Tweeter Capacitor Upgrade (Coincident PREs)

Cal3713
for sure change the binding post which are Brass to a Furutecor WBT next gen Gold over Copper ,and put in a Quality Wire the tweeter and mid are connected to. The inductor to create
the Xover ,and you can put in a much better inductor 
to a awg 12  Jantzen inductor far better especially for the Bass
i would think there is another inductor there somewhere as well as resistors, pull out the midrange and woofer you will see other things hiding in there. I have found that to be true case up grade 
the resistors Path Audio, the best if parts connecxion has them in stock, Ohmite Gold, Mundorf Supreme, or Mills 
resistor ohms rating on the resistor. It’s up to you.
best of luck  and use a good soldering station recommend at least 
80 watts and Cardas,WBT, Johnson’s, or Mundorf Silver Gold 
minimum of 5-5% silver solder content Cardas has. Flux built in
which helps a lot  to clear and bond surfaces.

In my extensive use of capacitors in components meaning DAC, preamp and power amplifiers, but not in speakers, I find the best capacitors are V-Caps (Oil & Copper versions).  I find that the Jupiter copper caps have an emphasis in the mid-range.  They have a very musical sound but the mids standout at the expense of the other frequency ranges.  Just more focus in the mid-range.  One of the manufacturer of panel speakers that I partner with also used the Jupiter caps and when I told them to try the V-Caps, they were surprised how much the sound staged opened up with greater detail and separation of vocals and instruments.  Another Audiogoner had Jupiter in his preamp and he herd the V-Caps in the components that I build where we swapped out the caps.  He heard the differences and decided to try the V-Cap coppers in his preamp versus the Jupiter capacitors, he also noticed the same advantage.  BUT it comes down to the sound you prefer and you also may have to try both to see the benefits in your own system.  Happy Listening.

@cal3713 Another vote for the Jupiter Coppers in your application as a cap to be placed in series with the Accutron tweeter.   I used the Jupiter in my Coincident Super Victory II for that application with a Duelund Silver by-pass, and could not be happier.  In the end, all we can do is guess.  The good news here is that it is not hard to improve on the Solens, but no one can tell you for sure what the "best" cap for your application is going to be.   Just be aware that the Jupiters are painfully slow on break in.  They oscillate between really good to really bad for at least 120 hours, maybe 200, and apparently it is common for them to require 400 hours to completely stabilize.
@audioman58 I am also perplexed by the crossover design in the PREs.  I don't know what one might find in the woofer cabinet, but since the preferred wiring arrangement is a direct connection from the monitors to the amps, with a second set of cables running to the woofers, and since the monitor enclosure contains only one crossover in series with the tweeter, I must surmise that the midrange is being run full range.  It would seem that the midrange is truly crossoverless, with no inductor or capacitor in series or even in parallel.  When I rebuilt the crossovers on my Coincident Super Victory IIs, I chose to stick with the stock Solen 12 and 14 gauge inductors.  I don't regret the decision, but of course it may have been possible to improve upon them.  I think the big bang for the buck here is going to be in swapping out the tweeter cap.  The PREs are already superb, in my humble opinion, speakers.  It may not take anything more to get cal3713 where he wants to be. 

I wonder how the PRE would sound with some paper in oil caps? It only uses two so it wouldn’t be that hard of a mod?

Do not willy nilly change coils!

You have to match the DCR or you can make fundamental changes to the tone, and not in a good way.

For the woofer coil DCR sets the bass level, as well as helps with baffle step. Meaning, you must measure the DCR and only replace with equivalents (within reasonable tolerances).

In parallel to the driver, changing DCR without adding R can really muck with the impedance curve and have unintended consequences.