Ricci

Speakerpower plate fits the hatch cutout nicely.

Looking good Jesal.

I thought something looked a bit off but I remember now you were building them at 32 high x 36 deep instead.

Hmm...That sounds like a bad air leak, or a panel resonance perhaps one did not get enough glue in the joint.

Something is not right. Investigation is in order. Good luck.

The measurements look good. That's a smooth response from 30-150Hz with no smoothing or processing. Looks right. Were these taken outdoors?

I'm not sure what to say about the noise. I don't recall anything like that from mine. All of the air noise I've encountered is from the ports at really high output near tuning. When airspeed gets high. The horn section has a lot more area and the airspeeds are a lot lower. I wouldn't expect anything like that especially at lower volumes.  Could be an air leak, a loose panel, wire touching the cone, or a driver issue. Might be worth double checking that everything is sealed good and tight especially at the driver mounting area. I never put any material in the upper section of mine. Is it something that you hear with you ears close to the cab or something that is audible from 10+ feet away? Is this with the low pass filter in place?

Speculation is it might have been the not enough glue on the joint at the former.

3 hours ago, dsl1 said:

I wanted to get it done two weekends ago but the CNC was having issues

Everything is cut now except the reverse side handle cutouts and the feet/stacking situation for a pair. I still don't have a good plan there. 

 

Me either...I got sidetracked back to working on content for the new website.

15 hours ago, dsl1 said:

Finally had an afternoon to cut some stuff.

Quick work as usual...I imagine you'll be the first person to complete a Skram and fire it up.

M_MS,

FLH's do indeed have their excursion maximum at the low frequency knee. This often means that their output is limited in that area first as the driver runs out of excursion. It makes their frequency response and extension a little bit misleading if they will be driven hard. Most other alignments such as ported, TH, BP6, BP8, Skhorn style hybrid, passive radiator etc, etc. have an excursion minimum near the low frequency knee.

Other than the above sealed OB and IB subs have no excursion notch, ported has a single notch and higher order alignments like TH, FLH and BP6, etc have 2 or more excursion notches. Beyond this it cannot really be said that one has less excursion, or THD than another. It depends so heavily on the individual design, drivers used etc...There is no simple blanket answer to a very complex set of interactions.

The absolute best way to learn this stuff is to download a program like HornResponse and start simulating different designs. Build, measure, listen, etc...

I have no idea the context of "enclosure interaction" or the intended meaning. All drivers interact with their enclosures. I'd actually say larger horns cause more interaction if anything. The response is being modified more greatly than the drivers free air behavior not less.

It's impossible to predict the distortion behavior. The measurements I took with the Ipal drivers looked really good. Your cab is slightly bigger so that should help but the drivers are different. Measurements for the win.

On ‎4‎/‎6‎/‎2019 at 8:49 PM, jay michael said:

If possible it would be great to see a sim for the 21sw152.  How high do you think this will play smoothly,  150hz? or perhaps even higher?  Compared to a Othorn it seems like one should expect a slightly higher output with more usable response up past 100hz?  For the people who have heard both the othorn and the skhorn, is there a difference between the type of sound between the two?  Curious about what to expect as far tightness, speed, musicality and felt impact on the dance floor between the two.  Having already built some Othorns would it be worth the effort to give the Skram a try?  Cheers

21SW152-4 models great in this cab. It's one of the smoother modeling drivers in it. All of the usual pro 21's should be a good match. 18Sound 21ID, 21NLW9601, B&C 21DS115, 21SW152, 21Ipal, RCF LF21N551 looks decent, Lavoce SAN214.50 and the new Eminence NSW6021-6. 

I'm hoping that it will be smooth up until 150Hz if needed. It should be. Actually I'm hoping it behaves similar to the Skhorn and is relatively smooth up until a bit past 200Hz allowing XO's well in excess of 120Hz if required and a predictable XO transition to the mains. Until I get finished cabs with drivers installed I won't know exactly but it should be close to the sims.

As far as sound of the cabs I actually preferred the Skhorn over the Othorn slightly, Skhorn seems a little bit cleaner at high output (lower THD) with a bit more oomph in the 60-120Hz octave, but both are still really good for loud music playback. I'd expect this cab to sound extremely similar to the Skhorn and perhaps a bit better in a Skram pair vs single Skhorn situation. Again I don't have Skram's done yet but that's what I expect. Unfortunately I got rid of my last pair of Othorns a while back so I no longer have those on hand for direct comparison. A lot of people are happy with them though.

