Jaekels and Itasca, Versabox design #4a- NE180-4/CAT378, and #4b- Bold North 2901/6501...

Wolf

Did the model 3-4 years ago now. Constructed xover from model, but I'm sure tweaks will happen.
Versabox shiny white like in Monoculus, swapping baffles and networks for these below. Saw some acacia butcher block cutting boards at Walmart that were inexpensive. Cut to size, chamfered edge, applied Danish oil, let dry, cut holes, and applied polyurethane. There were no voids in these, and the poly soaked in several times.
Yep, this is a series xover as I did not get a parallel with as few parts that I liked the look of.

JasonP

Those are going to be some wild and awesome looking baffles!

6thplanet

Neato!!

Gowa

Those baffles look sick!

Wolf

This is what the model and information looked like when I did it:

Wolf

I thought the horn loaded CAT378 tweeter would push the AC rearward enough to get closer to the AC of the deep cone of the NE180-4. Real measurements to follow...

Of note, I will be mocking up another project at roughly the same time. The Acacia block baffles were thick enough that I could route the opposite side of the boards for another set of drivers. The NE 5-hole and CAT 3-hole being non standard hole patterns allowed for a standard hole pattern to be used in opposition. The other side will be called Itasca, named after a lake in Minnesota. It will use the Misco Bold North BDT-290 and BWX-6501 drivers.

The Jaekels have a small chamfer on the edge, and the Itasca have a small roundover, just for identification sake.

rjj45

That's really a very nice F3 with a 180mm woofer and 15L box.

Nicholas_23

How is that 35 bump sounding though?

Wolf

I would agree, Don, especially for a midbass. Subwoofer specific woofers can do it and lower, but not many in that box and tuning.
Baffle images with tweeters and midbasses just sitting in the rebates:

Wolf

@Nicholas_23 said:
How is that 35 bump sounding though?

That was with the initial box sim in tow, and a larger box with lower tuning. It won't be there at all since the Versabox volume and tuning simmed above will get utilized.
No listening has been done as yet.

Wolf

Looking again, if I may have misunderstood your meaning, Nick, and you meant the 3.5k tweeter bump, I have revisited the simulation since what is seen above and tweaked some values. Since I have yet to take real FR whoops, this will likely change a little and is why I have not posted the modeled schematic. The top-end can easily be level adjusted, and I'm hoping the suckouts and peaks are not that severe as shown in the simulation.

traw

Ironically rebuilding new cab for those NE180's, though I have 8 ohm version that scored off fleabay, shew back in May24 I think. Re-pair with the seas titan 27tac's. In slightly bigger box since my small listening area and thus lower spl allows me to tilt toward bass heavy. Feel better seeing that 1.4k ish drop like I did, i'm not insane heh. Then noticed when tinkered with modeling it was sticky at that point, like boost coil, tilt down but the point stick. There are so many observations I'd wanna pick someone's brain on if could better articulate what I was asking. Luckily, here there's lots of free open thoughts and absent of crazy people dragging things into left field missing the point of discussion - so appreciate that.

Wolf

Since I'm using the same butcher block acacia boards for the Jaekels herein as the Itasca, just from the other side; I will be calling Jaekels #4a and Itasca #4b in the Versabox lineup. Itasca used the BWX-6501 and BWT-2901 from the Misco Speaker Bold North catalog. Itasca is the name of a Minnesota lake, and I felt since they were up to the task, the name was well suited. I guess it is kind of a two-faced alter ego implementation after all. If the mounting holes and terminal connections had not made this possible, I would not have been able to have 2 projects in the same board.

Data dumps from this afternoon, of both of these implementations....

Jaekels;
CAT378 followed by NE180-4, HD, then 0-15-30-45. These have 1/24th octave smoothing applied:

Wolf

And #4b; Itasca; same format...
...But before I post the grit...
Okay, some background is required here. I have 3 of the BWT-2901 tweeters. The first one had a buzz in it, so I got a replacement. After I measured the 2 that seemed fine, I went back and tried to see if the bad one was just a misalignment and see how far off they were from one another. You will see why I did this, as I wanted to get the best of the 3 if there were drastic differences. I will also include the impedances for the pair that did not buzz initially.

Also apparent is that these tweeters are bit different than the norm. They spec them to be able to play down to 1kHz to meet their Bold North woofers, and the 3rd order HD really bottoms out around 1k area. I am a bit perplexed as to why the 3rd order peaks in the middle of the audible bandwidth from 2k-3.2k to the level of 2nd order HD, but the rest seems like once it is flattened out that the HD will be improved in the reduced output areas.

Impedances, T/S:
BTX-2901;
Tweeter #1 is pictured before the alignment was checked:

BWX-6501;

HD/FR;
BTX-2901:
Tweeter #1 has been tweaked, and the buzz was eliminated;

FR is of sample #3;

BWX-6501;
Let it be known that the woofers were set at -9.5dB on my preamp dial for my HD measurements below. Typical listening volume is from -30dB to -15dB for most speakers.

ScottS

Itasca is not just any lake in Minnesota. It is the headwaters of the Mississippi River. I'm confident you can do it justice, but it's not an insignificant responsibility.

Wolf

Info I did not have, thanks!

Steve_Lee

Are those BTX-2901 tweeters broken-in yet, Wolf?
(Just curious if that 3rd order stuff is a result of some mechanical stiffness).

Wolf

I would say that they SHOULD be broken in well. I did not run the HD/FR sweeps with a series cap at all, and the FR were done first in the timeline. This means they were fed the full bandwidth, and the suspension should have had a workout if it was getting one. It is a textile dome from Kurt Mueller, same vendor SS and others use from Europe, so that is a good part.
Thoughts- These tweeters have a different internal layout than many others on the market. That said, here is an image from the Bold North website to illustrate what I mean:

There is copper in the faces of the gap, as shown.
I will say the main difference is that the felt ring pictured next to the cylindrical foam/felt plug atop the central pole is not present in all three of these tweeters. I figure this must have been a pre-production image and they decided it wasn't needed after the fact. There is no other damping in the cup than the cylinder as pictured, and I did make sure the cylinder was not contacting the backside of the dome. I did not remove the plug to look inside. There are drilled holes through the front plate under the surround to vent air compression into the first of the 2 chambers, the 2nd being the main one through the pole. Face is plastic, dished in profile, and the chamber-back-cup appears to be pretty stiff and solid. Terminals are easy to solder to, but if you are a person who likes more substantial terminals for disconnects, you'll need to add them. I soldered a set of short leads from the stock terminals to some 0.25" male tabs that I glued to the rear of the chamber for easier electrical attachment.

6thplanet

Definitely a different approach to the motor design.

Wolf

BTW, I have contacted them on my tweeter findings thus far, inquiring about the missing rings, etc. We'll see what they have to say.

Wolf

Okay, it looks like I have to send the tweeters I have back, and they will send me 2 good units when they've sorted this out. They were very helpful and wanting to fix the issues I've seen with these 3 units. Itasca is at this point on hold until further notice.

6thplanet

That's nice of them.

Wolf

Yeah, they were very thankful for the feedback.