peniku8

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.

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.

Cheers!

I got this gasket tape
https://www.amazon.de/dp/B0792JGC2H/

Easier alternative for handles:
https://www.penn-elcom.com/default.asp?PN=H1105G
for
https://www.penn-elcom.com/default.asp?PN=H1105

28 minutes ago, Father Francis said:

where do you find your prices?

https://en.toutlehautparleur.com/speaker-lavoce-san216-00ip-1-ohm-21-inch.html

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 

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.

Wow, exciting! Looks extremely similar to the B&C in every regard, kinda like the SAN214.50 is to the 21ds115.

Sadly only 10% cheaper, so not like this is going to be a game changer.

@RicciHow would you feel about M-Drive in a Skhorn? Overkill unless you go IPAL?

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.

Yea I have one. Opposed firing woofers is the way to go imo. I have a 2x10" dual opposed sub in the studio, it's great. But kinda required an even number of drivers, which makes subs quite a bit less portable

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.

@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.

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.

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.

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.

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.

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? 🙃

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.

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.

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.

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.

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

You have to be careful with PC based round trip latencies, the audio interface only displays its own latency, which omits USB controller latency for example, which is the main issue when it comes to USB based solutions. Even if the latency shows as 1ms in the interface settings, the USB controller will add another 5-10ms to that afaik.

Use thunderbolt (pcie) for direct communication with the CPU. There are also network based solutions, like DigiGrid, which looks compelling to me (been thinking about getting DigiGrid for the studio for a while now).

I think at this point I'm best off getting some Powersoft amps and the question becomes a theoretical question:

A controller needs to know a speaker's impedance over frequency plot, which the Powersoft amps can easily obtain, since they're directly hooked up to the speaker (it's an amp after all). So what I'd be interested in would be: is there a controller which accepts impedance plots to semi-accurately (temperature related) limit amplifier output power?

If not, you'd have to implement this yourself via EQ→Limiter→reverse EQ, which was the idea behind a free flow dsp.

On 1/28/2022 at 10:25 AM, Domme said:

My carpenter friend is unhappy with using 12mm plywood for the vent section (parts "I") because he wants to use lamellos for easier assembly and thinks 12mm might be too thin for them. I assume that if we use 18mm plywood instead and just make the whole cabinet 18mm wider to preserve the vents' area it shouldn't be much of an issue in terms of tuning. Is this correct or am I missing something?

Best wishes for the weekend,
Domme

I assume he is not making Dado joints with a CNC, if he wants to use lamellos. I'd personally just use 18mm ply for the braces and leave everything else as is. The impact will be so small, it's nothing to be concerned about. If you make the entire cab wider, the tuning will drop too, in theory. Both options may lower the tuning by as little as 0.25Hz or so.

12 hours ago, kipman725 said:

4 SKRAM with B&C 15DS115-4

Are you sure you meant the 15" drivers?

SW and DS will be better than the SBA in every regard. You'll probably lose like 2dB going with the SBA. If you don't mind saving a buck I guess they're fine, but as soon as it means bringing 4 vs bringing 6 cabs or 6 vs 8 I'd say go with B&C, even if they're twice the price imo. How much is the Eminence in Australia?