Thinking similiar to Statement/Khanspires but ...

[Kornbread]

There's one more build I'd like to do before getting started on a pair of keepers. If work and school don't get krazy, I'd like to have a pair of Cinderellas done sometime next Spring. They'll be a Christmas present for another BIL. Hopefully the 'keeper' build will start early next summer, but I'd like to have everything nailed down way before then.


Then it's on to something I want long term. The Statement and Khanspire seem to be calling my name, or at least something similar to them.

Questions:

If you were to use an active crossover, would your choice of drivers remain the same? After all, it is easier to mix and match drivers with an active crossover. Suggestions? (keep it $ reasonable) New rs's are out.

At the level of information retrieval these speakers are capable of, would using an active crossover be a step backward in sound quality? Will some "Fractal" (Bagby) information be lost in those 1s and 0s?

What problems am I going to run into attempting this?

[Zephyr]

I've been wondering the same thing, it seems that active filters are impressively capable.....if you have the considerable talent required to tell em what to do. The tyranny of the blank page. Beyond that, I do truly wonder if there isn't some additional magic in the well done passive crossovers, expanding, collapsing magnetic fields of the crossover driving the voice coils. I'm hearing that each can do the job but end result will be quite different.

Really interested in seeing what you come up with for a "keeper" design.

[filmslayer]

my towers , it's long thread but take a look at my sig .

[filmslayer]

also while helping me with my XO , jbrunner did a aluminum version and offered to share .

[Kornbread]

I know it's stupid, but I'm stuck on the looks of the WMTMW design.


filmslayer, where's the link?

Good info in there filmslayer, good write-up.

[filmslayer]

filmslayer, where's the link?

its in my sig , but for those that can't see it http://techtalk.parts-express.com/fo...(-pic-heavy-)=

[---k---]

Active crossovers have some advantages to passive crossovers, but it is not unilaterally always the case.

With the Khanspires, there is no padding on any of the drivers. Everything magically worked out (really it was all part of CJD's careful driver selection and plan). The passive crossover has sufficiently steep slopes. In my opinion, an active crossover would not provide sufficient improvement to this design to justify the extra amps and complexity that that brings.

If I were to rebuild the Khans today, I might consider a different tweeter and then different mids. But, that would be a move upmarket to a tweeter that costs 3x to 5x as much as the RS28. The RS drivers remain value leaders. I don't believe any new drivers have come along and significantly outperform them for similar price. The Khans are an incredibly balanced design, and I think that is part of what makes it so special to me.

If I were to rebuild them, I might try a funky cabinet to reduce the width and baffle diffraction around the tweeter. I'd also probably try and make them slightly deeper to give more room behind them.

To me, if I were intending to build this design, listen to it for a year and then strip it for parts, then trying to mimic it with active would probably make sense.

[Kornbread]

If I were to rebuild them, I might try a funky cabinet to reduce the width and baffle diffraction around the tweeter.

What, if anything, would some felt like strips of material accomplish?

CJD mentions the shielded 225/150 versions are no longer available. Just to be sure, these should be the replacements, and they should work with little, to no modifications to the design? rs150-8 aluminum cone #295-354, and rs225-8 aluminum cone #295-356? What about the newest paper cone versions of these drivers?

[---k---]

Yeah, felt would help. CJD recommends it and uses it on his big mains. I did play with it for a while. But I just don't like the looks, etc. They are amazing without, I'm not in a rush to put ugly bandaids on the front.

And, don't get me wrong. I don't think it is needed. Just thinking out-loud and daydreaming. You asked what I'd do differently if I were to rebuild them. I might try and expand my skills with something funky with the box. I'm not sure how easy or beneficial such change would be. But, something like PBN does with theirs, maybe?

Also, iirc, CJD said something about the funkyness in the tweeter response was in his mic and shows up in some of his other measurements. I'd have to check with him on the details, my memory is fuzzy. Hard to see in the graphs because of the different scale.s

Yes, the aluminum cones are darn near drop in replacements. The changes don't affect the crossover. With the RS225, you could make the box slightly smaller if you choose too.

The paper drivers are totally different. Same motor, but different cones give them different properties. I believe that a totally different crossover would be needed.

Me personally, the aluminum cones have lower distortion than the paper versions. The Khans have a sophisticated crossover with steep slopes that nearly squelches the distortion beyond the crossover points. I don't think the paper versions would bring much to the party ... lowering crossover complexity and more distortion.

[Kornbread]

Ordered a quad of the newest version paper cones rs150p-8a 6" before your response. I tend to prefer a good paper over the other fancy stuff anyway. Hopefully there are no bugs in these new drivers.

Which rs28? Silk or Aluminum, and why?

[Kornbread]

Look what the santa in brown delivered today, a quad of rs150 8a. I must say, looks are pretty unimpressive, hopefully my ears will be impressed.



Anyhow, doing some digging. The Statements look to have ~4.13 ft³ roughly 117L (after subtracting only the midrange tunnels) the port is 3" x 4" long, and the writeup says "The woofers are vented into 100 liters and tuned to
approximately 24 Hz. This tuning results in a roll off that emulates a 2nd order sealed response down to it's f10 of 20
Hz, and models an f3 of 33 Hz." (Curt) Using Unibox,and the metal cone rs225-8 #297-376, I get this. What's going on? Is there floor loading to consider since the port's only 2" above the floor? Not questioning Curt's math, just trying to learn. Still debating on the rs225 metal cone, or newest 8a paper cone. The metal is proven.

I like the physical size of the Statements, but either will do. There is also the possibility of doing either size box in a sealed, or vented configuration.

I don't want this to be an exact copy of someone else's design (even if their design is a proven performer), just want to make some of it ... mine.

Guys, what you think?

[Kornbread]

Been trying to learn Bagby's passive crossover designer. 11 components using the rs225p 8a+rs28a+rs150p 8a. Learning, don't shoot me. No BS compensation. Didn't input the xyz (why can't we use ybc?) dimensions. How bad is it? What do I need to do?

[jhollander]

I like the RS28A because I hear more detail over the F.

I get Curt’s and Jim’s numbers with 100 liters and the RS225S. Remember the net volume is less the bracing port and driver volumes.

WRT the sim a 3-way is hard. You should add in all the baffle responses, the correct impedance files, and the x,y, and z measurements and estimates. It’s big elephant to swallow.

[pknaz]

I don't want this to be an exact copy of someone else's design (even if their design is a proven performer), just want to make some of it ... mine.

Guys, what you think?

I think you should maybe change the shape of the cabinet a bit, or tweak the design in some other non-audible way. Maybe build a curved cabinet or some other cool shape, but keeping the baffle width and over all depth of the speakers the same.

[---k---]

I like the RS28a. With the right crossover, they sound great. I have not heard the fabric version.

Lots of options with tweeters. If you want to make something different/your own, that is an area to look at. I've always wanted to hear the Seas DXT tweeter. The RAAL that I've heard were always special, but way beyond my price range. The SB that CJD used in his Ansonica was nice. So many options. You just have to make sure it meets up with your mid, but since you're using he paper version it opens a lot more possibilities.

Way back when, my models matched Curt's. I didn't redo them when the updated versions came out and have never modeled the paper version.
A downward firing port into a small floor gap can affect the tuning, by effectively increasing the port length. I don't think that Curt was relying on this, but it is something to keep in mind. Rule of thumb I've always heard is the port tube should be at-least 1/2xdia away from any boundary to minimize effect (though my unscientific gut says 1xdia would be better). So 2" clear on a 3" port would fit this.