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Posts posted by peniku8

  1. I think the Powersoft X8 is the only amp I know that delivers the power you're asking for in a small space with more acceptable fan noise than those clone amps produce. It's by no means quiet, but the fans ramp up and down very quickly and in the video I've seen the amp didn't seem super annoying at idle.

    The X8 does 8x1600W into 8R in 2U, but will also drive 2R and below. You'll get SOTA processing and features, but also a SOTA price tag.

  2. 2 hours ago, Ricci said:

    Is this an outdoor measurement? How far away is the nearest large object? Building, truck, etc?

    Looks like about 8db down at 30Hz compared to 100Hz. The tuning seems to be a bit under 30Hz as well.  I'd expect about 4 or maybe 5dB down at tuning with those drivers. The HPF probably shaves another 1db off. Realistically this isn't too far off. Once all of the factors such as driver tolerances, construction methods, signal chain, measurement setup and atmospheric conditions are stacked up it can account for quite a bit of variation. I'd not worry about it too much if it's a little different from the model or other peoples measurements. 

    Is the mic equidistant between the vents and the upper section or closer to one vs the other? That could account for another 1dB.

    Did you add baffle gain calculated in Edge to the hornresp prediction?
    In my last project I got the predicted response to be within 1dB of the actual half-space response, but I had to double the baffle size in Edge (maybe that's the effect of the half-space loading: it mirrors the baffle on the ground basically), hence way more upper bass than hornresp predicted.
    I'm not sure how this translates to larger cabs, but it was spot on with my single 21", a tad smaller than the Skram.
    Hornresp was also fed with the set of complex inductance parameters. I used the specs for the 21ds115 you measured.
    Same thing applied to my 1x12" sub. Model response was spot on with the measurement.

  3. By "lack of cone control", do you mean non linearity in the translation from electrical to kinetic energy or do you mean cone flex? The former can be remedied by a stronger motor, the latter through a stiffer cone.

    Both problems are challenges to the designer, not to the end user. Any properly designed driver will play predictably based on the Klippel graphs. For B&C drivers I think it's the Xvar value, which is a general rule of thumb for when the driver behaviour will transition into non-linear territory. If this was a huge issue, big drivers wouldn't be so popular.

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  4. On 10/29/2016 at 3:50 PM, radulescu_paul_mircea said:

    The M-Drive can generate around 5000 watt long term and 2000 watts thermal equilibrium so in 2 minutes you increase the temp with 20 degrees Celsius

    Did you do those tests yourself? How was the M-Drive set up, did it have an additional heatsink/ventilation or just the module by itself with its two small fans?

  5. 16 minutes ago, Father Francis said:

    try check the DigiMod 3000PFC+3000AMP with this you can use DSP-D and DSP-4 and add the big heatsink , 


    i guess this would run you a pair 

    The 3000pfc's datasheet states 4000W of total (symmetrical?) power output, which would underpower 2 drivers, let alone 4. If you wanna use 2 21ds115's to the maximum of their capabilities you will need pretty much twice as much as the Digimods are capable of. I ran my FP13000 unlimited&bridged into the Skhorn (4R) no issues (music, not sine waves). That's a bit overkill, but I'm trying to run 4 drivers off one amp, which the M-Drive seems to be a good match for.

  6. Yea, certainly good for a no-compromises build for maximum output density.

    I feel like the M-Drive should be powerful enough to drive two Skhorns when you load em with 22ds115's.

    I think I'll buy one to test, I need a good amp with the Powersoft feature set anyways. And I'd prefer active subs.

  7. 1 hour ago, Domme said:

    Hey everybody, I am wondering if and how you seal the area between your cabinet and handles, cable terminals and so on to minimize air leaks. I was thinking about using some 1mm neoprene sheet and was wondering if someone here has got experience with it or what you are using instead.


