Ricci

8 hours ago, Rivilee said:

Has the LaVoce driver and built with Baltic Birch as specified. Not CNC cut but I've built several hundred speaker cabs over the years so it's well built. Includes a castor plate. How about $1200 and I'll be glad to deliver for expenses. I'm in middle Tennessee. I'll be glad to build more (with permission from the designer) if you want them.😁 

Do you have any pictures? Would you consider selling without the driver? 

On 11/1/2019 at 6:24 PM, peniku8 said:

@Ricci How would the K20 fare with 4 21DS115-8 in parallel on one channel? Impedance minima would be around 1.3 Ohm. I'm thinking about getting a K20, but if it's not performing well with that load I could also get a K10 and go for a 4 Ohm configuration. The difference between K20 and K10 is much less at 4 Ohm than at 2 Ohm.

It depends. The K20 will run stereo at 2 ohms, but it will limit long bass notes into low impedances considerably. Buss pumping can be a problem. The exact impedance and phase of the load and the bass content used will determine how well it does. I really recommend bridging the K20 or K10. They perform better with heavy duty signals into low impedances when fully bridged. 

21 hours ago, jay michael said:

Set up pic from our Halloween cabaret last night. Experimented with a 100hz crossover and found it to be the most impactful and cleanest config I’ve tried yet.  Techno and psytrance all night, sounded incredible. https://imgur.com/gallery/qrU6jyD

 

https://imgur.com/a/dacbWrI

Awesome. I wish you were closer to me so I could come to one of your events and get a listen of the Skram + SH46 combo. 

Hope everything is good with you Luke. 

Good luck with the sale. 

9 hours ago, menace said:

Ultimately this has to come at a cost to efficiency and/or extension.....

On another note, do you think you will ever finish the pale-horn design/drawing? Or do these hybrid designs totally supersede your interest now?( will be interesting to see the final analysis ie your measurements of an SKram loaded with 21sw/21ds vs the old othorn measurements).

Also this may have been covered somewhere else but whats the theory to these hybrid designs, obviously there is bass reflex... but how does the horn part work together with the bass reflex? There is the compression ratio working as a  cushion against the driver? What about the horn length, how is that fitting in?

HIL is still in effect. There's no way around it. 

I probably won't. The limited bandwidth of TH's or the added complications and size to the cabinet to be able to deal with the upper band resonances via tuned resonators limits their usefulness to getting much below 25-30Hz. IMO.

It's just my own variation on a 6th order bandpass mixed with a rear ported horn or whatever you want to call it. It's nothing new really, but the way I design them differs a lot from the way I had always seen them done. The most similar are pro audio designs with a big emphasis on the horn section and a port added to a relatively small back chamber. Not much extension below 40Hz. They are targeting being really loud >50Hz with those designs. There are some exceptions in the past couple of years from a few companies. In mine the upper section gets only a little sensitivity gain. It is mostly used for filtering noise from direct radiation of the drivers at high volume, lowering distortion a little and physical protection of the drivers. This leaves more of the cab volume dedicated for the low end where it is needed most. There's quite a bit more to it, but I've covered a lot of it in the MAUL and Skhorn threads. 

I've been messing with a more compact single 21" version more similar in size to the half Skhorn that was originally planned. It won't be drastically smaller but I'm hoping to chop a few inches off here and there without losing too much performance. 

23 hours ago, Boomer1950 said:

 I've settled on a 7ft^3 box with a 70 sq.in. port that is about 40" long which I hope gives me a tuning of around 24Hz.  I will be dividing the port into 3 pieces for added support & to give me the possibility of closing one or two of the ports.  I assume dividing the 70 sq.in. port into 3 ports will lower the tuning, but that seems fine to me.

Are you sticking with the box dimensions posted earlier of 20x26x29.35"? It sounds like you would be placing the driver and ports on the 20x26" face? 

It's hard to say exactly what is going on since there are so many variables. 

What voltage is being applied to the terminals during the measurement? Is the impedance really 15 ohms or greater? Is this 2 8 ohm drivers in series? Are you using a generic mic sensitivity spec or do you have an SPL calibrator? Mic sensitivity specs can be suspect in my experience. 

