peniku8

25 minutes ago, Domme said:

It's no easy project at all. I have some woodworking experience, but not too much, and had some help from a friend master carpenter and it was still a PITA to get it all right. Without his help I probably would have messed up the glue step because you need to be quick! Those huge surfaces are not easy to move around once you apply glue and it's almost the last step and you can still mess everything up... you also need strong clamps and MANY of them.

I would probably order all parts CNC'ed next time because even though it was worth for the experience and learning, when you count man hours it wasn't worth spending hundreds of hours just to save a bit of money. Anyway, good luck!

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?

12 hours ago, Derecaston said:

Choosing the right subwoofer can be a tough decision, but you've got some great options in mind! The Captivator 4000, RS2, and Pro18 are solid contenders. It'd be awesome to have some graphs and measurements to make an informed choice, right? For your theater and music playback, those low port tunings and high SPLs sound like a fantastic combo! While the thread might be a couple of years old, the quest for the perfect subwoofer never gets old! You could still check out audio forums or websites like d20 roller, where you can find a dice that will help you make the choice.

3 hours ago, rolo95 said:

Guys,

impressive work each and everyone who built the SKRAM

i have a couple of questions

1.- How many dB get lost  if i get the least expensive driver from the list , the Lavoce SAN214.50 or the RCF LF21N551

2.- what router bit is used to trim the 90 degree angles in the outside of the box where the outside panels meet to each other, so to look more pro factory made cabinet with chamfered/rounded edges

3.-  do you guys use any method so to stack 2 or 3 cabinets and some feet or corner cover that fits in to each other cabinets so to "lock" and do not let the cabinet run or fall when stacked in top of the other.

4.-  what area of the back driver chamber need to be filled with ikea pillow stuffing ?

5.-  is best to use the 8 ohm or the 4 ohm version?, i plan to run 2 8ohm drivers in paralel for a 4 ohms load in to the amp channel, im not confident enough to run @ 2ohms load regardless

6.-  do you need a CNC machine to cut the wood or you can make one with just a table saw.

 

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

6 hours ago, Lab_Experiment said:

Linear Frequency response is not the same beast as Linear Frequency Volume response. If you're replying please understand the distinction. I know it can be confusing.

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.

7 hours ago, Lab_Experiment said:

2. Was the unilinear volume response amplifier related or speaker/box related?

My answer to that question would be "source content" as per the explanation above (lack of compression; habitual).

7 hours ago, Lab_Experiment said:

3. If I build a SKHORN will it only sound good when I'm pushing 4000 watts?

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:

1. Apply corrective speaker/driver EQ (minimum phase)
2. SPL align
3. Apply Xovers
4. Take another measurement of the individual components/speakers now with everything that changes phase already applied
5. Phase align
6. 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.

6 hours ago, Leimahmood said:

i have four skram box in my theater room and two port block tune to 20hz iss there any specially eq needed the driver used is b&c 21SW152 4ohm

yes: room eq

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

4 hours ago, kipman725 said:

I was trying to avoid audio connectors so that the wrong cable didn't get plugged in. 

We are building 8 Skrams at the moment with B&C 21SW152.  I notice the suspension is super stiff out the box on these drivers but finding the space to do any kind of free air break in is a challenge while also building the subs.  Does anyone see an issue performing break in with the driver mounted in the subs and the hatch removed?  also failing that I guess break in is actualy not that important and will occour with usage?

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

7 hours ago, kipman725 said:

The thermal sensors sound interesting I have thought about adding 1 wire temp sensors to the magnets of our speakers but am a bit stuck for low cost gas tight connectors and cabling and also how to attach the sensors to the magnets. 

Technically, you'd use the thermocouple to set limiters and then remove it after that's done, so the simple tape approach would be sufficient. If you want something permanent, you could use thermal epoxy. As for connectors, well, I know that the NL4 MPRXX is air tight, why not use two connectors for the sub and two for the sensor?

depending on how close you are, you can bring them over to me and I'll measure them, I live in Germany but I'm right at the border to France

pm sent

1 hour ago, Father Francis said:

Is it just one or you have two ?

