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Ricci's Skhorn Subwoofer & Files

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Has anyone built one of these with MDF? I remember seeing someone mention it, although I can't remember who, that they didn't recommend building these with mdf. I was curious if there was a reason besides ugliness and weight.

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I don't think anyone has but you could. I wouldn't advise it for actual touring use but if they won't be moved that much it should be ok.

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2 minutes ago, Ricci said:

I don't think anyone has but you could. I wouldn't advise it for actual touring use but if they won't be moved that much it should be ok.

That's what I was figuring, I just didn't want to find out the hard way that someone made one with mdf and it came apart, lol.

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The material cost difference is minor compared to driver costs etc, just do it right from the beginning? From an assembly and bracing perspective I'd hate to do it with MDF.

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2 minutes ago, dsl1 said:

The material cost difference is minor compared to driver costs etc, just do it right from the beginning? From an assembly and bracing perspective I'd hate to do it with MDF.

True, the local Menards has 13 ply BB for ~twice-ish mdf, which would be fine, problem is, I don't have access to a truck anymore, and they want almost 600 dollars to deliver it. I can get Lowes to bring me 10 sheets of mdf for 59 bucks + wood. Both of the semi-local lumber yards I called won't deliver.

Honestly I don't mind mdf. It's only failed me once when a basement flood killed my lab12 horns.

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Wow thats crazy for a delivery charge. My plywood will cost me about $75each at the cheapest place for a B/C sheet each. SO things starting getting expensive when you need multiple sheets. Its also why I havent started my Skhorn yet. Baltic Birch would probably cost me about 200 a sheet. SO ya I tend to build a lot of things also in MDF. :)

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Same here, I've only done 2 sets of speakers with ply, always worked with mdf. 

I know it "feels" cheezy to use it on something like this. Going to try to get a quote from one more place that dsl suggested, but if it goes too far into 4 figures, I'll be using mdf, because I straight up can't afford it, especially if there isn't a specific reason, I.E "it's going to blow apart at the seams at S1." Ugly / 400lbs / not water resistant isn't high enough on my priority list to warrant twice or thrice the expense, normally.

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Also glad to see you got a quote you can live with and building it out of great ply.


Ricci is it best to ask Skhorn "versions," questions here. And will you be looking at designing a single driver version?

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On 9/15/2017 at 3:16 PM, SME said:

An 18" behind your couch?  That's a joke compared to what two Skhorn's will do.  IIRC, @Beastaudio is running *one* Skhorn these with together with 8 x 18s to handle the ULF.  If you are using these for home theater, you could probably just plug  a port or two for more extension.  If you make them easy enough to remove, you could even switch back and forth depending on content.

Naw. Only 6 18's with two of them being HST-18's nearfield to keep up. :D

 

On 9/15/2017 at 3:32 PM, DrDyna said:

They may end up being used for theater, but probably not very often. Primarily I'm just after pretty damn loud with low distortion. To date, the only subwoofer I've built that impressed me were the lab12 ths I built. Been building and chasing for about 20 years and I've mostly stuck to simple vented cabs, but the th is happier playing up at levels I find fun, so rather than build yet another vented cab that'll get me into the 120s sweating bullets, these are more likely to get me grinning. If I end up missing that bottom end, I'll start ordering 24s for next year's fun time.

 Swapping the plug in and out was one of the things that caught my attention when I started looking at this. Do I want dubstep mode or metal mode? Hmmm...

You are correct though, I'm sure the output will far outpace what a single sealed 18 would do, even at 1 foot from mlp distance. I'll come up with something, eventually. If I even miss it.

 

On 9/20/2017 at 10:54 AM, Ricci said:

Really freaking loud with low distortion and a side of Rocky Balboa TUFF is exactly what this cab is about.

This wasn't really made for being in a domestic space nor for use with only 1 vent per side open. That said IF it is used in a house the gradual roll off of having only 1 vent open might work quite well with room gain. I wouldn't be surprised if there is still more output than needed and managed to get down to 15 or 16Hz. Even with only 1 vent per side open it still has the equivalent of 2 5.25" ports or one 7.5" port. Personally I'd start with the 2 vent mode if using one in a home but I'd definitely try them all and see what works best. I just can't see using all of the output from normal 30Hz tuned / all vents open in anybodies home, so using the lower tunings seems like it should be worthwhile. 

Brandon or Ti,

Did either of you play around with blocking the vents?

I made a "two vent block" the same time I made the one vent block but have never tested it out either. I know with one vent plugged I can get dead flat extension to 20hz as anticipated. No need for any shelf or anything. The rolloff profile seems to fit perfect for that. I keep meaning to mess around with the 2 ports closed mode but end up just tweaking what I have to get it ever more dialed in. switching the plugs out would toss all that out the window. Many cold months ahead however, so I will be spending much more time tinkering. 

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Hello guys,

I have a pair of 18 Sound 18lw2400 laying around. I was wondering if my drivers are suitable for the skhorn?

I'm considering either this skhorn or a simple BR tuned to 32hz...

 

Thanks

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I'm not sure if they will work or not. I will run those drivers the next time I have a chance.

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12 hours ago, Ricci said:

I'm not sure if they will work or not. I will run those drivers the next time I have a chance.

I just happen to have this comparison. That is the 21SW152 max SPL verse the 18LW2400 Max SPL. I can show a 1 watt for the LW2400 if needed. The 2400 does roll off sooner as you can see.

