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Posts posted by peniku8

  1. 10 hours ago, SME said:

    Ahh, very interesting.  If that's true, then perhaps measuring distortion might be a decent proxy to assess how well the speaker construction is controlling these mechanical resonances.

    I mean, theoretically the entire cab acts as passive radiator, which means it amplifies frequencies. It does that well once those frequencies excite a panel resonance, which will then likely result mostly in harmonic distortion. I 'd guess that this kind of distortion has its own complexities, since, for example, a 3rd order resonance at 333Hz will excite 1khz, which will have a complex directionality emanating from a speaker side wall the size of a few square feet, so it might actually be challenging capturing this behavior reliably with a single microphone, especially if the mic is on-axis, which will probably not pick up many resonances coming from the side panels. Mounting multiple Piezos to the cab might yield good results. Piezos are pretty cheap and I happen to have a dozen (drum triggers). I might do some testing in that regard when I have absolutely nothing better to do at some point in the future 😅


    12 hours ago, lowerFE said:

    Oh yeah I want that Klippel near field scanner so bad! Especially for this speaker because it's asymmetrical in both X, Y axis and Z to an extent.

    That's some interesting note on the distortion from panel vibration. Do you have a link to the AVS thread with the software simulation?

    No chance I could find that again, it was buried in the middle of a random thread iirc. What the guy was posting looked quite thorough and well thought out, but I'm not sure how well his simulations would translate to the real world. His conclusion was that his top priority was minimizing panel flex after his research. Maybe those top of the line speakers with strengthening rods and plates inside or filling up the walls with sand has much more of a merit that we might anticipate. Another method I've seen was multi-layer walls EpoxyPaint-Ply-Aluminum-Ply-Resin, which of course makes the production much more complex and the speaker super heavy. Genelec studio monitors are made from cast aluminum entirely and cast metals have decent damping traits due to their porous structure (I think that's the technical explanation at least, might also be due to the crystalline structure). I've opened mine up, which you can see on here.

  2. Pretty cool thread I haven't come across yet. It's filled with knowledge and information; I'll read through the entire thing at some point.

    If you don't want to do all the measurements manually, you can just buy this, you know:


    And it's only around 100 grand including some peripherals you'll also need, sounds like a no-brainer to me (sarcasm off: I want it so bad!).

    Sturdy construction is important for sure. I recently built a few speakers lining the inside with Dynamat-like mats, to minimize panel vibration and I think if you do that, it's better to actually have thin panels, because the wood resonates in itself at some point. Knocking on 3/4" BB ply lined with Dynamat made much more noise than knocking on a 1/4" MDF panel lined with the stuff. That pretty much eliminates higher cabinet vibrations, but panel flex (due to the thin construction) will now cause issues at lower frequencies, which is why you'll need elaborate bracing. Combine that and the cabinet should be pretty dead.
    In my case, I used 3/4" plywood for the entire cab and used non-symmetric bracing cnc machined to maximize strength (bunch of triangles in the corners). Every (floorstanding) speaker was lined with about 10lbs of the damping mats. I think it would've been better using 1/2" plywood with more bracing instead (I now have a brace about every 8-10").

    I've seen a discussion about panel vibration on AVS some time ago and remember someone using a software to simulate/calculate distortion introduced by cab flex and he came to the conclusion that you reach the point fairly quickly where panel vibration makes up the largest part of your distortion when you're using at least half-decent components.

  3. I saw this on IG earlier, but I scrolled so fast I didn't realize it was a whole new design, I thought it was a slight redesign of the existing model.

    Stats are insane as "usual". Re of 0.26Ohm thou? Recommended to run two series drivers off a single X4L channel (which is running in bridged configuration)?

    BL²/Re is 1700, but the data sheet says 1600 and that T/S params are not fully accurate for the M-drive type transducers, if I understood that correctly, but holy cow. Has as much surface area as two 21" drivers. Does 5KW. I'm just not fully understanding the sensitivity ratings. Either way, 94db at 0.5V is pretty impressive for a 2.5kg moving mass.

    Do I want one? No, I want 10.

  4. 9 hours ago, Dionysus88 said:

    i have jl audio f113v2 x 2, the room stopped responding at around 18hz. With the 32 i can go down to 8hz

    Did you really just compare two overpriced 13" subs to a 32" sub? :P

    1 hour ago, kipman725 said:

    They seem to be sealed boxes won't they work fine into the 100Hz+ range?

    I have seen infra subs that are very narrow band using tuned pipe enclosures arranged in an array of varying pipe length to cover a frequency range not possible using a single pipe.

    I thought about doing this a while back, but I decided to not go that route, as I could imagine that the resulting phase issues would be severe, thereby working against myself (lowering system sensitivity and efficiency). Probably takes a lot of testing/aligning to get right, just like using multiple subs with different tunings (although FIR filters could help you out in the latter scenario).

  5. 21 hours ago, klipsch said:

    Nice texture on that finish! 

    Thank you, that was actually the fist time I've worked with Warnex (European equivalent of Duratex), but it worked very well.

