New member asking for sanity check on Monitor 7

Father_Redbeard

Hello, everyone! I spent the last two days combing through the knowledge here after purchasing a set of Monitor 7 locally. They sound good for most genres but some punk really gets fatiguing after a short amount of time. I understand that the non-Peerless tweeters can be to blame. Mine doesn't have those. It has the SL2000 in them. I understand there is a replacement that can be purchased and I've reached out to Polk already in that regard.

What revision are these?
Is RD0194-1 the correct drop-in replacement for this revision?
Since the mid-woofers are new (assembled in 2010), do I need to worry about epoxying the magnets to prevent slip?

I didn't get a picture while it was open, but the crossovers viewed from the MW hole appear to be different. I could only see one date that was 1988 (or 89, the last digit is smeared a bit). Is that normal or does that indicate it was also replaced?

The seller only disclosed the MWs being replaced. Unfortunately he also stated these were the Peerless tweeters. And me knowing just enough to say "i know that term!" but not knowing how to identify, took him at his word. That's on me. Lesson learned. I tried to see if we could come to an agreement to get some of the money I paid back and he ghosted me. Such is life.

As far as mods go, I want to do the tweeter replacement and crossover upgrade. I still need to read up on the latter. I know how to solder, but I do NOT know how to read a schematic well enough to know what goes where. So I'm digging for a more dummy proof photo tutorial that would help me figure that out. It's probably on the forum somewhere, but I haven't found it yet.

billbillw

Tweeter upgrades will vastly improve things. Yes, the RD0194 is correct for that. I'd still epoxy the magnets because it is still the same design and better to do it now and forget about it than have it shift 10 years from now. Welcome to the Club. The 7 is one of the best classic non-SDA Polks. Those look pretty clean. Enjoy.

pitdogg2

The MW6502 are not original, they're after market. They also look to have a foam surround instead of the butyl rubber the original had.
Reach out to this member and buy 4, then glue the magnets when you get them. These are new unused original Polk drivers.
https://forum.polkaudio.com/discussion/201843/fs-a-boatload-of-polk-mw6502-drivers#latest

Yes you will need the RD-0194 tweeters to replace the SL2000.
As far as reading schematics, pull your XO's all the info will be in your hand.

billbillw

pitdogg2 wrote: »

The MW6502 are not original, they're after market. They also look to have a foam surround instead of the butyl rubber the original had.
Reach out to this member and buy 4, then glue the magnets when you get them. These are new unused original Polk drivers.
https://forum.polkaudio.com/discussion/201843/fs-a-boatload-of-polk-mw6502-drivers#latest

Yes you will need the RD-0194 tweeters to replace the SL2000.

Good catch on the woofers.

Gardenstater

Those are late Monitor 7C. Not too much before they went to the Monitor 7 Series 2.

I didn't know that they were still making MW6502 in 2010 so I learned something. This site shows the same paper labels as yours. https://reconingspeakers.com/product/polk-mw6502-6-5-woofer/

RD0194-1 is indeed the upgrade silk dome tweeter for the SL2000. That's a "ZERO", not an O. The date on the tweeter label is probably the date your speakers were rolled off the assembly line or darn close.

Different crossovers would be weird since serials aren't that far apart, especially weird. Yep you do need pictures.

To be continued maybe by others on crossover mods ........🤣. I will say that if it were me and I didn't find it too daunting I would consider the tl mod and then you would want the RD0198-1 upgraded tweeters. A bit more refined sounding than the RD0194-1, according to forum member reports and DarqueKnight measurements in Tale of 5 Tweeters thread. Westmassguy did a thread on the tl mod for the 7C.

https://forum.polkaudio.com/discussion/182943/the-tale-of-5-tweeters-sda-tweeter-replacement-guide#latest

https://forum.polkaudio.com/discussion/192120/monitor-7-with-tl-upgrade#latest

Father_Redbeard

pitdogg2 wrote: »

The MW6502 are not original, they're after market. They also look to have a foam surround instead of the butyl rubber the original had.

They are rubber. And this link suggests they are OEM? Just not original of course. Is that not accurate? If not then that would be strike 2 from the seller lying to me. He said he called Polk and that is what they sent him as a replacement. Which at this point I wouldn't be surprised.

pitdogg2

Father_Redbeard wrote: »

pitdogg2 wrote: »

The MW6502 are not original, they're after market. They also look to have a foam surround instead of the butyl rubber the original had.

They are rubber. And this link suggests they are OEM? Just not original of course. Is that not accurate? If not then that would be strike 2 from the seller lying to me. He said he called Polk and that is what they sent him as a replacement. Which at this point I wouldn't be surprised.

Good to know that they are rubber. Speaker exchange and Midwest speaker both sell "polk" drivers that are basically jack of all trades woofers. By that I mean they are close but not the same parameters as original woofers. MW6511 and MW6503 come to mind.
The link I gave would be actually from Polk. A worth while investment if you plan on keeping.
Polk did do some small runs in that time frame of LARGE volume replacement drivers in that time period. So yes, they may have came from Polk. They look different enough, that gave me pause.

Gardenstater

If you have any questions about the schematic just ask, but this is probably your crossovers. One point may be the shunt inductor value was changed from 0.23mH to 0.22mH just after the date on your tweeters, so it is somewhat in doubt which you have but most people don't mess with the inductors since they are already air core. Some people go the extra mile and put in a Jantzen perfect lay or the like. The tl mod requires an inductance mod and I think westmassguy (RIP) un-wound a little wire from inductors in his parts bin of spare crossover parts since he was in the business of doing crossovers for quite a while before stopping.

You definitely have to remove the crossovers and get the values from the resistors and capacitors anyways. No getting around that.

https://us.v-cdn.net/5021930/uploads/attachments/4/6/7/2/8/18773.pdf

Father_Redbeard

I pulled the crossovers out and took some pics. Interesting that they look very different. One with obvious date stamp and the other without (that I could find).

pitdogg2

The value for the yellow cap is under the sticker.
Those are quite different XO's. Makes me wonder if they both have the same values.

Gardenstater

Wow! Let's see a side view picture of the oddball one, the second one in your photos. I've never seen a XO that looks like that one. The date on the first one, which looks more typical of what I have seen, is a good 8 months after the date on your tweeter. Did both tweeters have the same dates?

Father_Redbeard

More pics of the 'weird one':

EDIT: And yes, both tweeters have the same date - March 16, 1989

F1nut

Model #7...that'll make the gardener's head spin.

pitdogg2

The polyswitch ( little mustard yellow disc) usually we switch out for a .5ohm 10 or 12 watt Vishay-Mills resistor. They polyswitches will go bad and trip very easily and shut off the tweeter until you turn down the volume to reset. VERY annoying.

Is that KSC cap 12.6 uf?

F1nut

The 6 indicates uF. The K indicates +/- 10%.

Gardenstater

Are the inductors the same awg? I'm going to guess the crossover with the King Sun Capacitor, the big blue one, is from the speaker with the higher serial no.? Maybe the change in bobbin size of the inductor required a slight change in inductance to try to bring the voicing back into line with previous. Could be a larger wire size (smaller awg#) too.