Polk Audio Monitor 7C Crossover Modification Thread

VR3

Clarity Cap PX w/ Mundorf Mox -

First time I have replaced the polyswitch with a resistor... was a tricky fit

VR3

Modded Pair

Oldfatdogs

Once again you work your magic,well done.
I need to shoot you a pm soon about my 1Cs.
Dan

VR3

Thank you sir!

Look forward to helping you out!

george daniel

Nice work Trey!

VR3

Thank you sir!

smglbrth

Ok, these were the crossovers out of my 7C's so thought this would be a good place for a little review instead of starting a new thread.

First off, total modifications were the crossovers, Larry's rings for everything, new tweets from Polk (these are well broken in after a couple years) and new gasket tape. I also have the original stands attached which I spiked earlier this year. After letting them break in for almost a solid three weeks there is one word which really describes how they sound, "anal". I thought discs sounded really different before but this is a whole new league. Details are so exact it's uncanny, or no detail on some discs which make them sound worse than they already did (think harder rock here). Bass doesn't necessarily hit harder but is more distinct. I can tell, most of time now, how hard the drummer foots the bass, hits the toms/snare or cymbals. As far as vocals the "t", "s" and "ch"s are much more distinct as well. Overall I like the sound they produce after the mods although it took me a little bit to get used to.

Trey asked me a little while ago how the highs were since he replaced the polyswitches with resistors. Let's just say I'm not missing the poly's. With the resistors in place the highs are no hotter or less. Some of the recordings seem a little high, some seem almost non-existent. Again, it just depends on the recording, hence, my new word for describing a speaker, "anal". No, they still can't touch my 2A's for depth and soundstage but they do better with clarity, believe it or not.

Kudos to Trey for great crossover work, Larry for the rings, and the new tweets from Polk. All have turned these 1985 Monitor 7C's into a very, very special speaker. It's also a speaker that I don't have to touch for the next 25 or so years (which means one of my kids will probably inherit them). Later this year I will get to my 2A's.

If anyone has any reservations about spending the dough for the old monitor series upgrades (for a speaker you will actually use) just do it, I'm glad I did. A whole new league!

VR3

Excellent write up!

Thanks for sharing and glad you are liking them!

zane77

Another great job, hope you enjoy them'

gmjungbluth

Thanks for this write up - I have a set of 7bs at home that I am getting ready to mod in the same fashion (rings, tape, new caps and resistors) and I'm happy to hear that you liked the result.

This gives me more reason to get going on these puppies!

Nagafd

I think I blew out my mid woofer on left channel. One seems to have become misaligned at high volume. It really sounds bad at high volume. These should be able to take 150 wpc at 8 ohms, right? I was not even close to that. I purchased replacements from Polk, seems like it should be an easy fix, right? Should I also be looking to modify the crossovers. Have silk tweeters which still sound fine. Bass is really something that is left to desire though. I do not want to play these with a sub woofer. Any recommendations?

littlewoodboats

Whats the difference between the different cap lines from Clarity? I have followed a number of your VR3 modification threads and would be interested in what drives the choice. I am gearing up to do my Monitor 7 series II and am not sure which is the correct choice.

VR3

Before I started offering modifications for others, I started on my own personal equipment and quickly found some preferences to caps and resistors.

I like Clarity Cap, Mundorf Resistors/Mills MRC50/Duelund and Jantzen Inductors along with Supra and DH Labs wire, just has everything I look for, transparency, realistic reproduction, good details, staging, depth, bass response, clarity, etc etc with little color.

I have always found Sonicap/Mills to be extremely veiled in comparison to the Clarity/Mundorf combo. YMMV

littlewoodboats

Thanks for the reply. Looking at the Clarity site they show several different series. You seem to like using the ESA in tweeter circuits while this pair of 7's got the PX. While rebuilding two different model SDA here you used the ESA for the woofer in one while using the PX for the woofer on the other. I was curious why you use one model over another in the different positions.