Monitor 5A crossover oddity and other weirdness.

Hofy

I received my Polk Monitor 5A's this weekend and everything works and sounds good. Of course I will be doing a total rebuild on them, so I just had to open them up and check things out. Both the MW6500's and the crossovers are dated 5-26-82. Serial numbers are 131122 and 131107.

The first thing I notice is that the crossovers are different from all the photos and schematics I have seen so far. Mine have 2 resistors. 2.5ohm and 2.7ohm. Also one of the caps is 27uF. I can not make out the value of the middle cap on either crossover. I will pull the terminal cups later and see if I can spot it at a better angle. (see photos) Any ideas on this setup??

Second, from what I have read about the Peerless tweeters is that numbers starting 75 are Danish and 55 are American built. Mine have one of each. (see photos)

Third, I have also read that the polyfill should only be behind the MW and tweeter, none behind the PR. Both of mine have one roll of poly behind the tweeter in the top and one roll behind the PR on the bottom. I am pretty sure it did not slip down either as it is tight. I can always move it around to hear what sounds best.

Faustin

I have a early set of 4a's that have crossovers that are "unconventional" compared to other c/o's. I evencontacted Polk and they said that they appeared to be original and unaltered. Every component was dated 1982. From the info I gathered, the values of the caps, resistors etc are the same as the Monitor 10's. I have not done anything with the crossovers at this point. They have Peerless tweeters and sound darn good for a little book shelf.

You are correct on the Peerless - 7514 is Denmark and 5514 is US. Probably one blew and was replaced. Hard to say.

Polyfil on the bottom should be positioned above the top of the pr and stapled to hold it in place.

Hofy

When I rebuild these crossovers should I replace with like values or replace with standard 34uF/12uF?

StantonZ

Hofy wrote: »

When I rebuild these crossovers should I replace with like values or replace with standard 34uF/12uF?

If they are "original equipment" (not modified/replaced by someone else), then replace with like values. I have a pair of original 4's with peerless tweets, and the XO board is definitely different than my later Polks (but they sound great!).

Hofy

Between my OCD (CDO) and need to know, I just have to find out what is going on with these. I guess I need to find my meter with LRC so I can measure the inductors.

I also pulled a crossover out and was able to see that the 12uF is correct.

skrol

I have a pair of 5A with Peerless 55xxxxx (Made in USA sticker), single fuse, no polyswitch, from 1993, Serial 144852 and 144854. The XO resistors are 2.5 and 2.7 ohms, the caps are 12uF and 27uF. I don't know the inductor values. Mine also have rolls of polyfill behind the PR's which I believe is from the factory. There was also a lot of excess glue rattling around inside.

I have thought about experimenting with removing some of the polyfill from behind the PR's. Let us know if you try it.

Hope this helps
Stan

Hofy

Stan,
That is good to know you have a pair of 5A's from the same era. (I am guessing you mean 1983 not 1993.) I am goingto try repositioning the poly and also rebuild the crossovers with exact same values. I am also thinking of trying a second set of spare crossovers with the more common values.

skrol

Yes, I must be getting old; I keep forgetting what decade I am in.

I also had a pair of 5B from 1984. These did not have any polyfill behind the PR but they also used a MW6502 vs the MW6500 in the 5A. I never checked if the PR's were the same. I tended to like the bass response of the 5B over the 5A but the 5A is much sweeter on the upper end.

Hofy

I did a bunch more reading this weekend. I found some of Stan's old threads on his 5A along with some others. They really helped me sort things out. I had my speakers apart more than together the last couple of days.

I just finished placing my orders with Madisound and Parts-Express. Going with Clarity PX 12uF and Dayton 27uF on the caps. Mills 2.5 Ohm and Mundorf MOX 2.7Ohm on the resistors. Dynamat Xtreme, Hurricane nuts with 1" screws, and some 1/4"wide x 1/8" thick weather stripping. I already have the JB Weld on hand.

I will start a new thread on my exploits once the mods start. Then once I have these speakers sounding their best I will move onto making them look their best with new veneer and grill cloth. (I am already thinking cherry veneer.)

Faustin

I have a set of 5a's with Peerless from 1982. I have completed all of the mods and used Sonicraft Gen 1 for the 12uf and Dayton for the 27uf and Mills for the 2.5 and 2.7 resistors. Also replaced the binding posts with gold plated from parts express. They have approx. 350 - 400 hours on them now. High end is very nice. Have them side by side with my 10a's. The 10a's of course have much more low end but the 5a's are very easy to listen to especially in a small room.

Hofy

Faustin, thanks for the reply. I would love to have a a pair of the bigger monitors, but I am confined to a small listening room of 12 x 10 feet. Even stock the 5A's put out more bass than the Pioneer HPM40's they replaced so I am good.

I debated on the new binding posts, but mine are still like new and I use banana plugs, so why bother for now. I also could not find any place online to buy Mills 2.7Ohm resistors. (Other than Partsconnexion, and the fact that they do not calculate shipping until AFTER you pay made me stay away.)

skrol

I have bought from Partsconnexion a few times. They have been good with reasonable shipping rates. Orders can take a little long to arrive. I guess it is because they are coming from Canada. They certainly have some good stuff.
Stan

Faustin

Hofy wrote: »

Faustin, thanks for the reply. I would love to have a a pair of the bigger monitors, but I am confined to a small listening room of 12 x 10 feet. Even stock the 5A's put out more bass than the Pioneer HPM40's they replaced so I am good.

I debated on the new binding posts, but mine are still like new and I use banana plugs, so why bother for now. I also could not find any place online to buy Mills 2.7Ohm resistors. (Other than Partsconnexion, and the fact that they do not calculate shipping until AFTER you pay made me stay away.)

Actually the high pass cap was a Sonicap and the company that I purchased that cap and the Mills resistors from was Sonic Craft. You should be able to find their website. My 5a's were in like new condition and the binding posts looked great. Just figured for the extra few dollars and a minimal amount of time I would replace them when I had things apart.

Hofy

Well, almost everything I ordered is in. Hopefully this weekend I can operate on my 5A's. Stay tuned for another thread covering this.