Ricci

That should be fine. The mouth or driver acc3ss hatch is always the weakest spot with most traditional tapped horn folds. Usually they can sit on that panel in use. 

The file attached here is the most up to date. V2 has doubled bracing as shown in the attached print. The original had less internal bracing.

Moar!!,

I used measured driver specs with complex inductance parameters. I have them so those are what I use.

Of course there is correlation between harmonic distortion and large spikes in response. This is a well known phenomenon affecting any speaker (vented resonances for example). In this case the 3rd harmonic isn't high enough to worry about. The second harmonic accounts for nearly all the THD 100-120Hz but it doesn't break 10% until it is producing 134-135dB at 2m outdoor ground-plane which is extremely loud. A typical low pass filter would decrease the output and power demands in that range quite a bit. I've not noticed it in use.

Low pass filtering does increase delay. However with less low pass filtering slope your putting more power into the cab at higher frequencies. The same holds true at lower frequencies as well.  I think the issue with many of the worst sounding bandpasses or higher order cabs is that as designed the bandwidth is extremely narrow, perhaps an octave or an octave and a half and they have ringing and other energy storage issues. You end up with what is described as the one note sound. Then you throw the filtering and other EQ on top of that and you end up with a smeared mess before you ever put them into a room, which further makes a huge mess. I've tried very hard with the Othorn and Skhorn to make subs that have an extended & smooth response over a large range and that have very well damped behavior.  They are not as absolutely loud as they could be because of it. However I think the tradeoff is worth it because they sound nothing like the typical higher order cabs I've had experience with. I think a lot of others would agree.

When I say "room" in this context I don't mean someone's living room. I mean everything from a church to a night club to an auditorium to a theater to a huge arena. Most of the time subs will not be operating outdoors or in a huge stadium or arena, but will be in some sort of small / medium venue. These are still rooms with boundaries. In a lot of cases the subs will be back up against a back wall or corner, under a stage, flanking the stage, part of the stage even, flown up near the ceiling, ground stacked etc. There's a lot of variation.

Vents and maximizing output at the low frequency corner...If you assume that we have enough upper and middle range output and efficiency and need the most output at the tuning area and follow this thought process you will end up with direct radiating vented subs. They will always have maximal use of cabinet volume for the vented chamber and maximum vent area versus an alignment which loads the front of the drivers. It should also be simpler. Assuming you keep the cabs the same total size of course. I thought the advantages of this alignment overall outweighed the slight loss in maximum output near the tuning frequency and the extra build complexity. If you want maximum vent loading and output near tune go standard vented.

ELC and is a whole other area of discussion that should probably be handled elsewhere. It's a study of how our hearing perception works not how we should be hearing things. We don't need to correct for it. 30Hz is not supposed to sound as loud as 500Hz. It's been covered in some good discussions on other forums like AVS and DIYaudio.

The specs on that Lavoce do look good. Mentions Klippel derived parameters, gap and coil dims look solid and a shorting ring in the motor. Price is lower than most other pro 21's with similar specs. I've never used a Lavoce product. 

On ‎8‎/‎14‎/‎2018 at 2:18 PM, Moar!! said:

Ok, so I finally got some time to reply.

Ok, so I drew out a quick sketch by hand. This would be the layout. I don't see how anything doesn't fit in there.

In the above drawing, I took the same design volume as in the Skhorn sims and drew it into the same final design volume that the actual Skhorn is. Now, the sim volume and the actual volume within the actual Skhorn differ by some 65l, according to your numbers (18.35ft3(519,6L)vs584,3L) but for comparisons sake I've done as I have.

I've also skipped the one inverted driver in the above drawing, for fear of getting a drink accidentally tossed into the front chamber, sploshing about around the driver motor. *shivers down my spine*

Here are the inputs of the design that I've drawn:

