I did, of course, find the two links in the FAQ section on crossovers. One of which does take you to the PE website, but it is effectively a dead link. The second is a pretty decent overview of crossover topology and terminology but is still very basic.

 

There is no replacement for the RS28A-4. As for a redesigning a crossover that is a complicated procedure and not recommended. I suggest using the other parts, replace the tweet, find a proven design, then build that.

 

Guy seems to understand general crossover terms, slopes and what's required, also says he wants to learn and is very interested, and your response is, its complicated and dont bother... Are you for real?

Why is it not recommended to redesign a crossover?

Why is everyone on this forum against someone spending time and a few bucks to learn something. You can go out at night and piss away hundreds of dollars drinking and crap, staying home and learning a new skill and enjoying the process over a week or whatever sounds like money extremely well spent to me.

OP. Dont listen to the haters. This sounds like a good project to dive into.

Me, I would try and find a spec sheet of the old tweeter, and I would use something like DATS to measure the impedance and electrical specs on the new tweeter, using that you should be able to see how closely the electrical properties of each tweeter matches, if they are very close, they will honestly be pretty much a drop in. If not, then you might need to do something as simple as add a resistor to match levels better at which point you may as well build the box and set out to measuring and when you have measurements you can enter the crossover values of the old design and see what it comes up with, if you need to tweak from there it should actually be very simple.

Since its an older design, things like baffle step etc would already be factored into the old crossover specs. Do you have a schematic?

 

RS28A-4 which is NLA. PE substituted the RST28A-4

Looking at the spec sheets, they are not identical but quite similar, possibly within the production variation of either. I'd just go forward and see what you think.
https://www.parts-express.com/pedocs/specs/275-131--dayton-audio-rst28a-4-specification-sheet.pdf

If you are not happy, you could download https://www.roomeqwizard.com or such and measure to see if there is a response problem. Redesigning the crossover is possible, but you'd need response and impedance data to plug into a simulator. Practically this means buying an Omnimic or something, a lot of work, or quite possibly asking here and at DIYAudio.com if you have helpful folks nearby who are already set up for that.

 

Here is a FR simulation comparison done for me by a member over there using Jeff Bagby's PCD. I did send him an email asking for access to it, but haven't heard back yet. It looks like a really nice crossover design software.

I can post the crossover schematics on here if it would help. I do have two of the older RS tweeters that were originally ordered for my surrounds. I still plan on using them in the surrounds (they're 3 ways, too), but I was thinking about putting one of each in two of the front towers so I could do an A/B comparison.

Not sure how I'm going to do it just yet (just haven't had the time to think about it), but I want to slap together a quick switching setup to switch quickly back and forth between the two. Then add in a basic series resistor to lower the tweeter output.

I plan on ordering several different values so that I can see what sounds best. Is there any need for more than basic 10W resistors?

 

I did send him an email asking for access to it, but haven't heard back yet.

That's because by the time you sent him an email, Jeff had passed away from complications that CoViD-19 caused with his previous medical hurdles. May the man rest in peace. he passed away late March 2020, not long before your email.

I hope that provides you an answer as to why you haven't received a response.

 

I am of the opinion, run it, and try so long as it's fun. If you feel like you're hitting a dead end, and can't make progress to a level you can accept, punt, and call all money the entrance fee to education or entertainment, in whatever ratio you got it.

I would also suggest buying more parts, of various values, than you think you might need the for the first round. I like soldering too, but I'm too impatient to do passive crossover design.