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Everything posted by peniku8

  1. Sorry, the sensitivity in hornresp quarter space (plus baffle gain) is 12db louder than measured 2V 2m half space, not 6db.
  2. Exactly. Btw, you don't have to fill out all 4 sections. You can input S45 data into S34 and leave S45 off (all values 0). What angle does your horn have? With your values it almost looks like the offset part is angled at some 20°, is that what you're trying to do? From the parameters it looks like you're doing something like firing into the back at quite an angle with a straight section running along a side wall/bottom to the front. Quite ambitious packing that much of a front chamber and a 96cm long port into a space this small. Are you sure the back chamber volume is correct? Looks like a bit too much for a cab of the dimensions mentioned earlier. I also noticed that the quarter space sim (plus baffle gain and -12db) matches my real measurement much better. I multiplied the Hornresp output with the calculated half space baffle gain in Edge and basically got the same voltage sensitivity (-12db) curve as I measured, which was really satisfying. The driver did get a healthy 4 hour break-in period and I've used Ricci's semi-inductance parameters.
  3. I don't know much about particle velocity, except the basic fact that it causes compression at some point, and neither have I run compression sweeps of my cabs yet (waiting for better weather), but while looking at your hornresp parameters, I noticed that you haven't added the driver and front "chamber" volume anywhere. Normally you'd be using the driver's front air volume plus the small section with the thickness of the plywood you're using (was about 11000cc VTC with the IPALs iirc), but as to @Ricci's suggestion and my own comparisons with my finished cab, adding the driver's cross sectional area to S2 in horn resp results in a sim much closer to the real thing. For the 21" drivers you can add about 350cm² to S2 (driver+wood when back mounting).
  4. No, too much work. The straight port version is not practical for me anyways. I have built an MDF prototype with a straight port, but that one was tuned to 30Hz instead. I figured that even the 12BG100 doesn't generate enough output to justify a tuning so low for my application. In addition to that, the port area on that one was a lot less and way too small. I will build two to be used for a live setup for weddings and smaller gigs. Either way, most 12" subs on the market are tuned to 50Hz or higher, which just doesn't cut it for me and most of the remaining subs which would fit my SPL and extension needs are bigger/heavier than just 40lbs. That said, the 12BG100 surprised me with its weight. 19lbs is quite a lot for a 12" pro woofer with a neo magnet imo. I've finished the CAD files and am currently working on the CNC code. I hope to have one measured in the next few weeks.
  5. As long as there is none of the 2" foam on the back wall 😅
  6. Another point for the foam lining: The internal cable to the connector won't rattle if it touches the walls.
  7. Nobody knows? Alright, I'm just gonna build the cabs and see how it goes. It's just 70$ of wood for two cabs so w/e And even if the response is not ideal, these will be used with dsp amps exclusively so I can iron out some flaws at least.
  8. I'm guessing that you're talking about a Cardioid setup here, but there is alot more to this than simply flipping the phase of a sub in a stack. There are many way to do this, but most common would be either stacking subs in two rows (needs more floor space and additional delay+measurement work) or physically turning every 3rd or 4th cab around so that its rear faces forward. You'd then flip the phase and delay the signal according to the depth of the cab. Delay can vary, so its best to just try different settings, measure and listen. Typically, the 2 row setup increases front output and rear rejection and the latter one I described just improves rear rejection. In short, yes, it can be done. It will require some work and knowledge thou and if you come here asking if this would work in the first place, it'll probably be your job of setting that stuff up and aquiring the necessary knowledge. But as Leonard Lauder once said: Theres alot of crazy stuff you can do to array subs.
  9. 3 21DS115-8 in parallel per amp channel sounds like something I'd do. Their impedence minimum is pretty low and should be around 2 Ohm with 3 drivers in parallel. You could also get a point-symmetric setup that way. LCR. With a Skram beneath and on top of each main speaker if theres enough room. Put Skhorns in between for convenience.
  10. Ricci did just that some time ago iirc. There was a meaningful difference even below 100Hz if I'm not mistaken. Remember that reflections will pass through the foam multiple times on all walls. I think it was even published as article here on data-bass.
