rdp91356
Member
So after getting a lot of good information about recapping, especially this thread: http://www.audiokarma.org/forums/showthread.php?t=78978 I decided I would recap the crossovers my RS 2.5s. I thought my speakers still sounded great so I wasn't sure that I would hear much of a difference, and also afraid that I might change the sound too drastically from what I was used to. So I planned out how everything would fit and what replacements I would use and ordered my parts.
But I also wanted to really know what was going on with the old caps so I bought this ESR meter (from an eBay seller): http://www.peakelec.co.uk/acatalog/jz_esr70.html. It can measure the caps in circuit, but I also measured them out of circuit to be sure. The measurements were only slightly different in most cases, except for that 3.83uF tweeter capacitor -- I got crazy numbers measuring that in circuit. Below are the numbers testing all the old caps out of circuit. Much better than I thought they would, which made me wonder if I should just replace the ones that were the furthest out of spec and just solder everything else back the way it was. But I decided to replace them all since all the new caps were within 2% of where they should be.
1981 Infinity RS 2.5 original 30 year old capacitor ESR meter readings December 2011.
Left:
1100uF = 1202uF .07 ohm
700uF = 735.4uF .06 ohm
700uF = 768uF .06 ohm
125uF (75uF + 50uF) = 143.2uF .06 ohm
125uF (75uF + 50uF) = 135.6uF .06 ohm
50uF = 56.26uF .10 ohm
3.83uF = 3.64uF .08 ohm
Right:
1100uF = 1190uF .08 ohm
700uF = 744uF .08 ohm
700uF = 726.2uF .08 ohm
125uF = 133.4uF .11 ohm
125uF = 128.8uF .10 ohm
50uF = 55.85uF .11 ohm
3.83uF = 3.59uF .08 ohm
*Note the differences of the 125uF caps between the left and right crossovers. The left uses parallel 75+50, while the right uses single 125. What's even stranger about this is that the serial numbers are sequential and I am the original owner, so it came from the factory like this.
Replacement capacitors (from parts-express.com) All measured within 2%:
1100uF =
two Parts Express 500uF 100V Non-Polarized Electrolytic Capacitors
+ one Parts Express 100uF 100V Non-Polarized Electrolytic Capacitor in parallel
700uF =
one Parts Express 500uF 100V Non-Polarized Electrolytic Capacitor
+ two Parts Express 100uF 100V Non-Polarized Electrolytic Capacitors in parallel
125uF =
one Dayton Audio DMPC-100 100uF 250V Metallized Polypropylene Capacitor
+ one Dayton Audio DMPC-25 25uF 250V Metallized Polypropylene Capacitor in parallel
50uF =
one Dayton Audio DMPC-50 50uF 250V Metallized Polypropylene Capacitor
3.83uF =
two Jantzen 1.5uF 800V Z-Superior Capacitor
+ one Jantzen 0.82uF 800V Z-Superior Capacitor
+ one Dayton Audio Film & Foil DFFC-0.01 0.01uF 400V By-Pass Capacitor
I also made a few other improvements:
1.) New binding posts to replace the original crappy ones.
2.) Added a Neutrik Speakon 8-pole connector to make an air tight connection from the top end and crossover to the bottom cabinet (to replace the hole filled with six single wires and a blob of putty). I saw where another AK'er used this method on his 4.5s. I used 13awg 8-conductor speaker cable from parts express. Also, the small hole in the top of the cabinet where the wires com through is a flimsy 1/8" piece of pressed hardboard glued and stapled over a much larger hole in the cabinet itself, this was full of gaps, so I reglued and sealed that up and added a piece of wood to fill the larger hole for a sturdier mounting point for the Neutrik connector.
3.) Caulked all the seams inside the lower cabinet, new woofer frame gasket, and added a front to back cross-brace.
4.) Added a toggle swith safety cover to protect that important "single-amp - bi-amp" mode switch on top. I always thought this was mis-labeled since you can biamp using the internal crossover and keep that switch in single-amp mode. It should only be in bi-amp mode when using an active external crossover with 2 amps. IMO it should be labeled "internal crossover - external crossover".
Having never done this before I was a little nervous when I hooked up and tested the first speaker. It's all pretty straightforward, but still there is room for making mistakes. Especially getting the 6 wires in the right sequence between the male and female parts of the Neutrik connector. A mistake there could be very bad. There was definitely a difference between the new left and the original right so I was anxious to get the right crossover done.
I am happy to say it was a complete success! I am somewhat surprised that everything sounds that much better -- especially since the old caps weren't that bad. More detailed cleaner highs, cleaner mids, tighter, deeper bass (probably partly due to sealing up the bottom cabinet) Everything good about these speakers just got better. I don't think they sounded this good when they were brand new. I just finished them yesterday and the more I listen the better they sound.