    I got this gasket tape

    Easier alternative for handles:

  8. On 2/25/2019 at 1:20 AM, peniku8 said:

    I don't have enough knowledge about designing horns to be talking about this with confidence, but since the horn opening angle would drop to 6° from 12° if simply cut in half and adding a side panel the interior would need to be redesigned. That is if a horn works the way I think it does, if it doesn't please call me out.

    As for binding hardware butterfly latches would be great. I actually posted about this modular cab idea using butterflies on AVS some time ago but nobody seemed to be into it.

    You could even saw the original SKHorn in half and slap like 6 butterfly latches on that to combine it. Use weather stripping to seal it and you have your modular SKHorn.
    I wonder what it would sound like if just left in pieces  :D

    But I think we're going slightly off topic here, that could be discussed in a new thread ;)

    To answer my own ramblings from 3 years ago, since I know better now and I couldn't just leave this as is: since the two drivers fire into the 12° horn in a mirrored fashion, they will each behave as if they were loaded into a separate 6° horn. Sawing the Skhorn in half will technically work just fine.

    Most hardware rattles and I think it would be really hard to keep butterfly latches under control, so that idea is sadly also a dud.
    And no more wondering what it would sound like after sawing it in half without adding new side panels: it becomes a vented cab with lots of wasted extra space and a really silly driver mounting.

  9. You mean dado joints like on this board?

    I use them mostly to make the assembly easier, since it's hard to get the position wrong when everything slots right into place. It doesn't help much with structural integrity unless you do like 10mm or so I'd say. I do 3mm too.

    Doing this without a CNC is a massive waste of time imo. I only drew a sketch on to the floor board when I built my Skhorn and went from there.


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  10. On 4/28/2022 at 6:32 PM, rolo95 said:

    Ahh, kind of danley TH118, those are called tapped horns right ? or just horn subs

    The TH118 is a tapped horn, but neither my sub nor the Skram are. They're both vented frontloaded bandpass cabinets.

    They sound and perform great, but I wouldn't build them again. The 21ds115's move the stack (sub+ARCS=250lbs) around. If you're planning on making a line of cabs in front of a stage they'd all be moving all over the place if you drive them near their limits.

    I heard the Othorn experienced similar issues. Skram fires forward, so it doesn't 'lift' the cab when the driver is working.

  11. @rolo95My subs are my own custom designs. Imagine Skram with half the horn length and the driver downfiring.
    ARCS Wide/Focus have been replaced by their new A series, which fills the gap between point sources and line arrays less well than WiFo did imo. But Martin Audio released the Torus series, which seems very similar to what ARCS WiFo is, with some additional features. Probably in the same ~4k price range depending on your region/dealer. ARCS are quite a bit heavier than Torus though.

    As for SPL vs money I've been saying that 21" has been most cost effective for quite a while now, even before covid.

    Two 15ds115's will surely outperform a single 21ds115, but look at the price. I personally think it doesn't get much better from a cost per SPL point of view than 21ds115 or the very similar LaVoce driver.

    • Like 1
  12. 3 hours ago, h3idrun said:

    from what i have experienced with my crappy drivers 4x good quality 10s could sound amazing, and possibly have better power handling and heat dissipation than 1x beefy 21"

    Would be interesting to see what can be had, even if it only makes sense when you just so happen to have the drivers already.
    4 10" drivers have about 75% of the surface area of a 21. Looking at B&C's lineup, they'll have half the Xmax, but about the same power handling combined. So mid-bass would suffer a little, while you'd be giving up more in the deep bass.
    What's the beefiest 10" driver with usable Qes for the Skram? SEAS L26RO4Y looks pretty neat. Disregarding that 4 of them cost twice as much as a 21ds115, they should perform decently well, although worse in every regard compared to the 21ds115. Maybe they'd take more sustained power.

  13. I'm pretty happy with my 21ds115 powered subs (similar to the Skrams I guess, just a bit smaller) and l-acoustics ARCS wide tops.

