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Can a closed box really sound good?

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  • Can a closed box really sound good?

    Just like the title say's, "Can a closed box really sound good?" I've built my fair share of speakers, a few of those being closed box designs. And, I have yet to hear a closed box that I like the sound of. They always seem to add some kind of a honky, resonating-like odd sound to the speakers that I just can't bring myself to like. I ask this because I'm getting ready to build another set of speakers to replace my current computer speakers. Which consist of a bi-amped pair w/ Dayton Audio nd91-4 and nd16fa-6. For the new speakers I'm going with the SB Acoustics SD15CAC30-8 and SB29RDC-C0000-4. I already have some curved cabinets that would work for a somewhat small .31cf ported box that I'd tune to 45Hz, but they are a bit big for a desk. I rather like the idea of a .22cf sealed box instead, but the SQ thing scares me. My goal is SQ since they will be bi-amped with the 4 LM3386's in the amp that I built, and crossed with my miniDSP 2x4HD. My main concern is the coloration of a closed box Vs the open and wide soundfield that ported boxes seem to offer. Bass is not an issue since I have a 15" Dayton Reference sub tuned to 32Hz in the corner of the room, but I would like some good power handling without the need to passively high-pass them. Preferably though, I'd rather not use a sub since I can't properly blend it with the rest of the system because it would be split off the low-pass outputs coming out of the miniDSP. So, would you honestly, after investing a considerable amount of money on the rest of the equipment go with a closed box or deal with a large ported box on the desk?

  • #2
    What has been your Qtc tuning?
    "Not a Speaker Designer - Not even on the Internet"
    “Pride is your greatest enemy, humility is your greatest friend.”
    "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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    • #3
      I suspect that your negative experiences with closed boxes has nothing to do with the fact that they were sealed vs ported. I would venture to say the issues that you attribute to closed boxes were more likely just poorly implemented designs overall.

      1. Did you have the chance to measure the "honky" closed boxes? Was the frequency response irregular with several peaks and dips? How good was the phase tracking between the drivers?
      2. Perhaps the crossovers were not optimized and had significant overlap in the midrange region, thus a more forward, honky tone.
      3. What type of internal damping/stuffing material was used (and how much was used) in those "bad" closed boxes to absorb the internal reflections?
      4. What frequencies are the "resonating-like odd sounds" at? Ported designs versus sealed will differ mostly in the low bass (20 Hz to 80 Hz range).
      5. Read a little bit about the differences in Q, transient response, low freq rolloff (12dB/octave VS 24dB/octave) and then give each type a fair chance. They can both be spectacular if properly designed.
      ~Marty

      Baby Eidolons
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      Cables (Post #54)
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      • #4
        Excellent responses, thanks guys. As far as I can remember right now, the only two closed boxes that I used WinISD to design were the Dayton Audio Designer Series 6.5" and a Hi-Vi B3N. There is a good chance that it was the drivers that were the problem since I ended up not caring for the sound of the 6.5" DS even in a ported box, and the Hi-Vi required way too many crossover parts to get rid of the peaks. I think I'll go ahead and build an unfinished sealed box and have a listen before I settle on a ported box. But still, if it were you, would you go ported or sealed with the 5" SB Acoustics and tweet? Is the trade-off of a sealed box that has more excursion, and therefor worse inter-modulation distortion, better than the effect a port has on phase-shift and group delay? Personal choice, sealed or ported?

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        • #5
          Personal choice, sealed or ported?
          Depends on the characteristics of the driver. Drivers with a low Qts are better suited for Reflex enclosures, drivers with higher Qts are better suited for Sealed enclosures.
          Also Efficiency Bandwidth Product (EBP):
          "This measurement is calculated by dividing Fs by Qes. The EBP figure is used in many enclosure design formulas to determine if a speaker is more suitable for a closed or vented design. An EBP close to 100 usually indicates a speaker that is best suited for a vented enclosure. On the contrary, an EBP closer to 50 usually indicates a speaker best suited for a closed box design. This is merely a starting point. Many well-designed systems have violated this rule of thumb! Qts should also be considered."
          "Not a Speaker Designer - Not even on the Internet"
          “Pride is your greatest enemy, humility is your greatest friend.”
          "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

          Comment


          • #6
            I prefer sealed designs. Mine are usually very low Q, with more stuffing than needed. I like a lot of stuffing. They work well with my room, so bass is deeper than the f3 would make you think. There are trade offs on spl and power handling though, but small ported speakers run out of output, and have over excursion issues below tuning. Try some of the box modeling programs, and look at the excursion at about 16 watts, then 32 watts. Be sure to look at excursion at 30hz, and lower. If it's more than x-max, the IM issues are not gone, at least with some music. If you were to compare a 6.5" to a 4", the difference is night and day.

