peniku8

I'm not a fan of patch panels and breakout cables. More points of failure and more rack space needed.

Is your input limiter a multiband limiter or does it pull down the top end with the bass?

I usually don't run into tweeter issues, but also broke one once, which was due to old age probably (the surround shattered). My mains are ARCS WIDE, which have some pretty beefy B&C compression drivers in em I think.

1 hour ago, kipman725 said:

Symetrix or QSC or BIAMP DSPs do arbitrary signal processing with a flow graph approach.  You can download the software and design site files offline to see if it will work for you.  The Symetrix limiters accept side chain input which could simplify your signal flow.   Powersoft amps can limit on real power input to the driver.

I'm not quite sure why no one has developed an amp that senses real time voice coil temp from the copper/alu thermal coefficient yet but that should be possible (and guarantee driver survival from thermal failure).  A low frequency small amplitude excitation could be used to sense DCR.

Thanks for the suggestions, but they all seem to target an installation market with the phoenix connectors, I'd prefer XLR since the intended use is live sound.
It looks like every hunt for something like this leads me back to Powersoft. I've looked into lake processors, but they're big buck. So much so, that I'd rather just replace all my amps with Powersoft for ease of use and better reliability (over clone amps).
My clone amp is a dsp amp (10kQ amp section) but nothing but a peak limiter. I'm scared of letting DJs loose on the system.. without absolutely choking it in the first place just for safety concerns.. Maybe I'm just gonna do a few gigs like this until a bit more money came in and then go to Powersoft.. in late 2025 it seems, since Germany just been canceling everything everywhere for the past two years.

I'm looking for a system controller for a very specific setup: I need it in a EQ→Limiter→Limiter→EQ topology. Does this exist in some kind of modular dsp or would I have to cascade multiple units for this purpose? On the pc I'd just make a plugin chain as needed. Seems to me like hardware is a decade behind

Alternatively: are there speaker controllers which allow me to import an impedance measurement of my subs so they can properly limit according to power instead of voltage, so I don't have to build this myself with the aforementioned chain or EQs and limiters?

Excursion and moving mass mainly, both as much as possible.

5 hours ago, Poleepkwa said:

While this forum this seems to cater to subwoofers for pro-use, folks have been very helpfull and welcoming. Much appreciated.

You have a build somewhere on another forum? I tried to decouple the subs but since my whole backwall is open(and second floor), it did not help much. 

This also makes it  very hard to really pressurise it properly. The sealed Faitals do a good job, but it still lacks that "chest compression". That said I am still learning about EQ and setup so that might also be apart of it. I first.

I usually do not listen very loudly, so this Boss platform seems very promising for not much money.

I posted a few pics somewhere in this thread, but you'll find all the information you'll need in there anyways:

https://www.avsforum.com/threads/the-hideaway-theater.2991522/

I second the BOSS idea, I have tried it and it's really nice. You can build one in a way that it only elevates your seating by an inch if you want to keep it low profile. It won't make any noise, but will greatly enhance your bass 'perception'.

Mounting drivers to your walls is a bad idea, as the vibrations will transmit through them (unless they're infinitely stiff) and probably still end up disturbing others. De-coupling your sub from the floor with a rubber mat or foam works wonders sometimes too.

I used two jbl stage 1210 in my BOSS build.

6 hours ago, SME said:

The Sanway "clones" may perform better or worse than the similarly named Lab Gruppen brand amps.  I'm not even sure how closely the Sanway amps resemble the original designs.  The "clone" may just be in the branding.  It actually wouldn't shock me if the Sanway amps actually perform better.  Of course, I doubt anyone will be buying and measuring one of the original ones any time soon.

That said, while 130 ms might be OK for rock kick-drum, dub-step and related genres typically have bass with a lot more compression.  In my example track from above, the "average power is 1/4th of max" applies when I analyze the whole song, which has a few brief breaks from the sustained bass.  If I exclude those brief rest intervals, the average is closer to 1/3rd the max for passages that are a minute or longer!