  11. Doing so will dampen resonances and make for a better frequency response at the cost of a fraction of a db of output. It's not always needed, but generally a good thing to do. Especially when maximum output is not a key factor. You can put the foam anywhere where it does not obstruct the airflow. With your port pretty much on all side walls. I used spray adhesive to glue the foam to the Skhorn and staple gunned the foam to my Z21. I personally hated working with spray adhesive. What are you doing with the PVC pipe? Will that be part of the port?
  12. To me it sounded like the adapter would be installed after the RCD. That would last as long as powering on the first electronic device...
  13. Keep in mind that music is not a continuous sine wave. If you're putting out 500W true long term average into a sub, that's already pushing it. When converting a circuit down in amperage, remember that an additional breaker is required. 8 AWG is way over the top for any normal speker application (unless you have 100m+ of wire run maybe) and is only used in this case to keep the testing environment as linear and constant as possible to get accurate test results from the DUT. For usual PA applications I'm using either 11, 13 and 15 AWG, depending on what I'm powering. For when we set up the PA for not-so-small stuff, it is usual to have at least a 63A 3 phase 230V service. I have not come across Powerlock/Camlock yet. I don't know why you would link ground and neutral. That sounds like a horrible idea to me.
  14. If you didn't trip the breaker it was not the limiting factor. However, the wire gauges will be smaller on the 15A circuit (Or higher? I still can't figure out AWG. LESS COPPER!) and thus, voltage sag will act like a compressor on your signal in the earliest stage of your equipment chain possible. The smaller the wire, the more voltage sag you'll get. When I turn up my clone amp in my house in France it dims the lights. When I do so in my house in Germany, no voltage sag occurs. Maximum sustained power output of the amp is around 4KW for several seconds. 3KW long term. I saw the amp draw over 15A from the wall on the 230V circuit. Skhorn in a 3000cuft room. Loud! I'll be using 30m (100ft) of 8AWG speaker cable for heavy duty sub testing to mitigate cable losses (with the amp on a 230V 32A circuit).
  15. I'm using wood screws+gasket tape on anything but driver and hatch. Since you don't have an access hatch I'd only use hex inserts for the driver. Don't forget to line the driver with gasket tape. I wouldn't glue any hardware to the cab.
  16. Sorry I think the post wasn‘t clear enough. I was trying to highlight the correlation in terminology of ‚order‘ and ‚db per octave‘, which is why I didn‘t mention filter type at all. I‘ve described cascading filters a few posts before so I didn‘t include that in this post again.
  17. Thank you, I love every aspect of these. They sound incredibly good and since the driver is in a horizontal position, sitting on them is an experience lol! I can tune them 5Hz lower if I want to and that only takes about 30 seconds per cab to do. I revised the CAD files and overhauled some joints for the next batch. There are some visible seams which I didn't bother sanding and I will try to not use Kreg screws anymore.
  18. It's just a different way of describing the same thing. Every 6db/octave is 1 order. 12db/oct is a 2nd order filter, 18db a 3rd order and so on. Well it's based on a bigger design I have not yet built, but I needed capable subs which could easily be handled by two people, so I went with a 320L cab which comes in at 63kg with casters. (The casters on the cab were a horrible idea, they resonate at 42Hz. I will build a caster board for future versions) The measurement was a quick 2m 2V groundplane (4 Ohm 21ds115) at 50°F/10°C outside in my backyard with no objects within 20m. The graphs shows the two required EQ points to EQ the response flat, but they should sound pretty neat inside a small to medium sized venue even without EQ. The two cascaded biquad HPQs form a BW4. When I've made up my mind whether to post the build thread on AVS or on here I'll do so. The thread will contain more in-depth views and info which I don't want to clutter the Skram thread with. I will however not release any plans for those. If you want some and live in the EU, shoot me a PM 😉
  19. I have liked a 120Hz crossover setting when recently testing out my own bandpass-horn designs. Took 2 PEQ points to get the response within ±1db from 30-190Hz and the EV tops I used to test them with didn't have such a good mid/upper bass (impulse) response. If you're running the system flat and use a low shelf to shape the response to your liking, this crossover point works really well with these types of subs. Now if you like using the subs' volume control to shape your signal, I'd suggest running a lower crossover or just not doing so at all. I don't like hot subs crossed over any higher than 70Hz. You could also try crossover shapes with an even smoother knee. Cascade two BW2 and you'll get a LR4. Cascade 4 BW1 and you'll get what my Chinese amp lists as "Bessel", but it is not. Bessel is in between BW and LR, thus forms a +1.5db point at the crossover frequency in theory. Cascading 4 BW1 filters will result in a 4th order filter with considerable overshoot, so you could overlap the responses of subs and mains more and run subs hotter while maintaining a natural slope. You can experiment a lot with it, but I'd recommend doing so in a controlled environment outside with measuring gear. Once you get a response you like, it's easier to integrate that into a room instead of fighting both the room and the speakers at the same time imo.