Output and sensitivity between the 2 cabs isn't a whole lot different overall. Othorn is a larger cab, heavier cab that is 4" deeper, so it likely will have a bit more max output in the 25-35Hz area and a bit more sensitivity over that range too. HIL and all of that. The Skram will likely have a bit more from 35-70Hz or about that. This is with all of the Skram vents open. It is more flexible and can go deeper once the alternate vent tunings are factored in. Top end above 70Hz is a bit of a wash. When I say more output I mean in the neighborhood of a couple of dB or less while using the same drivers. Not huge differences. Once I get to test the real cabs I'll know for sure. I'd say it's more of a lateral move to something a bit different rather than an across the board improvement.

Thanks for sharing Jay.

Where you been Kyle? As Scott said it's basically an update to the cosmetics of the old inukes. I believe the guts have been confirmed to be nearly unchanged. There was some speculation that they worked on HF load invariance though. The new ones definitely look better.

On ‎4‎/‎6‎/‎2019 at 1:46 PM, Kyle said:

Could be a leaking surround, you would be surprised what they sound like. A ticking noise is not out of the question here. I can't say anything for sure but I do know if there is not enough glue on the pro cloth style surround, it can permeate air. It can be fixed with more glue applied right on top with a brush.

This might be the right stuff. I just did a quick google search so don't take my word for it! You need a little painters brush to apply on top.

https://www.simplyspeakers.com/speaker-repair-adhesive-mi-1291.html

 

 

 

 

In my case it is definitely something inside the motor under the spiders. Driver in free-air. It's not really audible once in the cab. Eminence is replacing the woofer that ticks and want to diagnose the issue. The Lavoce driver exhibiting the same thing I haven't contacted them about yet.

PDF Print added to the first post for download. I'm having trouble with the DXF print giving an error. I'll have to look at that later.

14 hours ago, Infrasonic said:

I want a bigger one.

 

 

 

 

Excellent work as always, Josh. You should get paid for this stuff, ya know.

You always do!

When I go bigger I end up stuffing more drivers in the cab!

The only 18 I've modeled is the Pro5100 TC Sounds, which looks good.

Changing the baffle cutout for the 18" would be the only change needed to fit an 18.

By the way. The reason I'm not posting the HR inputs is due to the way the vents behave. The vents are loaded into the corner and back wall which will increase their apparent length and tune like a physically longer vent. HR has no way of knowing this so the vent length HR input is longer than the physical vent length to hit what should be the correct tuning the cab will have with the amount of vent area. Doing this causes the vent resonance to be somewhat lower in frequency and more severe than it will be. In order to get the vent resonance in what should be the correct frequency range I shorten the vent length to the physical length, but this raises the tuning of the cab. To compensate for that in the sim I have adjusted the vent area down to hit the expected real tuning correctly. These are the sims shown. To further complicate things overall vent volume and area affects the amount of efficiency that the vents have. More volume and area= more gain. Also a single large circular vent has upper end resonance behaviors that are different than multiple smaller vents of the same area that are square in cross section. HR doesn't know this either. I saw this same type of behavior with the MAUL which loaded a huge vent right into the back wall of the cab and to a lesser extent the Skhorn.

Anyway I'm interested to see what the vent resonance turns out like in the real cabs. It could end up with almost no effect on the response (hopefully) or it could create a large notch as low as 160Hz (WCS). As usual I think it will be in between. I'm going to wait till I have real data so I can adjust the HR inputs to reflect the vent behavior before posting the inputs.

6 hours ago, USRFObiwan said:

Exciting stuff Ricci! I guess the 21NTLW5000 will just fit in there. 😛

I also think you should flip the skids 90degr on the long sides you could use 2 per side instead of 4. saves some material and routing. I cut the skids myself from 15mm HDPE plastic sheets.

I looked into cutting some HDPE or similar. I left the skids on the longer dimensions because it should be a bit more stable. I'm still not entirely sure which way I will go for feet / stacking yet.

It should fit no problem. There is still no availability of that driver here in the US. I see it available in a few shops across the Atlantic but I haven't seen anyone that actually has them yet. Seems like they've been advertising that driver for a long time now not to have stock.

Simulation with the 21NTLW5000. Standard sim with factory specs is the black line and actually looks pretty good. Using the generic high LE function uglies up the response a lot (grey line). It doesn't load the vents as strongly as the more efficient drivers. I don't think it will behave like high LE graph though. Unfortunately there aren't any semi inductance specs available for the driver to do the more accurate sim. Hopefully someone will pull an impedance measurement from one and post those soon.

1 hour ago, m_ms said:

@Ricci

Good looking (and likely performing) single-build of the SKhorn - anticipating measurements/testing.

Do you see yourself returning to Tapped Horns or even Front Loaded Horns with future builds? Does the SKhorn (singles or not) sound like TH or FLH's with similar tuning frequency - seeing that it houses its driver hidden inside the enclosure, or how would you describe it sounding different?

