Ferrofluid

@timlub   Tim. Thank you for your detailed reply. I really appreciate it. I want to say first if all that I would not even think of doing this if I didn’t have someone to install and solder the crossovers in for me. When I first bought my ARC REF 750s and was playing them the first few hours I had a tube arc and it took out a resistor. I called up my ARC dealer here in NJ and he hooked me up with an awesome Technician. I ordered what I need from ARC and when the parts arrived he came to my home and installed and soldered everything and also checked both amps out and gave them a clean bill of health. And said that they are in excellent condition. So when I told him and showed him and had him read about those ( supposedly) upgraded (better sounding 🤷‍♂️) crossovers on EBay he said that they sounded good. And that he would have no problem replacing and soldering them in at my home.Now mind you and I know he does not build crossovers or maybe he does not know much about building crossovers other than how to install and solder them. So he is just probably also going by what he read about them from what I sent him. Ok. Now I have some questions and opinions from u Tim. Knowing that my speakers are from the 90s and since I had them now about 8 yrs now and really never had a problem with them. Would u think I would need to change or replace the caps and all that is involved in the cross overs ? Wouldn’t that be like an amp dating back to the 90s ? Changing upgrading the caps and resistors etc ? Also what I did want to mention is the only issue I do have with my speakers is the highs coming from the tweeters being too bright along with the voice. Now it’s not all the recordings but many. My question is if I do change and upgrade the crossovers can something be done about that with the crossovers from the tweeters ? Now let me also say that I only listen to digital. I also have a ARC Ref 6 that I bought brand new a few years ago and only put on 600 hrs. I did just have gotten it upgraded from ARC to the Ref 6 SE. and have it now for about 2 months. All my tubes in my amps and pre amp have about 700 hrs on them so I know it’s not from the tubes. But it’s really that brightens and some recordings are too bright IMO. Other than that the speakers sound phenomenal. Especially the powerful bass. And I really thought u was going to loose ALOT of that when I replaced my Krell FPB 600 which are known for thunderous bass with B&W s. But it’s definitely not the case. I did loose some but definitely made it up for all the other quality’s with the ARC 750s. Now I also wanted to ask you IF I did want to upgrade all my 8 crossovers can u possibly make them for me with your expertise and knowledge? 

@timlub Also forgot to tell u I also have and am using 2 Krell B&W BAFs. ( Bass alignment filters for my 800 Matrix.u can also see my system and all the components and cables etc etc from my profile. 

So, I hear you, but again. I would not rebuild those crossovers. A few parts replacements yes, but you would need to measure every inductor for its resistance then figure into the crossover, when the resistance changes on this tweeter, mid etc, how many other parts have to change value to keep the crossover at the same frequency.  When you change coils,  It appears to the other parts in the crossover that you have actually changed the impedance of the driver itself.  So, your speaker goes a little out of whack when you change the parts, a little more on the mid parts and even more on the woofer.  It can change a speaker to being withing 2 % matched parts to being off 20% in matched parts.  I'm being a bit tough with that description, but the point is, the more inductors there are in a design, then the more you change, the more you risk of destroying the original design. 

So, unless you just don't like the original design, I would only do key parts changes. I have not looked at a schematic, I don't know the slopes chosen or the topology of the crossover, butterworth, likwitz etc.  Now parts choice is a can of worms that very few would agree upon in this forum.  Capacitors,   There are more types than this, but in speakers, normally, you have Electrolytic, then step up to mylar/polyester, then poly carb then polypropylene, then polystyrene and lastly teflon. If I recall correctly, B&W used a lot of Solen parts.  I find the Solen parts to be very decent sounding,  they don't get harsh, they may be a little dry, but they don't do anything particularly wrong.  These boutique caps can get very expensive and yes, I can hear a difference between these parts, but for most people, I believe that they would find a nice improvement changing parts, but not night and day. So for my taste, I would take start with the series caps and all resistors.  This should make a nice change, not cost you a second mortgage and no matter who bought your speakers, the main character of your speakers remains intact and you have simply made a true upgrade by anyone's opinion.  The wrong mod can hurt their value.... I hope this makes since,  Tim

Just take it to the local mechanic 

@timlub   Hey Tim. I definitely hear what you are saying and totally makes 💯 sense. I really would like to get the most performance out of those speakers and I know totally agree what u are saying about only replacing the necessary parts and caps. Maybe some better wiring too ? I would really love for you to do the work on these crossovers for me if u would like to take on the job. I appreciate your time  everything you said to explain all of this for me. And I’m sure I’m making the right decision now not buying those crossovers from eBay. And he also sent me a pic of the new crossovers and they look totally different with a lot less parts and caps. And it looks like they are mounted on a piece of plywood and not a circuit board. If they are. I forget when I installed them when I got my speakers.