Unidentified caps on RTA12 crossover
Michael8it
Posts: 192
I have identified all of the caps on my RTA12 crossovers except for 2 - they run in parallel to C2 (@ 4.4uF) and C3 (@ 14.6uF). They are both physically small, reddish brown, and say "Ross Labs" on them. They were not on the schematic.
If anyone knows what the value of these are please let me know. I did re-write a proper schematic for this, and if I can get these values Ill post the new schematic to the files on here.
Thanks,
Mike
If anyone knows what the value of these are please let me know. I did re-write a proper schematic for this, and if I can get these values Ill post the new schematic to the files on here.
Thanks,
Mike
Carver C-1, M-500 MKII, Yamaha HTR-5835, Polk RTA 12BM's (M-for mod'd).
Post edited by Michael8it on
Comments
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They are probably the 750pf silver mica's Polk liked to use for bypassing.
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Remember, early RTA 12s 1978-1980 ( on the stands with 6500 drivers) have only one Xover and are different then Bs and Cs
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Sorry geppy I don't see the relivance.
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I guess geppy was warning us that we might be giving misinformation.
I will concur with FTGV that what you are seeing is probably the Silver Mica and you can eliminate it from crossover. It is not needed after the updating. -
The Xovers on the early 12s are different then Bs and Cs and there are even 2 versions of those.
The Bs and Cs have 5 caps on the top Xover and 2 on the Xover in the cabinet. The early 12s have NO Xover over in the cabinet and the one on top can have 7 or 8 caps on it.
I think there is some relivance there as they are differnt animals to some extent. -
I have a question for the OP. Are they small round disc shaped items you are speaking of? Do you have fuses on the back of your speakers?
They may be Polyswitches. They are reddish brown and very small like the size of an M&M.
If not then my first thought that they are the bypass caps stands. -
OK but the OP already indicated he had the RTA12(not B or C)and with the cap values for the hi pass caps as shown in the schem. for that model.(4.4uf and 14.6uf).If the little caps are in parallel with them ,the value would need to be small so as to not alter the crossover point.Since in the day Polk loved to use the 750pf silver mica's as bypasses which leads me to believe thats what they are.The Xovers on the early 12s are different then Bs and Cs and there are even 2 versions of those.
The Bs and Cs have 5 caps on the top Xover and 2 on the Xover in the cabinet. The early 12s have NO Xover over in the cabinet and the one on top can have 7 or 8 caps on it.
I think there is some relivance there as they are differnt animals to some extent. -
Your probably right on on that point. No argument there.
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They are in fact bypass caps. I compared them to another crossover from a 12B which has them labelled and they are indentical.Carver C-1, M-500 MKII, Yamaha HTR-5835, Polk RTA 12BM's (M-for mod'd).
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Throw them away, do not replace.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
