Ricci

This is looking great.

I must say I'm a little skeptical of the planned signal processing you have going on in the bass range... Boosting + subharmonic generation? I know you are packing as much as you can into this tiny enclosure but it sounds like the woofers and amp will be operating at or near their limits most of the time with all of that processing. Heat buildup, long term reliability and thermal shifting / compression may be a concern with a jam packed and completely closed off internal airspace. I guess you won't know until you try it.

Did you end up with the AT woofers?

How about something in a pic to give scale to these?

I'm back to work on plans for a single driver version of this. It's going to lose 6dB maximum output and 3dB sensitivity of course but I think it'll be ok. If I chop this cab exactly in half it would be a 24x27x32" enclosure.  I'm thinking I might upsize it just a bit to get a little more vent area and airspace for the driver. Perhaps 24x30x32 or I might go all of the way to 24x32x32. That's still 4" smaller in 2 directions than the Othorn. I'm debating on it because the smallest size / weight possible is a big plus but so is maximum performance.

Are you making fun of the business I started?

Haha...I don't know, is the amp mounted on the back of the heat sink really a 20w chip amp dressed up like an SP? 

You're just jealous you didn't come up with that fleecing business idea first. LOL!

We're in the wrong field. We need to be selling $10 to $20 items at 100x the cost! Let's see how can I sell a $20 woofer in a $30 cab with a $50 amp for $2K retail???

Here's another thought:  "You used ultra-high end audiophile drivers in a CAR AUDIO enclosure?!?!" 

That's right! I wanted that car audio boom with the audiophile clarity. I have some cable lifters coming that should really help tighten things up that final little bit. Got a deal too, only $7000 for them.

So I heard these for the first time.

They are more than wonderful. That system goes down to 27hz clean and immensely powerful.they are so loud I was shocked. I heard the Danley BC218 last year but these are in another league.

Really? I've been hearing that the DBH218 is a really good cab.

Now that I have *finally* heard the driver, I have to wonder what one of these using UH-21s would be like. 

It would suck terribly. It would be hollow sounding, boxy and bloated. Lacking in dynamic capability. Poor definition, punch and texture. Boomy as all heck. Notes lingering around for 2 extra beats. Smelly bass. Just plain shitty.

You know just your average bandpass fart tub.

Any plans to test AE subwoofers or Bill Fitzmaurice bass horns like the table tuba or THT?

I've unfortunately had issues with my AE TD18's since day one, so they have never made it to high power testing. In fact I've got one with a scraping former right now after working fine for a year or so. Been like that for a few months and I haven't even contacted AE yet because I'm kind of over it. Maybe some day. I already know they are not going to be deep bass, or power handling champions. I really like them when they work, so it's not a big priority to torture test one and potentially have to get it reconed again.

I wouldn't mind evaluating a THT or one of the other ones but I'm for sure not going to build one to do so. Someone would have to loan me one for a while and no one has ever offered. Same thing applies to some of the DIYSG flatpacks, McFly subs, or LilMike's designs. I'd do it but I'd need the subs provided to me.

For sure. Just add drivers until you've got way more headroom than needed and that takes care of it. I do still run sealed subs at home and I don't have issues with driver noise, but that's a 3,500cu ft room and it's easy to do that in such a small space. Move to a 60,000 cu ft space, outdoors and move back a good 30ft from the cabs and it's a different deal. Gotta match the tools to the job.

Before I had the GH's and Othorn's I had 4 XXX 18's sealed in the warehouse room and it was just not the right type of system for that. Just wasn't loud enough and took way too much amp. I'd have probably cooked them after a while just trying to get adequate output. I knew that going in but it was a temporary stop gap while the horns were being built.

IPAL loaded that is I presume? Does it dance around in it's own footprint or do the dual-driver-config cancel the forces out?

There's very minimal cabinet movement even when being driven hard thanks to the opposed drivers. Even though they are a few degrees off from being perfectly opposed it works quite well. That was a major goal for me with this design and part of the reason I didn't do half single driver cabs right off the bat. The Othorn and to some extent other powerful single driver cabs have a tendency to shake quite badly at high output. When you have 500g oscillating 25mm peak to peak 40x per second that exerts quite a bit of force into the entire cabinet structure. Even 200lbs of mass will shake around easily with that bolted to it. The Othorn has a bit of a "hop" to it in the vertical orientation.

Are there any noticeable SQ differences between this and the Othorn's.

 

 

As has been mentioned many a times and then general consensus is that the Othorn's were "great sounding". Do the Skorn's seem any different SQ-wise or is all about the same when you have this kind of fire power (no nasties til the ragged edge)?

 

 

I put quotes cuz I've still never heard them.