    PM90 components are obviously top of the line, but I personally prefer scalable solutions (the ARCS wide can be used as single 90x30° loudspeaker or in a fixed curvature line array with ARCS focus (15°) speakers).
    PM90 won't achieve uniform audience coverage over a large area, but it'll do exceptionally well for small clubs or small outdoor shows. Or when you just want higher SPL closer to the stage.


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  14. On 4/22/2022 at 6:14 PM, rolo95 said:

    one skram will sound like 2 SRX828 ? 

    No, even the Skram won't make a 21" driver sound like four 18". Looking at the specs it should outperform or be on par with a single 828 though, as long as the Skram has an adequate driver with adequate amping.


    On 4/22/2022 at 6:14 PM, rolo95 said:

    I know you suppose to have a 2:1 ratio on subs, so 2 subs per one top

    That depends on your subs, your tops, the location and the kind of show you're producing.
    But I guess 2:1 is a good ratio for these kind of shows. Also, the guy you're describing had 4 18" drivers for 2 tops, so it's 2:1, isn't it?


    On 4/22/2022 at 6:14 PM, rolo95 said:

    also if i were them i would cluster the 2 bass cabinets on one side , they are loosing 3db right ? cause they are not putting the subs side by side?

    No, not really. Indoors, setting up subs in different locations will make for a better spatial average across the room. In wide rooms or outside, where some of the audience stand at the sides at a heavy angle to the PA, you'll run into lobing issues unless you stack your subs (you'd stack them center). But since your room isn't that wide and I suppose the subs were set up rather close to the side walls, you won't have to fight lobing. Also putting tops on your subs means you won't have to bring stands :)


    On 4/22/2022 at 6:14 PM, rolo95 said:

    power amps i have is not that great, 1 dbx driverack PA over 1 PLX3002 , one XLS2500 and one XLS2000

    Even more of a reason to get high efficiency PA drivers over a bunch of cheap car audio ones.
    It means you'll get a few more db out of the subs within your available power.

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  15. By saving a few bucks on drivers you'll end up having to bring twice as many cabs to a gig.

    You'll end up spending more on wood than you saved on the drivers. Plus having to haul more subs around.

    Definitely not worth it imo, not even taking the difference in sound quality into account.

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  16. 15 hours ago, rolo95 said:

    btw, the tops were some 80's jbl MR925's  4 of them, they are heavy as F... so i want to change that also

    if i had the dough , i think i will get SH50's for tops and tell somebody to build 8 skrams 4 me

    So your JBLs are too heavy and you wanna replace them with SH50's.

    Are you aware that the SH50 is over twice the weight of your JBL? 🙃

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  17. iirc the LaVoces were in a parts express deal for 400 flat or something, 3 years ago.

    I paid 410$ for my 21DS115's. Now they're around 650. That's up over 50%...

    Imo it makes no sense to build the Skrams if you intend on putting non ideal drivers in it. A good subwoofer is a good subwoofer, but that's the entire system of driver+cabinet. Even if the cabinet design is stellar, it'll make a bad subwoofer if you don't put the right driver in it. That's also how DIY got a bad name over here. And just outright bad designs of course.
    Build something else if you wanna use other drivers or design a simple vented cab if you have a specific driver in mind. Designing a vented cab with a slot port is really simple.

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  18. 7 hours ago, SME said:

    Damping factor is kind of an anachronistic term from when amps (made of tubes) had non-negligible output impedance, so damping factor was high enough to significantly alter the bass response in ways that varied depending on pairing of driver and amp.  I don't know if I'd call this "distortion" though, in that in audio distortion usually implies non-linear distortion whereas increased "damping factor" looks a lot like a shift in T/S parameters.  It's likely something that can be completely corrected with EQ (except for the lost power, of course).

    I think we'll have to differentiate between three effects of damping factor.

