Mystery Capacitor and the Tangent RS4 Crossover

You've got 12/18 slopes with impedance compensation on the woofer and frequency compensation on the tweeter.  

@imhififan   ..... Quick question for you.  I don't know this tweeter, so I have to ask. Have you seen the impedance curves of this tweeter?  Are you considering the inductor to ground? Are you considering the 3 ohm resistor in series?  
Not being  familiar with the impedance curves of this tweeter, these questions need to be asked. 

@imhififan            Your basic advice is sound... It would put you in the league.... 2.7, but if the original caps are electrolytic and they change to a quality film, the ESR of 3 capacitors alone can be a difference of up to another ohm or more. ESR is measured at different frequencies, so you would need to take that into consideration also. If the op was willing to do some experimenting, its worth a try, but to just replace all of that with a 3 mic cap would not be recommended.
op @bruce19 The 2.25 mfd, 1 mfd and .47mfd add to each other to combine values, the 10 mfd after those then decreases that value.

3.72, 10mfd parallel = 2.711

But beyond that,  I have to believe that they would not have gone to that expense to do it that way, a small film cap would be cost effective vs all of that mish mash.  My head says that overall you are correct, but I'd want to run real measurements and see why they ran the .47 the way they did vs just putting it straight in parallel with the other parts. When building I tend to verify everything in measurements.  

@bruce19     The pink cap is a film cap,  most likely a mylar.  If you are doing the work yourself, I would recommend replacing the parts with Polypropylene caps throughout.    If they were mine,  I'd do a complete crossover rebuild based on listening to the parts individually and measurements.    Its hard to give much advice without a ton of information that we will not likely get on a thread like this.  Good luck,  
Tim 

You'll find out if you nice symmetry when your finished.  The folks at Madisound are nice folks, but through the years, I've learned to get it right, I had to do it myself.  I didn't always get accurate advice. Hopefully, all will work out well for you. I started building speakers in 1979 and started in the speaker business in 1980.  

@millercarbon
I hear ya, I have been to at least 20 C.E.S as a buyer, not as a vendor. Even on my end, it was easy to see how cutthroat it could be from the vendor side. Years ago, Randy Patton who briefly owned Threshold, Sumo, Meitner, PS Audio and a few others, recommended me to Martin Logan. I had a call from them asking me to come interview in Kansas. I had no interest in moving to Kansas and did not go for an interview, but that started me thinking about doing my own thing. I would still love to produce speakers, but as I eluded to earlier, I’m getting older. I would love to market this 15 inch 2 way.... At this point, not likely.

Hi, @bruce19 I started modifying speakers when I was a store manager at CMC Stereo. I visited the audiophile shops in the St. Louis area regularly. We had a retail store called SpeakerCraft that custom built speakers. In 1980, I took a job as General Manager at SpeakerCraft, we had a division called Marcof Electronics, we built Moving Coil head amps, cables, modified cartridges, tables and built several Amps and Preamps..
It was there that I established a fairly in depth knowledge of Speaker Design. I had a good enough foundation that over the years, I was able to expand my knowledge to a complete understanding of speaker design. The owner there had and still has a full knowledge, but when I left, I just hadn’t absorbed it all yet. I have done hundreds of repairs and builds in the past years, even here on Audiogon, I have done several modifications, a couple of repairs and a couple of designs for members. In my Listening room, I currently have an MTM with 6.8 inch woofers and a dome tweeter, I have a 3 way with a paper cone 10 inch woofer an aluminum 5 inch mid and a ribbon tweeter, I have a pair with the top end Heil AMT with a 12 inch woofer and I am currently enjoying a 15 inch woofer and 1 inch dome in a 2 way. These speakers are 86 db 4 ohm, 87 db 8 ohm, 94db 8 ohm and 95 db 5 ohm. So, that’s the best I can answer, what kind of speakers I build... As far as professionally building. My 15 inch 2 way turned out so radically good and most audiophiles would not believe a 15 and dome to be able to sound as it does, that I truly explored going into manufacturing. I bought domains, registered a name, but no shows, my industry contacts are as old or older than I am or worst... Dead. So, recently I bailed on that Idea.

The 15 stays between 5 and 6 ohms at all frequencies, the tweeter stays between 4.3 and 5 ohms.  Any Audiogon member is Welcome to my home in Weldon Spring Mo (St. Louis area) for a listen.