I like the sound of both. I'd say they sound fairly similar below 60Hz. I'm going from memory on the Othorn cause it's been a while since I heard some. Seems like the Skhorn design sounds a little smoother up top. That shouldn't be surprising since it doesn't have the little peak at 110Hz that the Othorn does. I always EQ'd that down but there is no need on this one. I don't know, all the measurements say the Skhorn should be at least as good, but since I don't have both on hand for direct comparison, it's all guess work. One thing I like about horns and this cab is the output is high relative to driver excursion and the driver is buried in the cab. That was a big part of this cab was that the drivers are completely inside so you can't hear mechanical noises from operation until beating on them hard. Direct radiators just always seem to start developing some non-bass noises right when the output is getting to the level wanted. There's still vent noise to contend with but I haven't figured out how to defeat that one on a cab with this much output yet.

Basically you have huge headroom, relatively low power levels needed, very low distortion at sane playback levels, good decay rates, reasonably smooth response up well past the crossover and all of the output is from horns or ducts so driver operation noise is buried in the cab. It's a recipe for a sub that can sound great and be fun all at the same time IMO.

I'm still waiting for Ti (Dsl1) to let his rip in his living room...Still can't believe he has that in a house.

Possibly. I'd expect 2 Othorns with Ipals to have a slight advantage right near 25 to 35 but that's about it. Of course two Othorns is 50% bigger than one of these cabs too.

The 21ds115s should be more of a straight up comparison to the 21sw152 loaded Othorns so we will see. I did run some music through it with the SP amp last night in the warehouse space and the amount of headroom and slam is unreal.

I'll be testing it with 21ds115's this summer. That should tell us quite a bit. The other drivers don't seem to lose much sensitivity so it will really come down to maximum output. The powerhandling will go down some but I'd still expect one using even the budget 18" options to be comparable or better to one Othorn while using less amplifier

Here's a little comparison of the Othorn and the Skhorn. I've had a few questions about how they compare.

When designing the Skhorn I knew it would exceed the performance of the Othorn but thought it might fall a bit shy of equaling two due to the cab only being 50% larger than an Othorn. After looking at the data I think it came closer to equaling or in some ways exceeding a pair than I thought.

Sensitivity comparison: 10 meters which is more accurate in general with large cabs like this. 20 volts into the Othorn (3.85ohm min imp) and 14.1 volts  into the Skhorn (2.15ohm min imp). I've included the Skhorn in both all vents open and 2 vents open configuration. The overall sensitivity is quite a bit higher for the Skhorn in both cases. With a pair of Othorn cabs (adding 3dB) it would be even or slightly better below 50Hz but still quite a bit less over the 50-100Hz octave. Also I prefer the response shape of the Skhorn with its smoother, slightly rising  response up to 150Hz. It should make processing and blending to the other speakers easier.

This is the starting level for the long term sweeps for both cabs. The Othorn starts at 1.21 volts input. That calculates to about 0.38 watts into the 3.85ohm min impedance at 28Hz. The Skhorn with all vents open starts off with a 0.74 volt input which calculates out to a coil melting 0.25 watts input into the 2.15 ohm minimum impedance at 63Hz. The higher level sweeps are at max level for the Othorn, at the 130dB at 50Hz sweep with 121 volts input, where driver excursion and thermal handling are at the limits. The Skhorn measurement is also at the 130dB at 50Hz sweep but is still relatively comfortable at this level. You can see how the Othorn has started to compress relative to the Skhorn.

This is the maximum long term sweep achieved by each cab. The Othorn is being driven at 121 volts which calculates out to about 3800 watts being applied into the minimum 3.85ohm impedance at 28Hz. The Skhorn cab is probably receiving about 113 volts. The measurement asked for 131.6 volts from the amplifier but it was steadily clipping and did not put out that much. 113 volts would correspond to roughly 6000 watts into the 2.15ohm minimum impedance at 63Hz. The Skhorn has 2 drivers so each would be seeing "only" 3000w at most. The Skhorn likely could have went another 3dB further with this type of test but providing enough amplifier to get there really isn't feasible.

This is the amount of output compression occurring during the maximum level sine wave sweeps from the last graph, when compared with the minimum base level measurement. The Skhorn performs better here as expected from having 2 drivers. The output is only compressing by about 3dB or less even with the amplifier causing some of it itself. The Othorn is compressing around 4-6dB in some parts of the bandwidth.

CEA-2010 type testing with the bridged Powersoft shows much the same trends. The Skhorn offers quite a bit more distortion limited output especially above 40Hz.

This is the maximum short term output recorded for each speaker.