Try to put these inputs in HR, put a 27hz 3rd order low pass and a 70hz 3rd order high pass on it, and compare it to the regular Skhorn sims with a 25hz 4th order low pass and a 68hz 3rd order highpass on it, with a 197hz 3q -10db EQ on it to pull that peak down.
One will find that the two designs are incredibly close as far as phase, group delay, excursion and driver power goes. The inputs above has a slight output edge near 35hz in the sims, otherwise the response is identical. The efficiency shows that the design above doesn't emphasize output around and above 100hz as much, and that it emphasizes 25-40hz more instead. 
As far as the points above goes, would it be worth it to redo the whole design because of them? Hell no. 
Where it gets interesting is in the points below though:
It has less output above 100hz, so it rolls of the response where the bulk of the distortion is , it's an easier build (no angled cuts), it's better boundary coupled (0,25-1db more output forward and hence also less backwards), it's a bit more force cancelled, and it's got bigger ports for less compression and less vent noise (20% less port particle velocity).
All in all, it should make for a design that fits well within the size of the cab, is a bit louder, a bit cleaner, and a bit easier to build. All in all, I think it's a good idea for a slight development of a design that people clearly have a VERY good time with! 

I looked at the sim and it is quite close below 80Hz.

This one should have less efficiency and less output above 40Hz on paper. It should have a bit more output near tuning. I'd say the original sims as being the slightly bit louder cab overall for music apps or live sound (kick drum, percussion fundamentals, most of the content being above 40Hz etc.).

I've found over the years I like smoother responding wider bandwidth systems vs systems optimized for more sensitivity over a narrower band of operation. This is part of the reason I decided not to do a straight slot. I wanted extra upper bass output and extension well beyond 100Hz as part of the design goal. Often times you'll see guys using subs for 30-70Hz and another set of kick bins for 70-140Hz or whatever. Usually due to sub bins with degraded upper range behavior or just not enough output. I'm not a fan of that approach. I'd much rather have one cab that can handle everything. I think the sim you proposed would be fine. I tried to get the top end as extended as possible on this one.

Another reason I didn't choose a large straight slot was to more fully enclose the drivers inside the cab. Most of the time I notice non harmonic mechanical and operational noises before HD gets to be offensive. The acoustic roll off of the slot above 100Hz should help lower HD a bit, but with the driver cone edge only 10" from the end of a large slot with line of sight to the outside world I'd expect there to be more operational noise leakage, though HR doesn't show too much of a difference. I'd like to see that tested actually. Also the drivers would be a little more susceptible to rain or a drink spill, but either arrangement is safer than a direct radiator cab!

I didn't go with a push pull driver arrangement due to the minimum clearances needed for the drivers  (10.5" driver depth + a large dustcap and +40mm excursion worst case scenario minus some for the baffle thicknesses and depth to the dustcap below the frame plane) and the fact that most high excursion sub drivers make quite a racket from the motor and suspension when pushed hard. Even more of a reason was the uneven loading it would present on the drivers. It would be much more involved and difficult to design the cab to evenly load the drivers with one inverted. Not impossible but it would complicate things. I'd give a rough guess that there would be about a 25-30L difference in the vented air volumes seen by the drivers. Tuning would be slightly different unless compensated for and the throat area would be a concern. I know this has been done in plenty of cabs before but I don't know if I trust it with the kinds of pressures that can be developed inside something like these. I didn't think the potential lowered even order distortion outweighed the concerns with uneven loading and possible mechanical noise from the inverted driver motor. The forces inside these can be pretty ridiculous.

The force cancelling works really well on it. It's not like the drivers are 90deg rotated from each other or even 45deg. It's only a 12deg offset and it's a 250+ lb sub. In use the cab has  no perceptible rocking from the driver operation. That small amount of offset from exact opposition plus the sheer size and mass just doesn't add up to any real rocking forces fore and aft. Technically I'd guess a perfect driver opposition would measure a bit lower with an accelerometer but in practice it worked like expected and it's a complete non issue. Regular old panel vibration and bracing is a much bigger concern. The Skhorn has been quite good as far as that is concerned when compared with most other large cabs, but this is always a battle on big subs with tons of output.

About Edge and directivity. Keep in mind that the math is simplified and goes back to the point source mic placement method. If the radiating points are spread on one sub and focused on another you can never truly get the same mic distance from the two. In practice there is a very large area that one is trying to cover usually inside of a room with boundaries. It's complicated. One sub is more diffuse but that's not necessarily always a bad thing. Edge is a good tool but I don't get too caught up in an apparent half dB advantage here or there. Most of that directivity happens above 80Hz unless the baffle area starts getting truly large.