Pressures inside a cab can get very high especially if testing for system output capability. Finding a mic or sensor and mic pre-amp that can take it won't be easy or cheap most likely. 

Don't forget that despite subs being "omni-directional" they exhibit some directionality at higher frequencies, baffle effects and the apparent acoustic center is often a significant distance in front of the sub. All of this tends to result in measured SPL that is somewhat higher than predicted by simulation. 

Here is what the response for the sealed SHS-24 in 300L (10.5 cu ft)  would be and the excursion profile at 126.5 volts, which is the maximum for the SP1-6000. Specs are based off of what I measured from my D2's but scaled for D1's so the impedance is correct. Semi inductance specs are used. Basically this is a 28" cube. As you can see this looks nothing like winisd. I'd suggest learning HornResponse if you are serious about designing speakers. I wouldn't worry about the excursion passing 50mm below 4Hz. No driver is linear with power out to that level and content that low in freq is very unlikely to ever be full power. Also  the Torpedo amps have a 3Hz 1st order high pass anyway, which most amps do. 

Here are a few comparisons. 

This is still using the big 850L enclosure but cutting down the vent length and area and tuning to 10Hz. Light grey line is your original plan. Once you add room gain to this that peak at port tune is going to be WAY too hot. It'll have to be addressed with the HPF and EQ to cut it back anyway or anything that hits that narrow frequency range is going to be heavily boosted relative to everything else. Also this is just an absolutely huge cabinet. Outer volume will probably be approaching 40 cu ft on your original plan.  

This is similar to what I will probably go with. 425L tuned to 10Hz with multiple vents for different higher tuning options. This is literally half the size of your original plan. Still a very big sub but quite a bit more manageable by 2 people. Yes it gives up some output below 20Hz but relative to the huge size disadvantage it's not that much. This is with the 10Hz tuning. This would work a lot better with typical room gain, but still might require a bit of a cut at 10Hz. 

This is the same 425L cab with 2X the vents from the 10Hz sim which would raise the tuning to around 14.5Hz. As you can see this compares very well with your original plan that is 2X the size, which is indicated by the light grey line. 

Sealed is the easiest option. Anything from 200L to 400L per driver should work. Bigger allows the driver to use more excursion with less power. Even at 400L the SHS-24 should be safe from bottoming with an SP1-6000 but it would be getting close. 300L is probably a good intermediary. I'd not recommend something as small as 3cu ft (85L) Even the full output from an SP1-6000 would not push the driver to 20mm excursion. Heat would be a very real enemy in a cab that small. 

3 hours ago, BBLV said:

 

Hey man...Unfortunately what you would be building would be nothing like the winisd sim...

You are looking more at something like this. 

I've been thinking about this myself. The SHS-24 is a tough driver to tune really low and port well. It moves a ton of air but it doesn't really call for a very big enclosure for a smooth response. Big air spaces cause a large peak at the port tuning. It's difficult to get enough power on it to effectively use the excursion also. 

It really depends on your goals and how much you are willing to compromise. 

The cab you've specified is about 850L with a vent area of about 871cm and a vent length of 169cm. Tuning is around 12.2Hz. Personally I would not use a vent that long. It puts the vent resonance down below 100Hz. My limit on port length I generally set at 40" or 102cm which puts vent resonance at about 150Hz and a half octave above the typical sub LPF. It will greatly decrease your port area though. If you want to increase driver excursion, tuning lower helps  but again this either increases vent length or decreases area. 

If it were me and I was willing to go that big I'd go ahead and tune the cab to almost 10Hz by cutting the vent size way back to a length of 102cm / 40" and drop the area to roughly 363cm which would be equivalent to two 6" Aeroports. You will lose some output from 12-20Hz but it's not as much as you would think. Only a few dB. Airspeed gets really high at 10Hz but should be decent at maximum output above 12Hz. You gain extra extension and output below the original tune, the vent resonance gets pushed up to about 150Hz and the overall size of the system is reduced by about 13%. Don't forget that in a typical home listening environment room gain kicks in and by the 10-14Hz range it is not uncommon to have 10dB of gain. You will likely have to cut back the peak at tune and the low end in general or it could sound overwhelmingly bottom heavy. HR modeling with specs measured from my SHS-24's including complex inductance shows about an 8dB peak at port tuning. Add in roughly 10dB of room gain and you can see where this frequency bandwidth is likely going to need some EQ. Also content at maximum level down below 14Hz is really rare. I don't think you will be running a pair of these at full output at those frequencies very often. It will do things to your home and furnishings. I know from experience. What I'm saying here is I don't feel like all of the extra sacrifices that are caused by making the ports such a large area and length, are worth it for a few dB more output that is unlikely to be called on much, both from an output standpoint and a frequency bandwidth standpoint. Even with greatly reduced port area it should be more than enough for any sane playback level you'll be using in your home. 