    I used two 1KW stage lights to speed up the drying process, which shortened drying time to 15 minutes, which was a massive help. Gonna get some curing lamps for future projects.

  6. 3 hours ago, kipman725 said:

    Placement looks fine, the main thing is to have more subs and place them in a diverse set of locations around the room, they don't care which direction they point.  Real rooms differ from the research (in your case you have a large lossy door on one wall) so its not necessarily true the best locations would have been mid wall anyway.

    Box volume isn't very important (as long as your using EQ) as what produces the sound is the cone moving in and out a larger box is just requiring less power to reach a given SPL when operated below Fc.  

    I think he is planning to run a double bass array, which works best if everything is perfectly symmetric. I'm not sure how well this particular arrangement would work, but I guess it wouldn't hurt to try.

  7. 6 hours ago, Bobby said:

    Don’t know if I can afford to buy B&C,but I find the Lavoce saf184.03 for 200€ and can buy 8 of them( can accommodate another two sealed cabs behind the screen)Presume the 8 can give me the kickbass that I’m looking for and makes a drum solo sound more real life like and think that output is not a problem, but do they reach 20Hz and a little bit under in the ULF? or are there alternatives to the Lavoce until 300 per driver?


    200€ for the 184.03 is very good, it's about 240 where I usually order. 8 sealed 18" drivers with some 15mm of one way excursion will probably be enough to dig below 20Hz. Maybe not below 10Hz, but that's better handled by dedicated TR devices anyways.

  8. On 9/27/2020 at 12:21 AM, stoneeh said:

    I tried measuring with the CEA 2010 standard [...] I'm pretty sure I measured correctly

    CEA2010 seems straightforward in theory, but is a real PITA in practice. So much so, that people are saying that you can't compare measurements made with different setups/by different people. The results can vary as much as several db, even when everybody thinks their setup is perfect. There is an interesting read on ASR on how temperature influenced bass response and the differences are quite big. I'm certain that would also show up in large signal distortion measurements.

    I've read somewhere that Don Keele compared his measurements with a loudspeaker manufacturer and somebody from an audio magazine and their results were up to 3db apart at some frequencies. It might've been in the paper I attached, but it also might've been elsewhere.

    So it's generally advisable to approach and compare those measurements with care.

    CEA2010 Average.xls CEA-2010.pdf

    On 9/21/2020 at 8:48 AM, SME said:

    When designing a sealed system, it's always a good idea to look at excursion vs. the max power (based on amp choice) vs. frequency, which can be viewed in most design programs.

    That's what I tell people as well. Make the sealed sub as big as you can, until you can reach Xmax at Pmax. Usually the cab will be smaller than what it takes to do so, so it doesn't make sense bothering with a HPF, unless you wanna reduce the load on the sub, like when you HPF it at 15Hz because your sealed 12" sub won't have meaningful output below that anyways.


    14 hours ago, Kyle said:

    I don't add one on my sealed HT sub, then again, I made a mistake once with the amp maxed out and now I have a voice coil ring dent on my metal dish cone :(

    Still works fine tho!

      Was it a 5400?


  10. When doing roomEQ I try to avoid positive EQ points of a Q of higher than 2 or 3, because it starts sounding bad quickly. In my studio I have a point at 31Hz which goes to -35db (almost round room), adjustments of this magnitude are normal.

    Where are you crossing the sub to the mains? The way the graph looks, you might have the sub on wrong polarity crossing at 60Hz, but it might also be a room issue as well. Try to flip the phase of the sub and see what the new measurement looks like.

  11. Pretty sure you'll be fine with just the Othorns and the PM90s. @dsl1 uses them with two SKHorns and is pretty happy with them, so I've heard.

    Also, I'd say 100Hz is more upper-bass than mid-bass. If crossing the Othorn at 80Hz or higher, remember to take care of the spike at 108Hz, but other than that, the combo should perform nicely over the crossover region.

  12. The 18N862 is 670€ while the 21DS115 can be had for 450 (430 each if you buy two), but I think both of those would be overkill for a music setup.

    I recently bought a 15TBX100 for a friend, which is just 200 bucks. It will perform nicely in the available space.

  13. I could probably do it, but I'm booked out at least until the end of October. Had a glance at your assembly and it's quite a big project with all the bracing going on and stuff. Also, I'm not exactly sure how I'd ship that flatpack from Germany to the UK and if that would be a reasonable thing for you to do. Shoot me a PM and we can talk about the details.

  14. 4 hours ago, Droogne said:

    General opinions on mixing a Skram with sealed subs. Is there much to be gained (below lets say 35hz)? Or is this too narrow to benefit (a home theatre), or will interference make it impractical (after basic DSP). 

    I can only talk about the SKHorn, but I'm happy with the output in the 1/3 vents configuration down to 20Hz. Air velocities get out of hand below that, but above 20Hz it's certainly enough for me. A single cab might have a hard time at or below 20Hz, even if it's bigger and has more vent area compared to half the SKHorn. I never got around trying the SKHorn in the config with only one vent blocked, but I like it the way it is now. I actually have quite usable output down to almost 10Hz when listening to music at low levels, the track below sounds surprisingly clean, even if distortion grows quite quickly below the tuning point (I think it goes down to 13Hz or so; so much for "you can't hear below 20Hz").

