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Modified SB15NRXC30-8 vs. Scan-Speak W15/8530K-00

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  • Modified SB15NRXC30-8 vs. Scan-Speak W15/8530K-00

    This shootout pits the $201 Scan 5.5" Revelator against the $51 SB 5" woofer with the uncoated paper cone. To make this a fair fight, some DIY has been applied to the SB driver.

    Click image for larger version  Name:	zzzzrev and sb15 sliced.jpg Views:	1 Size:	247.0 KB ID:	1439577


    The competitors weigh in on the impedance sweep with a very close match-up!

    Scan: Fs 48, Qts 0.49, Qms 3.9 Le 0.24

    SB: Fs 48, Qts 0.47, Qms 4.3, Le 0.12


    Click image for larger version  Name:	SB Scan Shootout.jpg Views:	1 Size:	99.8 KB ID:	1439578

    So, how do they look? Well, looks are important. The SB looks well-built, clean and simple. The Scan impresses immediately. A more elegant frame, uniform coating on the cone, 5-hole mounting. It's clear the Scan-Speak has a larger voice coil than the SB, indicating possibly better long-term power handling and more peak output. Advantage- Scan

    Click image for larger version  Name:	zzzzz Scan pics 094.jpg Views:	1 Size:	103.7 KB ID:	1439579


    Let's talk distortion. I took a lot of measurements, but have decided not to show the distortion plots here for clarity. In general, all distortions are low for these drivers. The one area the Scan does better is distortions below 200 hz, mostly 2nd order. Both drivers show distortion rising below 200 hz, which is why you should use larger drivers for that range. If you do need a 5.5" subwoofer though, the Scan Rev might be on your list.

    How do they sound? The drivers were evaluated as part of a speaker system. A 0.46 ft. cabinet tuned to 43 hz, fully damped, CLD walls, 1.75" radius edges. Passive crossover [email protected] 2.4k, active to sub at 70hz during listening.

    Starting with the unmodified SB15, it's immediately obvious that this driver needs some work. It's simply not an acceptable choice for a 2nd order slope. The break-up harshness is apparent in almost everything. Bells have excess ringing, sometimes ear-piercing. Instruments lack separation. Vocals have a slight veil with occasional minor edginess. A bit of sibilance, not much. The image is slightly indistinct and slightly forward. No comparison with LR4 slopes will be considered, so don't ask.

    The Scan-Speak was built for this challenge. One of very few factory offerings that take readily to 12dB acoustic slopes. Why do it that way? Why, better imaging, of course, having a better phase response. The Scan settles right in, making you think you are a good speaker designer. This is why you spent the big bucks, right? Oh, about the sound - Bells have good spacing, with no excess ringing, but the tone is unnatural. Vocals have a pleasant fizzy character, including some soft sibilance, not objectionable, but obviously not exactly right. Instruments are difficult to separate. Undermelodies are not too clear, and imaging is correctly placed, but not very accessible. This is an OK speaker.

    The modified SB has pole cavity treatment and damped slots in the cone. It has in-band performance identical to the stock driver. What's amazing is how much the out-of-band sound matters. Bells are clear, vibrant, full bodied, no excess ringing. Vocals are a revelation. No more glaze/veil. Instruments have distinct separation. Subtle sub-melodies are easier to pick out. This driver is not perfect, but it is easily much better than the others. The modified SB15 is the clear winner!

    So the modified SB isn't just the value leader, it's the better sounding driver, by far.

    Why did the Scan W15/8530K-00 lose this comparison? Well, the design is a bit dated, and the SB15 clearly has a better motor, with much lower inductance. I might also suspect the Kapton former could contribute to the colored sound, whereas the SB has a glass fiber former. Another area is the dust cap, which can be quite influential.