I'm probably going with a 425L ported cab with half the vent area of what is proposed above. The size of the system will also be half of the above though. 

It's easy to see why most people go sealed or IB with the 24's. Simply put it in a 26" cube and it'll perform very well. No worrying about vent tunings, port velocity, resonances and it's a fraction of the total size. 

19 hours ago, Droogne said:

Also @Ricci, how did you determine port length? If I go by the length through the center of the port (659,8mm+153mm =  812,8m) + 1/2 of the port height (135/2 = 67,5mm) I get 880,3mm, not the 857,1mm you listed in the parameters. 

 

I believe I described how I determine port length earlier in this thread, or perhaps it was the Skhorn thread. I can't remember where exactly. I use line sketches in SW's and previous experience to determine the functional length. I'll see if I can find the post. Edit: It was on page 10 at the bottom of my long post. 

I'm surprised that you have ended up with an even longer length.

Droogne I've done square ports before and they work well. The ideal is round and heavily flared or shaped which I've also done where it makes sense. Have you read the available AES and other papers on ports? There are many. Compression and chuffing noise do not necessarily correlate. There are also papers which point to some possible advantages with multiple smaller vents despite the increased skin effect.

In the case of the Skhorn and Skram variable tuning is an integral part of the design that I considered fundamental. That is why they have many smaller vents instead of a larger single. Also it is structurally very strong. When considering them as individual smaller vents they are not too far from square. 

Its all about the tradeoffs. I think you may be overestimating the effect a change to the shape may have on compression. A single square or even round vent the area of one of the Skhorn vents isn't going to gain much. They will still overload and compress. The area is not enough to cope with the demand once the sub is pushed at tuning. This is true of almost every sub tuned under 20Hz. In the Skhorn's native tuning with all vents open with 3X the vent area this isn't really an issue as the testing showed. At the end of the day it's all about vent area in my opinion. 

On 10/20/2019 at 7:11 AM, Droogne said:

Didnt think about that, thats true. Could you theoreticaly model this by the 'pressure' function? In any case, bit of a derailment here, so I'm just gonna start a side topic to explore this further. What I noticed was that 

the peak sound pressure in the mouth was around the same in at mouth (around 9-10 pascals, and a little bit lower for the sloped port) and exactly the same at the throat. So going from this I dont see a disadvantage of doing it like this. Lowering the velocity by at least 25%, without increassing pressure (if this is related to power compression ofcourse).

 

 

 

 

Don't miss the forest for the trees. It is not only air velocity at the mouth that is of concern, but also at the throat or entry inside of the cabinet. If the port is flared, bowtie or otherwise more complexly shaped the performance at the "choke" points should also be examined. Any of these points can trigger compression. It's more complex than just airspeed at the mouth. You may decrease audibility of air noise but greatly increase output compression. The Bowtie type of slot vent is probably the easiest to incorporate into a design but it increases the total size of your speaker, or you end up with not much in the way of improvement, due to downsizing the minimum area of the duct to keep the same tuning. I decided not to bother with it for this design due to size and packaging constraints. 

More involved programs such as ABEC or Akabak can model, velocities, pressures and accelerations at any point in a pipe, duct or horn. 

I don't see why it wouldn't work. 

The reason I always try to fold the horn/slot section is to avoid firing the driver directly into an outer panel. There is usually room for only minimal bracing in front of the cone, no damping material and depending on how the driver is accessed it may even be a hatch. There is a lot of acoustic power concentrated into a small area with only a single panel of wood separating it from the outside world. It can result in audible radiation/vibration from the panel at war volume. It's a larger problem with bigger diameter drivers like 21's due to the larger panel area. Just something to consider. 