This suggests that one should provision *a lot of spare headroom* into systems that play this kind of music and pay much more mind to long-term power capabilities in components.  For example, the 21SW152s may have an edge over the DS115s for such systems, and it's definitely important to know how much output an amp can sustain for those minute long sustained bass passages.  I wish there was an easy / straight-forward answer, but a lot really depends on details including the particulars of the content.  One of the nice things about over-provisioning an audio system if one can afford to do so is worrying less about accidentally taking it too far and breaking something.

Regarding wiring, I assumed the 4mm figure indicated by @domme referred to diameter and not cross-sectional area, which would have units of mm^2.  A cylindrical wire with 4 mm^2 of cross-sectional area is about 2.25 mm diameter.

Yea, it all depends on the gig. If you need those long sustained bass notes you'll have to think about getting more drivers, but you can also save on amping by bringing one Speakerpower amp instead of two Powersofts or something. You'll lose 6dB of peak headroom or whatever, but you get the same sustained power with less gear. You might get away with 1KW of amping per driver for such gigs, depending on how hard the source content is compressed.

About the wiring, it seems the "²" might not be displayed on your device properly, Domme and I both used "mm²" units, which is the same as mm^2 or sqmm.
Here is a pic what it should look like:

5 hours ago, SME said:

If I may suggest you consider amps other than the FP14400, keeping in mind that amp power ratings are often based on some unspecified "burst" capability, which doesn't even last long enough to be meaningful for subs.  The other thing to keep in mind that is that most Class D amps need to be run in a "full bridge" or "full bridge tied load" configuration in order to not become unstable when driving subs at high levels.  Some amps like (e.g.) Speakerpower and some ICE products are full bridge on each output channel.  These are essentially already bridged internally.  Other amps like Powersoft and probably the FP14400 are half-bridge on each channel.  These amps typically provide optional bridging functionality, which I strongly recommend when running subs off of them.

According to my tests, the Sanway FP13k should be able to burst its rated power for ~130ms, which should be plenty for typical kick hits (sustained notes at max will fry the drivers anyways, so why bother). I'd expect the og amps to perform similarly or better (I sure hope that's the case).

The instability when running unbridged amps only occurs when running the amp asymmentrically to my knowledge. The FP14k is running in 'half-bridged' mode as you say (onec channel's input and output polarity reversed to run mirrored symmetrical loads on the channels), which is a bit easier on the power supply. I've run both my 10kQ and my 13k asymmetrically; full tilt on one channel and much lower power on the other and never ran into issues.

As for the power ratings, Bennett recommended to set a long term average limiter at 1/10th of the rated program power, which would be ~350W, so 700W for two, which gives us 19A. That sounds a bit more reasonable, but the drivers will be fed a lot more juice temporarily of course, like you showed in your example.

Looking at the DIN VDE 0298-4, 2x4mm² is certified for exactly 40A in section 'E', which essentially means free wire outside. That norm targets a 70°C (158°F!) operational temperature. Yikes!

2 hours ago, Domme said:

I never considered the damping factor before, but did some research on it and tried to reproduce your numbers. I succeeded when using the following formula:



Is this the approach you took? If so, you most likely have forgotten to include the output resistance of the amplifier and much more important the voice coil. If we only consider these, we get the maximum possible damping factor (Re taken from 21DS115-4 TSP and halved because of parallel wiring):



If this model is correct then the damping factor can never get below this value. Even in 16R operation and with perfect cables we only get a DF of ~14. So it looks like cables only have a small impact on the damping factor unless they are extremely long or thin. Anyway, I was planning to use 4mm² cables. Not because of the damping factor but for current density and voltage drop reasons. Still, I see the benefits of using higher impedance drivers.

Sorry if I got a bit off-topic here. I promise to make up for it later by taking a lot of pictures 😘

Not sure what you're doing with Re there, but it's not supposed to be there.

