peniku8

16 minutes ago, SME said:

I suggest turning off that EQ.  Such dips are often caused by localized interference effects which listeners should largely be able to hear through.  For me, those frequencies are felt at least as much as they are heard when they occur in complex music, so if you are feeling more sensation at those frequencies, it probably means you've got peaks there.

Judging the audible aspect only, the EQ sounds 'right' thou. The room is lacking in these regions or let's say it has got way too much in others. We already had a discussion about the studio space already thou and I kinda decided to leave it as is until I change out the subs entirely. A non-ideal sound reproduction is not good, but a constantly changing one is even worse in a studio.

I have an amp that operates in bridge mode using 1+ and 2- and I have another amp which bridges to 1+ and 2+. The latter does make less sense to me, but it depends on the amps internals I guess. Could probably also run 1- 2- if you wanted. Seems like the dip switch to bridge the amp does less than it seems to. There are also amps which bridge automatically, depending on the wiring iirc.

You can also reach the effect of having more tactile sensation than one might suggest by the volume by having a wooden floor. So Far I've been in two venues with a wooden riser for either FOH or a very small stage and both increased the tactile sensation manifold compared to the tarmac floor. You're also fooled to percieve a higher volume. 

The second occasion where I noticed this has to do with room cancelations; in our studio to be precise. We have a small dip around 63Hz and another dip at 75Hz, which I EQ'd out. Now the FR itself is pretty flat but you feel an increased tactile sensation from these frequencies. That's a bad thing for the studio environment

I've already isolated the sub from the ground mechanically, so it's pure acoustic tactility.

6 hours ago, SME said:

Excellent questions!  My formula is for center-to-center spacing and it assumes point sources.  The cabinets do radiate over a width, which can help but doesn't make much difference until they get pretty close together.

Otherwise, I think you have the right idea.  The 1/4 wavelength is really a fuzzy rule-of-thumb.  What you *really want to avoid* is playing frequencies whose 1/2 wavelength is the distance between centers.  Then the subs will be literally fighting one another. 

I swear, no matter how much we encourage newbies on this site to go bigger than they think they'll want, they practically always start talking about "adding more" soon after their first DIY project is complete.  It really is a long running joke in the world of DIY subs. 

There is a nice paper by Electro Voice on different sub arrays and their dispersion patterns. Correct delays are the key for larger events. Controlling noise pollution is also a big topic for open air events. Beam forming also helps achieving a more even coverage. Many examples are impractical space-wise, but I liked the V setup.

On the DIY side, I never felt like adding a second SKHorn to my HT :P 

Was planning on building two SKRams for my live setup, since the SB18 are not always available, but I'll likely just go with my own design. It's smaller and I really wanna see how it performs.

On 9/8/2019 at 11:55 AM, SME said:

Totally OT, but I listened to parts of the new Tool album "Fear Innoculum" with a friend today with generous volume.  The kick drums on this album really are phenomenal.  "Chocolate Chip Trip" is particularly noteworthy and seems like good demo/show-off material.  My only gripe is that it would have been better with no dynamics.  The limiter on the drums was a bit obvious at times.

Not a massive Tool fan, but I think I should give the record a spin. Had a listening session with my uncle lately and Pink Floyd's "Shine On You Crazy Diamond" just sounds so very clean and impactful. Now I couldn't help myself and had to turn it up again. Gotta say the fast kick drum on The Algorithm's "Trojans - Hard Mode" hits pretty hard. Celldweller's "Faction 14" is my go-to track for any system and it gives the subs some nice workout. SKHorn takes it like it's nothing thou 😎

Reducing the amount of compression/limiting would not be a good thing for 99% of the audio systems around. Most of the time people listen to music as background "filler", crazy dynamics might be pretty distracting, one might assume.

Quick comparison of the Eminence vs IPAL in my cab. The slightly higher Xmax gives the IPAL .5db over the Eminence when excursion limited, but you can see that the IPAL is about 2db more efficient over the relevant output spectrum.

Red means excursion limited, green is 10KW fed into the driver. So this is an efficiency graph basically.
Red/Green in the Eminence, blue = IPAL.

Edit: Just for reference, the DS hits 130.5db before exceeding Xmax at 45Hz

Built the cab in Inventor today and simmed it according to the CAD model. First graph is the Eminence at 1W into Znom. The DS also models very nicely (for system EQ) because it looks like only two PEQ points would be needed. In all the models I made (also from the big design) I noticed that the Eminence seems to drop off a little earlier compared to the DS or IPAL.

The interal volume ended up at 40L less than I anticipated, which is why the tuning rose to 33Hz. I will probably make it a little larger and shorten the port (currently 60cm long, no bend). The pic is 300L external, 60kg with the driver.

