peniku8

Whoa those edges look rough. No compression bit used here?

I typically like to grab the HR sim and use the filter wizard so that the maximum excursion below tuning doesn't exceed the maximum excursion above it. With a 4th order Butterworth that typically lands a few Hz below the tuning point, which is around the same point as you suggest, for this cab's native tuning of 30Hz.

Draw a 1:1 sketch onto the wood (optional but helpful). Then make a 6° jig for the table saw and cut it where it needs to be cut

I couldn't help myself...

Here is a small guide of what you need to obtain accurate measurements of a subwoofer: Equipment: Microphone with a known frequency response (ideally an omnidirectional mic, something like a UMIK for example, but technically for this purpose any microphone with a calibration file for on-axis (free-field) sound will work) Audio interface Amplifier DUT (Subwoofer) A computer with REW, ideally something portable Measurement process: Calibrate your electrical chain (I'd personally not recommend this step to beginners as it's possible that you'll be making things worse. So if you don't know how to do this you can omit this step, since it's likely not gonna make a huge differency anyways if you have decent gear) SPL calibrate your mic (not needed if you just care about frequency response) Find a suitable open space to obtain your half-space measurements in. This means outside on a flat surface with no objects within a certain distance to your DUT (say ~10m or 30ft; parking lot for example or your backyard if it's large enough Place the subwoofer in the intended configuration with the radiating source (aka reference axis) towards the microphone Place the microphone one the ground and at least 4 times the widest dimension of the baffle/frontal area (typically diagonal) away from the cab, which would be about 4m in your case Take a measurement sweep in REW. Start with a low level to avoid mishaps and define a sensible sweep range (for example starting two octaves below the expected tuning point and ending two octaves above the intended maximum usable frequency, which would be something like 10Hz-500Hz in this case) Interpreting sweeps is an entirely different topic, but I hope I didn't forget anything here so you can obtain some high quality data!

no, go for it.

I mean, these are all problems that can be solved. If you pay me a bit extra I'll modify the cab to your liking and then you can compare my price to the CNC quote you get Shipping would be around 100€, looking at a quick google search. I would just prefer to not have to paint it (the vinyl wrap can just be ripped off). But you'll have to get yours painted too, so either way you'll have to figure that out.

Wait, you're in Germany? I'm selling my Skhorn, without the drivers. I'm in Germany too, hit me up if you want it

Well just think about it.. the port is how wide? 600mm? Now you increase bracing thickness by 18mm total (three braces iirc). So you lose 18mm of port width from your 600mm which is 3%. Make your port area 3% smaller in hornresp and see how much the response changes (hint: no).

As the title says, I'm selling my Skhorn. I took the drivers out and built single driver subs with handles for PA use, because I don't have space for a subwoofer anymore after moving. As such, I'm just selling the cabinet without the drivers. The port blocks are still installed. Plenty of pics here: https://www.avsforum.com/threads/skhorn-build.3037204/ Asking for 1000€, that's about its plywood cost atm (18mm BB). Fixed price, for anything less I'll rather keep it. I live in Germany near Luxembourg. No shipping, unless you handle everything. I have an epal pallet which I could put it onto. Would charge 50€ extra for that. I can not transport it either, so it must be a local pickup. Has 4 wheels installed on its back currently to move it around easily.

Heya, I wanted to update this thread with my recent findings comparing straight ports with shaped ones from two 21" subs. I build two cabs of identical size and tuning loaded with 21DS115-8 drivers, where one cab has a straight port and the other one has a port with continuously changing area. The shaped port has a moderate ratio of 2.5 (largest to smallest area). I put both cabs up for compression sweeps at 2m half space and the results are quite interesting. Port compression is visible at around 20V for both cabs, but I don't care much for fractions of a dB of compression. It starts getting interesting at 64V, where the shaped port went 0.5dB into compression and the straight port was at 1.5. The difference remains 1dB at 90V, but now we see power compression starting to kick in as well, centered at around 75Hz. Here are both cabs at 128Vrms input: The difference is still around 1dB at tuning, but now we see a stark difference of around 2dB near 70Hz. The cab with the shaped port behaves much better overall producing a smooth curve, which would still sound excellent at those levels, while the straight ported one starts being kinda all over the place. The difference at tuning is easily explained: the aerodynamic port reduces 'air resistance' so the cab is more efficient there. The expansion at 45Hz I can explain too, or at least speculate: This is where impedance and particle velocity is high, which means no power compresison in this region and vortices forming along the surface, reducing friction with the cabinet walls. The dramatic difference at 70Hz I have no clue. The port does nothing at that frequency... Interestingly, the sweeps at 181V look similar, because both drivers are heavily into power compression at that point, but the shaped port wins out by 1dB on average. Distortion looks pretty similar across all levels, except for the 128V sweep, where the cab with less compression also has quite a bit less distortion (around that 70Hz). So, conculusions.. It looks like overall a shaped port can extract 1-2dB more out of a subwoofer of a given volume, depending on which frequencies you need for your application. The cab with the straight port performed almost identically from 40-60Hz, but for other frequencies, it might be the difference of bringing 6 to bringing 8 cabs to a show. On another note: hornresp predicted this subwoofer's max output at 44Hz to be 124dB (1m full space), limited by Xmax. But I measured 129dB (2m half space) with just 7% THD... 5dB is a pretty big difference, especially since hornresp doesn't factor in any sort of compression...

