Monitor 4 Crossover Question
kevinko
Posts: 165
A fellow forum member is upgrading the crossovers from my original 4s w/Peerless. I shipped them to him and here is what he found:
"Your crossovers are NOT the published Monitor 4 circuit. Nor are they anything I've ever seen in a Polk.
From first appearances, I thought they used a Monitor 5 Jr circuit, but it's not even close to that. The good news is there is only 1 cap to replace. The bad news is I don't have it.
It is in parallel to the tweeter, so it is not as critical as one in series. 5.8uF is a somewhat unusual value. Most manufacturers seem to offer a 5.6uF, to which I could add a byass for the extra 0.2uF."
Attached at the very bottom is the schematic I received from Polk CS.
Apparently there is a discrepancy:
"...the cap is clearly in parallel with the tweeter, not the mid"
JS's drawing of my crossover:
Any opinions on my options here?
I was originally going to have him install Claritys but other recommendations are welcome.
"Your crossovers are NOT the published Monitor 4 circuit. Nor are they anything I've ever seen in a Polk.
From first appearances, I thought they used a Monitor 5 Jr circuit, but it's not even close to that. The good news is there is only 1 cap to replace. The bad news is I don't have it.
It is in parallel to the tweeter, so it is not as critical as one in series. 5.8uF is a somewhat unusual value. Most manufacturers seem to offer a 5.6uF, to which I could add a byass for the extra 0.2uF."
Attached at the very bottom is the schematic I received from Polk CS.
Apparently there is a discrepancy:
"...the cap is clearly in parallel with the tweeter, not the mid"
JS's drawing of my crossover:
Any opinions on my options here?
I was originally going to have him install Claritys but other recommendations are welcome.
Comments
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The schematic Polk gave you is for the version using the SL1000 tweeter.
Post a picture of your speaker and its crossover.
I don't know who JS is, but he is correct that the .02uF will act as a bypass cap, which you do not want. I'm surprised this person doesn't know that Sonicap has a 5.8uF.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 -
Polk's schematic says "HF1000"... And I don't believe they made a Monitor 4 with the SL1000. So something is amiss.
Anyway, thanks for the info about the Sonicaps.
Cute little things ain't they?
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They kind of fell into my lap. I did a nation-wide Craigslist search for Monitor 4s and found a seller in Pennsylvania who was willing to ship them to Wisconsin.
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HF stands for high frequency and 1000 means SL1000.
Anyway, best to replace the components as found.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 -
Something is very wrong. In a simple 1st order High Pass circuit, there's a Capacitor in Series with the Tweeter. An additional shunt inductor down stream, parallel with the Tweeter will create a 2nd order High Pass circuit. A cap in parallel with the Tweeter will not filter low frequencies.
In a the Low Pass, the components are reversed. The Inductor is in Series with the woofer, and the Capacitor, if equipped in in parallel, downstream.Home Theater/2 Channel:
Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer
dhsspeakerservice.com/ -
westmassguy wrote: »Something is very wrong. In a simple 1st order High Pass circuit, there's a Capacitor in Series with the Tweeter. An additional shunt inductor down stream, parallel with the Tweeter will create a 2nd order High Pass circuit. A cap in parallel with the Tweeter will not filter low frequencies.
In a the Low Pass, the components are reversed. The Inductor is in Series with the woofer, and the Capacitor, if equipped in in parallel, downstream.
I was thinking the same thing. That circuit should not work. I think someone messed with the crossover.
Also, how does the small wire disconnect shown work with a Peerless? The ones I have seen have 2 medium sized disconnects (the same size as the driver tabs). I thought only the later model tweeters has different sized tabs -
The Peerless from that era were normally soldered. If they weren't, then that quick connect appears to be the correct .125"Home Theater/2 Channel:
Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer
dhsspeakerservice.com/ -
HF stands for high frequency and 1000 means SL1000.
Anyway, best to replace the components as found.
I thought that HF1000 was Polk's designation for the Peerless. ? -
News to me.
The date on that schematic is way past the time Polk was using the Peerless.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 -
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Another 4 crossover from a previous thread:
http://forum.polkaudio.com/discussion/174722/monitor-4-with-peerless-too-bright
Mine again for comparison:
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Any opinions on this new re-configuration?
The old again for comparison:
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Happy to find this old thread. I just bought a pair of Polk Monitor 4 speakers with the peerless tweeters, MW6500 drivers, rosewood vinyl, a fuse holder and the same crossover's you have discussed in this thread. The crossovers have a hand written date of August of 1982. I also purchased a donor cabinet with no drivers but it did include the crossover and grill cover. This crossover has a printed sticker and is dated December 1983. It also matches the crossovers of the pair I purchased as well as the crossovers discussed in this thread. Crossover pictures are attached. So my question, just replace the capacitor and run them or should I reconfigure the crossover to address the observations of Westmassguy and the fact the capacitor is in parallel?
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Just replace the capacitor. On a second second look at a 2 1/2 year old post I don't think the cap in either crossover pic is in parallel. Your pics show one lead of the capacitor going to the tab that then goes to your tweeter positive (correct?). Where does the other cap lead go? If it goes to one side of the fuseholder (that is connected to the positive speaker post) the capacitor is in series.
Even if it is hard to see where every wire goes just trust that Polk put it together right. Sure there are a few documented errors in assembly that come up occasionally. But I don't think they screwed up every time they made one of their simplest crossovers. Just snip the leans and solder in a decent film cap. Easiest "rebuild" you could ever dream of.
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I have some Monitor 4's from 1982 that no longer have great sound (one's real bassy, the other trebely). The cones look good and move easily so I think it must be the COs. The COs are the fused type that were used on Monitor 5B's, and they look completely different that what I see here. In addition, they are a little different than the the posted schematics for 5B's. Image attached. Should I just get 5B COs from ebay and go for it?
Post edited by robertjgeoghegan on -
Monitor 4 crossovers appear to be all over the place.afterburnt wrote: »They didn't speak a word of English, they were from South Carolina.
Village Idiot of Club Polk -
I cannot make out the values of all of the caps, but I had a pair of early 4's that had crossovers that were identical to a Monitor 10 crossover. Did not make sense, but they were original and I rebuilt them with the same values that were on the board.
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Faustin: Now that I have seen the Monitor 10 diagrams by dorokusai, my M4 CO is the same (caps are 12, 12, 34uF), except I don't know the values of the induction coils on mine. (My sketch above has an error in it.) Do you have a good source for the caps and resistors for replacement? (I would assume the coils are bullet-proof and can stay.)
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^^^^^^^ - Sonicraft if you want higher end components. Parts Express for less expensive Dayton caps.
