No bass from Monitor 5B's
garyspong
Posts: 2
Hi all,
Long time Polk user here having enjoyed my Monitor 10s second-hand from a friend circa 1995. Anyway I just picked up a pair of Monitor 5b's from Goodwill for $14.99 for the pair. Got them connected to my Denon PMA-500V to discover no bass response whatsoever. I opened them to find what I thought to be a gutted woofer: no voice coils or magnets. I've since learned that passive radiators don't have these and that they're not connected to the XO. That's fine, but why do I only get sound from the tweeters (SL2000) and centers (MW6502)? Wires are all connected and polarity appears correct. I can't locate any obvious damage to the drivers or XO. What is the first step in diagnosing the problem? I'd like to upgrade to the replacement tweeters mentioned elsewhere, but that can wait until I've determined the problem with the bass. If it's a matter of upgrading caps or resistors I suppose I can do that. I've searched high and low for answers here to no avail. Any help is greatly appreciated.
Thanks, Gary
Lebanon, Indiana
Long time Polk user here having enjoyed my Monitor 10s second-hand from a friend circa 1995. Anyway I just picked up a pair of Monitor 5b's from Goodwill for $14.99 for the pair. Got them connected to my Denon PMA-500V to discover no bass response whatsoever. I opened them to find what I thought to be a gutted woofer: no voice coils or magnets. I've since learned that passive radiators don't have these and that they're not connected to the XO. That's fine, but why do I only get sound from the tweeters (SL2000) and centers (MW6502)? Wires are all connected and polarity appears correct. I can't locate any obvious damage to the drivers or XO. What is the first step in diagnosing the problem? I'd like to upgrade to the replacement tweeters mentioned elsewhere, but that can wait until I've determined the problem with the bass. If it's a matter of upgrading caps or resistors I suppose I can do that. I've searched high and low for answers here to no avail. Any help is greatly appreciated.
Thanks, Gary
Lebanon, Indiana
Post edited by garyspong on
Comments
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The first thing to check for is air leaks. Push the PR in and hold while watching the mid-driver. It should move out and then slowly retract.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 -
Make sure thier not wired out of phase too.SDA-2BTL with custom IC
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Thanks. I'll check for leaks. I do wonder about the phase issue. I've read several threads and there seems to be much confusion regarding red, blue, green and white wires and which are connected to pos or neg. My speakers have black and white wires. The tweets are connected thus: +/black wire , -/white wire. The center speakers have no +/- markings, but there is a red dot on the right connector. The left I assume is black, as that is the color of the driver housing. So they are black/white wire and red/black wire. Based on that I suspect they could be out of phase. I suspect also that this must have been maddening even for the people assembling them, and I wouldn't be surprised if mistakes were made all the time. Receivers and speaker terminals generally use red for positive. Black or white was variously used for negative. Introducing black and white wires to connect them internally has I think hopelessly confused the issue for many.
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There's no confusion about vintage Polk speakers. Black or blue is positive. White or green is negative. The red dot indicates the positive terminal.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