    Why would you not do this? Every time. I'll tell you. Maybe you don't like anything DIY. Maybe you don't like constantly being drawn into the music. Maybe you don't want to visualize how the singer is positioned in relation to the microphone, and start wondering what brand of microphone sounds like that. Maybe you don't want to remember that Johnny Cash is old, because you are pretty sure you can see the wrinkles on his face. Maybe you just want to hear the vague sound of the tin whistle instead of hearing all the subtle mouth work. Maybe you just want music to exist somewhere in the background, preferably behind a curtain. MAYBE you care more about resale value than how the speaker SOUNDS.
    "Looks like you may have to design your own speakers. Its not that hard." -DE Focht

    Diffraction Happens

  • #2


    Click image for larger version  Name:	SB15 vs Rev vs SB15 mod.png Views:	0 Size:	16.6 KB ID:	1439582

    The in-box raw, ungated, unsmoothed plot shows that these are a pretty good match below the break-up area. My mods supressed most, not all, of the nasties. The loudest SB was 1.2db more sensitive than the Rev, but sloppy application of excess glue brought the modded SB down to within 0.5dB of the Scan, and became a virtual drop-in replacement. I expect to see a little better performance in my 2nd gen of this mod.

    Note that all 3 drivers exhibit the 1.2k dip common to many modern high-end drivers. I don't really like it, and I'm fairly certain it's audible, but so far it looks like the cure is worse than the disease. I did not prefer the cone-edge treatments.

    Click image for larger version  Name:	SB vs Rev vs SB mod 45 degrees.png Views:	0 Size:	15.6 KB ID:	1439584

    This 45 degree plot is 1/24th smoothed for clarity, and shows just why suppressing break-up matters. Looking at the dip in the green plot at 4khz, you see evidence that the break-up on the Revelator is not fully dealt with, as I had long suspected.
    "Looks like you may have to design your own speakers. Its not that hard." -DE Focht

    Diffraction Happens

    Comment


    • #3


      Here's the Modded SB15 vs. The stock SB15 with 12dB crossover in place, unsmoothed. 45 degrees off-axis.

      Click image for larger version  Name:	SB vs SB mod with x-o 45 degree.png Views:	0 Size:	14.8 KB ID:	1439586
      Last edited by jbruner; 05-04-2020, 11:40 PM.
      "Looks like you may have to design your own speakers. Its not that hard." -DE Focht

      Diffraction Happens

      Comment


      • #4
        what is the cone edge treatment? what is the XO point? The dust cap looks very similar on both after the treatment - how does it contribute?

        Comment


        • #5
          Originally posted by ani_101 View Post
          what is the cone edge treatment? what is the XO point? The dust cap looks very similar on both after the treatment - how does it contribute?
          There is no cone edge treatment on any of these. I tried and then removed several different treatments to the first half of the surround. The x-o is described in post #1. The dust cap on the Revelator appears to be a bit softer and thicker than thin, stiff cap on the SB. The Rev has no damping in the cavity under the cap. This resonant cavity almost always causes audible problems. The Rev mitigates this with a well-damped dustcap, but I think the natural roll-off from the high inductance helps in this area. That said, I have noticed that soft dustcaps in general don't sound good. The worst I have heard are those really soft rubbery ones.



          Click image for larger version

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          I installed a thick felt ring on the pole of the modified SB15. This had a great effect on the FR and the sound quality.

          Here's an SB15 (blue line) , with just cap and cavity mods (green), and also sliced cone (magenta).



          Click image for larger version

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          "Looks like you may have to design your own speakers. Its not that hard." -DE Focht

          Diffraction Happens

          Comment


          • #6
            Thanks JBurner. did you cut out the SB dustcap and added the felt ring? did you stick something on the underside of the SB dustcap to damp it? I don't recall what exactly, but you had also modified the dustcap of the the Dayton PM180.

            Also I didn't understand if the Rev has a well damped cap or not...

            "The Rev has no damping in the cavity under the cap. This resonant cavity almost always causes audible problems. The Rev mitigates this with a well-damped dustcap, but I think the natural roll-off from the high inductance helps in this area. "

            Comment


            • #7
              Thanks JBurner for the Interesting evaluations. I have a Pair of Scan 15w 8531 and a pair of SB15. I agree that in stock form, the Scan sounds like a $200 woofer and the SB sounds like a $50 woofer. Also, there is excessive SB 15 sibilance that I couldn't solve.
              Is the mod difficult? Where do you get replacement dust caps and cone? Can you share the crossovers you use?

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