You're correct that amp impedance is part of the unwanted impedance, but I left it out on purpose, since its impact is vanishingly insignificant compared to cable resistance (in this scenario and in typical PA applications in general).

Here is a table of the impact of cable resistance on the outlined setup above (2 21DS115 in parallel with 15m of 4mm² cable), calculator provided by Benchmarkaudio, modified by me for a better overview:

You can see that the amp's output impedance (nominal damping factor) hardly plays a role here (10kQ (250) and 14k (500) are marked in green), since the cables bring it down from 250/500 to 12. Total response error through your operation range is about 1dB, which is about your maximum loss, depending on the frequency. This also causes phase issues, which means even more reduction at the crossover frequency.

You also see ~1dB/10% energy loss in the cable. That's 1,4KW of the FP14k at full tilt. And that's with a beefy 2x4mm² cable.

I attached the calculator to this message for anyone who wants to play around with it.

Further reading:

https://benchmarkmedia.com/blogs/application_notes/audio-myth-damping-factor-isnt-much-of-a-factor

https://bennettprescott.com/downloads/dampingfactor.pdf

http://www.cartchunk.org/audiotopics/DampingFactor.pdf

DampingFactorCalculator.xlsx

14 hours ago, Domme said:

@peniku8Thanks for your reply and summary of the drivers. I already cancelled the order earlier today because I decided to do additional research and get some input from more experienced people. Unfortunately, I will not be able to start working on the cabinets until somewhen in February anyway.

However, one thing confuses me: you are speaking about the 4R DS first, but in your comparison you listed the SW and DS in their 8R version, which the FP10k could not fully support, at least not in 4-channel mode. Did you recommend them because of my plans to maybe upgrade to 4 Skrams later with the damping factor in mind or was there another reason? Until now, I never noticed that there is no impedance recommendation on the SW/DS in the initial post. I must have thought it was 4R because it was still in my head from all the Othorn stuff I read earlier. And then I picked the FP10k to match it.

I can't wait to finally get started with building 🙂

Prices are identical between 4 and 8R versions and performance is very similar too. You're right that I recommended the 8R versions because of your upgrade plans in the future and the fact that 2R doesn't like long cable runs. You could also build one pair of 4R Skrams, put them on the 10kQ and then build another 4 with 8R when you get the FP14k and run 6 when needed.

Running 20m of 4mm² cables (typical length I bring to a medium sized gig) you end up with a damping factor of 12 into 2R, which isn't exactly great. To increase it to twice the value (over 20 is decent), you'll need to double the cable thickness (could run a 4x4mm² cable with two wires in parallel each to essentially get a 2x8mm² cable), halve the cable length (will you never need more than 10m?) or double the impedance. If your amps are always close to the subs go for it I guess. If you're not so sure about that, be aware of the issues running low impedance might cause.

The FP14k will pump out the most power into dual 2R, but more power is meaningless if your system sounds bad because the damping factor is nearing single digits.

@Dommewelcome to the forums, nice to see a fellow German here

I can imagine that a single 2x12" sub sounds a bit light on its feet in larger venues. I frequently do shows with only a pair of 12" subs (12BG100) when budget is tight and often wish for more, especially when it's outside. Two Skrams would be a night and day difference for sure. They're similar to the other pair of subs I own and the difference in output to even regular 18" subs is incredible. The Skrams are a fantastic choice, but remember to put big casters (100mm or bigger) on them if you have to roll them through uneven terrain.

About the Eminence, I think Ricci meant they're easier to drive compared to the 1Ohm Ipals (since that's its direct competitor, disregarding the whole IPAL system itself and disregarding the 2Ohm IPAL driver). Impedance wise, the SW152 is the highest. Efficiency wise, the DS115 is the best, by a small bit. The Eminence has a bit more excursion and slightly higher power handling, about two thirds of the way between DS/SW and IPAL. It's like +2db from them to the Emimence and +1 from the Eminence to the IPAL.

