Monitor 4 Help

Faustin

I bought a pair of Monitor 4's a few months ago with peerless tweeters and have decided to rebuild the crossovers. After removing and inspecting the crossovers, they do not look like any other ones that I have seen on the forums. The speaker appear to be early monitor 4's and the dates on the crossover circuit boards are 3/19/82. The boards are also marked "4". The back of the cups are marked "4 3014" and "4 3015." One cabinet had a mw6500 and one had a mw6502. From a post a couple of months ago it seems that the first 4's used the mw6500. Does anyone have any early 4's that have these crossovers that would confirm that they are correct

??

skrol

Off the cuff and without being able to read the component values, the cross-over looks legit. Someone may have replaced one of the mid-woofers with a 6500.

Faustin

According to a Polk Replacement sheet, and info from a post a couple of months ago, the original monitor 4 had the mw6500. That came from Kim at Polk. It seems that all other 4's after the originals used the mw6502. Just trying to find out if anyone has a pair of old 4's to confirm the crossover configuration etc.

westmassguy

Bruce, see if you can identify the values on all the caps. If you have a LCR Meter, measure the inductors also. I looked through all the single driver Monitor Schematics, and not a single one has a shunt capacitor like yours do, except for the revised, late production models that used the SL2500 Tweeter.

StantonZ

I have a pair of pre-1982 Monitor 4's, but have never opened them up because I decided I didn't want to mess with the XO's. I think the comment about the 6500 drivers is right, but I can't comment on the XO values from the picture provided (and I don't see why someone would have swapped out both XO's from a later 4). It's easy enough for me to look at the serial number sticker on the back, but I don't really want to open them up unless it's a matter of "fixing something that is broke" (which doesn't appear to be the case).

pitdogg2

Maybe one of the magnets slipped and they called Polk CS and got the 6502 replacement....

Faustin

pitdogg2 wrote: »

Maybe one of the magnets slipped and they called Polk CS and got the 6502 replacement....

That is what I think happened. I have been in contact with Polk cs and am waiting to see what they have to say.

Faustin

StantonZ wrote: »

I have a pair of pre-1982 Monitor 4's, but have never opened them up because I decided I didn't want to mess with the XO's. I think the comment about the 6500 drivers is right, but I can't comment on the XO values from the picture provided (and I don't see why someone would have swapped out both XO's from a later 4). It's easy enough for me to look at the serial number sticker on the back, but I don't really want to open them up unless it's a matter of "fixing something that is broke" (which doesn't appear to be the case).

Maybe just pretend something is wrong and take those 4 little screws out and take a quick peak.

On3s&Z3r0s

I can definitely confirm that Polk made Monitor 4's with Peerless tweeters and MW6500's. I bought a pair a couple years ago where both MW's were frozen and one cabinet was cracked beyond repair, so I donated the tweeters and wrote them off. The crossovers were entirely different and much more primitive seeming than yours (here's the thread if you want to see the crossovers: http://www.polkaudio.com/forums/showthread.php?120946-Crossover-Gurus-rehab-advice-for-mangled-Monitor-4s&p=1602320#post1602320). Another member who had recently purchased a similar pair had the same XO's as mine, different from yours. But I agree that yours look stock. Maybe Polk was experimenting during that period. If I were in your spot I'd go ahead and just buy new parts with the same values as what's in your XO. Can't hardly go wrong doing that.

Faustin

I did contact Polk customer service and emailed them quite a few photos. They said that they appeared to be original and not altered. I had to agree with them and asked if they had a schematic or any other documentation to back up or confirm that they used what appears to be a early 10'a crossover (same values) in these 4's. Their response back was" these are the original crossovers with no modifications". I again would have to agree that they are original and have not been modified, but were they really intended to be put in a 4 cabinet??

StantonZ

On3s&Z3r0s wrote: »

I can definitely confirm that Polk made Monitor 4's with Peerless tweeters and MW6500's. I bought a pair a couple years ago where both MW's were frozen and one cabinet was cracked beyond repair, so I donated the tweeters and wrote them off. The crossovers were entirely different and much more primitive seeming than yours (here's the thread if you want to see the crossovers: http://www.polkaudio.com/forums/showthread.php?120946-Crossover-Gurus-rehab-advice-for-mangled-Monitor-4s&p=1602320#post1602320). Another member who had recently purchased a similar pair had the same XO's as mine, different from yours. But I agree that yours look stock. Maybe Polk was experimenting during that period. If I were in your spot I'd go ahead and just buy new parts with the same values as what's in your XO. Can't hardly go wrong doing that.

I can confirm his confirmation, and would have suggested the same thing: just replace your XO parts with what you can visually confirm. I think sorting our your driver issue is of greater concern.

Faustin

I am going to use the MW6500 drivers. I have one good one and I am searching for another one. Are there any out there?????

pitdogg2

been several on bay watch lately

alkermes

My Polk 4's are also early models, but slightly newer than yours according to the serial numbers (#05820 on one of them). I posted pictures of them on the board last year. The crossover uses the same caps but they are put together differently, the whole thing is hot glued. They have the MW6500 drivers.

I just picked up new caps and may get to the recap today after being inspired by your post, I will take some pictures and post them.

I hope you get you new MW6500 soon!

Faustin

I do remember your post in regards to your 4's. The crossovers were quite a bit different. But yours uses the same caps and resistors as the ones I have? Mine have 1) 34uf cap, 2) 12uf caps, 1) 2.7 ohm resistor and 1) 2.5 ohm resistor.

alkermes

I looked at the pictures of the crossover and was thinking the caps looked the same, as in the same manufacturer -- not the values, I didn't look at those. Sorry, I should have been clearer!