StainlessSteve

I just want to say something that's been bugging me. RMS means Root Mean Square, and it applies to AC Voltage or AC Current, in converting them to their equivalent in DC, because they alternate and DC doesn't. But watts are watts, AC or DC, so there is no such thing as "RMS watts". https://en.wikipedia.org/wiki/Root_mean_square Rant over. I would suggest simply do not turn up your speakers to the point where you hear distortion. Listen for port chuffing, woofer breakup, etc. If you smell your coils getting hot (which you will if you put your nose up to the port while playing at too high volume) turn it down. But for the most part, finding an exact limit is pretty much impossible without burning or bottoming out your speakers. There's a good chance that automatic EQ adjustments considerably lessened the maximum output power of your amps by reducing the input signal. This is very common with auto-EQ methods, but you can always turn it off, see if it gets considerably louder without touching the amp gain knob, then turn it back on and see if it gets quieter again. If so, then you found your problem. Don't get a bigger amp if you could already push these speakers to destruction with that amp (which I'm sure you could). Instead, just manually EQ using REW or other software. Or if you have the money, pay someone to do it for you. Good luck, -Steve

That box is 34.6 cubic feet, or 16 cubic feet larger than the original, and the "passive all vents open" results show 125.6dB at two meters at 25hz. I would expect there would be more output capability with a bigger amp, but if not, there's not an improvement in terms of output per liter per any frequency.

I edited it so it is just thunder: https://drive.google.com/open?id=1dmN4q3OXe12GgiBEeOInnNC5YkMYPluF

Here's an FFT of the file you edited with the touching removed:

Yeah, I have no idea what the popping is at the beginning, it seems to me to just be a user-end CPU/RAM problem because I mostly hear it in Adobe Audition and only sometimes in some parts. I think I did touch it later when you said to make sure it wasn't wet but I went through and edited all that out to make a version of just thunder, so I figured it would be better if you had the full version.

Yes, meant to post that up top, so I edited it. Here is a link to a recording I did: https://drive.google.com/open?id=1eG0YMrh_eD0DW5hvtKOJJGttlsO0PmsD Hour 16 minutes, 16 seconds long and 157mb.

Yes, I have heard all the Danley recordings. I do have a few recordings of different thunder with Adobe Audition I took, but I can't figure out how to record with my calibration file loaded. My only idea is to convert it to a Spectrum sound card calibration and record with Spectrum Lab. My sound card and falls off starting at 20hz, and my mic falls off at 4hz, which means the loudest note was below 4hz and there is even more sub-20hz content than I could capture. I've attached my mic calibration and the Spectrum Lab sound card cal format: elf_compensator.frs narrow_band_response_0_degree.frd

Here is a RTA of thunder I took with my calibrated-to-4hz Dayton EMM-6 and a TASCAM US-1641 which starts dropping off at 20hz. The mic was inside a window behind the curtain with its windscreen on and SPL is uncalibrated but it clipped my mic just when it hit that peak at 4hz, and I had my mic at 3/4 of gain, so it was a pretty loud peak. The second image is with no smoothing was taken during the RTA. The first has 1/48th octave smoothing and is the total peak. I live far out in the country so there are no sources of infrasound from vehicles or factories except for a very low level 14hz tone from a glass plant about three miles away.

Oh, my apologies Mark. I didn't realize you were so knowledgeable in the area of the tapped horn.

Without room gain eight of those cabinets would be able to hit 153dB at 40hz according to Ricci's measurements, with room-gain that would be even more. I would love to see some measurements! Lukeamdman hit 152dB at the listening position with eight ported Incriminator Audio Judge 21 and two Ipal 21" Othorns. And if anything else beats that (besides Tom's sonic boom generator) it might be popalock's 32 sealed 18"s and two sealed 24"s or Leons who built eight ported HS-24"s alongside his four LAB subs.

Since Tapped Horns have their horn section defined by the location of the front and backs of their drivers, they do not entirely benefit from extensions. This is the reason that their response shape doesn't change when with multiples, unlike front loaded horns. This cannot be simulated with hornresp as the cabinet use all five available segments. Akabak would be the easiest way to simulate it that I know of, but I don't see an advantage. Don't mean to be the bearer of bad news.