One way I like to think about this is with 2 different philosophies. The first would be maximize the baffle area for the cabinet (think DTS-10 shape or similar) and get as much out in front of the cab with the drivers and design as possible. However at what point does this become impractical? Let's say the cab has a 60x60" baffle and is very shallow and gets some extra forward gain over a very similar design with the same driver which has a baffle of  30x30" but is much deeper. At some point you run into limitations in available depth to use and/or available baffle area. How many 60x60" baffle cabs are going to be able to be arranged? In a lot of cases not too many and eventually you just need more cabs and drivers. You could fit 4 of the 30x30 subs into the same baffle area as the 60x60 that would outperform it. The best case as far as potential output density per baffle area goes is that one entire face of the sub is radiating surface area. That's not going to be the best for directivity control though. You also end up with deeper cabs to get your cab volume. Tradeoffs.

Vent area is vent area I'll give you that as an advantage for sure. This is the #1 priority I would have when redesigning the Skhorn. Mostly to work better with the lowered tunings. I try to avoid turns in vents when possible though. The reduced area of the slot for the drivers would increase air velocity over the horn expansion type though. I have some new thoughts on designing vented subs that I haven't gone to far with yet but I'll share once I think it through a bit more.

Anyway that's part of the thinking behind not doing the straight slot or push pull drivers originally. It all comes down to tradeoffs and design choices. None of it is black and white it's all grey area and what makes sense for each case.

My point was when you are satisfied that you have the best simulation for the goals, design the finished speaker. You may find that what seems good in theory isn't practical to implement when it comes time to fit everything in the box. 

 I considered everything mentioned during design and decided they weren't worth the effort, were impractical or overly complicated to fit in the cab dimensions, or came with other compromises that outweighed any potential benefit. In my opinion of course. With a clean slate and a different cabinet shape or dimensions who knows...Someone else may prioritize entirely differently. 

BTW I'm not saying these are bad ideas. They are worth considering. It is difficult to get everything you want into the final product sometimes. That old issue with compromises needing to be made. Etc...

Yes data is for version 1. I never built and tested v2. It should offer some minor improvements but they are incremental not game changing. Acoustic performance differences should be relatively minor. I'd suggest the Othorn or Skhorn for live sound or reinforcement. 

MOAR! 

Only 1 person has built a modified version which is Paul. He scaled it up. Mine is intentionally very dense. I think you'll find it is way easier to do a 5min sim in HR that "beats" something else. Once it comes time to design the finished product is where the rubber meets the road. There are reasons I didn't do many of the items you mention and I wouldn't make most of those changes if starting from scratch for various reasons, but I've already looked at all of this during multiple designs. At the end of the day there are a lot of considerations in cab design that have nothing to do with the acoustic sims. It would be interesting if you designed the cab and built it. 

Awesome stuff Jesal. Sh50's I've heard a time or 2. That should be a great combo. 

Great. What drivers Are you using? Are you going to paint it? I see you have wires running out the port. Do you plan to add a speakon terminal?

That is going to be a HUGE sub...

Very cool Paul. Keep us up to date on your journey. You have helped me get my interest in a half version back. Perhaps I'll get time to finish it off this year.

So Paul...Are these  Skhorn+ cabs just to play around with or are you going to be using them for "work"?

I wish more people had the chance to hear these.

Interesting. I had no issue with the bracing on mine but the original version is smaller. I was quite happy with how solid the cab design turned out. Opposing the drivers helped a lot too. 

I really like the sound of this cab too. A little odd that 40Hz seemed soft to you. Mine kill at 40Hz. Perhaps it has something to do with most pro subs being tuned closer to 40Hz and vent or mouth velocity

17 hours ago, radulescu_paul_mircea said:

The deep end is imense. I have a pair of xoc1 TH18, we got 2 Vs 2 with their own processing and limiters on a K10 and the 2 large SKHorn got +10 dB on a 2 minutes average pink noise dBz and +18 dB at 30 Hz .

That's what I'm talking about... So you would still be a little ahead overall vs 6 Xoc1 TH18 and still no comparison down near 30Hz.

What do you think of the sound subjectively?

What type of alignment are those? TH?

On ‎6‎/‎30‎/‎2018 at 10:31 PM, maxmercy said:

I can see this, by correcting response at one location, you create problems and ringing at others.  