/Mikael

I don't see myself doing many TH or FLH's in the future. FLH makes more sense for systems without size restrictions, looking to extract maximum from a single driver and those without the need to go very deep. I might employ it for 80-300Hz range or so in the future but it's doubtful I'd do a subwoofer. 30Hz extension is bare minimum for something I consider a "sub". FLH's can be bested in the lower register by smaller more output dense alignments. They can sound very good. TH's I've found that the limited bandwidth and limitations imposed by path length needs and folding options cause them to be difficult to design well. More importantly the harmonic resonances in the response are audible and can cause major issues with harmonic distortion and ringing. In order to keep this up out of the sub bandwidth, well damped and above the low pass filter it's difficult to get extension much lower than the Othorn IMHO. TH's are best with extension to the 30-40Hz range IMHO. When done right they can sound killer as well, but the driver is more exposed usually so they have a bit more operational noise than FLH's. Better driver cooling though. The hybrid BP's I've been doing can be smaller than TH's, much smaller than FLH's and can almost match the TH's output. They are still somewhat tricky to design well and package but easier than a TH and easier to build. The response can be made to lack the upper end response issues more easily. The driver is buried in the cab so mechanical and operational noises are diminished, which is a big deal to me, but the air exchange and cooling is a lot better than a FLH. They are a bit more tolerant of a wider range of drivers as well. The sound is definitely clean and visceral when done right. 

In summary I have heard excellent examples of all 3 sub types. I'm a big fan of burying the drivers in the cabinet. Reducing the direct operational noise of the drivers especially when operating at high excursion / high output scenarios makes a large difference to me. The tradeoff is it may be difficult to tell just how hard the driver is being worked. 

Here are some HR sims with the 21DS115-4 and the Lavoce SAN214.50. Both are using measured specs with semi inductance from drivers I have. Dark line is all vents open. Grey line is with one vent blocked. There will be some slight differences due to the inability to model the vents and horn slot exactly, but they should be relatively minor. 

21DS115-4 

SAN214.50

Hell might as well throw the NSW6021-6 in there too. Also using measured specs with semi inductance. 

16 hours ago, radulescu_paul_mircea said:

What you hear in the video is the noise I get that keeps getting louder with time. It certainly is a suspension and glueing problem.

 

Very similar on the coil and gap but not magnet and coil material. If the coil is copper it means it is thinner for the same Re if the length is the same. This might mean that the gap width could be smaller so even if the amount of magnet is not the same, it might have a similar magnetic field inside. But that's just speculation.

 

That's reasonable speculation about the motor / coil specs. There are some differences, but the gap and coil overhang geometry is very similar. Weight is almost exactly the same. I like the spider setup with a spacer ring on the Eminence better though.

Did you recone a 21Ipal yourself? I'd like to see pics of the guts if you have them.

Your video does sound like a suspension issue. I'm hoping to be able to put up a video showing what I'm seeing on the Lavoce driver and the others this Thursday night. I won't have time until at least then. BTW the Lavoce driver seems to be quite capable so far.

Plenty...Website changes, new drivers, a bunch of sealed cab tests. Hopefully Skram testing this summer. Website change and data migration has taken up most of last year and this year so far. Looks like it is getting close though.

6 hours ago, radulescu_paul_mircea said:

Yes, I've seen that. The overhang is 21 mm, pole piece is 19 mm so the coil length should be 61 mm, huge. Probably the best 21 pro driver for vented alignment. Also, the BL^2/re product is around 330 and and that double separated suspension should make a very good sound 

Coil overhang is 14.63mm. Xmax including 1/3rd of the gap is 21mm. It does that easily. Spiders are mirrored and large enough to maintain linearity. Big shorting ring, etc...Very similar to 21Ipal gap and coil specs. 1mm longer gap and just 0.3mm longer coil wind.

For comparison the coil overhang on a RCF 551 is 10.5mm and a 1/3rd gap xmax spec of 16.5mm.  The  DS115 is 11mm overhang and 15.67mm including 1/3rd of the gap. 

I think you may have had a different issue with your drivers. That's not what mine sound like. What I've been seeing is a higher pitched "ticking". Could be the video recording quality though. I'll see if I can get something to upload. 

3 hours ago, radulescu_paul_mircea said:

First of all, wow, you already have that Eminence driver to test? I want a set of 4 but I have to wait for 4 moths at least. 

Im a 50min drive from them and they are production samples. Full production is a ways off still. Results are very encouraging so far.

6 hours ago, Ukko Kari said:

 My hypothesis is that the shorting ring or rings are loose, and moving in response to forces generated by the coil. 

Thats another option. Might be the correct one too. It is present even with nearly imperceptible excursion levels. It is almost non existent once loaded in a cab and doesnt seem to affect the performance otherwise.