Rt55i Crossover Upgrade
Options
phillip559
Posts: 24
Hello, so I just picked up a pair of Rt55i. I generally love the sound, but there is very faint distortion. I assume it must be the crossovers because it happens with both of them. One of them is more noticeable than the other. They are in great condition, and I love the sound generally. The sound is ever so slightly off, but when listening really close it's somewhat noticeable.
In sum, I would want to know how to replace the capacitors and resistors. I feel like there would be no point in buying a used set of crossovers since I would probably run into the same problem before time.
Any advice is appreciated. Mainly, a how to on getting the right parts. I searched a round a bit, and was still left a bit confused. Or if there is a list of what I would need to buy, that is perfect. Where to buy from, etc... Thank you!
In sum, I would want to know how to replace the capacitors and resistors. I feel like there would be no point in buying a used set of crossovers since I would probably run into the same problem before time.
Any advice is appreciated. Mainly, a how to on getting the right parts. I searched a round a bit, and was still left a bit confused. Or if there is a list of what I would need to buy, that is perfect. Where to buy from, etc... Thank you!
Comments
-
First you look at your crossover to get the information from the components Polk used. The RT55i schematic has been lost or unavailable for awhile now. Looking at your XO could very well help you diagnosis your problem. It will give you values you need to order parts.
-
First you need to determine where the faint distortion is coming from, the tweeter or drivers.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Okay, so I found a picture on ebay. It looks like it will take 9 MFD 50 V and 16.5 MFD 50 V...
Can the voltage on the replacements be higher? What about the uf value too? Do I need to care about the resistors? Haven't had a chance to take the unit apart, but I am going to replace them one way or another. Thank you! -
Voltage can and will be higher with poly caps. The uF value should be the same as stock. Yes, replace the resistors with Vishay Mills.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Got it, thank you. I was able to find capacitors. I see there is a 5w 2ohm resistor, but the other one says 5w 3ohm 5j... does that require a specific type? I have only been able to find ones with w and _ohmj not _ohm _j. Also, the yellow 3.0j 100v is?
-
The yellow is a 3.0uF 100V film capacitor (tolerance unknown) and the other resistor is 3.5 Ohm which you would replace with Vishay Mills which are wirewound non self inductance types. There are other options for resistors of course and many are more expensive.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Yes, those are basic 5 watt, 2 ohm and 3ohm sandcast / ceramic style resistors. Those are the only values you need to be concerned with. F1nut is suggesting that you upgrade to better Vishay Mills brand resistors. Its totally subjective and you decide if the extra cost is worth it to you.
The yellow component is a 3 μF (micro Farad) 100 V Mylar poly style capacitor. There are several old threads on this subject with pictures, the schematic, discussion, etc. I have linked a couple here:
RT55 crossover schematic: https://forum.polkaudio.com/home/leaving?allowTrusted=1&target=https://us.v-cdn.net/5021930/uploads/attachments/9/9/3/4/4/46071.pdf
https://forum.polkaudio.com/discussion/163764/rt55-crossover-refresh
2.2 Office Setup | LG 29UB55 21:9 UltraWide | HP Probook 630 G8 | Dell Latitude | Cabasse Stream Amp 100 | Boston Acoustics VS 240 | AUDIORAX Desk Stands | Mirage Omni S8 sub1 | Mirage Omni S8 Sub2 -
Walt Thanks I've been on the hunt for that schematic !
To the OP going up in wattage value on the resistors is just safe insurance. When you're looking at about $4-$6 each and only a about .50 to $1.00 in difference go with the higher 10 or 12 watt Vishay Mills or Mundorf resistor. -
phillip559 wrote: »Got it, thank you. I was able to find capacitors. I see there is a 5w 2ohm resistor, but the other one says 5w 3ohm 5j... does that require a specific type? I have only been able to find ones with w and _ohmj not _ohm _j. Also, the yellow 3.0j 100v is?
Some use alphabet letters to indicate the tolerance. In this case J means +/- 5 %.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Yes, those are basic 5 watt, 2 ohm and 3ohm sandcast / ceramic style resistors. Those are the only values you need to be concerned with. F1nut is suggesting that you upgrade to better Vishay Mills brand resistors. Its totally subjective and you decide if the extra cost is worth it to you.
Not nitpicking I just don't want the OP to get the wrong resistor. The 2nd one is 3.5 Ohm not 3 Ohm.
George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Thank you everyone for the replies! It has helped a lot. I purchased a set of xo on ebay for $23. Figured it's hard to go wrong at that price, and probably don't see that deal often lol I replaced the xo on the speaker that had more prominent distortion. It definfely helped. I am still going to go ahead and do the upgrade since they will benefit regardless. Love the sound on them so worth the upgrade imo.
There were a number of black spots and the glue was a complete different color than on the replacement units. Does that mean they were running too hot?
Actually, it is evident. The glue melted down. The replacement units definitely do not look like that. The speakers appear to sound fine... how is that so?
