Polk 7C or series 2? Crossover upgrade questions

daviddi92

Hi guys,
New to the forum and recently picked up a set of polk monitor 7s. I'm thinking they're 7c's based on the sl2000 tweeter. But the date on the woofer is from 1990.

Any one able to confirm if these are still 7c?

Also, looking to upgrade my crossovers and the parts I came up with are:

Clarity cap px 12uF
Jantzen 33uf
Mills 2.5 ohm 12 watt resistors and jumper the poly switch

Does these parts sound good to go?

I haven't decided if I want to change the tweeters to rd0194 or 198, but looking at the schematics I can change the caps and resistors and decide on the tweeter choice later correct?


Thanks in advance everyone!
David

stevep

You need to decide between the RD0-194 and the RD0-198 tweeters now since the crossovers are different depending on which you have. Look at the schematics between the M7Rev and the M7Series2 to see the differences.

The little yellow device next to the sand cast resistor is the polyfuse and many take them out of the crossover circuit since they don't seem to age well and up the resistor value to 2.5ohms to account for it's normal resistance.

daviddi92

I saw both schematics, I am seeing that they both use 12uF and 34uf caps and the 2 ohm resistor. Couldnt I change those and then if I decided to use the RD0-198, I would just need to change to the 0.27 mH inductor 0.5ohm and the 5.8uF cap?

Or am I missing something?


Sidenote @stevep I think I remember you from the DSM forums about 10 years ago, ecu repair was it?

mn_polk_guy

Thats is a 7c crossover and the 194 is the drop in replacement. you are correct about changing the 0.27 inductor and 5.8uF cap to use the 198. If your going to do the work the 198 is the better tweeter.

dromunds

Is it that much more to upgrade the Clarity Cap PX? CSA?

stevep

daviddi92 wrote: »

I saw both schematics, I am seeing that they both use 12uF and 34uf caps and the 2 ohm resistor. Couldnt I change those and then if I decided to use the RD0-198, I would just need to change to the 0.27 mH inductor 0.5ohm and the 5.8uF cap?

Sidenote @stevep I think I remember you from the DSM forums about 10 years ago, ecu repair was it?

LOL, yes that's me.

The way I read the schematics only two parts are shared. The 12uf capacitor and 0.22mH inductor in the tweeter circuit. The resistor is a different value, the added 8uf capacitor and all the woofer parts are different, 27uf cap and 1.75mH inductor

Are we looking at the same schematics?

daviddi92

mn_polk_guy wrote: »

Thats is a 7c crossover and the 194 is the drop in replacement. you are correct about changing the 0.27 inductor and 5.8uF cap to use the 198. If your going to do the work the 198 is the better tweeter.

Are these the only changes required? Everything else stays the same correct?

dromunds wrote: »

Is it that much more to upgrade the Clarity Cap PX? CSA?

I just read people using the PX. The CSA is about $10 more each so I can go ahead and use the CSA if they are a much better quality.

stevep wrote: »

LOL, yes that's me.

The way I read the schematics only two parts are shared. The 12uf capacitor and 0.22mH inductor in the tweeter circuit. The resistor is a different value, the added 8uf capacitor and all the woofer parts are different, 27uf cap and 1.75mH inductor

Are we looking at the same schematics?

I thought so! Lol

Hmm, Im reading the M5b_SL3000mod schematic as I had read to use that one by others.

Maybe I am wrong though!

dromunds

I have a pair of 7C's with PX's, but I have also since done some other speakers with CSA's (I also used some ESA's because they were half-price at the time - if you could find some ESAs at half price that would be super but probably long gone but otherwise the CSA's are superior to PX's and I would think the CSA's would be worth it.) I have not been keeping up with Clarity Cap's newest stuff but I sure liked the CSA's and ESA's.

daviddi92

dromunds wrote: »

I have a pair of 7C's with PX's, but I have also since done some other speakers with CSA's (I also used some ESA's because they were half-price at the time - if you could find some ESAs at half price that would be super but probably long gone but otherwise the CSA's are superior to PX's and I would think the CSA's would be worth it.) I have not been keeping up with Clarity Cap's newest stuff but I sure liked the CSA's and ESA's.

Awesome, thanks for the recommendation. I will go with the CSA's and hopefully can find a deal still going on.

stevep

daviddi92 wrote: »

Hmm, Im reading the M5b_SL3000mod schematic as I had read to use that one by others.

Maybe I am wrong though!

I was looking at the Monitor 7 Series 2 schematic circa 1990, That's what Polk did when they switched to the SL2500 tweeter. I don't see a official Monitor 5+ Series 2 schematic just the SL3000 mod project one you're likely looking at so I can't compare to other series 2 revisions. I don't remember reading about MW driver differences so I can only assume that Polk made the woofer crossover changes for other reasons.

mn_polk_guy

The m5 sl3000 schematic is the one I followed successfully

stevep

Heck, people have just slapped the RD0-198 in "successfully" after accounting for the connector differences. They were happy until they found out it was wrong...

Without actual speaker measurements it's hard to say which the most "correct". I suspect few of us could hear the differences between the m5 sl3000 tweeter crossover and the M7S2 version and if we could it I again suspect it would be up to personal taste as to which was "right".

The M7S2 version doesn't change the tweeters inductor over the SL2000 revision and uses a more generic 8uf capacitor across the resistor while deleting the polyswitch.

Anyway, I don't have a dog in the race just pointing out that based on the information Polk has released they did something else with their product.

F1nut

Just an idea, but maybe just stick with the original 7C crossover design, update the components and install the RD0194. That way you know everything is correct. I guarantee you will be over the moon with the improvement.

In other words, stop trying to reinvent the wheel.

pitdogg2

Agree ^^^^

another thought as you could tie two 17uf together to make the 34uf...