Ricci's Skhorn Subwoofer & Files

[thebuckaman]

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.

[radulescu_paul_mircea]

@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

 

[Ricci]

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.

[Ricci]

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.

[radulescu_paul_mircea]

@Ricci

Thank you for the reply. I am a bit concerned about that behavior, it is not related to the loading in the horn,but the behavior of two reactive loads linked in series, that see different voltages based on the difference in impedance and electrical phase.

Anyway, the subs are extremely potent, the content below 40 is so present and clean! I wouldn't be afraid to put them next to Funktion One F132. Unfortunately the clone power supply was not up for the task and after less than an hour with a sub on each channel, it died. Then I tested them with 2 Crown 5002VZ in parallel mode, each sub on a channel and the deepest bass was achieved , it could sustain 85 volts in impedance minimums without any sign of backing up, but the punch and headroom was smaller than with the clone. 

The next step is to completely change the bracings, build another pair, load them up with 21ID and IPal modules, buy a K20 and then compare them 2 vs 2 and see what happens, whichever is best. I bet on the K20+ 21Ipal combination but one could never be sure until I get the tests results. I would love to use these with SpeakerPower modules, each driver on its own amp, with 4-6 kw, because IMO , that's when the party is really starting. Unfortunately it's hard to buy them from the states.

[SME]

I don't see how a pair of drivers in series could cause a problem.  Three or more drivers, yes, but only two?

Anyway, I installed a 3/4" wall between chambers in my D.O. sealed sub because I was paranoid about local acoustic loading effects and wanted to option to possibly run separate signals to each end at some point in the future.

That pic looks great!  I'm sure your neighbors love you.

[radulescu_paul_mircea]

This is the excursion of two 21Ipal in series in the same enclosure, with the CMS having a difference of only 10% between them.

The place where I did these tests is a parking lot from an old factory where we have the workshop. It is surrounded only by other workshops and some offices that were closed at that moment. The parking lot is big, around 50 by 60 meters and if I go as close to the middle as I can, the frequency resolution is very good and I can get good accuracy down to 20 Hz.

[Ricci]

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

[SME]

In practice, how much does CMS actually vary in different manufacturing samples (assuming the same batch of parts)?  I know we see lots of variation when we attempt to do measurements, but that's not necessarily the same thing.  The value obtained may depend a lot on the details of the measurement, and the value is known to be quite sensitive to temperature and humidity.  Both of these kinds of things should be expected to affect both drivers equally.

[radulescu_paul_mircea]

Sensitivity referenced at 1W/1 m measured at 4 meters, 2.83 V in 0.5 ohms on BPH221 vs 28.3 V in two 8 Ohm F121subs 

[Ricci]

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

[Ricci]

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?

[radulescu_paul_mircea]

The drivers used are 21Ipal , yes . The drivers in F221 are an OEM combination from Fane with Precision Devices, neo driver. The subs are extremely loud , but not on their own .

I did some tests regarding the frequency response of a single vs double F221. The tests have revealed me something really cool. The magnitude response stays the same, it just goes up with 6 dB ,double the sound pressure, but the maximum clean output CEA bursts results go higher. Practically a better acoutic impedance will give better load and lower excursion.

Plus, the electrical impedance goes a bit higher on average so the real sensitivity for 1 W is increasing

CEA-2010 max burst, 2 m ground plane , measured at 4 and 8 meters to avoid mic clipping

1*F221 1 channel of ffa10000

25- 107.9
30-116.1
31.5- 118
40-133.1
50-135.7
60-137.1
80-143.2
100-142.6

2*F221, 2 channels of  FFA10000
25- 116.8
30-125.5
31.5-128.5
40-141.5
50-143.6
60-144.7
80-147.9

100-148.1

[MemX]

On ‎6‎/‎23‎/‎2018 at 11:56 AM, radulescu_paul_mircea said:

Anyway, the subs are extremely potent, the content below 40 is so present and clean! I wouldn't be afraid to put them next to Funktion One F132. Unfortunately the clone power supply was not up for the task and after less than an hour with a sub on each channel, it died. Then I tested them with 2 Crown 5002VZ in parallel mode, each sub on a channel and the deepest bass was achieved , it could sustain 85 volts in impedance minimums without any sign of backing up, but the punch and headroom was smaller than with the clone. 