 

How can 'precise' correction of a reflection be 'corrected' for many locations?  The peaks and dips will occur at different freqs depending on location from the speaker..

JSS

Good questions. Your first comment is why I stepped back from excessive amounts of EQ and trying for "perfect" graphs, even ones taken over large areas and averaged.  They usually sound very bad despite looking great and allowing forum bragging rights. Notch type high "Q" equalization is especially bad to my ears usually.

I bet the F121 or 221's get loud as hell but that's a big, heavy cab for only a 43Hz corner. Doesn't look like they'll do much <35Hz regardless of them being a FLH. On the positive it looks like they meet or exceed their sensitivity specs which is rare to see. I'm kinda surprised the "SkhornXL" matches or exceeds the sensitivity below 67Hz despite a corner 15Hz lower.

Which drivers were in the cab for this measurement? Ipal's?

One of those looks quite a bit better as a subwoofer to me.

Hey Paul...yes I modeled that out of curiosity after the MAUL debacle with series "loaded" drivers. Yes if you change the driver specs  some differences arise but what you have shown isnt too bad. Dont forget about how quickly suspension bits start to tighten on these pro drivers  after 10 to 15mm. Not to mention the BL loss. The driver excursion should even out at the limits. Its fine for me. YMMV

On ‎6‎/‎20‎/‎2018 at 4:02 AM, radulescu_paul_mircea said:

@Ricci

Did you have any problems linking the drivers in series on a single amp? From what I get in sims and in free air tests, the excursion goes mad if the parameters are just a bit different on the 2 drivers. Also the loading can change the behavior

 

I did not with the 21Ipal's. It performed as expected. Tested it to the limits of the amps with a SP-6000 and also a K20 bridged. In all 3 tunings to boot. No issues at all in any use or test I've thrown at it. There are a few other guys with these now as well and they've not reported anything either.

If it bothers you a simple addition for peace of mind for the Skhorn layout is to simply add a 1/2" solid panel from the front panel to the back. It would literally be two completely isolated cabs in 1 box if that is done. You would have some slight changes in the upper end response due to changing the "special sauce" a bit though. Nothing to worry about there.

On ‎6‎/‎11‎/‎2018 at 1:56 PM, thebuckaman said:

Quick question, can both the 4 or 8 ohm versions of the B&C 21sw152 and 21DS115 be used in the SKHORN? Any difference in performance between the 4 and 8 ohm versions?

 

Thank you in advance.

4 ohm are a little better according to modeling due to slightly higher motor strength / lower Qts. Both should work though.

Looks like mission accomplished to me. Response shape is good. 30Hz is absolutely hammered.

The 21Ipal will take a beating and those impedance mins pull a lot of current. Not surprised the amp gives up first. I ran the K20 bridged into the 2 ohm load which is in no way recommended. It operates decently but same as the FP amp it does not like the huge current dump required and protects out.

2 hours ago, SME said:

A 45% on Rotten Tomatoes isn't, like, "Conan: The Barbarian (remake)" bad.  And it looks like it's not terribly long either.

Something like 103 minutes of constant wind noise?

Never bring that movie up again...? 

I absolutely have a soft spot for the original Barbarian movie with Armhold Musclehugger and James Earl (Baseball Vader) Jones. The soundtrack is the shit. The new one was such a fail on so many levels.  

103min of wind noise might be right...

2 hours ago, SME said:

LOL!  If it's too loud, you're too old!  It's like the equivalent of an SPL car in a listening room.

But seriously, it's hard to argue with this point.  If he actually ran the bass so hot as to use all the Othorn capability for movies, what's the point of having the Terraforms?  Or are you trying to talk him into buying another 12 of them?  

I know right?...You know things are bad when I'm trying to be the voice of reason for someone's bass habits!

But seriously...I'm thinking sell off 8 Othorn cabs and 4 21's. Use that to help fund 2 Skhorns with the remaining 4 21's which will damn near be = to 4 Othorns but less cubic volume than 3 of em. Use the new found space to bring in another 4 Terraforms to BEEF up the <30Hz. WIN!

I'm kidding sort of but 8 Terraform's and 2 Skhorns does sound like a hell of a system.