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Ricci

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Ricci last won the day on October 6

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About Ricci

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    Super Bass Overlord

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    Male
  • Location
    Louisville, KY
  • Interests
    Bass...Subwoofers, audio, video, drums, recording, craft beer, performance arts, poetry...

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  1. Maximum horn compression ratio?

    I will look at this when I get a chance. Very busy at the moment getting some more tests ready to upload. Off hand. Interesting fold. Have you considered weight of the cab and internal pressures at high output? Bracing of the panels etc? Check the particle velocities, acceleration forces and pressures at the throat and exit. They will likely be extremely high with such a high compression ratio. Also absolutely model with the Le option checked which derates motor force some.
  2. Replacement AVR / processor

    I'm still using the old Onkyo 886 myself. Probably get the Denon DN-700AV when I do change unless something better comes along. Related to the clipping with WCS signals... Most of us with big, capable systems, by default have HE / sensitivity. I've done a lot of gain investigation with my current components. My REF playback is at -7 on the master with my FL and FR channels at -15 channel trim. This is largely set by the high sensitivity of the CF-4 speakers and the extra hot input sensitivity of the Emotiva XPA-5 amp. The sub channel runs about 3dB hot at -7 trim with my K20 input sensitivities at minimum. The Onkyo will spit out over 12v through the SW jack without clipping but I do not know what point it would occur internally with a WCS. Back when I did all of that testing I did not have an easily accessed WCS signal. K20 clipping occurs well below 12 volts input. I could always increase the input gain on the amps if needed but I don't run REF +15 on the subs virtually ever. Is anybody actually running their processors at (0) for assumed REF with the channel trims near 0 or higher? You really shouldn't need to with high capability speakers but this makes me curious.
  3. JTR Speakers Captivator 212Pro Discussion

    Perhaps you are right. The point about mechanical damage happening due to a stress or strain overload of the cone is likely true. You would almost expect a catastrophic failure or fracture somewhere. I still don't think this is related to "normal" over excursion. Those things can surely happen, but I would expect them to happen in the low bass register as well. Assuming a sealed cabinet, in order to produce xmax at 80Hz we would expect output roughly 12dB higher than at 40hz. There can be some differences of course due to real world signal reproduction and other variances but this is close. So if a driver produces 110dB at 40Hz at 15mm excursion we would expect it to produce roughly 4dB higher output each 1/3rd octave up when driven to the same 15mm excursion. 114dB at 50Hz, 118dB at 63Hz and 122dB at 80Hz etc. Velocity and acceleration forces increase accordingly as well. reaching the same excursion an octave up requires 2x the cone velocity and 4x the acceleration. In some cases there is some form of distress or other "bad" noise that occurs well prior to this 4dB per 1/3rd octave expected increase. You mention that a dramatic drop off in motor force or "control" of the moving assembly is lost at the excursion extremes which is true. This could result in an overshoot effect where excursion would increase as the moving assembly is not "grabbed" and returned. Sort of like a loss of traction on the voice coil. However for the SPL to not increase with the greater cone displacement it basically has to behave in a manner that is not following the waveform of the drive signal. It would be a sort of clipping almost. Sort of like the speaker jumping out of the track provided by the electrical waveform. Indeed when I experience this it often is accompanied by a captured waveform that is completely different than expected and utter garbage. If the output waveform is not the 80Hz or whatever expected and is instead some terrible distorted mess with squared off components it would reduce the measured SPL. Perhaps it doesn't appear at lower frequencies is because the velocity and acceleration forces are lower and the suspension can better deal with controlling the assembly. Hmmm. I'd never quite thought of it like that. That may just be a possibility. I do seem to see it more often with lighter weight moving assemblies and softer suspensions though. We are way off topic and none of this pertains to the Cap212-Pro exactly, but this is a fairly common occurrence using the K20 for burst testing.
  4. Ricci's Skhorn Subwoofer & Files

    I don't think anyone has but you could. I wouldn't advise it for actual touring use but if they won't be moved that much it should be ok.
  5. Just made all of the good stuff for this visible. Please discuss here.
  6. KRK Systems 12S2

    All discussion of this 12" commercial unit and its measurements should go here. Thanks.
  7. JTR Speakers Captivator 212Pro Discussion