  20. So you're saying that the transient intermodulation distortion can be mitigated when feeding a speaker a smaller bandwidth signal? This should be true, but I can't attest that this effect is audible or if it's even a problem at all, as long as the speaker is being driven within its linear operation range. I don't know if this effect is even relevant for loudspeakers and I haven't managed to find much about this on the internet. I've only come across TIM measurements of amps. And slew rate of amps is typically not affecting audio quality, unless you're planning to do something wierd. I don't think it's possible to improve the other two aspects of the transient response (ringing and group delay) with a simple HPF. @SME I'd agree that a resonance of lower Q is more audible than a resonance of higher Q with the same gain, but I think that the resonance of higher Q will be more annoying for the listener. When I'm working on a mix I almost never use narrow additive EQ points, because those tend to sound unnatural (unless you're going for a specific stylistic effect).
  21. I'm in the process of designing a small vented PA cab for B&C's 12BG100, tuned to around 40Hz. The current design utilizes two straight rectangular ports with a combined port area of 120cm². Problem with the port is that the handle placement is so awkward, that I'd have to make the cab wider than I'd like to, which is why I'm planning to go with a shaped port. The fact that doing so would also lower port compression a little is a nice side-effect, but it's not my main concern here. I basically want the port to "bend around" the handle. Pics below. I'm simulating a rear loaded horn in hornresp to be able to be more flexible with the port input data, but I'm not sure if this is the correct way to approach this, or if there are better alternatives. I had to increase the chamber volume by 10% to match the simulated response of the vented cab. I sliced the port into 4 segments to model it as accurately as possible. The cab in the middle is far from done and needs a few modifications still, since I just quickly threw this idea together in Inventor to grab the measurements for hornresp. The sims are very similar between the straight port and the shaped one. Am I on the right track?
  22. I'm using the SKHorn in 1 port mode in my HT. I get no usable output below 18Hz (chuffing related), which is fine because I'm sitting on a tiled basement floor. Only TR I can get is from my mini riser. Use regular oval-head screws. I use those black ones commonly used for sheet metal, which work great on plywood too. There are gaskets for the handles which are less than a dollar (penn elcom) but you can also use 20x2mm gasket tape like I did. I like the screws, they make for a clean look.
  23. And btw, last time I manually routed an MDF sheet, I completed a full depth cut (1/2") for a 12" driver in probably less than 4 seconds at 20k rpm with a quarter inch bit. I've seen feed rates in MDF being up to 4x as high as in plywood, it cuts like butter. I have a 4" (two blade) tool for the Moulder, which the manufacturer recommends running at 9k RPM. When running at 2k, you'll get severe backlash and I literally had smaller workpieces fly through the shop because of low RPM. So in essence: start with high RPM and see what feed rate works best for you. Then lower the RPM until dust turns into small pellets and the wood doesn't burn anymore. Did you make plans on how to do the assembly already? Glue and clamp? Kreg screws (those will not work well in 1/2" MDF, I didn't catch what thickness you got)?
  24. While you might burn the wood and dull the tool with too much generated heat (when moving too slowly for the set RPM), it's more likely that you get backlash when feeding too quickly with low RPM, which is more dangerous in my eyes. A firm grip on the router is important and imo the tooling should allow for almost any feed rate. RPM and feed rate and their relation differ with material, tooling (diameter and shape, amount of blades) and eventually the desired surface finish. There are great feed rate/rpm calculators, which should get you a rough idea on your settings. The chips should not be dust, it should be small grains.
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