As comparison, here is a sim more to my liking: 30L more rear chamber volume, 5cm shorter port, 21DS115-4 at 2V:

Looks like a pretty neat cab if not EQ'd for rock live shows. Just don't cross it over any higher than 80Hz to avoid that nasty spike at 170Hz.

I'll make a separate thread once I gathered more info and tested the actual cab. F10 is at 24Hz, roll off is about 26db/octave and group delay about 1 cycle at Fs. Looking good so far

DIY is definitely the way to go if you want the most for your money.

You said that you'd love strong reproduction down to 20Hz, so a vented design tuned to 20Hz or a little lower would be your best bet. There are a few smaller designs on AVS, like the smaller ones from the Marty line which is pretty popular. They also seem to be very budget friendly and are not hard to build, plus I think you can also get flat packs. Add an NX3000D and you're golden.
As for your thoughts about 18" vs 2x12".. 2x12" will probably about equal the 18" in SPL, be more expensive but allow you to be more flexible with placement, so you can get a better room coverage. That being said, your room is actually pretty good for bass. The ceiling not being parallel to the floor for some parts of the room reduces room modes.

In any way, if you're fine with manual labour, I highly recommend getting into some woodworking. It's a lovely hobby 😊

2 hours ago, Ricci said:

Looks somewhat similar to a design I had a few years ago but ended up going in another direction. IF it's the one I've seen a few screenshots of. Good luck in the endeavor. 

As far as this Eminence driver goes I hope they get their stock built up soon. I need that 2nd pair eventually. 

You can see parts of it in the SKHorn thread where I illustrated the vent blocks. Will probably be long til I can even think about building one, but I modeled a downsized version with only a single driver and it looks like I'm at least building a prototype within the next few months. The hornresp model shows a voltage sensitivity averaging 98db from 30-100Hz with the 21DS115-4 and it's +-3db from 30-150Hz in the ballpark of 250-300L external volume. I'm basically aiming for a "compact" 21" cab which is not a direct radiator. This is the first Hornresp simulation I've done without actually recreating the cab in Inventor, but it should kinda work. For the big version it was the other way around, I just had this crazy idea and built it in Inventor. Then measured it and put in the parameters into Hornresp and started tweaking. IPAL models best, no surprises here. Crazy good driver, but also crazy heavy, crazy expensive and amp-crazy.

35 minutes ago, SME said:

Is your modeling with constant voltage or constant wattage?  Depending on your amps, you might be able to get more useful output into the eminence.

Constant voltage modeled at 1W into Znom for voltage sensititivy tests and amp limited to 10KW for the maximum output models. 10KW into two series IPALs should be achieveable with a K20 (one channel) or X4L.

This cab is the type of cab that doesn't depend on amps, the amps depend on the cab 😅 I'm very excited about it but I won't spill the beans before I haven't built a prototype and actually measured it. The model uses Ricci's tricks to get to the accurate SKHorn simulation and uses complex inductance, so I tried everything to get it as reliable as possible and it looks damn nice. Just need more drivers, more free time and lots of plywood. Already got the CNC 😁

After doing some modeling in Hornresp on my own cab design, it looks like the IPALs are still a hair above this driver. The latter costing quite a bunch less, having basically the same weight and about half an inch less mounting depth makes it very attractive thou. What I like the most is that it seems to boost the 30-50Hz region in my cab while still modeling pretty smoothly. This is a great addition to the market. It's about 2/3 of the way from the 21DS115 to the 21IPAL imo, judging from the models.

Can't wait for the other manufacturers to up their game in the 21" market. A ~2.5KW 25mm Xmax low inductance driver under 1 grand would be heaven, still kind of realistic and a serious statement.

Man Jesal, these subs almost look small in the pic. It looks like the top of the screen is at about 1.5m, but then you see the full sized door behind it...

I should really get my sub design tested. Seeing how well these types of cabs perform (in combination with the 21" drivers) excites me.

I would just build a prototype of the cab I designed but I need more drivers and A LOT of wood.. there are some other things further up the list (like a Bordeaux build or three..)

13 hours ago, Jeff L said:

Looks like price is $749

MSRP was/is about 200$ more

1 hour ago, jay michael said:

Yeah, Phone videos don't do it justice for sure.  I've often thought about getting a good video camera with a quality external mic to get better video and sound from our shows, another item on the to do list.

  

I have a Blackmagicdesign Ursa Mini 4k outfitted with two Neumann KM184 and I absolutely love that combo, but it's way overkill and probably far out of any reasonable budget if just for show recording.

4 hours ago, SME said:

Very nice!  I experience a very tight thump on my living room system.  It sounds bit shy below ~60 Hz, but that could be the particular music or a filter in the iPhone mic.

