The Uluwatu - another new Curt C design?!

[bearhaus]

Re: The Uluwatu - another new Curt C design?!

yeah flat to 20hz sounded crazy to me. I am still very much a beginner but I thought it is very hard to measure anything < 200hz accurately. That's why I fielded my question.

I've been contemplating a larger build for quite some time now and if these will get to at least the low 30s I'm jumping on them this week.

[tomlang]

Re: The Uluwatu - another new Curt C design?!

...if these will get to at least the low 30s I'm jumping on them this week.

+1

[Silver1omo]

Re: The Uluwatu - another new Curt C design?!

...A little miscommunication between Alejandro and myself. He has little English and I have no Spanish, so the google translator was working overtime across the pond, and some things apparently just don't translate all that well.

C

If you or anybody else need some help translating to or from Spanish send me a PM. My native language is Spanish and my English is not that bad :P

[divdev]

Re: The Uluwatu - another new Curt C design?!

I finished my build of these.

It isn't perfect but I did flush mount the drivers using a hand routed template. It took me about two nights of experimentation to get a satisfactory template. Woodworking isn't my forte so I was happy with the resulting baffle.

There is a fair amount of wiring work so the prefab crossover in the newly available kit definitely seems a worthwhile time saver to me. I probably overdid the 7mH with my choice of a 14awg inductor. I mounted the crossover at the bottom and the terminals low on the back. If you do the same be careful because the port is very large and may interfere.

The low bass response is immediately apparent. I'll try to post a few listening notes after I've had some time with them. If anyone near Londonderry, NH is interested in listening to them drop me a line.

Of course, many thanks to Curt for the design.

[divdev]

Re: The Uluwatu - another new Curt C design?!

A few more build pics.

One oddity to note is that a few of the 5" cones (from Madisound) had spatter that looked roughly like they had been sneezed on. I included a detail photo of one driver whose dust cap had some of this. Not all the drivers had this and I personally find it inconsequential, but if you are serious about aesthetics it's something to watch out for.

[tomlang]

Re: The Uluwatu - another new Curt C design?!

Would this be considered a transmission line of sorts?

[lowpolyjoe]

Re: The Uluwatu - another new Curt C design?!

Looks great divdev! Definitely mean looking with that monster flared port.

[knowledgebass]

Re: The Uluwatu - another new Curt C design?!

Nice job on the flush mounts!

[tomlang]

Re: The Uluwatu - another new Curt C design?!

CNC machine being programmed...

[divdev]

Re: The Uluwatu - another new Curt C design?!

tomlang I'm totally jealous! You may want to consider adding a rim to the port home to flush mount the flange.

[tomlang]

Re: The Uluwatu - another new Curt C design?!

Yes, it needs a rim for the port as well as being pocketed on the back side of the front for the sides to meet. And of course I need to toolpath the other panels. Call me cheap, but I think I'll just use the 4 inch pvc pipe as a port and the vifa BC25SC06-04 tweeter which I already have...

Note the crossover schematic. Are the two resistors I have circled simply typos as they don't seem to be represented anywhere?

[divdev]

Re: The Uluwatu - another new Curt C design?!

I noticed that those two resistors were spec'ed out but not used so I just ignored them and it seems to have worked out fine for me.

[curt_c]

Re: The Uluwatu - another new Curt C design?!

yeah flat to 20hz sounded crazy to me. I am still very much a beginner but I thought it is very hard to measure anything < 200hz accurately. That's why I fielded my question.
I've been contemplating a larger build for quite some time now and if these will get to at least the low 30s I'm jumping on them this week.

You are correct in that below the Schroeder frequency of the room the room modes will predominate, and make any meaningful measurements nigh on impossible. While almost certainly meaningless, the 20 Hz response plot did look cool, though…

However, cool that might be, the radiation impedance of a 5” driver mandates it will not be capable of reproducing 20 Hz with any sort of useful SPL. Most vented designs utilizing 5” drivers will be good down to the mid 40’s or so.

But, a couple of things are working in our favor at these low frequencies. There may be some small amount of room gain caused by pressurizing the room. The 4” port size was chosen for a reason: All those little SB drivers push a lot of air out the port at its tuning frequency. Probably more significant is with the Uluwatu’s near the front wall, we will receive some boundary gain which will reinforce the lowest frequencies.

The bottom line: Do NOT expect to use these as subwoofers. –It ain’t gonna happen. Do expect that under the right circumstances they will get down into the high and even mid 30’s with some authority. Used with subs, you might even find the bass is better with your holey gym socks stuffing the ports.
–Your call there, and of course stuff to taste.

I finished my build of these .

Nicely done! Looks better than mine for sure!

Would this be considered a transmission line of sorts?

All vented designs are transmission lines. -Some are just better optimized for appropriate standing wave performance than others. This is a folded MLTL, with the port in the center of the line, which maximized its output.

Are the two resistors I have circled simply typos as they don't seem to be represented anywhere?

Yep! R4031 and R4032 are leftovers from an earlier iteration. They are to be ignored, and I’ll get the website updated.
Nice catch! Amazing how many times one can look for stuff like this and still miss it…

C

[bearhaus]

Re: The Uluwatu - another new Curt C design?!

Thanks for the detailed response Curt. That is more along the lines of what I was expecting...

I've been wanting something larger for my new media room and have been saving up for a set of Finalists for a while now but then saw this design. I want something more full range than the little bookshelves I've built before. My only experience with a full range speaker is from Cerwin Vega, enough said. I just really don't want to have to use a subwoofer for music....

[curt_c]

Re: The Uluwatu - another new Curt C design?!

All else being equal, and in my opinion, the midrange of a 3 way design is always going to better the midrange of a 2 way design. For pure music with some HT use, I'd personally go with the Finalists. It won't play as loud as the Uluatu's but it plays plenty loud, and the midrange is very seductive.

C