18 hours ago, menace said:

This is what I have come up with so far. Was thinking of fixing the mesh at the end of the mesh that's easy to get at with screws and washers and the other end will kind of grip into the wood by the sharp ends it has from being snipped to size. The mesh is about 1.6mm strand size, its easy enough to bend by hand but will still have a bid of tension on it from being pulled into position by the screws.

What do you guys think? Could it vibrate perhaps?

 

 

This should work to keep critters and junk out. Perhaps add a thin strip of foam under the screen where it contacts the wood to reduce the possibility of any audible vibration. 

18 hours ago, jay michael said:

These will make 6 in total

 

Dang...Firepower!

19 hours ago, jay michael said:

2 more on the way https://imgur.com/gallery/dRGsebY

You will have 4 when these are done? 

Do you hear any scratching or feel it rubbing if you gently push in on the cones? Is the sound more similar to a tapping sound or a ticking? Myself and some others did receive some 21Ipal's which were making a tick or tap type of sound. B&C replaced mine. I suspect that it comes from a loose shorting ring, but I'm not sure. It sounds like you may have the same issue. 

20 hours ago, Droogne said:

OK, as in equalish to the Lavoce and other cheaper drivers?

Based on the specs it should be. I've never seen any 3rd party data on it though which trumps MFG specs IMO.

Unless it is significantly cheaper I'm not sure I'd choose it over one of the Lavoce, B&C or 18 Sound models. If you are getting a great deal by all means give it a shot. 

On 10/3/2019 at 5:46 PM, Droogne said:

I've asked this before, but I'd like to know if the Beyma 21SW1600ND would be a close match to the cheaper drivers. I can get a pair for 450, and my initial modelling (based on the manufacturers disclosed specs) are great. 

 

Anyone who can chime in? 

It looks ok based on Beyma's specs. A little light on motor force but should be fine. The unknown is what the complex inductance specs look like but based on the published impedance curve it shouldn't change things too much.

Pretty much +1 on everything you said. LOL.

I don't do any live mixing anymore. It's a tough job and the guys that are good at it with good equipment don't get enough credit or pay usually. 

Here's one more from a current project. Instrumental ambient weird prog stuff. This show was opening for John 5 who is amazing and a really good guy. You may not have heard of him but he plays for Rob Zombie among many other things. 

On 10/2/2019 at 5:07 PM, peniku8 said:

I get what you're saying about feeling, but for me it's all about the overall sound, both when I'm behind the kit or in front of the stage.

I don't play with triggers live, but thought about setting it up for our IEM system. And yes, the gigs are exhausing 😅

https://www.youtube.com/watch?v=7-awEQjlSk0 [Live]

https://www.youtube.com/watch?v=PA6-rMbrF1E [Recording]

To get back on topic, for our shows the bass drops need to be as loud and go as low as the system can handle of course!

Awesome man... A lot of guys I know use triggers for death/grind/black stuff and it's fine if you've got a good engineer and PA but when the PA is undersized or when they have technical problems it's bad. We toured with a couple of bands that actually brought their own PA for their vocals and drummer. 

Here's some old videos from way back in my first band...1997-2004. The recordings are trash but the video is kinda required info.  Definitely not for everyone.

Also...Consider that you will still need to be wary of very high duty cycle signals over the short term. Things like air and water cooling will help with long term heat buildup in the motor and coil, but not so much with rapid heating of the coil over a short time period. Coils can be burned VERY quickly in some cases with a bad scenario. With that said I wouldn't assume that you will be able to increase the short term peak signal handling of the system at all and this is what has the possibility of reaching driver Xmax for the most part. The longer term signals that make most of the heat buildup aren't normally going to be causing excursion issues. In fact greater excursion helps cool the voice coil and motor. With that said I definitely wouldn't go smaller with the cabinet. 

Ipal module will fit on the hatch. The hatch is the same as on the Skhorn and I believe I posted the files for the hatch with a Speakerpower SP series and the Ipalmod cut out in the Skhorn thread. As mentioned you want the sensor close to the cone and apex of the horn.