Screen Shot 01-10-18 at 06.16 PM.PNG

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Well that doesn't look too bad. Of course the 18's aren't going to have the same amount of headroom as the big dog 21's...

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I would suggest, if you have the room, build the Skhorn. Build some adaptor plates in case you decide to upgrade. PLUS when using the 19hz tune you want have to worry about port noise with the 18's.

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On 1/12/2018 at 3:26 PM, chrapladm said:

I would suggest, if you have the room, build the Skhorn. Build some adaptor plates in case you decide to upgrade. PLUS when using the 19hz tune you want have to worry about port noise with the 18's.

Would port noise not have a direct coloration to spl as apposed to driver size?

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On 1/15/2018 at 6:51 PM, menace said:

Would port noise not have a direct coloration to spl as apposed to driver size?

You would have some port chuffing with the 19hz tune and using the 21's. BUT since the 18's dont move as much air as the 21's you will most likely be fine with 19hz tune and using the 18's. Thats what I was saying in my earlier post. 

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Is there a way of explaining how is it possible that the sensitivity of the speaker to be 107 dB at 100 watts/ 10 meters at 100 hz? I've tried everything to get that sensitivity in Hornresp and Akabak but with no results.i usually get a play response from 40 to 120 hz at about 102 dB. The rising response is not present in any simulations, except if I take into account the directivity increase at higher frequencies , but even with that, I can't seem to duplicate the results. 

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I'll have to get back with you tomorrow on this once I'm on my PC and can look at it in more detail.

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I've managed to get this sensitivity curve when I simulated the acoustic load of the air around the enclosure, as if it would be another waveguide with a very rapid expansion, but acting on the enclosure . In fact that, coupled with some acoustic resistance in the enclosure, higher losses through friction, increased viscosity in the port and enclosure gave me the most similar response. 

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First post around here. *Yay*

Rad, I think you can attribute both the rising response and the high sensitivity up top to directivity. Under sane and normal circumstances, the highest sensitivity you can reach in half space is 105-106db. Of course, in quarter space, you can add another 6 to that. The bigger the baffle is in relation to the wavelength, the more the source will be seeing a quarter space scenario. (Then ofc you might be able to see another db of sensitivity here or there, caused by diffraction off of the edges of the baffle.)

This right here is a pretty neat little piece of software: http://www.tolvan.com/edge/help.htm
It calculates the gain caused by the baffle. (It also does calculate what kind of a passive crossover you'd need to compensate for the baffle gain.)

Toying around with that software(doubling the height of the cab to emulate a half space scenario), I find that the baffle adds about 1db at 30hz, rising to a 4,5db addition at 100hz. That should explain most of the phenomenon.

Untitled.jpg

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Welcome to the forum Moar!! Thanks for the link. I did not have that program.

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20 hours ago, radulescu_paul_mircea said:

I've managed to get this sensitivity curve when I simulated the acoustic load of the air around the enclosure, as if it would be another waveguide with a very rapid expansion, but acting on the enclosure . In fact that, coupled with some acoustic resistance in the enclosure, higher losses through friction, increased viscosity in the port and enclosure gave me the most similar response. 

The more detailed Akabak simulation that I have is a closer match. HR is great but it doesn't have enough segments and other options available to sim the more complex enclosures as well as I'd like. I should probably update my HR Skhorn record and see if I can get it closer to the measured result.

As far as the sensitivity measuring much higher than the simulation that is common. Nearly every sub I've measured comes in at least a bit higher than the sensitivity from the sims would suggest. I have long suspected that directivity may be part of that. There are also all of those other intangibles, like the driver behaving slightly different than the small signal parameters, inductance effects, resonances inside the enclosure, vent behaviors, etc.

Are you using ABEC3? Care to share a bit of your simulation? I find ABEC3 extremely tedious to use due to all of the scripting required, so I avoid it most of the time.

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Welcome Moar!! Thanks for the link, it is a very useful tool. I needed that in my life ;)

Playing with it I've been getting very interesting results, some of them really incredible. Even from a single enclosure, the Directivity starts to go forward even at very low frequencies like 40 Hz.

This made me go out in a parking lot with 4 single 18 subs and to take directivity measurements.

  

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Testing the Directivity index of different configurations of subs and summation. Wow!! With only 4 single 18 in a square stack, one gets a huge front to back directivity.
I've tried a single, double vertical, double horizontal, 4x 2 by 2 stack, 4 tall and I forgot about 4 horizontal but I was already frozen by then. 
On axys , 90 deg, 135 and 180 degrees off axis, at 1, 2, 4 and 10 meters.
Well calibrated mic , ECM8000 with absolute SPL calibrated from a B&K 2270 to 0.1 dB ( hard work to do that unfortunately, I'll get a new mic very soon), Focusrite Scarlett 2i2, REW with loop, 20 meters from any wall, sweep measurements and RTA. I also did CEA2010 bursts , maximum SPL and loads of fun!
Plus some playing with a closed enclosure loaded with dual 21Ipal isobaric series.
Amplifiers were a FP14000 clone, one Crown XLS 2002 and one Martin MA2.8.

I'll need to find a way to post pictures here, I have some graphs, I have 130 measurements , I'll make some plots , some excel work on them.

@Ricci yes I am using ABEC 3 but barely. It is way to complicated for now and I don't pretend I am getting any easy progress. I have an Akabak script on my older laptop (it doesn't run on Windows 10)  that I could copy and post or send to PM. It is not very detailed but with the additions I managed to get a higher Directivity and a closer response.

  

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