I have one Skhorn

I don't have time to answer to everything, but I noticed you're looking to build an extremely light subwoofer, but the driver you're looking at has a ferrite magnet and it's almost 18kg. I'd recommend looking at something like the 18NW100, 18NBX100 or 18DS100 instead. You'll be saving 7-8kg on the driver alone and in the instance of the 18DS100 you're getting more performance (but it's 100€ more per driver). For pro audio subs I'd never go with ferrite drivers, unless weight is a non-concern (which it almost always is).

That being said, 35kg is a low target. You'll need to make it from relatively thin (12mm?) BB ply and have good cross-bracing inside to keep it from flexing.

11 minutes ago, klipsch said:

Tragic! I'd take it off your hands, but shipping across the pond is probably a bit expensive. 

Yea you're probably better off building a new one. You've got that cnc, so should be easy

Technically, 4-6KW burst RMS sounds pretty good for high powered drivers, as long as they're not like 10dB into power compression at that point. I'm in the process of designing and building new subs and will be testing them extensively with thermal sensors and in regard to power compression. They're a bit different from the Skram/Skhorn, but use 21ds115's, so the results might be interesting here as well.

On a different note, my Skhorn has been sitting in the basement unused for 2 years and I'm not sure if it'll see any use any time soon, it's a bit sad.

I'm gonna switch from clone amps to Powersoft soon. It means I can safely extract a few dB more out of my subs, thanks to the vast limiter selection Powersoft offers. Or consequently: bring less gear and ride closer to the edge of what the system can handle, without worrying that it's going to destroy itself. With non dsp amps (or amps with bad dsp) you always have to worry or overprovision your system, which gets annoying over time.

Funds and space for entirely new subs will be less than what you'd need (overall) to get additional subs to fill out the lowest octave.

Looks like you're just collecting ideas at this point, since neither funds nor space for your initial proposal is available either.

You can possibly replace your 8 subs with 4 Skrams and get the same midbass output, plus better sub bass, but you will likely need new amps as well. Well, to use them to their full potential at least. 3-5KW per Skram should be a good match with TotL drivers (burst; they will melt if you give them 5KW sustained averages).

I can just echo the others here. Once you get proper subs to supply the bottom end you're looking for, these cabs will also be able to replace your current subs. And if I was space limited, bass horns would be the last thing I'd load into my truck. IPALs it would get, in tiny vented cabs.

By the time you have enough Othorns to keep up with the midbass of the other horns, you can get rid of the USBv2s entirely. Beisdes that, the Othorn isn't an infra design, they will probably not add as much as you'd hope for. If you want infras, you might want to look into a custom vented cab tuned to ~20Hz or so, but you will need a lot of juice (and a lot of cabs). And then ask yourself, do you even need them?

5 hours ago, chrapladm said:

I simulated the driver and it looks doable but SW152 looks much better. Problem is the BC is $2500aud each almost. The Beyma is much cheaper. The eminence is also around 3000 each.

Wow that's hardcore, I bought my last 21ds115's for 380€ (600AUD), but they're up to 640€/1000AUD now, which is a price I'm sure you'd be very happy about still. It's crazy how bad it is when you don't have an official distributor on your continent.

Where can I find measurements of these subs? They seem to be as big as a double 18 while only having one driver, looks pretty oldschool to me when amps didn't have the power on tap than they have today.

9 hours ago, m_ms said:

"Guesswork" to you is using one's ears to others. At the end of the day it's what matters (i.e.: listening), but if measurements is what makes your day in this specific amp context, go ahead and look up specs and try and be the wiser on the actual perceived effect. My assumption is the in-room frequency response won't change, but that's not to say there can't by any sonic differences.

What would the sonic differences be, if both amps produce the same frequency response and produce less distortion than the speakers do (which they do, unless they're defective OR clipping)?
If this listening test was a DBT with perfectly matched gains (with a voltage meter) and ONLY the amps were swapped (ideally via switch in rapid succession), then the comparison is fair, but as soon as it involves sighted bias or any other uncontrolled variables the test is invalid.

Did you measure anything at all or is that all just guesswork?