Randomly came across this old topic and I thought I'd elaborate on what (probably) happened here, in case someone comes across this in the future: Some amps have their 2nd channel running double reversed. Their input phase is flipped and then the output wiring is also reversed, flipping the phase back. This seems to make it easier on the power supply, since one channel generates a positive voltage swing, while the other goes negative, creating an overall balanced load on the PSU. It's kinda like running bridged. Since the output wiring is flipped on channel two, 2+ will be neutral. And since both channels are running on the same PSU, ch1 and ch2 have a shared neutral, which means you're running 1+ and neutral, essentially the same as 1+ and 1-. If you hook up 1+ and 2- while feeding both channels the same input, you're running bridged (differential) automatically.

I was under the impression that the variable input voltage thing was a doing of the SMPS itself, not PFC. Are you sure these amps have PFC? I got an email from them announcing the D-3004 with 4x8600W@2Ohm but in the follow up mail their rep said that the amp isn't really 2Ohm stable lol. But if it really performs up to spec, you could run 3 Skrams per channel for a total of 12 cabs off of a 1U amp, which would be pretty sick. But of course pushing the amp pretty hard.

Nice endfire setup! I'm in the process of building a 4th sub (not Skram but also 21") and will bring all 4 to a wedding next month. I also got a mail from CVR that they released a new 35KW 1U amp. Would love to test it but can't really justify buying stuff just for fun yet lol!

Nice! Now you just need to get appropriate amping and the setup will slay. Btw, it's called "infrasonic" (sound), not "subsonic" (speed)

If you have an air compressor, buying a brad-nail gun is a better investment than buying clamps imo and it makes building the cab way easier. If your cuts are clean and you don't have to use construction glue, that is the best solution. Danley does it like that. If I didn't buy a large press to put the whole speakers into, I'd do the same. If you really want to use clamps, I can recommend to buy extruded aluminium to spread the clamping force over the length of the edges like I did in my Bordeaux build:

Wow, is this a spam post written by ChatGPT?

1. the LaVoce is a perfectly adequate driver. If you're in the US, the Eminence driver will output like 2dB more. In Europe the price difference doesn't make any sense 2. a roundover bit 3. I machine circles in the top of the cabinet where the (round) feet sink into 4. uh none; you can line the walls not near the port with foam if you like 5. you answered your own question 6. that's up to how good your woodworking skills are - I built an SKhorn without a cnc

I'm probably going to sell mine; you don't happen to be in Germany? lol

Sealed subs are not suited for live sound applications. They won't have enough headroom down low

What you're talking about is compression and expansion. There are a lot of factors that can cause compression in subwoofers (a change in input gain results in a *smaller* change in output change), like the voice coil getting hot (impedance rises, so the same amount of voltage generates less power; also known as power compression), air velocity in the port getting too high (port compression), the driver reaching excursion levels where the magnetic field strength gets lower (over excursion) or simply the amps' limiters kicking in, to protect the drivers from destroying themselves. To express the effects of compression with your wording it could be something like: -volume change from 70% to 75% is very large -volume change from 75% to 80% is small -volume change from 80% to 85% is imperceptible Since you describe the opposite effect, if I undersood you correctly, this doesn't apply, since you're seemingly describing expansion. There is only one cause of expansion in subwoofers that I am aware of and it is minute. So, if expansion doesn't happen inside a speaker, what's the thing you're hearing? I think the explanation is fairly simple: it's the lack of compression. You're not used to hearing capable systems that can reproduce content with their full dynamic range, in which case the SKHorn would be one of the worst choices, since it's one of the most capable subwoofers out there. Another explanation would be bad deployment and what you were hearing at "75% volume" wasn't the subs being super loud, but everything distorting badly (which will be perceptually louder, since our hearing is more sensitive at higher frequencies and distortion will mostly produce frequencies higher than the stimulus). Most venues and festivals I mix have underdeployed systems and/or are badly set up. The last festival I mixed at had a stack of 3 2x15" subs on either side of the stage. All three cabs were different, which was the first point of concern, but the biggest issue is the physical deployment: you get terrible lobing and super uneven bass response across the audience (see my recent post on AudioScienceReview on this topic). I haven't experienced the effect you're describing. Most of the time I'm fighting compression and uneven response across the audience. The issue you're describing can have many causes, but "subwoofers being overly dynamic" it is not. My answer to that question would be "source content" as per the explanation above (lack of compression; habitual). The difference between 1000 watts and 4000 watts will be 6dB in theory. In practice, some compression will have set in at 4000 watts of input power and it will be less than that at certain frequencies.

Cool video, I haven't seen that before. Gotta do this too, been too lazy to phase align my PAs but I really should. The alignment tool in REW looks super cool, this is the first time I see it. I used to take a bunch of sweeps changing delays until things looked right lol. Btw you don't need to run the timing reference to a speaker, you can do a straight (electrical) loopback instead. When integrating multiple drivers via dsp in speaker designs, I do it in the following order: Apply corrective speaker/driver EQ (minimum phase) SPL align Apply Xovers Take another measurement of the individual components/speakers now with everything that changes phase already applied Phase align Take another measurement for validation And then when the PA is set up I'd probably align the PA with the Snare drum, because that will likely be the loudest sound coming from the stage and in smaller venues that will actually dominate the overall sound. Not applicable to DJ gigs of course, but something to keep in mind if you're working with acoustic sound sources. I'll be rocking Powersoft soon so I'm looking forward to getting all of this running.

yes: room eq

Why the double baffle? What's your panel thickness?

should be fine since the horn loading isn't a high-pressure loading so it should almost behave like in free-air just take an impedance sweep, set the sine wave to the resonance and give'er should be good to go after a few minutes near Xmax and yes, it'll occur with usage, but you'll have to do a few gigs before you can set up the system properly with measurements n stuff, because calibrating the system with subs that'll be slightly different each gig doesn't make much sense