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Ricci's Skhorn Subwoofer & Files


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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 c

Here's the design I'm going to be using to replace my Othorn. It's been "almost" done for a long time now but I finally made an effort to wrap it up to the point that it is ready to build. Originally

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

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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.

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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.

 

Good work! That's a lot of testing :)

 

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?

 

Very cool you did the active version measurements as well. Congrats on another fantastic design Josh!

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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? :rolleyes:

 

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

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

 

I was thinking when I looked at all the results that must have been a brutal day of testing or spread out over many days of testing. Heck, I think just testing all the modes of a variable tuned sub is a pain in the ass, and what you tested took many times that amount of work. I hope you wore sunscreen. Anyway, great job, and incredible sub. 130 dB at 30 Hz is insanity! bravo!

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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.

post-5-0-00967100-1492628554_thumb.jpg

 

 

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.

post-5-0-23004200-1492629120_thumb.jpg

 

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.

post-5-0-93065100-1492630700_thumb.jpg

 

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.

post-5-0-58641700-1492631371_thumb.jpg

 

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.

post-5-0-02045000-1492631673_thumb.jpg

 

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

post-5-0-95717600-1492631762_thumb.jpg

 

 

 

 

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.

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Hi Josh! Very interesting design thread to follow. Thank you for that

 

With drivers more similarly priced to the 21sw152(21ds115, 18xl1800?) Would there be any benefit using skhorn rather than othorn?

 

Will be interesting to read your notes!

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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

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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.

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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. :(

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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.

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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.

 

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?

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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.

 

Bolded part: for real! Just when the getting gets good, they start making funny noises. Time to double or quadruple up on subs again. D'oh!

 

or

 

 

M.A.U.L dat shit

 

Heheh... nice post, Josh. Always good stuff, my man. :)

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Bolded part: for real! Just when the getting gets good, they start making funny noises. Time to double or quadruple up on subs again. D'oh!

 

Don't tell me you are having this problem with your wall-o-bass.  Are you?

 

The obvious solution is to have my listening room with its enormous room gain at 20 Hz and a ways above.  I don't need to build horns when my room behaves like one with sealed sub.  My problem is that I may break something if I try to push as high as I can go.

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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.

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Don't tell me you are having this problem with your wall-o-bass.  Are you?

 

The obvious solution is to have my listening room with its enormous room gain at 20 Hz and a ways above.  I don't need to build horns when my room behaves like one with sealed sub.  My problem is that I may break something if I try to push as high as I can go.

It was more of a general statement of circumstance.

 

Of course, like you, I mostly get room noises when I push it hard.

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