Ricci

Right but that's unloaded. Clipping will occur at a lower voltage into a low impedance. If I recall the 6k would be something like 95volts into 2 ohms.

Not sure why my post got deleted by my browser. I forgot about the HR input picture from the first post. I will be building the Skhorn with a pair of 21SW152's. I unfortunately have to wait for BC to build the second 21 in Feb. So that will be another 1.5 months until I get the speaker in hand. I will be using Penn Elcom handles for my build and possibly the SP4000 plate amp. I will be amp limited but I cant afford the SP6000 plate amp for another 300. This amp will already be pushing my budget but I would like to try the SP amps. If I need more SPL I will just build another cabinet.

With a 4000 on those drivers it will be plenty loud for a single cab. Actually that should be about perfect for the cab if you block 2 ports for the 25Hz tune. 80-85volts with the 2 drivers in parallel. You won't quite reach xmax with all ports open but it will be significantly louder than an Othorn anyway.

Since I dont have the input screen for HR on this sub what wattage/voltage should I aim for per 21"?

Post #1 has the preliminary cabinet inputs in HR for a 21. Subject to a bit of tweaking depending on how the finished version measures. Should be close. Change the driver parameters depending on the driver wanted.

As far as the amplifier required it depends on the driver used and how they are wired. With most of the drivers I've modeled this should have about 1 to 2dB sensitivity advantage over an Othorn from 35-95Hz. It will make a lot of noise with just a 500w amp. If you were to put a pair of B&C 18PZB100's in there and plug some ports to drop the tuning a 500w amp should be a decent match. If using the 21sw152's or one of the other big neo pro 21's and you are looking to get everything out of it a 4-6 kw rated amp should get the drivers near xmax or slightly past. Of course cutting that in half to a 2-3kw amp only loses 3dB.

What I'm saying is you don't have to use a 6000watt monster amp on one of these. It is a sensitive cab so it's going to do a lot of work with even a limited amount of power.

New 4K tv to watch while working in the shop?

32 handles for 2 cabs. Didn't realize till I went to buy them. At least I got a price break for so many.

Oh damn that's just what we need! A few pebbles scattered about the room. What are we thinking with bass traps, measurement systems and modern dsp? Simply strategically place a few minerals and instantly get that last 1%. Only $99 too. What a steal.

Yeah a bit more listening. Really like it. Both this and the Othorn do something right that I'm not sure how to quantify.

It's probably the extra speed and slam these designs offer.

I spent months making sure these would be super ultra mega fast and airy sounding. On my first prototypes I actually had too much speed and I found out that the cones were breaking from the G-forces involved in stopping and starting so quickly. In fact one of the early prototypes exploded into a flaming inferno when I fed it 1.21 giga-volts and the air friction inside the cabinet became too great due to the extreme high-speed and airiness. The sound was so tight that the bass notes stopped and started faster than my ear drum could respond to the pressure changes. It was almost like the bass wasn't even there. I'd actually created a bass system that was too tight with too much speed. In fact these new cabs would often need delayed by 3 or 4 seconds so that the HF from the tweeters could keep up.  A lot of this had to do with the arrangement of the panels inside the sub that create the particle vortex processor chamber and high velocity, phase recombining, acoustic injection system.  After a lot of tweaks I finally have it detuned to a point where it isn't weaponized and is safe for domestic use but still maintains every bit of the speed and tightness almost 73% of the time.

Very very cool. Glad to see you are making some progress.

Yes have a UMM-6 calibrated mic. Let me know what you'd like to see. 

I know you're busy but if you get a day to mess around I wouldn't mind seeing a close mic of a vent and of the horn/slot both with no processing. Also an in room at the listening position would be cool. It's going to be a few months probably until I'll be in a position to take my own measurements so I'm really curious how close it turns out to the models.

Done any more listening?

I'd agree that the Skhorn type of cab is easier than an Othorn or GH. The simple plan is attached. Adjust bracing, hardware, drivers, hatches, cab width to taste. That's really all you need to be important with is what's in the attachment. The rest can be adjusted to your material or tools, etc. That's really all there is to it. Get the port panels and the short slot horn path/driver baffles correct and built out from there. Even those are more tolerant to inaccuracies than with a TH or FLH. Most of it is figuring out how to get the drivers in and out and brace the damn thing.

I did the original Othorn and GH files with cnc in mind but more people seemed to build them with regular tools so the dimensions on the cnc print all had to be adjusted and I ended up with 2 prints and sets of assembly files. Also each cnc shop will likely have to make tweaks and adjustments anyway due to their particular setup and tooling so it just makes more sense to do a single print that can be built by the regular Joe's with table or track saws and let the cnc shops make their own adjustments needed. They would usually have to anyway.

Yes , I like it a lot. The driver is backwards and stuck to the grill to increase cooling.I simmed it and it can get 142 dB în HR from 31 hz with only band pass filter and 3 PEQ entered.Quite easy to set it. port particle velocity at 50 m/s so not bad.at the mouth it will go to about 28 m/s and that will act as an efficient cooling method. The efficiency is very high, more than 12% from 33 hz up in singles

Want to share the HR model you cooked up?

Retail price on the PK? I'm going to guess $10K each.

That should be about right. SW's estimates about 180 for the empty cab. Another 10-15 lbs if all hardware is used. Add another 5-10 lbs or so if a plate amp is used. Looks like one using all the handles, pole mounts, hardware, duratex'd, plate amp with the dual Ipal's should come in right at or just under 300 I'd guess.

Hey dsl1,

Here's a rough stab at suggested signal processing. This is based on the model only and could probably be improved with actual measurements. Do you have any way to measure the response?

Anyway.

EQ 194Hz , q 5.0, -7dB

Low pass filter, 3rd order or steeper. 60-120Hz depending on taste / system.