I love the picture of the setup.  It looks so compact, and yet I'm sure it can pack a wallop.

Depending on the model it drops off quite a bit down low. In an example iPhone 5 calibration file I saw 30Hz being down by 15db.

Mine is similar, there is basically nothing below 25Hz, but I couldn't find the cal file in the system to have a look at it

Got the ok from @Ricci to post the metric SKHorn plans I made. It's a compact 4 pages and I built my cab with these.

I made the horn bracing from one piece as I found that to be less work, even without a CNC.

SKHorn Metric Drawings.pdf

8 hours ago, SME said:

It's for a different project, a plain-vanilla vented cabinet.  I'll probably start a thread for it soon.  Either way though this discussion is relevant to the Skhorn.

Vent round-overs certainly won't prevent chuffing, but I believe there's evidence that round-overs can improve flow characteristics at moderately high velocity, perhaps allowing an extra 1-2 dB before chuffing does become noticeable or before compression becomes serious.  It's a minor detail but worth it IMO when vent area is a bit limited as it is with both the Skhorn and the design I'm working on.

Also, I care more about avoiding/reducing compression, which sets in quite a bit sooner, than I do about chuffing.  With compression, the spectral balance is distorted substantially as level is pushed higher.  In use-cases where high accuracy/SQ is important, this is likely not acceptable, which effectively limited usable output to a level that may be much less than when chuffing because audible.

Can't want to see what you're up to! When I think about the SKHorn I think about large venues with the capacity for over a thousand people, and there probably only the first two or three rows might notice vent noise. The roundovers are not much work thou, so why not just add them. I also placed roudovers on my current 12" project at vent entrance and exit, as far as it was possible for me. Very easy job with a roundover bit.

13 hours ago, SME said:

Thanks again for the suggestion.  I am thinking along similar lines, though I do still need to be mindful of the round-overs.  I'm also keeping the bracing dividers to 12mm.  I'm trying to keep the weight down.

Are you talking about the SKHorn or a different project? I don't think flared ports are gonna save you from vent noise (below 20Hz) when running with the 1 vent per side config, and I also don't think that flared ports are needed when you're running with 2/3. I can push the drivers to Xmax at 20Hz with 1 vent open per side and not get any air noise.

If you did it like this, the port block could sit on the area marked in red, which could be lined with gasket tape to make a perfect seal. Maybe you can find hex inserts small enough to screw into the vent braces (make these from 1" ply maybe?) and it would be made to last, easily interchangable and would not wear out.

4 minutes ago, SME said:

I forgot that Ultimax come in 12s and 15s.  I so rarely see the smaller versions get used in builds.  Most probably don't see a point when 18s only cost a bit more, unless they really need something small.

Is this a mixed-use room?  If not, why the concern about looks?  Very small subs generally provide poor performance to cost ratio, so you give up a lot for looks.  Given your budget, I'd suggest going with vented enclosures.  A lot of details would depend on your room behavior.  If your room is like mine (which is slightly bigger, albeit open to a hall), you'll have a huge amount of room gain in the 20-60 Hz area, in which case you could probably get away something fairly small (but limited in output at the low end).  Using a smaller 12" or 15" driver and a "tower" form-factor you might be able to keep the footprint especially small.

The UM18 is almost twice the price here as the UM12. The UM18 is more expensive than one 21DS115 even. And no, it's just a control room in the studio, but we will probably move to a different place next year, which I don't yet know the size of. And I get the impression that for tuning a 12" cab to 18Hz you'd need to go quite big. Also, the vented design tuned to 18Hz might not be quite as punchy in the 60-120Hz octave (?), which was why I just wanted to go sealed (along with the fact that I can build all cabs within an hour if I wanted to).

I guess I can just get 4 drivers, build small sealed cabs and whenever I feel like I want more I'll go with a different design. I'm thinking about buying a CNC too, so projects in that size would be a breeze

31 minutes ago, SME said:

Is that 0.2 mm with or without the weather stripping?  I would assume the tolerance would be less important with the "weather stripping" in place.

BTW, is that actually weather stripping?  Or is that gasket tape?  I looks more like gasket tape in the picture, which is fine because that seems like the better choice.  I'm also more inclined to put the gasket tape on the port blocks for better aesthetics and to avoid obstructing the vents or cause unwanted flow separation.  I'm not sure if typical gasket tape will be durable enough for frequent addition and removal of the plugs.

I'll keep thinking on it.  Thanks everyone for the input.

The .2mm is without the gasket tape and it already sealed quite well just being wrapped in vinyl because there was so little of a gap. And yes, it's not weather stripping (apparently?). I'm not very faimilar with these items so I have no clue what the difference is (on top of which I'm not a native English speaker, which makes it just a tad harder).

