care of the heavy breathing. I do not plan to design any "full range" speakers in the future. I think there are more important areas to dedicate the real estate, the build time and the increased cost - such as saving for an amp, driver and enclosure to build a dedicated bass pump.


    I am a basshead from my car audio days, and that taught me the value of taking the burden off of the midbass drivers. That is all.
    Don't listen to me - I have not sold any $150,000 speakers.

  • #2
    Re: Extension or ELSE!!!


    I have similar feelings about tweeter application - what's with the need to drive a tweeter down to 1600 if the mid is perfectly capable up to 2500 or beyond? Why not just cut the difference and be very happy knowing that at 1900 or 2K your tweeter is WELL within its comfort zone?


    • #3
      Re: Extension or ELSE!!!

      No matter how big or small the driver, it's all about displacement. It is why the ND105 does well in a TINY box for a 4" (20mm x-lim of corse), but a tweeter at the end of a long enough pipe and it will resonate at 20Hz... It is funny when somone boasts amazing bass from a 3" and it is in 2ft3!

      Everyone wants to be the first to have a 4" play to 20Hz, and everyone wants to be the first to produce impacting, room filling bass from an even smaller driver. It is just not possible. To get rich, deep sonics is.

      Its all about expectations. I love a 4" bookshelf that extends to 60Hz well. It has its own unique sound. I also love a 10" extending to 30. One is not better than the other, just different.

      This can lead down the road of "variance from the orignal signal", blah blah blah, but at the end of the day, as long as the builder/designer is happy, who the **** cares?

      edit: Furthermore, extending the heck out of the bass just ruins its transient impact and makes everything sound like a fart...


      • #4
        Re: Extension or ELSE!!!

        Agreed...I get tired of reading posts where someone is trying to get a 6-7" driver to reproduce "room-shaking bass" below 40Hz or so.

        Since most of the music is from 50Hz on up, what's the point??:rolleyes:


        • #5
          Re: Extension or ELSE!!!

          While I totally agree with Johnny's assessment, I do think it may be room dependent. I have a small 10 X 12 room that I use for a mini man cave with 2 channel only. I built Jim Griffin's Aurasound MLTL-MTM with the small drivers because not only did I not want to give up the real estate, with a real 45 watts from an old NAD, they give me all the bass I need in that small of a room.
          Audiophiles listen to the equipment, not the music.


          • #6
            Re: Extension or ELSE!!!

            You make some good points Johnny, but you have to admit, it's a lot of fun to stand in front of a 4" 2-way and hear some serious full-range sound. And they are really impressive when you show them to your friends.

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            • #7
              Re: Extension or ELSE!!!

              Small speakers just plain suck . . . ;)
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              • #8
                Re: Extension or ELSE!!!

                Small speakers just plain suck . . . ;)
                Of course you say that tongue in cheek, but I do kinda agree. Proper scale is very important in reproducing a convincing image, and small speakers just can't do it ... they sound, small. About the only way to get a realisticly sized image out of small drivers reproducing vocals is to run them open baffle.

                You're totally right about trying to wring bass out of small drivers. Sure the simulation may show F3 down to 45hz, but the end result is unsatisfying. So you're right, why bother when subs can be made so cheap.
                Vapor Audio


                • #9
                  Re: Extension or ELSE!!!

                  There are more applications for small or even tiny speakers than there are of mains. Likewise, there are applications for speakers that aren't suited to fitting a subwoofer. In those applications where you don't have room (or budget) for a sub, and the smaller the speakers the better, why not shoot for as good a bass extension as possible?

                  I don't really understand what the problem is. There is room for big speakers, little speakers, and everything in between isn't there? I like the idea of being able to choose between small speaker designs that offer either better sensitivity and performance when paired with a sub, or better full range performance when used alone. Both design philosophies have merits.


                  • #10
                    Re: Extension or ELSE!!!

                    In the bass department, there is no replacement for displacement. I've found that if you push small drivers to deliver the displacement - regardless of x-max, they suffer higher up relative to their performance in the mids if the low end is not forced to be there. There are probably lots of technical reasons that I can't articulate.

                    I agree Pete, they suck, in a relative sense..... just like a '96 2.0L turbo VW R GTI and a '68 396 cu L78 Chevelle. They'll both put out 375hp, get you to the speed limit, but the low displacement option just don't sound as good - whether pushed to the speed limit, or idling there.


                    • #11
                      Re: Extension or ELSE!!!

                      I can see both sides of the reasoning. Many designs try to really push Hoffmans law with smaller displacement. I believe what happens though is that some see the laws as hard and fast instead of scaling from one extreme to the other.

                      It also comes down I think to what is the intended use of the speaker. For music, I tend to shy away a bit from using a sub except for the lowest octaves and even then I rarely look at extension much below 30Hz or so. But even then I want the mains to be able to replicate down to at least 60Hz with proper volumes and not over taxing the mid quality. This setup generally sounds better to my ears keeps the sub from being easily localized.

                      When using a set for movies where there is more info added into the bass area, a sub is a must. But I still want the mains to handle as much info as they can reasonably. Whats reasonable? Matters of preference I suppose. The general consumer has been brainwashed into believing that a small speaker is capable of doing it all. When we look at cellsm computers, tvs and all of our other gadgets, they've gotten smaller, so why wouldn't a speaker fall into the same logic? We know here it doesn't, but try convincing your average consumer of that!


                      • #12
                        Re: Extension or ELSE!!!

                        If you are into the High efficiency speakers w/o caring too much about grabbing the lowest octaves give pro sound drivers a look. My latest center channel project is using a 8" Eminence Alpha-A pro sound driver. In a vented alignment I'm getting relatively high F3 (for an 8" vented) of 50hz in a 1.2cu ft cabinet . However the woofer is rated at 94db/w which gives good output even after BSC is applied.

                        Making a center channel that gets down below 50hz is ridiculous since most people use with a sub anyways. Come to think of it not much music really gets below 50hz unless you count the electronic "basshead" type stuff.


                        • #13
                          Re: Extension or ELSE!!!

                          For me, it's all about the intended application. I tend to be a fan of small, cheap speakers, but I also have a lot of opportunity to use them in situations where they make the most sense. A lot of my smaller speakers are set up flanking a TV in a bedroom, or to provide musical fill in a dining room. In some of these cases, SPL is not at all a concern, but I still like to have some bass, and often, I'd like to have it without the complexity or added cost of a subwoofer. I've got some of those ND-105s that I plan to utilize in a small 2-way for my dining room, which currently has a pair of tiny 2-ways that I built with some Vifa/JBL buyouts from 5-6 years ago and one of the small Dayton tweeters. The ND-105s will go much deeper, and will still get way louder than my wife will tolerate. Why would I bother going to a different woofer with less extension for the sake of higher sensitivity? It doesn't fit my needs in this case.


                          • #14
                            Re: Extension or ELSE!!!

                            Johnny, I agree with you 100% on "unforced" output. However, I don't have a sub, and really don't anticipate building one (or two). A comment that has come up from time to time from people who have extensively listened to TMs plus sub vs large TMW boxes is that large 3 ways seem to be integrated a bit better top to bottom. Comments, anyone?

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                            • #15
                              Re: Extension or ELSE!!!

                              I don't ever seem to get a sub to integrate as well as a real 3-way. For this reason, I really don't seem to ever gravitate toward subs for music listening if I can help it. I've got a sub to augment the natural rolloff of my main speakers in my living room, and I've got it so attenuated that usually I can't even tell if it's on or not.