High pass, 3rd order Butterworth 24Hz with all ports open, 3rd order Butterworth 20Hz with 4 ports open.

That's great man. Can't wait to hear what you think of it. I've never even heard one yet.

I'll try and get you some suggested filter settings today. It was just a high pass at like 25 and a single band eq notch for that peak above 150. I'm not sure how large that will be since HR tends to exaggerate peaks a bit plus the low pass should knock that well down too.

Another brand that I know off of using this design principle (except KV2 ) is Traktion Sound , a small company with some interesting looking subs and speakers.

http://www.tractionsound.com/loudspeakers/bps221-harpia.php

They have a separated sub for 30-40 hz with dual 21", probably very efficient in the pass band and another for the rest of the range ,smaller with dual 18".that is probably a very good approach for best efficiency.

Where do you keep finding this stuff!? LOL. That's another company I've never heard of.

BTW it seems like Bassboss might be the old Bassmaxx renamed? I had heard of them.

That's

Band-pass horn in Othorn dimensions on the market ALERT!

http://www.bassboss.com/subs/vs21-rum-punch-sub/

About 2 db less than the othorn though.

I

Interesting. Yep that sure looks like what my half a Skhorn would have. Too bad they don't give you any real info on the vent tunings or the raw response shape. The one response shown is processed I'm sure. The response specs are quoted after dsp too.

Seems like a good time to be in pro audio. The cabs out now are way past what was available 5-10 years back. Looks like a full on arms race is going on. Prices are shooting way up accordingly as well. Pretty easy to spend $5K on one active cabinet these days. Of course it's not like one of these Skhorn cabs is cheap either. Figure a pair of 21sw152's, a SP-4000 plate amp, wood, duratex and hardware. That adds up pretty quick.

Couple weeks!? I was thinking Saturday

Awesome!

Back in action + a bit of progress.

Hell yeah. At this rate you'll be putting power to it in a couple weeks.

That sounds dreadful indeed SME.

I'm going to see Rogue One tonight at the local Regal cinema. I know what to expect. Little support of the low end to speak of, some harshness on the loudest scenes and quite loud playback overall. In fact this theater seems to be borderline too loud for some people and kids. On the other hand the video quality isn't too bad and the dialog always seems to be a bit hot but at least it is heard.

One way to up the challenge a bit is to dive deeper into these huge cabinet designs that are fun to model and every once in a while build.  One great property about acoustics is the ability to scale things.  Maybe burn some late nights working out what a sliced fraction of such a design would look like, what parameters are needed for a 15", 12", or even 10" driver to maintain the same response?  Might any of those parameters be something you can find?  The suitable smaller drivers might not have the same excursion, but things might get interesting if you can actually use multiple units.

 

No matter the type of alignment I'd say that being able to scale most all the performance qualities to be an interesting challenge.  Ricci mentioned the Bose boxes earlier, and ironically the 6th order bandpass was a now expired Bose patent.  Sometimes looking at designs in a different scale or with different technologies we stumble on some fun possibilities.  If you can make a $1 driver sound impressive in something the size of a briefcase, what can you do if that's the size of a refrigerator with high excursion parts?  Similarly, maybe when scaled down there are parts from a different market or application that you wouldn't have bothered modeling, but in fact the math suggests it scales nicely in some interesting design. 

 

Personally I still would love to have the time to create my concept of a subwoofer system using 3 or more bandpass designs intended to blend together into a multi-way subwoofer with the ability to place each bandwidth in efficient locations.  The upper 1/2 of the bandwidth really gets interesting when you look at small modules and bandpass designs with significant gain.  Of course getting better results than just a pile of compact sealed subs always comes back to the execution.

 

Excuse the diversion, back to big obscene subs. 

Good points. What if you were building a 16cu ft cab for a single $500 18". How do 2 15's a few 12's or even a bunch of 10's or 8's compare in the same space? Things like that.

It's often easier to find the smaller drivers with specs that are closer to what is needed. They usually have a smaller voice coil so inductance can be lower and the smaller SD makes it easier to find drivers with a moderate to low Qts. Cheaper to replace if one blows and multiple smaller coils to share power often ups the long term thermal handling substantially. Way back when I was working on improving the GH I had a mocked up version using 6 Alpine 10's. Looked good really. Sad thing was the 6 SWR-10D2's were slightly cheaper than the single 18" LMS driver. Little bit heavy with 6 of them though and I found the issue with running drivers in series along the path length of a tapped horn.

People talk all kinds of crap about Bose but they have some of the best engineering talent around. it's just that their team is often given the task of making the most out of the absolute cheapest drivers that can be bought in order to maximize profits. They do a good job with it. I almost feel sorry for them not ever getting to use their skills on the transducers themselves. If they actually had a chance to use a $100 (At Bose cost) bass driver instead of ones that literally are probably <$5, they could probably do some impressive things.

 

Sent you an email Ricci.

I didn't forget. I'll get it to you eventually.

With the lower priced 18's with lower xmax it's not going to take that much amp. Now with the 21's with 15mm or more xmax yes it is going to take some amplifier but still nothing crazy. It's not like you need a bridged clone or anything. 1 channel should be plenty

Look closely at both sims. There are 2 responses. One with all vents open going to 30Hz and one with a vent blocked on each side which extends to 25Hz. Thats probably what is being seen. Like I said I expect the tuning to come in a hair lower on the real thing.

Chrapladm I like the new 18RBX100 B&C for the budget option. Send an email if you want.

I need a cnc...Jealous.

Less pressure in the throat actually. 2 drIvers with 2x the throat area but the drivers are not pushed as hard individually. Plus the horn doesn't load down as far.

Are you doing a single? Going to run drivers in parallel or in series? 4ohm or 8 ohm drivers?