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Ricci's Skhorn Subwoofer & Files

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RCF LF21N551 arrived and tested. The driver is extremely well built, it is more powerful and efficient than my 21SW152 and the parameters better matches the SKHORN XL enclosures. The BL is pretty close to the specs, the excursion capability is excellent, with 18 mm gap and 39 mm dual layer inside outside coil, better but noisier cooling strategy. The triple point joint is reinforced with epoxy resin and the leads are glued to the spiders . The mechanical noise doesn't really appear even at 5.5 cm peak to peak excursion in free air but the turbulences are loud. I recommend it in these enclosures with all my heart.

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I've seen it, even posted in the thread. There are many ways to fold this style of cab up. There are a couple of other ones floating around also. Other than that I try not to comment on other people's designs too much. Many times they aren't ever built, or if they are there is never any reliable objective results shown. Who knows.

In other news I have picked back up on working on a single driver version finally. I've basically got the cab layout and fold nailed down. I just need to decide on bracing and hatch then put the models and print together which takes a bit. Hopefully I'll have it done by the end of the month.

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23 hours ago, lawbadman said:

Hey Ricci,

Will the frequency response for the single be the same as the dual version?

It will be a bit different. Not hugely but it is a different fold and layout. I increased the size a bit since I'm not worried about keeping it as compact as possible like with the dual 21 Skhorn. Same similar design principles to the MAUL and Skhorn but another totally different cab.

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2 hours ago, Ricci said:

It will be a bit different. Not hugely but it is a different fold and layout. I increased the size a bit since I'm not worried about keeping it as compact as possible like with the dual 21 Skhorn. Same similar design principles to the MAUL and Skhorn but another totally different cab.

Nice! Different port dimensions too?

 

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Yes...Different ports. I'll post more about it when I get closer to being finalized.

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Hi all,

We are thinking about building 8-10 of these, we are based in the UK and mainly cater for outdoor festival stages playing sub orientated dance music up to 2-3000 people and club events of around 1000-1500 people. 

Im slowly working my way through all the information there is on this design on all the various forums. While I am doing so I would like to ask some questions if that's ok:

What should I expect if i was to run a stack of 4-6 of these? has anyone done this? 

I can get very good deals on Faital Pro drivers, has anybody tried or got a sim of the XL1600 (I have 4 of these already) or the XL2000? 

Is it correct that the cab size is the same for an 18" driver and a 21" driver?

It is my understanding that the B&C 21SW152 is the best driver bar the Ipal, how much of a difference in output and low extension would there be between the 18" Faital and the B&C 21SW152? 

Some of these questions I'm sure there are answers to that I've not come across but though I would ask at the same time as reading as it could be quicker. 

 

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Hey Revolt,

As far as I know no one has run more than 2 cabs yet. This is a significantly more powerful design in a semi compact size than any others I'm aware of on the market. Especially in the 25-40Hz range. 6 or 8 should be devastating. The only things that are likely to compete or exceed these on a 1 vs 1 basis are Danleys largest most expensive subs like the BC415, TH812, or DBH218LF and other major companies top of the line largest, most expensive subs. M-force based systems, etc...As far as subs go you can accomplish a lot with cabinet design and " magic" ,but at the end of the day you need power handling, cone area and the ability for the drivers to move a lot of air via high xmax. Dual top of the line 21's are used for a reason.

The Faital 18's give up displacement capability, cone area and I've not simulated them or tried them in this cab. Out of what Faital offers the 18XL2000 is probably the best match without giving up too much output. I'd really recommend 21's though. The extra cone area helps out a lot. If cost is an issue the Lavoce SAN214.50 models very well. I'm not sure what it would cost in the UK but here it is very reasonably cost ($450 usd). I have 2 on hand for testing and so far it looks like a lot of driver for the money.

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29 minutes ago, Ricci said:

Hey Revolt,

As far as I know no one has run more than 2 cabs yet. This is a significantly more powerful design in a semi compact size than any others I'm aware of on the market. Especially in the 25-40Hz range. 6 or 8 should be devastating. The only things that are likely to compete or exceed these on a 1 vs 1 basis are Danleys largest most expensive subs like the BC415, TH812, or DBH218LF and other major companies top of the line largest, most expensive subs. M-force based systems, etc...As far as subs go you can accomplish a lot with cabinet design and " magic" ,but at the end of the day you need power handling, cone area and the ability for the drivers to move a lot of air via high xmax. Dual top of the line 21's are used for a reason.

