Hey there,
I think I can help. I remember seeing some of those crossovers in real life. Lots of parallel electrolytics with film.
The biggest issue with rebuilding old crossovers like that is that the ESR of the 1980's era caps are much worse than modern, so you can in fact alter the sound, and in some cases drop the impedance so low the amp no longer drives them properly, or the crossover no longer does what you think it's doing. The former is a more subtle problem that newbies often get trapped by.
So I strongly suggest you purchase a DATS V2 and measure the ESR of every cap system before replacing it, ESPECIALLY in shunt (going to ground) configurations. You'll need to add small amounts of R to compenstate for lost ESR.
https://www.daytonaudio.com/product/1051/dats-v2-dayton-audio-test-system
I also strongly encourage you to do a complete electronic analysis prior to replacement. You don't have to do the acoustical measurements, just the electrical. Measure the impedance curve of the entire speaker, and each driver, and simulate the whole thing. This will be a useful guide as you contemplate replacement parts.
You can do this for free with XSim.
http://techtalk.parts-express.com/forum/tech-talk-forum/62978-xsim-free-schematic-based-crossover-de...
You want to pay attention to the simulated impedance curve and the voltage transfer functions. These will allow you to compare any changes you are contemplating.
And, of course, the same goes for any coils. Ensure you do NOT reduce the DCR of the originals unless you are sure the transfer functions are equivalent.
Otherwise, I encourage you to visit over in the DIY audio forum.
Best,
E
I think I can help. I remember seeing some of those crossovers in real life. Lots of parallel electrolytics with film.
The biggest issue with rebuilding old crossovers like that is that the ESR of the 1980's era caps are much worse than modern, so you can in fact alter the sound, and in some cases drop the impedance so low the amp no longer drives them properly, or the crossover no longer does what you think it's doing. The former is a more subtle problem that newbies often get trapped by.
So I strongly suggest you purchase a DATS V2 and measure the ESR of every cap system before replacing it, ESPECIALLY in shunt (going to ground) configurations. You'll need to add small amounts of R to compenstate for lost ESR.
https://www.daytonaudio.com/product/1051/dats-v2-dayton-audio-test-system
I also strongly encourage you to do a complete electronic analysis prior to replacement. You don't have to do the acoustical measurements, just the electrical. Measure the impedance curve of the entire speaker, and each driver, and simulate the whole thing. This will be a useful guide as you contemplate replacement parts.
You can do this for free with XSim.
http://techtalk.parts-express.com/forum/tech-talk-forum/62978-xsim-free-schematic-based-crossover-de...
You want to pay attention to the simulated impedance curve and the voltage transfer functions. These will allow you to compare any changes you are contemplating.
And, of course, the same goes for any coils. Ensure you do NOT reduce the DCR of the originals unless you are sure the transfer functions are equivalent.
Otherwise, I encourage you to visit over in the DIY audio forum.
Best,
E