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Feb. 2018
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How about a larger Sealed speaker???

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  • How about a larger Sealed speaker???

    I read lots across hifi forums about the wonders of the Sealed speaker & questions why there are so few around.

    I myself own P3ESR & love what they do. I would love to hear what a sealed design with a larger 8" driver could do.

    I imagine there would be quite a market for it.


    So come on Alan, get cracking!

  • #2
    I dream of that too. Love my P3ESRs, and concerning my difficult room it is probably the best choice for me, but a larger sealed Harbeth sure sounds interesting.
    Love my P3ESRs

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    • #3
      A ported speaker can go lower in frequency compared to a sealed speaker of the same dimensions. The response then falls away at 24dB per octave whereas a sealed speaker will fall away at 12dB per octave.

      My experience is that a few decades ago it was difficult to hide the fact that a speaker was ported. It had a certain character in the way it reproduced bass freqencies. Modern designs do not give away the ported nature of the speaker so easily. I think that is because computer aids can help to get all the parameters right so the port integrates properly with the design as a whole. I believ that was a more difficult task in days gone by.

      Ported speakers are generally more difficult to place in a room compared to sealed speakers. The biggest advantage of ported speakers is that for a given size the -3dB point will be a lower frequency than for a sealed speaker. That counts for much these days when huge sealed speakers would not be accepted in most homes.

      Alan has said that the reason why the P3 ESR is a sealed box is that there is no room for a port in a speaker of that size.

      Comment


      • #4
        I like this idea, but what I've learned so far the biggest issue in lower two octaves isn't to port or to seal, but to fix the room. My subwoofers are sealed, though
        However, the biggest improvement I got was when I started to use the DSP on the lowest two octaves. Adding bass traps in the living room was not an option so in my case...
        ...in my case only subwoofers go through the DSP. I wouldn't like to push anything above 150Hz through the DSP, yet someone might have no issues with this.

        Sealed, active crossover (read this as bi wire) Harbeth with bass management for your imaginary 8" driver, well, that could be something.

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        • #5
          Originally posted by Strummer View Post
          I read lots across hifi forums about the wonders of the Sealed speaker & questions why there are so few around.
          A sealed speaker design has a better low-frequency transient response as a result of its 2nd-order 12 dB/octave roll-off in the low frequencies. The downside with a sealed design is that its sensitivity is about 3 dB less than that of a vented speaker if their enclosure volumes and low-frequency cut-offs are the same. Alternatively, the speaker designer can trade-off the higher sensitivity of the vented enclosure to obtain a more extended low-frequency response. These days, many vented speaker designs appear to be based on what are known as QB3 alignments or similar. These quasi-Butterworth alignments have an initial 3rd-order 18 dB/octave roll-off rate in the low frequencies below the -3 dB cut-off point. The QB3 alignment provides a more compact enclosure and produces a transient response that is a bit more damped than a standard 4th-order vented box alignment.

          If there were to be a sealed loudspeaker system based on an 8" driver, then assuming that it had the same enclosure volume as the M30.1 and approximately the same low-frequency cut-off , and the 2nd-order low-frequency alignment was tuned to be maximally flat, this hypothetical sealed speaker would have a sensitivity of approximately 82 dB versus the M30.1's 85 dB. To bring the sensitivity back up to about 85 dB, the enclosure volume would need to be doubled from the M30.1's approximate internal cabinet volume of 28 litres to about 56 litres or so by using a suitable driver. That translates to a sealed enclosure whose external dimensions need to be approximately like those of the SHL5plus. This hypothetical sealed enclosure would give us a -3 dB cut-off at 50 Hz or so, compared to 40 Hz for the SHL5plus. For that size of enclosure, is the marketplace really going to be accepting of the reduction in bass extension? I really don't know, but it would seem that various manufacturers don't think that such a product would sell all that well when competing against similar-sized vented systems.

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          • #6
            Why not leave such decisions to Alan? It is not as if the likes of the M30.1 have invited criticism.

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            • #7
              I have built a pair of active speakers with 8 inch woofers. The MiniDsp crossover corrects the bass slightly to compensate for the smallish 25 litre sealed enclosure. Due to the efficiency of the design, a Quad 306 driving each side gives plenty of volume. The result is good extended bass that's very tight and controlled. To take the bass response even further down is possible with DSP correction but the cost would be much higher power requirements.

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              • #8
                Originally posted by garethwatk View Post
                I have built a pair of active speakers with 8 inch woofers. The MiniDsp crossover corrects the bass slightly to compensate for the smallish 25 litre sealed enclosure. Due to the efficiency of the design, a Quad 306 driving each side gives plenty of volume. The result is good extended bass that's very tight and controlled. To take the bass response even further down is possible with DSP correction but the cost would be much higher power requirements.
                Getting extended bass bass response at reasonable SPLs is not really possible with a single 8" driver. The driver excursion requirements are by necessity going to be very large. That's where adding two 10" or 12" subwoofers would prove beneficial. They would be designed with large low-frequency excursion capabilities in mind, and if suitably chosen can achieve a -3 dB point at 20 Hz without too much trouble. With the use of MiniDSP to take care of the bass management side of things, a 12" subwoofer partnered with a two-way system comprised of an 8" sealed woofer plus a 1" tweeter would certainly be a high-performance configuration.

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                • #9
                  [QUOTE=witwald;n70619]

                  Getting extended bass bass response at reasonable SPLs is not really possible with a single 8" driver. The driver excursion requirements are by necessity going to be very large.

                  Absolutely. One option I am considering is to have 2 settings. HiFi and Party. Party mode will be employed to reduce the lower bass output when my teenage daughters are let loose on the system.

                  Comment


                  • #10
                    Interesting stuff.

                    I'm just so impressed by my 'ickle P3ESR, I can't help thinking if I could get the exact same, just with an 8" driver, it would be my perfect Speaker.

                    There's just something about a 2-way that I seem to prefer over 3-ways & floorstanders.

                    I don't need ultra low bass, I use a pair of JL Audio e-112 Subs.

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