    Those are different things. Breakup modes due to bending forces in the cone geometry and composition are basically resonances. These occur even at very low volumes and are a separate issue IMHO. Basically they are inherent to the driver. This is something that does not occur until the speaker is driven extremely hard. Usually harder than any user scenario would ever push it. If things are continually pushed harder and harder the forces on the speaker increase and eventually something will break or start to behave very badly. Have you ever looked at the forces involved to produce some of the burst output numbers recorded? Acceleration or velocity for example? The forces involved are way beyond the scope of normal use. Lighter more flexible materials will tend to give more. What happens to the mass at the edge of the cone when the voice coil acceleration at the center of the cone is constantly increased? I doubt it is IMD or flux modulation effects I just don't see them making the sorts of noises I've heard. In some examples a driver will go from producing a relatively clean pure sounding tone to a clearly mechanical almost bottoming out sound in the 63-125Hz bands with only a small increase in the input signal. However it is not actually bottoming out or hitting suspension limits and the amplifier is well below clipping. That is easily verified. The signal captured goes from a normal looking reproduction to a complete unnatural mess.
  8. JTR Speakers Captivator 212Pro Discussion

    I have a theory that some of the lighter cones start to flex due to extremely high forces placed on them during the burst testing. It is something I have noticed on those types of drivers over the years. At the 80 to 125Hz bands the driver may not be able to reach xmax or even the THD limitations for the testing before something starts to sound wrong. This will usually be noted as mechanical noise on the burst chart. I stop at that point because it is a clear indicator not to proceed further as damage may occur. It is just a theory and could be any number of things though. In this case it really doesn't matter that the cab wouldnt take more than 110v. It means a less powerful and costly amp can be used and get all of the available performance.
  9. Acoustics Studies

    He has some good articles on his site if some of you are unfamiliar with it.
  10. B&C 21DS115

    I woukd definitely use it when modeling any subwoofer. You have to remember that the final result will likely be a bit smoother due to losses and unaccounted for variations in the real speaker. I like to look at sims with and without both and make sure both look ok, but the LE model will be closer.
  11. B&C 21DS115

    The 21SW115 is definitely not a match. The 21DS115-4 should be ok. David, the response should be somewhere in between the LE modeled and without LE modeled in HR.
  12. Upcoming Testing Possibilities?

    Final quarter of 2017 update. JTR Speakers Captivator 212Pro results have just been posted. KRK Systems 12S2 subwoofer testing is done. Should be posted next. WW Speakers / Mark Seaton designed X21 cabinet loaded with B&C 21DS115-4 driver testing is done. Will be posted ASAP as well. This was tested with both vents open and with a vent plugged and with both the Powersoft K20 and an Inuke 3000DSP. That's 4 full measurement sets. We're killing a lot birds with one stone on this one. We have some information on the Inuke 3000DSP amp driving a real load. We have the 21DS115-4 driver itself, which a lot of people are interested in and lastly we have the X21 vented cabinet which is available off the shelf to fit a variety of pro 21's. I tell you the cab is built solid and of course Mark designed it well. It is not cheap but it certainly offers an easy button option. Next up is a set of 3 subwoofers from one of the commercial vendors. I'm not totally sure these will be public on the site since the MFG reserves the right to decide whether the results are public or private. I believe they will be though as so far their behavior appears to be well designed. And...After that...I have a couple of cabs from a pro audio company that will be on deck. Not sure these will be public yet either but I suspect so. I'm trying to get this all tested and posted by the end of the year. That's the goal. I have more DIY type driver tests sitting in the wings too.
  13. Any discussion of this speaker or the measurements should go here. Enjoy.
  14. Ricci's Skhorn Subwoofer & Files

    Really freaking loud with low distortion and a side of Rocky Balboa TUFF is exactly what this cab is about. This wasn't really made for being in a domestic space nor for use with only 1 vent per side open. That said IF it is used in a house the gradual roll off of having only 1 vent open might work quite well with room gain. I wouldn't be surprised if there is still more output than needed and managed to get down to 15 or 16Hz. Even with only 1 vent per side open it still has the equivalent of 2 5.25" ports or one 7.5" port. Personally I'd start with the 2 vent mode if using one in a home but I'd definitely try them all and see what works best. I just can't see using all of the output from normal 30Hz tuned / all vents open in anybodies home, so using the lower tunings seems like it should be worthwhile. Brandon or Ti, Did either of you play around with blocking the vents?
  15. B&C 21DS115

    Yep saw this a while back. Thanks for posting it though. I've got some testing done with this driver in a vented cab that I'm working towards getting posted. Hopefully in the next 2 weeks. I haven't had a chance to do a comparison against the 21sw152-4 stuff yet either. I really want the sealed test so it will be the exact same cab. My quick feeling is that the ds115 behaves about exactly as we would expect from the specs when compared to the 152. Higher distortion, heats up worse due to the smaller 4 layer coil versus the big 6" diameter. Overall the 152 might still be a bit better performer but it is about $100 to $150 more expensive also.
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