Amp wise, I currently run two 21DS115-4 off a 10kQ like you're planning on doing. It's damn loud. For the FP14k idea you'd be better off running two 8R cabs in parallel per channel. I would personally avoid running two 4R cabs in parallel, unless the cables are like max 10m and pretty thick (4mm² at least), or damping factor will come bite your ass.

For driver selection, I don't know what you paid for the SWs, but here are the cheapest prices I could find in Germany:

2 21DS115-8: 1074€ (my personal choice - I have 4 of them)

2 21SW152-8: 1194€ (not much of a difference to the DS)

2 NSW6021-6: 1958€ (~2dB more headroom)

2 21IPAL-1: 2072€ (~3dB more headroom, basically limited to plate amps or extremely short wire runs)

That makes the Eminence ~80% more expensive than the 21DS115.
If the 2dB higher headroom is worth that for you, then go for it.

5 hours ago, DaMar42 said:

RCF LF21N451 has 58mm max excursion...

@peniku8 are you going to share your 4x21" design?

The RCF has an Xmax of 13mm, which doubles to 26mm peak to peak. If there was a 21" driver with 29mm Xmax everbody on this forum would be all over it already (unless it's north of IPAL price)

I'm not gonna share that design, because I'm in the process of starting a loudspeaker business and it's a design I'm really excited for/happy with (on paper so far). But I can say that it's the same basic idea compared to the Kraken, just in a nicer (and smaller) package imo. And it's gonna be available as a passive cab, so people can use it with their fav system amps they already own. That makes it much more scalable than the Kraken, at least easier so. It's gonna save a lot of weight and space compared to regular double 18" designs and probably sound nicer too.

5 hours ago, Ricci said:

This is a beastly looking sub. Shew it's huge and expensive though. It's the size of 2 Skhorns or 3 Skrams. That'd be a fun comparison. 

Fun fact it's 25% bigger than the MAUL cabs and weighs about the same. The tunings are much different though. 

Definitely 21DS115's...The p2p excursion listed is probably mechanical maximum. Not linear xmax. Looks like they doubled up on the wall thickness near the hatches. This is one spot I was wondering about potentially being a vibration concern. 

Regardless it looks like a beast. 

 

Peniku8,

DSP presets can be protected in Armonia. 

Right, I haven't even really looked at the size, but it's like 30-35% bigger than my quad 21" design. And I thought my cab would be cumbersomely huge, but this is nuts! The only other cabs that makes this look kinda reasonable that I know of are the F132 (a tad bigger) or the Danley monster (BC218), which is 50% bigger than the Bassboss.

And yea, then I don't understand why they haven't made the network connection available if they can lock the dsp.

4 hours ago, SME said:

Last I checked, the vast majority of DnB and Dub Step music go below 40 Hz.  Plenty gets down to 30 Hz if not lower.  A sub synth processor can also add more bottom.  If done well, I believe adding extension is often impressive enough (in perceived intensity) to justify the SPL that was sacrificed.  The biggest issue is that too much content is filtered too high.

Random example of SubHarmonic Synthesis, which illustrates this point well, since he switches it on and off and also plays it solo later on:

This is used on a low string section now, but the same thing works with basically any source. I have something like that as effects channel on my live mixing console to fatten up the kick drum/low toms if needed. Or to turn a Cajon sound into a bass drum sound (which is amazing!).

3 hours ago, SME said:

I wonder where the vent resonance is.  That may be what limits the max usable frequency.

21DS115!  I have a couple of those I bought to make some compact vanilla vented subs for a kind of semi-pro demo system for my audio processing, but I got distracted by other projects and then the pandemic happened.  Now I wonder if I should put them into a pair of SKRAMs instead, for what purpose?  I don't know.  The apocalypse?  I'm already very satisfied with the capabilities in my living room, and I don't even know where I'd store them.