The data above indicates to me that the Skhorn performs pretty close to a pair of Othorn cabs. The Othorns could potentially still have a bit more output around 25-35Hz, depending on what vent configuration the Skhorn is in and the amps used, but this is expected due to the larger enclosure volume and a slightly higher sensitivity for a pair over that range. From 50-100Hz the Skhorn seems to offer a significant advantage even over a pair of Othorns and that's a very important range for sound reinforcement / music. There also appear to be some advantages on the basis of cabinet vibration / stability, less overall size, frequency response through the crossover region, distortion and spectral decay.

Hey Dave. Yes I need to get one of those. Doing a little testing yourself?

Thanks ShadyJ. Yes it was one very long day and I did get sunburned. Multiple tune subs are a bitch to test. You got that right.

I think this might be the one to finally take to the local bass competition. I really need to do that someday.

Did I not put gasket tape over the hatch braces on yours? That was my original intention, think I may have forgotten on yours. Screwing them in is probably a better idea once you're happy with everything. Sounds like overall your hatch bracing design worked pretty well? Not too much vibration on the hatch panel?

 

Did you figure out a nice way to block the air leaks from the port blocks?

I'm glad you put the gasket tape on yours. I totally forgot to mention that.

I'm going to use liquid paper or something to coat the ends and put the hatches on to mark their placement. Then predrill the hatches, put gasket tape on the brace stubs, bolt the hatches back on and then predrill the stubs and screw in. What's another 4 extra screws on those hatches?

Port blocks turned out well just screwing them in with a bit of strategic gasket tape.

I'm happy with it.

Long term testing done...

All vents open 30Hz tune. With SpeakerPower SP1-6000

2 vents open 25Hz tune. With SpeakerPower SP1-6000

1 vent open 17Hz tune. With SpeakerPower SP1-6000

1 vent open 17Hz tune. With Powersoft K20-DSP Bridged as typical Data-Bass test to compare against SP1-6000

Burst testing done...

All vents open. With SP1-6000

2 vents open. With SP1-6000

1 vent open. With SP1-6000

All vents open. With bridged K20

2 vents open. With bridged K20

1 vent open. With bridged K20

This took something like 12 to 14 hrs in a single day.

The K20 testing is the usual passive cab Data-Bass testing

The SpeakerPower SP1-6000 (Single side of a SP2-12000 actually) was used to see what the performance would be like when using an amount of power that could be built in as part of a finished system.

Basically this cab took 4 sets of sine sweep based tests and 6 sets of max burst tests back to back from these amps all day. It'll take a serious beating. Probably the worst abuse I've ever subjected a single cab to in a day and it just kept on without a hitch.

It's sensitive, really efficient and loud as hell 25-90Hz. Distortion is pretty good over that range too. Anything beyond that frequency range is kinda gravy. The response shape came in close to what I expected from the advanced modeling. Quite smooth and extended for a high order loading like this. The cab is really dead and inert.  I did have some noise develop from the hatch with the speakon jack around certain frequencies with extremely loud sine sweeps, but I figured out that it was the wires resting on it and the brace stubs buzzing against the hatch. Those are supposed to be screwed into, which I somehow forgot to do. I suspect after wrapping the wires with some foam and screwing into those points through the hatch  it'll be cleared up. As expected it performs best with all vents open or with 1 vent blocked per side. Running it with only 1 vent per side open works, but it gives up 25-50Hz output and the single vents get overloaded badly around tune. I could get obvious air noise out of the vents but it was much worse with only a single open on each side. Of course that's all with test signals outside. If a more realistic playback level was used with normal content it could work. As expected the weakness is the amount of vent area and the limited airspace in the vented chambers. I think I like the performance with 2 vents open on each side the best. I'll probably run them that way most of the time.

Done!!! Well except for what's going to be a freaking novel worth of notes. I'll get to em when I can.

It's LOUD. That should do for now.

I'm trying...Information overload trying to get everything ready and uploaded. I'll probably get the measurements put up and write the book worth of notes later. Got testing with JTR imminent too.

Actually no. All I have is one 18 on hand.

Do we know what scene has that huge amount of <5Hz content? It would be a very rare system indeed that can do anything with it. Even with a BIG sealed system, transducers or IB the typical electronics roll off chain is going to be way down in level below 5Hz. Probably a good thing too cause look at the peak level on that at 1Hz!

PL definitely takes a few days to get it off your hands and any clothing will be ruined. Good stuff though.

Yesterday was the day. Spent about 12hrs testing the Ipal loaded version in every configuration with the SP6000 amp and the K20. It's capable and after the equivalent of 6 full tests back to back, I can say it won't be easy to blow one. It's going to take a while to get through all of the information in detail.