The Faital 18's give up displacement capability, cone area and I've not simulated them or tried them in this cab. Out of what Faital offers the 18XL2000 is probably the best match without giving up too much output. I'd really recommend 21's though. The extra cone area helps out a lot. If cost is an issue the Lavoce SAN214.50 models very well. I'm not sure what it would cost in the UK but here it is very reasonably cost ($450 usd). I have 2 on hand for testing and so far it looks like a lot of driver for the money.

How does the Lavoce SAN214 compare to the 21DS115?

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2 hours ago, lawbadman said:

How does the Lavoce SAN214 compare to the 21DS115?


We will know that this summer.

 

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Thanks Ricci,

I will look into the Lavoce. Reason I was keen to know the difference between the 21 and 18 is because I can get 2x XL2000 for the same price as 1 B&C 21SW152. It wont be too hard to make baffle reducer to test the XL1600 that I already have and put them up against the B&C in an a/b test just to see if the extra £/$ is worth the difference in output. I can also get a good deal on 18Sound. Was looking at the 18NLW9601, how do you think it looks? I will be able to get some to demo. Also have you ever had any problems with drivers failing or over heating when running for long periods?

It looks like my cab builder is going to be making a start on the first pair next weekend so I will post some updates if people are interested?

 

 

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That might be enough for a small apartment, or so.

 

Jesus.

 

How much time is spent on time aligning all those speakers and ensuring a "great" sound stage?

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We have been tuning it for 5 years 😅 We spent a lot of time on it last year. There are a few all pass filters needed to align out of band phase and we now use FIR filters from about 500hz up. 

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On 2/16/2019 at 2:09 PM, radulescu_paul_mircea said:

RCF LF21N551 arrived and tested. The driver is extremely well built, it is more powerful and efficient than my 21SW152 and the parameters better matches the SKHORN XL enclosures. The BL is pretty close to the specs, the excursion capability is excellent, with 18 mm gap and 39 mm dual layer inside outside coil, better but noisier cooling strategy. The triple point joint is reinforced with epoxy resin and the leads are glued to the spiders . The mechanical noise doesn't really appear even at 5.5 cm peak to peak excursion in free air but the turbulences are loud. I recommend it in these enclosures with all my heart.

I can get a better deal on the RCF than the B&C. Did you try them in the SKhorn?

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18sound should work also, either the 21id or 21nlw9601. RCF lf21n551 Looks workable. 

Whichever of these 21's is most cost effective should work well for you. 

I've never had any trouble with burning up drivers in the Skhorn. Don't think anyone else has. Its got 2 drivers with the highest power handling ratings on the market and a decent air volume and air exchange rate. This was also part of my goals with the design. It will take quite a bit to overheat a pair of 1800w AES rated drivers. Unless you are talking about running a whole bridged amp on each one I wouldn't worry about it. 

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5 hours ago, Ricci said:

18sound should work also, either the 21id or 21nlw9601. RCF lf21n551 Looks workable. 

Whichever of these 21's is most cost effective should work well for you. 

I've never had any trouble with burning up drivers in the Skhorn. Don't think anyone else has. Its got 2 drivers with the highest power handling ratings on the market and a decent air volume and air exchange rate. This was also part of my goals with the design. It will take quite a bit to overheat a pair of 1800w AES rated drivers. Unless you are talking about running a whole bridged amp on each one I wouldn't worry about it. 

It really depends on the amp, musical content and limiting. Even a  pair of 21Ipal in series on a K20 amp channel can get overheated in pro audio use. A lot of heat builds up if the music content is centered around 50hz octave, near an impedance minimum. In this area , not only the driver excursion is minimum, but efficiency is pretty low, current input is very high and no air movement happens in the back chamber. I did an experiment where I put dance,pop, rock, hip-hop, reggae, etc music in a player and did a spectral content average, a long term FFT, with about 10 hours average and the 50 hz band is +7 dB over the rest of the low end spectrum (35-200 hz) , with 30 hz being 13 dB lower and dropping from there quite fast. That type of music sounds absolutely awesome on these subs but they heat up very very fast so the limiting strategy has to be well understood and used with care.

On different kind of music, like dubstep and DNB, the spectral content has a peak near 39 hz and 30 hz is -6 dB , a lot of under 30 content is present. This very well received by this sub, a lot of diaphragm excursion is present, the vents are working a lot and air is exchanged , so the drivers can keep on going, way cooler, way louder.