    Integration with sealed should be fairly easy if you stay away from the tuning point (I'd tune it to ~25Hz and cross at ~40 with a 4th order or higher slope). It will take A LOT of sealed subs to keep up with that cab's mid bass thou :P



  15. When going with the larger angle (60°) I‘d move the drivers as close together as possible, simply for the space efficiency. In that case, you could basically reduce S1 to like 500 and also substract 1000qcm from the other cross sections. 
    Ftc and Atc are left empty in my case because that section is integrated into S2.

    You can try to shape the rear, similar to what Ricci did in the Othorn, but I don‘t think it‘s gonna have any real impact with the 60° angle and after moving the drivers close together. It‘s a bit annoying to manufacture those parts for sure.

    For the AE drivers you‘d have to find the complex inductance parameters; I think you could eventually use these from the 15“ unit Ricci measured. This is a special case, in which I‘d not fully trust HR to simulate it by itself, since these have an exceptionally low inductance (double clicking Le which turns it RED and enables semi-inductance simulation).

    • Thanks 1
  16. 39 minutes ago, Audiovideoholic said:

    Ok. I see what you mentioned about the 60* and how that takes the peak out for less distortion. 

    I will have to double check the sealed volume for that model to make sure I’m looking at the correct design. 

    on the sealed volume note, when modeling does one put in the single cab/driver volume or entire system volume(double in this case)? I thought this was only modeling one driver of the two? If it’s modeling the total system then the voltage would also need to be doubled when checking the excursion? 

    Thanks again!


    You used an offset driver alignment and specified two drivers in series (electrically) in hornresp. As such, you also need to combine both back-chambers into one in hornresp.

    Looked to me like you calculated the outer volume of a single chamber. I approximated the inner volume of two chambers with the drivers installed, which would reflect the finished cab as it should be.

    In your model, at 75V, each driver is fed 37.5V, as they're 'connected' in series.

  17. We should have a look at the cab itself first. If you want to mount the HS24 at a 45° angle to create a 90° offset between the drivers, you'd need mount the driver at about 17-18" into its baffle (otherwise the magnet won't fit in the rear chamber), which results in a 5" gap of unusable throat in the back, which would not be ideal. The highest you can go while having the driver mounted as far back as possible is an offset of about 60°.

    The slot itself is too small imo to contribute meaningful output in your range of use, so I'd take w/e is the least spiky in response.

    How did you calculate the rear chamber volume? I end up with 300l. One chamber is about 180l, minus the driver volume probably around 150l. And that times two of course, since you have two back chambers.

    Keep in mind that the examples below have the same back chambers, which means the one with the widest driver offset will be the largest cab.

    I'd personally prefer the 60° offset version. The 20-40Hz sensitivity is a little less compared to the straight slot, but the spike at 100Hz is basically gone, which lowers distortion.

    I added the Hornresp file to this post.




  18. Btw, here is a comparison of a sim I did with the approach mentioned above, in a cab similar to yours, but with only one driver plus a vented back chamber.

    The real (half space) measurement is the wavy line. The purple line is the Hornresp export (scaled quarter space; not much different from the og half space export) and the cyan-green line, which is closest to the measurement, is the Hornresp export plus baffle gain exported from Edge. The baffle gain was scaled to half space (twice the baffle area).

    These were not gain-matched, but voltage matched, so the final simulation is pretty spot-on with the actual result. I did another design on the same principle and it was within 1db of the predictions.


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  19. If you want to get a better understanding of T/S parameters, I'd recommend finding out how each parameter is measured and understanding what that measurement process tells you about it. That'll give you a pretty good understanding of what's going on and makes it easier to interpret data, instead of just working with numbers using abstract units. I thought I had a pdf about it somewhere, but couldn't find it now.

    • Like 1
  20. To my knowledge, the throat chamber is the volume in front of the membrane until it enters the actual horn/slot section, not the entire horn section itself. Think filling up the driver with water with the membrane facing up.

    For a back-mounted 21" driver that's about 350cm² is cross section, which I add to S2 (Ricci's trick). I guess it's similar for the front-mounted (I guess?) HS24.

    This is what my inputs look like:



    • Thanks 1
  21. Welcome to the data-bass!

    Do you have a schematic of the cab(s)? I'm unsure if you're planning to

    - Build two sealed 24" cabs which will be placed with the drivers facing eachother, creating a slot similar to an IB manifold in the baffle wall

    - Build a single cab with two 24" drivers in a similar configuration to the above, which basically creates a band pass

    As for the AE drivers, it sounds like you're planning on doing the latter, but you mention that the drivers would be placed at an angle, so I guess kinda like SKHorn without the front panel and sealed, plus I guess the intended angle would be more like 45-90°?

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