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Discussion Starter #1
Has anyone ever upgraded or rebuilt crossovers, maybe replaced capacitors in their old speakers? I have polk audio rt55 mains, csi400 center, and rti38 surrounds, have had them forever and would like to breath new life into them. I have pictures of the individual crossovers but need some guidance. thanks
 

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A simple recap involves replacing the capacitors (typically lower quality electrolytics and polyesters) with higher quality/audio grade metalized polypropylene types. Go as expensive as you want but the returns diminish as the prices go up.


You'll need to read the values off the stock caps or get ahold of a schematic. Remember that any deviation from the stock values will have an audible effect. That may or may not be desirable.
 

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Discussion Starter #3
So is replacing capacitors considered an upgrade? Is there anything else that I could do? As much info. as I can get on the subject is much appreciated. I have read of people upgrading the crossovers and wiring in mid to entry level speakers and noticing quite a bit bore clarity, imaging, and smoother response. I would like to see if other members have had much success or even tried modifying the polk rt series speakers or if it is even worth it?


Here is a link to pictures of all the crossovers so you guys can see what I am dealing with here. the first 2 are of the back of the csi400(center), next 4 are of the RT55(mains), and the last 3 are of the rti38(surrounds):
http://s938.photobucket.com/user/jaybob1807/library/polk%20audio%20rt%20series%20speakers?sort=4&page=1
 

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Quote:
Originally Posted by jaybob1807  /t/1521531/reworking-old-crossovers#post_24456642


So is replacing capacitors considered an upgrade?
Only if you're replacing cheap non-polarized electrolytics with poly or mylar. Yours do have NPEs that could stand replacing. There's little to no benefit in 'upgraded' polys. You can chalk up the miracle results claimed from using $200 caps to placebo effect. Your crossovers are quite rudimentary, and a better design might be an improvement, but crossover design is a field that requires years of experience to perfect.
 

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Do you know of anyone who does this sort of thing? Do you know any businesses that do this or is it something you just need to figure out on your own? Do you suppose my money would be better spent just getting new speakers?
 

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Quote:
Originally Posted by jaybob1807  /t/1521531/reworking-old-crossovers#post_24461376


Do you know of anyone who does this sort of thing? Do you know any businesses that do this or is it something you just need to figure out on your own? Do you suppose my money would be better spent just getting new speakers?
There are places that do it, I can't vouch for any of them as I do all my own crossover designs. A superior crossover is one of the things you get when you step up to brands like B&W.
 

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Discussion Starter #7
So where did you learn how toTo build and upgrade crossovers? I have always wanted to learn how but don't even know where to start. Mr. Fitamaurice, have you heard any of the diysoungroup offerings? How much better is the tempest 12 than my system, or say the zaph Sr71 or possibly even the revelator?

Thanks for the advice too by way, I appreciate it.
 

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Originally Posted by jaybob1807  /t/1521531/reworking-old-crossovers#post_24463862


So where did you learn how toTo build and upgrade crossovers?
I design loudspeakers for a living.
 

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Discussion Starter #11
So does anyone have any idea how much of an improvement upgrading these crossovers would provide? Maybe the speakers aren't even worth it.
 

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Quote:
Originally Posted by jaybob1807  /t/1521531/reworking-old-crossovers#post_24454682


Has anyone ever upgraded or rebuilt crossovers, maybe replaced capacitors in their old speakers? I have polk audio rt55 mains, csi400 center, and rti38 surrounds, have had them forever and would like to breath new life into them. I have pictures of the individual crossovers but need some guidance. thanks

Replacing defective capacitors can have excellent audible benefits. Non Polarized electrolytics can last for 20 years or more or fail in a few years, depending on stuff you may have no control over.


A lot of BS has been written about capacitor upgrades. Very few people do anything but slavishly swap parts and make exceptional claims. For example, how many cap upgrade aritcles test the old parts to see if they are defective or do good listening tests or technical tests to compare the before and after? I can refer you to someone who writes a lot of questionable stuff on this topic - Darque Knight at the Polk forum.


One of the fundamental principles of repairing and upgrading audio gear is: "If its not broke, don't fix it!"


If it is broke, it should be easy enough to detect, confirm and manage.


Most of us have pairs of speakers. It is possible that bad caps can appear in both speakers at the same time, but its less likely. Do your left and right speakers sound the same?


You can go through and unsolder caps (at least one end) and do tests on them. The first thing to go is usually their actual capacitance and Digital voltmeters with simple capacitor testers are not that expensive.


Crossover caps should meet spec within about 20% or better.


An impedance meter should give similar results on both speakers over the audio range.


Good sources of repair parts and test equipment are MCM Electronics, Parts Express, and Madisound.


This is a good question for the DIY speaker forum here at AVS.
 
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