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            • #7
              People seem to like Jeff Bagby's Continuum. Not saying it sounds good, just that people seem to like it. I've never heard it.

              Have you ever built a sealed speaker designed by someone else that is generally regarded as "good sounding", only to find it "honky'?

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              • #8
                Originally posted by djg View Post
                People seem to like Jeff Bagby's Continuum. Not saying it sounds good, just that people seem to like it. I've never heard it.

                Have you ever built a sealed speaker designed by someone else that is generally regarded as "good sounding", only to find it "honky'?
                Continuum sounds good but runs out of gas fast with bass heavy music. I do generally prefer sealed cabinets and with the continuums crossed over at 150-200 to a pair of sealed rss315hf woofers it sounds very good. I keep the q of my sealed systems at around the standard max flat q of .7 and dial in a little eq if I want extra punch. My brother likes a lot of bass so he runs sealed with a q around .9 for a little bump or general prefers ported systems tuned for a little boost in the 50-60hz range.

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                • #9
                  Wow, what an unusual post, since most often ported systems are reported as having weird resonances and such. Get better at designing and building closed (infinite baffle) enclosure systems, otherwise stick to bass reflex.

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                  • #10
                    The speakers that I'm using are listed in the original post. The woofers are suited to both sealed and ported enclosures equally. As far as modeling goes, I have modeled them using WinISD Pro Alpha. According to the simulation they will have less output at frequencies below about 80Hz than the 3" nd91-4's that I'm currently using. That's a trade-off that I'm none to thrilled to accept. However, I think I'm going to go ahead and try the sealed box first since I have plenty of subs sitting around the room (w6 tapped horn, Dayton reference 15", a bose sub I'd never consider using, and a transmission line and 1cf ported for another w6 I have).

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                    • #11
                      Originally posted by Drewdwn93 View Post
                      ... However, I think I'm going to go ahead and try the sealed box first since I have plenty of subs sitting around the room...
                      Good idea, save the excursion for the subs.
                      ( My subs, which are reflex, take over the bottom octaves, for the mid bass drivers, which are sealed. ).
                      Did you measure the T/S parms?
                      "Not a Speaker Designer - Not even on the Internet"
                      “Pride is your greatest enemy, humility is your greatest friend.”
                      "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

                      Comment


                      • #12
                        Under "Resources", fire up the WSG (Woofer Selection Guide). Click (to sort) on the "Sealed F3" column header. Ignore the 15"HO entry of 3 Hz !
                        Skipping over the (NLA?) IB entry, brings us to the UM15. 33Hz in 4 cu.ft. Give that one a go. You'll have a deep revelation.

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                        • #13

                          If one is truly getting a "honky" sound from their woofer systems, they may want to look in the following frequency ranges (700 Hz to 1.2 kHz per Colloms) or (500 Hz to 900 Hz per the 2nd referenced chart) as shown in the charts below. In these ranges are typically soft woofer cone (paper & polypropylene) resonances (bell mouth mode), or possibly crossover concerns.

                          Below is a chart from Martin Collom's "High Performance Loudspeakers" book:
                          _________________________________________________

                          COLORATION

                          Boomy, 50 - 80 HZ
                          Chesty, plummy, 100 - 150 Hz
                          Boxy, hollow 150 - 300 Hz

                          Tube like, tunnelly 400 - 600 Hz
                          Cup like, honky, 700 - 1.2 kHz
                          Nasal, hard, 1.8 - 2.5 kHz

                          Presence, upper hardness, wiry 2.5 - 5.0 kHz
                          Sharp, metallic, sibilant 5.0 - 8.0 kHz
                          Fizzy, gritty, 10 -15 kHz


                          A link to another chart:
                          http://www.independentrecording.net/...in_display.htm

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                          • #14
                            Originally posted by Drewdwn93 View Post
                            I have yet to hear a closed box that I like the sound of. They always seem to add some kind of a honky, resonating-like odd sound to the speakers that I just can't bring myself to like....My main concern is the coloration of a closed box Vs the open and wide soundfield that ported boxes seem to offer.
                            None of this sounds like an apt description of closed or vented box characteristics. If you want to easily compare the characteristics of closed to ported, take a ported speaker that you like, roll up a towel and shove it in the port. It's that easy.

                            Since you are using a subwoofer, if you don't require the extra low end extension that a ported speaker provides, then by all means stick with a sealed box, it can be smaller and then you will apply a high pass filter anyway so the cabinet response is not all that important.

                            "I just use off the shelf textbook filters designed for a resistor of 8 ohms with
                            exactly a Fc 3K for both drivers, anybody can do it." -Xmax

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                            • #15
                              In a word.....YES!

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