Ricci

It is complicated. The key word here is subjective. IMHO there really isn't a wrong way. All that matters is if you like the way it sounds. I'm not necessarily talking about just bass balance or response shape with these comments BTW. We've all heard people wax poetic about the goal being to be transported to the live performance. This is an impossible fools errand IMO. The live performance from who's perspective? Front row, stage left, right, dead center? Most recordings these days are created with a totally fabricated sense of space and "venue" by the recording engineer anyway. A lot of the content is totally computer created. You could say that you want to recreate what the recording or mastering engineer heard but this will be very difficult too. Most studio control rooms are as variable as our own systems. I've been in my fair share of them and very few of them are totally flat on axis, with controlled directivity. The amount of room reverb and the room size vary a LOT too. Mixing balance, quality and artistic expression is all over the map on top of that. If you personally like more bass, less treble, a mountain of mids, whatever...Do it.

Yep. It's a ripole. There's some good information on them at DIYAudio forum.

Crispy coils are what's for dinner! Sorry to hear about that Tahoe. PL380 is a serious amp. How many Skrams do you have? All 21SW152 loaded?

Careful using slow sine waves for this type of testing. It's a good way to cook a voice coil.

I've been busy with other things and haven't done much related to bass or subs in a long time. I still have the 2269H and some other drivers that I need to GP test in the sealed cabs at some point. I may get back to it next spring. Maybe not.

I don't use a HPF with sealed subs either in testing or my systems. I'm careful during testing to not push the level too high and in my systems I try not to have enough amp on tap to bottom the drivers with the box size used.

I'd echo SME here. The Othorn is still a very good sounding design but I'd consider the Skram instead. It's smaller, lighter, has flexible tuning options and is simpler to build. Output and SQ should be the same if not a bit better due to the more extended top end. Issues don't start till higher in frequency that the Othorn.

Been there myself...Sucks.

You could do something similar and shrink the cabinet and slot volume somewhat to better fit the 18". The 18 doesn't need as much airspace to work in.

I'm not entirely sure what it would be for the SI 24's. The cone holds a lot of volume but the surround is huge and protrudes a lot unlike the pro drivers. Also the frame is really thick on these and it'll be front mounted which moves the whole assembly forward quite a bit. It may actually be less than a back mounted 21" pro. This is probably a good generic guess. AVH...300-350cm2 for each driver should be added to S2. This is used rather than Atc/Vtc. It has a better track record, in my offset designs at least. Also the AE drivers have extremely low inductance. I doubt the complex inductance modeling will make much difference at all on them. I wouldn't worry about it. Yes the inductance modeled correctly would be slightly more accurate but it'll be a very small difference on these. These are the exception rather than the rule for bass drivers.

Are your FR measurements above after EQ? If so do you have any from before EQ? The waterfall indicates the decay rate of the sub in your room. It looks like you have a bit of a resonance at 27Hz, 42Hz. Not bad though most rooms do. Seems like you might have a bit of ground hum at 60Hz...

Hello Enrique... What is your budget for the subwoofer? What would be a maximum size you would like for the sub? LxWxH?

I see. Very cool. Have you had a chance to fire them up yet? Any issues with vibration?

You mean the 18DS115? In this cab, or? I'd recommend the 21 for this cab.

Also...To reiterate, most of the parameters are directly linked to, affected by and calculated from others. None of them really exist in a vacuum. To further complicate things these are known as small signal parameters and many of them will shift greatly once the driver is subjected to large signals. Subs in particular operate with what would be considered large signals.

I wouldn't bother with triple thick baffles. Most of the vibration reduction would be from coupling the drivers through the cabinet walls in the opposed arrangement. Double thick baffle is good for counter sinking, but not really needed for strength in most cases.

This is from the MK1 HS-24 so I'm sure the MKIII has had some tweaks made. In the absence of the complex inductance data for the MKIII I'd suggest using these specs. It'll be closer than not modeling semi-inductance as it's pronounced in these Plug these into HR by double clicking on the LE box. It is activated once the label turns green. Measured Complex Inductance Parameters Re' 3.572 Ω Leb 0.951 mH Le 14.868 mH Rss 74.784 Ω Ke 0.451 sH

SME answered well. It's complicated. With almost any driver the performance starts to degrade as it is pushed to higher excursion. This really cannot be answered with a single number like xmax that mfg's try to use. The 21Ipal will go to about 30mm one way if not a bit more if you REALLY hammer on it but it does not sound good by then. It gets cleaner at 20mm one way, and again much cleaner at 10mm one way than 20mm.