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Looking forward to the single driver cab.   I bet it's a popular design if it's easier to build than the othorn.   

 

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All speakers have inherent differences in power handling vs frequency. Its assumed that any serious outfit would work out limiting or amplifier matching depending on content/ use, amps and drivers for their individual case. It depends quite a bit on all of these factors. I can say that with my pair I've beat on them hard and haven't had any issues but I'm not banging off the clip / limiter for 12hrs with extremely compressed content either. YMMV.

If you have the ability to do true long term power averaging I'd set it to somewhere between 500-1500w depending on drivers to be truly safe but that is a absolutely huge amount of average power with typical music crest factor. Way more than it seems. If you are matching the amp rating to the recommended driver AES power rating range and not exeeding it or running consistently into the limiter it shouldn't be a concern. Running a 9kw rated k20 channel for all it is capable of into a single 21ipal loaded Skhorn with a driver power rating half that wouldn't be recommended. Some common sense is needed. Running about 2 to 5kw of amp per cab depending on the drivers used and application is about right. The amps would be clipping or limiting the peaks well before the average power is reached with normal music.

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We will be using Linea Research 44M20's to power these, Im planning to run 2 drivers per bridged channel at 4r. The DSP has 3 different limiters, voltage, thermal and Xmax. I usually use the peak rating for the voltage limiter and the RMS rating for the thermal limiter. I haven't played around with the Xmax limiters yet but its something I will defiantly use on these. 

Also I would like to ask if its is possible to make the cab 60mm longer? I was thinking to make the ports on each side 30mm wider so that 2 of our low mid horns stack perfectly on one SKhorn laying down on its side. What affect would this have on the tuning and performance do you think?

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If the extra 60mm is added to the vents only it would raise the tuning a bit. I'm not sure how much exactly but I don't think it would be more than a couple of hertz at most. Probably not a big deal.

I would mainly use the rms limiter and leave the xmax and voltage limiter set out much further. The drivers mentioned here typically will not actually damage themselves mechanically without severe abuse and they audibly let you know first. Also with the standard tuning and a high pass below 25Hz it will take a ton of voltage to induce over excursion. Peak voltages I'd likewise leave set way out. The cab will take it for short term peaks. The main concern is long term heating up of the coils so the rms limiter should be the biggest focus.

The Linea's look good but I don't have any experience with them yet. Seems like they are getting popular. Looks like that would be a good choice to run 4 Skhorns (or more) per amp. With 4 ohm drivers you can wire 2 channels bridged for a rated 10Kw into a pair of Skhorns.  

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Assuming I understand the dimensional drawing, the ports are 3" (76 mm) wide, so adding 30 mm to each side would make the ports 140% bigger in cross-sectional area.  Vent tuning frequency scales with square root of port area, so tune will be ~118% or around 1/4 octave higher.  That's like 35 Hz vs. 30 Hz.  This assumes a pure vented alignment, and I'm not sure how the 6th order aspect will come into play.

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The Linea amp is a serious power amplifier. It will sustain 900 watts continuous indefinitely and it will indeed give you over 5000 watts of power into 2 ohms for any useful length of time per channel. It is using IGBT on the output stages and lots of capacitors on the channel and power supply. I managed to explode the final stage of one 44m10 playing my SKhorn XL version using Ipal driver squire fast , but the 20K is way more stable in 2 ohms. The problem was bus pumping from the very high back EMF.

I would suggest you to used 4 ohm drivers and use each sub on each channel instead of bridging it . This way you will use all the DSP capability of the amp and you can make more configurations like cardio and end-fire. The difference in stability is not big, a bridged class D amp will be a tad more stable at high reactive loads , but the back EMF will discharge in the endstage instead of the capacitors so for the same output power , more heat will be generated.

In my tests ,a pair of 21Ipal in series will have higher minimum impedance but lower average than 2 *4 ohm drivers in parallel in the same enclosure. The average current is also higher because of a higher reactance , higher moving mass . So the stress on the amp is higher but a Linea amp channel will be well suited for it.

Regarding limiters, for pro use, I suggest to make use of all of those limiters. The X-max limiter is excellent to be used when you force the system and you hit the peak limiter or maximum voltage quite hard. It will help you with keeping the high pass where it should be no matter what the input stage is doing.

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