I got another idea for this modular port design, which I'll post in a minute. If you got the tools this might work pretty well, but the port board only being 12mm makes it a little harder (less sturdy).

This was my idea with the F6, which can be put into a 0-latency chain via a WSG compatible console.

I just found that the maximum attack time of 500ms might be too fast in some (most?) cases, but this example shows how you could protect cabs with an excursion minimum around 32Hz from overheating due to sustained low crest factor signals (sine waves in this case), without affecting any content but that specific frequency.

On 8/7/2019 at 9:16 PM, SME said:

I noticed earlier in this thread you discussed making and improving vent block to adjust the tuning frequency.  Can you provide any details of the design and how it attaches to the front-end?  I did look at the pictures and noticed that you don't appear to use any round-overs at the vent exits.  I'm hoping I can find a way to securely block rectangular vents with round-overs.  Good luck, ehh?

I did it like this and have no issues with air leaks, the port blocks are about 0.2mm smaller than the gap they sit in. This would also work with rounded edges.

https://www.avsforum.com/forum/155-diy-speakers-subs/3037204-skhorn-build-3.html#post57499060

1 hour ago, Ricci said:

Something like 4 Ultimax 12's or 15's would probably do what you are looking for, but I don't know the costs over in Germany. Probably far higher than here in the US. Peerless XLS-12's might be an option as well. With 12's you will need some excursion and the BG's just aren't going to have it. 

B&C 15DS115's? 

The Ultimax 12's look pretty good, I could get 4 for just under 240€ each. Peerless has much lower power handling, 7mm less Xmax and costs the same. 15ds costs the same as the 21ds so uhh... I'd rather build more SKHorns

2 hours ago, SME said:

Can you clarify what you mean by 85 dBC?  Is this a calibration target?  And if so, using what kind of test signal?  Also, have you considered that a more neutral sounding "house curve" may require in-room SPL that's quite a bit higher than a flat in-room response?  This "house curve" should arise naturally when using an anechoic flat monitor.  As calibrated/optimized and while listening at an overall level appropriate for monitoring typical "loud" music tracks, my system can theoretically hit ~106-108 dB RMS (at the seats) in the (roughly) 20-50 Hz range if full-scale sines are playing in both channels.  With more dynamic content like movies and tracks that haven't been crushed, those numbers can be a lot higher.

Anyway, the good news is that small sealed rooms have a lot of LF gain, so you'll get plenty of mileage out of small sealed subs.  However, your room is not tiny, and that budget won't go very far to get good performance out of cabinets that are so small.  To do so requires a lot of motor strength, which usually means expensive magnets and extra shorting rings to keep the upper part of the response clean.  One fit for purpose sub would be this one: https://stereointegrity.com/product/hst12-12-subwoofer/, but I don't know that you could afford even one of those on your budget.  You also need a lot of amp power to use the excursion capability of a sub like that, and to overcome its very high mass which gives it only ~80 dB sensitivity.  A pro sub like the 12BG100 is kind of the opposite situation.  The mid bass capability is *much* better (93 dB sensitivity), but it only has maybe 1/3 the excursion, meaning -10 dB max capability in the deep and ULF bass compared to the HST12.  The HST12 also has more motor strength, and so will output more deep/ULF frequency using the same power.

Is the need for a 14" cube form factor a limitation of width, depth, height, footprint, or all of the above?  If you could step up to an 18" driver, you'd have a lot more good options and get a lot more value for your money.  I personally think pro-style 21" is a very nice sweet spot.  Compared to four HST-12s, four B&C 21DS-115s stuffed into "tiny" 575x575x350mm (ish) cabinets should cost less, have more output at the bottom, and provide *way better* overall efficiency above 30-40 Hz or so.  The Lavoce SAN214.50 gives similar performance to the DS115 and may be less expensive.

Anyway, it's something to consider.  I've seen a few conversations around here wishing for better 12" sub options, for either pro or small room usage.  If you have to stick with 12", then the driver you really want probably doesn't exist.   

85dbC was what I measured during one of our mastering sessions, to get a general idea. This was with the sub measured to flat at the MLP and a house curve bumping it to +10db below 60Hz. We're a studio for music and our content is absolutely crushed.

We're not really limited in space, it's just due to the looks of it. I could probably fit 3 SKHorns behind the desk, but it wouldn't be pretty. I like the 12BG100, the only thing that's bothering me is the Xmax. 21" would get me further with less money, I've realized that a few times already, but I don't think I could justify the footprint.

Keep in mind that there will be 4 sealed cabs and that our single 8" is basically (almost) enough already in terms of SPL. I doubt that 4 sealed 12" would perform worse than a single vented 8"