This Kraken looks real snazzy but is obviously humongous and awkward shaped.  I don't see the point of going beyond a dual-opposed configuration like a SKHORN, and as evidenced by its relative popularity, the advantages of the SKRAM seems preferred by most builders over the advantage of dual-opposed configuration in the SKHORN.  I like that the SKRAM has more port area per driver, which also makes it more usable with a single port plugged for a bit more extension.

So the Kraken gets points for going just a little lower than 30 Hz, but the SKHORN and SKRAM are configurable and can be tuned much lower when the application calls for it.  A way better deal if you ask me. 

I have 4 of these drivers and am really happy with them. Two have been on a bridged clone amp and were able to take just about everything I hit them with (2x8R parallel on the bridged FP13k for the real deal). Just not sustained loads, because the amp sustains 4KW, which is pretty much 5x as much as the drivers will do for long term average. I got the 'burned' smell out of them once

The advantage of high driver count cabs is mostly just power density and power to weight ratio. Look at the Kraken and now imagine the cab uses no bracing, just acoustically needed elements. You'll notice the sides and top+bottom will already have good strengthening, just thanks to the horn paths and ports, which reduces weight because you only really need a minimal amount of bracing. And ofc, showing near 150db figures from a single cab is cool too, right?

I think the drivers share a rear chamber, so you could stuff a port if you really wanted to and lower the tuning. You will have to fight the low-cut in the internal dsp then though, which probably renders such an effort futile. Maybe open the amps up, there should be a way to connect them to your PC. The standard powersoft dsp board comes with a network port for this, maybe it's hidden away. Maybe they use LOTO?

@Ricciyou've worked with Armonia, do you know if you can password restrict dsp access? I'm planning to release a studio monitor series based on Hypex amps, where I can restrict dsp access to certain features only. I'll leave basic stuff like gain controls, input selection and input EQ available, but (obviously) restrict access to driver EQ, crossovers and limiters. If that's possible with Powersoft I don't get why Bassboss didn't make this available. Network controlled gain, crossovers and input EQ are nice things. Presets even more so

I've seen their Kraken sub a while ago (maybe a year?) and it's very similar to what I'm working on. Or will be working on once I get a new CNC which can fit large enough panels... (which is happening right this moment!)

This pic can be found on the driver section of the product page:

That's a 21ds115. Same choice I'd go with, it's a solid driver. 58mm peak to peak is a bit ambitious, maybe grossly distorted, way into non linear behaviour... unless the pic is not the correct one and it's in fact either the Eminence or the IPAL.

The cab is basically 4 short horn paths which are open to the front and 4 vents in the corners, it's a 'cab in a cab' design like my idea, which probably makes it very sturdy. Nothing folded here. Data sheet says good to 90Hz, but the response is probably pretty decent up to like 150.

I'm not a fan of the amp modules used. A gain knob and (presumably) a crossover knob with only analog XLRs in a 17k$ sub? What year is it, early 2000's? I'd at least expect an AES input and a network integration (remote control). The last thing I want is to go check my subs if the gain knobs are all the way up on every gig... But afaik these are Powersoft modules, so the amplification itself is top notch. If it's really 4 IPALs with 2 IPALmods, 17k sounds reasonable. If it's 4 21ds115 with regular digimods, not so much. But I guess it would still compare well to L.acoustics pricing, considering their KS28 double 18" (passive!) is 8 grand. Either way, the hardware and the implementation are great imo, it should sound great and make about as much noise as two Skhorns indeed. A bit less upper/mid bass due to the shorter horn maybe, but other than that it should be up there.

I like the design philosophy, I don't like the form factor. Quadratic cabs look so wierd

Yea, I typically only test up to 100db, since I mostly test HiFi components. I put DE360 into my center speaker, which would've been more annoying to test. Being inside a small room only a few feet away from a 120db HF source.. I don't know if I need that. But I know that my center speaker will also never reach those levels so it's fine for now

I wonder how the 18sound BE driver compares, it sure is expensive too.