The next step is to completely change the bracings, build another pair, load them up with 21ID and IPal modules, buy a K20 and then compare them 2 vs 2 and see what happens, whichever is best. I bet on the K20+ 21Ipal combination but one could never be sure until I get the tests results. I would love to use these with SpeakerPower modules, each driver on its own amp, with 4-6 kw, because IMO , that's when the party is really starting. Unfortunately it's hard to buy them from the states.

 

Would one or more of the Bossobass amps be suitable if the Clone amps are not up to it?

http://bossobass.com/Bossobass.com/Home.html

There is a description of the A14k on the Raptor page:

http://bossobass.com/Bossobass.com/Raptor Systems.html

but the Amplification page itself is giving me a 404...

http://bossobass.com/Bossobass.com/Amplification.html

 

I've not seen @Bossobass Dave for ages on here, though - is he still going?  Is he still selling kit??

[radulescu_paul_mircea]

I got myself a Powersoft K20 for these and tested them at full power for 20 hours,the amount of power and the stability that amp has is way way higher than what the clone or the Crown could ever dream off.

I set the limiters and processing and I installed them in a small club for further long term tests. 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 .

 

 

[Ricci]

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?

[radulescu_paul_mircea]

The sound is the best I have ever heard, including F132+F221 combination.

It lacks the 40 Hz punch a bit, there is a slight issue with that area when the drivers are in series. I need to take them out again and get some impedance measurements series and parallel to see if there is any difference at very small signals. I felt that 4 TH18 would match the output of two of these between 37-47 Hz. But yes, absolutely no match at 30 Hz. I get about 4.5 dB of compression on very long sines , 0.3-0.6 sec but no noises and the chuffing is pretty much absent. I would love to compare them to a set of KS28 from L-acoustics, Gravity 218  and 30 from PK sound and other subs that say they go down to 30 Hz.

I don't like that the hatches are not as solid as I would like and the bracings inside are very ineffective, I need to rethink them altogether. I'll probably change the whole thing to see what improvement I can make disregarding cost. Some aluminium braces, some very well rounded port ends, playing with driver position, some different new ways of cooling the driver even at excursion minimums to increase the life expectancy of the coils , thinking of some kind of net for safety on ports because now someone could throw a bottle inside an that would not be very helpful.

I am now very much interested in a larger version with the horn loading the driver lower and better . But the weight is already high, 165 kg , so we'll see.

 

 

[Ricci]

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

[SME]

A crazy idea I have is that there may be a psychoacoustic boosting effect around the area where the response is beginning to roll off.  So something tuned at 40 Hz will tend to emphasize 40 Hz a bit because of its roll-off shape.  Something tuned lower will tend to emphasize a bit lower.

[radulescu_paul_mircea]

From what I can figure out from the output prediction on Direct from Danley, this sub is on par with TH812, including efficiency, impedance graphs, response and SPL 

 

 

[Ricci]

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.

[radulescu_paul_mircea]

The idea behind this build is to learn. I started my company to sell subs, because here in this part of Europe, there is a very deep lack of powerful high quality bass 

Mostly I wanted to see people's reactions, the power density, the extension, to see if the weight and dimensions are a big problem.

They are now installed in a basement where we got them by hand.

I wanted to see about the power compression, port noises, chuffing, I have learned how and why to install protection grilles, handles, wheels, I wanted to see if I can improve their performance in any way without any other compromise except cost and complexity. I wanted to learn about braces, hatches, accessibility. These gave me a good insight on all of these

These subs will be loaded with 21ID and Ipal modules and will permanently stay in rent in a small club where people love good sound. Based on what I learned, I'll continue my other designs and after all 4 designs will be ready and I'll have a stock of 4 of each, I'll publish the specs, measurements, graphs , technical details , pictures and videos and I'll start selling those. 

 

[Ricci]

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.

[radulescu_paul_mircea]

The new sub design in grey vs this one including some power compression effects added as eq  , 140*140*70 cm so 40% larger.

I put 2 vs 2 because from my experiments with subs the response doesn't go lower when multiples are used but they can take more power with less excursion and distortions, so it is a bit closer to real world results. 

I'll use 7075 alluminum braces to save volume, add stiffness and decrease weight. The drivers will have 2 additional ways of cooling so in normal full power usage, it will closer to 2 SKH larger, but the same number of drivers and amp channels as one.

[Ricci]

That is going to be a HUGE sub...