Cool!!! How thick is the acrylic? How is it going to be fastened to the wood? I don't see any screws?

As long as the volume of the ported section and horn section stay the same. Also the port area and length must stay the same. The horn length also must stay the same. The Beyma drivers are supposed to be good but they are a bit light on motor force for these cabs.

Here's my random thoughts. Shorting sleeve is mentioned but the 1kHz Le rating is way up there at over 2X the Re. Also the shape of the impedance curves shown indicate a very sharp increase in impedance vs freq above the minimum imp above resonance. Indicates a lot of inductance also. Heavy 5" coil and a huge motor with lots of steel. They have not posted the Zma data for download yet, which would allow it to be analyzed with Bolserst's semi inductance excel program to back out the semi Le specs for modeling. Shipping weight is listed at 115lbs. I suspect these drivers are in the 90-100lb range. Two or 3 times as heavy as the pro 21's. Can't see anyone using the Vortex 21 for pro audio work with that kinda weight. Drivers that heavy are a PITA to deal with especially in multiples. Imagine a double 21... Both drivers seem to be nearly identical. They model almost exactly the same except that the Vortex has slightly higher efficiency and upper bass due to the lighter mms. Most of that is probably just from switching surround types and perhaps the cone or dust-cap. The rest of the spec comparison and specs lead me to believe that the motor, frame, coil and spiders are identical. It's possible that the roll surround is much better behaved at high excursion than the traditional pro type (less noise more linear). If not I don't see a reason to pick the Kraken other than if you want that type of look. The Vortex is higher sensitivity and efficiency with apparently the same amount of excursion and it's a tiny amount lighter. Judging from the cutaway pics it looks like the top plate is about 15mm and the coil is about a 45mm wind height. Coil overhang would give 15mm overhag with no adder. 1/3rd gap adder would put it at 20mm one way which is close to the claimed spec. The coil would leave the gap at 30mm one way. Unless there is a lot of fringe field and overshoot the maximum excursion is done there and also sound horrendously distorted by that point. Of course I'm speculating based on an un-detailed drawing but this should be close. Spiders don't appear to be mirrored. There is mention of a warning system to prevent damage. I believe this is the ring shown under the bottom spider sticking up above the top plate. Looks like the bottom spider will contact this a few mm before the bottom triple joint would contact the top plate. This will probably sound very bad but not be immediately damaging. It looks like the bottom spider triple joint would contact the top plate around 30-32mm in. I'm guessing the spider will contact the ring around 27 or 28mm incursion based on that. Since the coil would leave the gap completely at 30mm I don't think it will be easy to push these drivers that far anyway. Spec wise I think these look good. They have a low Qts and high efficiency. EQ is used on everything these days and the goal is usually more bass from less space. The pricing also looks good especially in multiples. My biggest gripe would really be the 100lb weight followed by the question mark of how bad the inductance is.

Should work fine with 4 8ohm drivers.

Let us know how it goes. On both accounts.

I did. The old 7560's which I believe were the same as the Crown M600 and a couple of other re-badges. It's been a long time but it was something like 1500w burst into 4 ohm and 1000w for a very long time and would do it at 20Hz. Doesn't seem like much these days. These aren't really amplifiers intended for "music" signals. These are industrial grade equipment for labs, measurements, running motors, MRI's, etc. HEAVY loads. They do audio just fine but are WAY overkill for bumping some music. Kinda like taking a Mack tri-axle dump truck to pick up 100lbs of mulch. I love how they rate their amps and provide all of the engineering specs. Compare their data sheets to those for Behringer or Yamaha amps. This is how gear used to be spec'd. I wish it still was. Amps really should be rated in terms of voltage and current capability into various loads at different frequencies IMHO. A 7810 or 7796 is a monster power source even if some 20lb amps produce more power on paper. The ratings are MUCH different. Yes they are heavy as hell. They have to be. You'll never get this type of ruggedness and sustained power output out of a 20lb amp. If I was filthy rich I'd have a stack of these installed on 3 phase to run the subs, just because.

This would be an interesting design. If you can try to use at least a 6" port for each driver. (180cm2 area). Dual opposing the driver will keep cabinet vibration down from the reciprocating driver mass.