Measuring tweeters shouldn't be that hard. Get a room that is big enough for a 5-10ms gate time and you can measure down to 500hz quite well. I bought and compared a bunch of tweeters and mids for current builds. Put them on the intended speaker baffle, EQ flat and compare distortions at varying levels. Of course not the massive IEC baffle

In room gated distortion measurement of an inexpensive SBacoustics tweeter on a tiny 4x4" baffle. 8' ceiling height:

Wow, dedicated MBMs with Skrams and horn loaded tops! Do you even need those? That's a lot of upper bass.

That's a lot of data! I like that most of the distortion is the relatively inoffensive 2nd harmonic. The near 130db sweeps must've been a pain, I'm already annoyed when I take 100db sweeps with hearing protection in the studio. I have a vacuum cleaner hose which has an incredibly annoying resonance. I suspect it produces something like 110db at around 10khz. It's almost unbearable when I use over ear hearing protection with IEMs beneath, playing music.

I'd be interested how the B&C horn with the DCX would compare. It's a fair bit cheaper too, I suppose. 1k+ for a compression driver is insane. Similar price regions to the Beryllium ones I forgot the name of.

It's good to see that power compression doesn't distort the frequency response too much and is only 1.5db approaching 130db.

Have you looked into importing a Chinese machine? You can probably find users of many machines sold there in some forums to see how they actually compare. I'm probably gonna import a CNC router soon(ish?).

https://www.alibaba.com/product-detail/Allcct-big-3d-printer-1000mm-3d_1600339853783.html

I do wonder what happened to this project. Seems to me like the amount of work (and knowledge) you need to put into speaker design caught him off guard and demotivated him.

I'm not a huge fan of PS audio, as Paul tends to spread misinformation to sell snake oil, but the video was alright I guess, bar the fact that he called infrasound "sub sonic" (which is a speed category). I think the rotary sub is similar to an infinite baffle arrangement in the sense that you need a lot of air volume behind the "driver" (essentially a separate room) and the SPL in that room/rear chamber will be the same as in the cinema. Typically it's easier and cheaper to integrate even a dozen subwoofers into your cinema than to basically build a cinema around one device.

Theres also the guy from Sweden(?) who turned his floor into a subwoofer (housing 16 18" drivers iirc in a large horn made out of bricks). I'm sure it's amazing, but I think it's obvious why we don't all have something like that..

Put 4 dual opposed sealed 21" cabs into your HT and you're gonna be pretty happy with the ULF, I'm sure. Want more? Buy/build more subs. Not enough space? Buy higher end drivers.

Personally, I'm not a fan of ULF. I prefer to keep sub 15-20Hz purely tactical through non acoustic devices, like Crowsons or a BOSS platform. Going that route means I can go with something like the Skhorn, plug a port and get good output to about that region, add my tactile device and not be missing much.

22 hours ago, Ricci said:

I used to use stepped sine tests for distortion testing of subs. Quickly realized that's a bit too brutal at the maximum drive levels I was using. Cooked a few learning that the hard way. 

Yea, even at the shortest setting the signals are still half a second long. That's pretty brutal.

4 hours ago, SME said:

I poked around on the site long enough to notice the stated figure had a footnote "[1]" that appeared to be dangling.   I could not find "[1]" anywhere else.

Was looking for that too, but could not find anything...

At least Klipsch is transparent about this, here is their top of the line consumer product (single 12" the size of a potato):

And this is from Klipsch's top of the line actual cinema subs (single 18" the size of two-three Skhorns):

which is fair enough I guess.

But sadly there will be people bragging about how their 12" sub can do 130db, manipulated by "false" information. 122db at 20Hz is what the Skhorn did in my room. And that was on an amp as powerful as probably 20 of the amps they use in their 12" potato. 120db+ at 20Hz is no joke, it's the point where stuff in your house starts coming down from the walls!