Larger before and after images here:
crossovers before
crossovers after
But I also wanted to really know what was going on with the old caps so I bought this ESR meter (from an eBay seller): http://www.peakelec.co.uk/acatalog/jz_esr70.html. It can measure the caps in circuit, but I also measured them out of circuit to be sure. The measurements were only slightly different in most cases, except for that 3.83uF tweeter capacitor -- I got crazy numbers measuring that in circuit. Below are the numbers testing all the old caps out of circuit. Much better than I thought they would, which made me wonder if I should just replace the ones that were the furthest out of spec and just solder everything else back the way it was. But I decided to replace them all since all the new caps were within 2% of where they should be.
1981 Infinity RS 2.5 original 30 year old capacitor ESR meter readings December 2011.
Left:
1100uF = 1202uF .07 ohm
700uF = 735.4uF .06 ohm
700uF = 768uF .06 ohm
125uF (75uF + 50uF) = 143.2uF .06 ohm
125uF (75uF + 50uF) = 135.6uF .06 ohm
50uF = 56.26uF .10 ohm
3.83uF = 3.64uF .08 ohm
Right:
1100uF = 1190uF .08 ohm
700uF = 744uF .08 ohm
700uF = 726.2uF .08 ohm
125uF = 133.4uF .11 ohm
125uF = 128.8uF .10 ohm
50uF = 55.85uF .11 ohm
3.83uF = 3.59uF .08 ohm
*Note the differences of the 125uF caps between the left and right crossovers. The left uses parallel 75+50, while the right uses single 125. What's even stranger about this is that the serial numbers are sequential and I am the original owner, so it came from the factory like this.
Replacement capacitors (from parts-express.com) All measured within 2%:
1100uF =
two Parts Express 500uF 100V Non-Polarized Electrolytic Capacitors
+ one Parts Express 100uF 100V Non-Polarized Electrolytic Capacitor in parallel
700uF =
one Parts Express 500uF 100V Non-Polarized Electrolytic Capacitor
+ two Parts Express 100uF 100V Non-Polarized Electrolytic Capacitors in parallel
125uF =
one Dayton Audio DMPC-100 100uF 250V Metallized Polypropylene Capacitor
+ one Dayton Audio DMPC-25 25uF 250V Metallized Polypropylene Capacitor in parallel
50uF =
one Dayton Audio DMPC-50 50uF 250V Metallized Polypropylene Capacitor
3.83uF =
two Jantzen 1.5uF 800V Z-Superior Capacitor
+ one Jantzen 0.82uF 800V Z-Superior Capacitor
+ one Dayton Audio Film & Foil DFFC-0.01 0.01uF 400V By-Pass Capacitor
I also made a few other improvements:
1.) New binding posts to replace the original crappy ones.
2.) Added a Neutrik Speakon 8-pole connector to make an air tight connection from the top end and crossover to the bottom cabinet (to replace the hole filled with six single wires and a blob of putty). I saw where another AK'er used this method on his 4.5s. I used 13awg 8-conductor speaker cable from parts express. Also, the small hole in the top of the cabinet where the wires com through is a flimsy 1/8" piece of pressed hardboard glued and stapled over a much larger hole in the cabinet itself, this was full of gaps, so I reglued and sealed that up and added a piece of wood to fill the larger hole for a sturdier mounting point for the Neutrik connector.
3.) Caulked all the seams inside the lower cabinet, new woofer frame gasket, and added a front to back cross-brace.
4.) Added a toggle swith safety cover to protect that important "single-amp - bi-amp" mode switch on top. I always thought this was mis-labeled since you can biamp using the internal crossover and keep that switch in single-amp mode. It should only be in bi-amp mode when using an active external crossover with 2 amps. IMO it should be labeled "internal crossover - external crossover".
Having never done this before I was a little nervous when I hooked up and tested the first speaker. It's all pretty straightforward, but still there is room for making mistakes. Especially getting the 6 wires in the right sequence between the male and female parts of the Neutrik connector. A mistake there could be very bad. There was definitely a difference between the new left and the original right so I was anxious to get the right crossover done.
I am happy to say it was a complete success! I am somewhat surprised that everything sounds that much better -- especially since the old caps weren't that bad. More detailed cleaner highs, cleaner mids, tighter, deeper bass (probably partly due to sealing up the bottom cabinet) Everything good about these speakers just got better. I don't think they sounded this good when they were brand new. I just finished them yesterday and the more I listen the better they sound.
Larger before and after images here:
crossovers before
crossovers after
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