    -power loss (negligible for sound quality if you don't clip your amps)
    -response shift (neglegible if you use EQ to compensate imo, which is also the point you addressed)
    -lack in physical driver damping

    The last point apparently only becomes an issue once the damping factor gets really bad, like single digits, but from what I understand, shorting rings in your drivers achieve that on their own already, so it might not be much of an issue at all anymore. Would be interesting if someone with more knowledge on this could chime in, maybe I'll send Bennett a mail.

  19. 7 hours ago, seamus said:

    Is it a good idea to target a curve (that isn't flat) when designing a cabinet?

    Target maximum efficiency everywhere (within your design goals of course) and correct the response in dsp. This results in lowest distortion levels and best headroom.

  20. 15 hours ago, SME said:

    The way I read this, your described workaround is functionally the same as just engaging "bridge mode" in the first place.  This makes perfect sense, especially if the loads on each channel share a common ground.  Which is to say that one should just enable bridge mode anyway because it's easier.

    But this does not necessarily allow for *asymmetric* loads across multiple channels, which is basically the point of having multiple channels in the first place.  Asymmetric loading between different subs can be useful in some situations, but not all amps can reliably do this if subs are involved.

    And I would say the "worst case scenario" isn't having the amp shut down.  The "worst case scenario" is designing with an amp that is not adequate.  OP is wise to carefully choose the impedance to match the intended driver and amp configuration.  And as noted by others above, damping factor is not a problem with proper matched wiring.

    No, with my workaround you still have two independent channels, but internally it will appear as if they are bridged. You leave channel A alone and swap polarity of both the input and the output signal on channel B. You use both channels separately. If you now tied A+ and B+ together, your amp is running bridged, but instead you connect your channels to separate subs. B+ connects to Sub- to have all speakers running in phase.

    Since some amps (like lab gruppen and I suppose most other tour grade amps as well) already do this internally, B- will actually be carrying the hot signal and B+ is ground. This is because the wiring has been reversed internally to change back the polarity to normal (0°). If you feed both channels the same signal, you should be able to run it bridged via A+ and B- without engaging the 'bridge' switch.

    Some people call this running your amp 'half-bridged', but I don't think that's an appropriate description. It's just using one of the steps, you need to do to bridge your amp, for something else, so it's like saying the workbench you built is half-subwoofer, just because you built it out of plywood.

  21. 15 hours ago, SME said:

    Don't worry about damping factor, but do keep in mind that many amps are not designed to power subs unless they are used in their bridged mode, in which the amps for two channels work together to power the load.  The bridged mode typically doubles the impedance requirement, so an amp rated into 4 ohm loads will typically require an 8 ohm load when bridged.  You could use this to power a single 8 ohm sub (with a lot of power and one amp per sub), or you could connect pairs of 4 ohm subs in series and run each pair off a bridged amp.

    From what I gathered, this can be an issue which is relatively easy to avoid.

    It mostly only becomes an issue when you load channels asymmetrically, i.e. subs on one and tops on the other. In this case you amp might power cycle at worst (I suppose no proper amp will die from that). To improve stability, just run channel pairs that can be bridged with the same signals.
    To further enhance stability and/or amp performance, reverse the phase on one channel input and reverse the wiring on its output. This won't affect the subs, since it's a double polarity swap coming back full circle, but the amp will run a mirrored config internally, which is actually what most modern amps do already. An amp that bridges from 1+ to 2- should be running this config. Brian from Speakerpower posted about this on AVS some time ago, when he was still working there.

    Despite this advice, I've been running my system on TopL(A) SubL(B) TopR(C) SubR(D), since my amp's 4pin speakons are wired for A+B and C+D, so I'd have to use a breakout cable to change this, which isn't very convenient. I would, if I had issues, but never did, so I just left it at that. Been pushing 4R 21ds115's quite heavily with no issues.

    Oh and just to throw it out there, there is a 16R variant of the 21sw152. It's probably 50MOQ and only directly from B&C, but hey, it exists, just like the 2R IPAL :)

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