Polk Monitor 7 - crossovers going south?

DozerCSX

Greetings - I am the original owner of a pair of Polk Monitor 7s from 1986, and I had them in storage for 10 years; now that they're back in action, they seem as accurate as ever, but I sense the bass has been reduced somewhat from what I recall. Can anyone tell me whether this might be a result of the crossovers weakening, or going bad? Would inactivity affect the crossovers? Is there a way to check their health?

westmassguy

The Crossovers have Mylar and NP Electrolytics. Mylars don't age, but Electrolytics do.

ken brydson

Check for air leaks? I'd start there for missing bass.

Nightfall

Torn rubber surrounds on any of the drivers or passive radiators?

Are you playing them in the same room you played them 10 years ago? Is the equipment the same? Cables the same? Lots of variables.

TCK

Welcome. Yes, it's probably time to refresh the crossovers, always a good idea on 30 yr speakers. I would also check the Dacron insulation in the cabinets. Take the passive woofer out & push the Dacron back up towards the tweeters. It should not be below the passive. This will give you a better bass and will tighten them up a bit.

DozerCSX

Thanks guys - great ideas to work on - I just did a quick inspection for leaks - they are in almost perfect condition, nothing obvious; I did notice that the left speaker is sitting on a thin, flexy half inch plywood, which is clearly sucking up at least some of the sound energy - I'm putting them on polymer feet over solid wood bases tonight to see if that helps; pending on that outcome, I'll see about "opening the patient... BTW here are some pictures - they are 7Cs, with a story - in the 1989 SF earthquake, the right speaker fell on its face and damaged the tweeter, so I replaced it with a Peerless - the original SL2000 is still on the left speaker...

dkfreebird

That tweeter looks like the Rdo 194 that is a replacement for the sl2000 and is a lot smoother sounding tweeter.

Nightfall

That's not a Peerless, looks like a SL2500. Replace both with RDO-194's, they can be bought directly from Polk.

They look like they're in pretty good shape, nice speakers.

DozerCSX

Turns out the right side replacement tweeter is an RDO 194, not a Peerless - I purchased it directly from Polk at the time - and it is a bit smoother sound than the original... yeah, probably time to pick up another and "make 'em match."

Nightfall

I thought you replaced the tweeter in 1989?

DozerCSX

I damaged it in 1989, I didn't fix it for several years afterwards (I stored them for a while then, as well) - probably like you, I've gone through many, many speakers over the last 30 years... ;-) But I've kept these as my personal favorites, kind of like my 1989 pickup truck.

DozerCSX

So, I've done a couple of sound checks and inspections last night - the environment I'm using now (a garage) is much bigger than where I've previously used these - but the cables and gear are actually higher quality than before; the room definitely swallows a lot more of the sound, the speakers are further from the wall, and even raised with pads off the pressboard; still, I think they are down on bass. Any recommendations on crossovers or kits? I've never attempted anything like a crossover upgrade before, insights appreciated!

Nightfall

How big is the garage? I suspect much bigger than the Monitor 7's are capable of pressurizing properly. You might need a sub.

DozerCSX

You may be right - it's a detached two car garage, 19'lx17'wx10'h - interestingly my RT800i's could do the job out there, but they had two 6" woofers, plus a large ported tower enclosure; when I put my ear next to the M7 woofer and PBR I can hear the lower octaves, but it does seem to get swallowed up in the room moving just a short distance away. I may try my sub out there and see what happens this weekend...

DozerCSX

Gents - so, I think I got it sorted out - turns out there was a bit of pilot error - I use a Parasound AVR-1805, and I had the L/R speaker toggle set to "small", not "full range" - I did get back some low bite in correcting the setting, but the whole exercise allowed me to convince my wife to let me pick up a Polk PSW10 - now with the combination of Monitor 7c's running full range plus the PSW10 all set up and driven properly, I can now overwhelm my garage insulation with full range sound... thanks! (Based on your inputs I'll still be picking up a matching tweeter, and look in to new crossovers, but for now things appear to be working well)

Nightfall

Glad you got it figured out. Enjoy your Monitor 7's once again, they're great speakers.

teekay0007

DozerCSX wrote: »

Gents - so, I think I got it sorted out...the whole exercise allowed me to convince my wife to let me pick up a Polk PSW10

Monitor 7s. (Sweet!) Check.

New tweeter. Check.

PSW10. Noooooooooooooooooo!


A new/used sub will fill out your sound nicely, but the one you're looking at is the first one I'd tell you to move on from.

At a minimum, if you are sticking with Polk, I'd go psw110 or 505. However, the PSWPRO440wi or 550wi, or even the psw111, would serve you SO much better.

Others here will certainly chime in with some non-Polk suggestions too.

Nightfall

Chuff chuff chuff

DozerCSX

Re: PSW10 - found an online fix which takes 10 minutes and completely removes the "chuff" - massive sonic improvement, check it out: https://www.youtube.com/watch?v=gKsMdcjh8KM

heiney9

Nightfall wrote: »

That's not a Peerless, looks like a SL2500. Replace both with RDO-194's, they can be bought directly from Polk.

They look like they're in pretty good shape, nice speakers.

Sl2500 and Sl3000 have a foam ring around the dome (between the bezel). For future info.

And sometimes they turn a goldish color, this is an SL3000, but the foam ring looks the same on a SL2500



A RD0 replacement for reference

heiney9

Nightfall wrote: »

I thought you replaced the tweeter in 1989?

The RD0 replacements have been around for a long time, not as far back as 1989 though.....sometime in 2001,2002, IIRC. They were referred to as the SL2000T at that time.

Someone will correct me if I'm wrong

heiney9

Here is a post from 2003, but I know the SL2000T was available prior to this post.

http://forum.polkaudio.com/discussion/comment/113462#Comment_113462

Jaybeez

I currently have a 404 mated with my 7Cs and it sounds pretty good. I keep the volume down and let the 7s do most of the work. Just a little bottom end fill is what I was looking for.

pkquat

2cents post from what I have been reading on the forums about tweeters and crossovers and such, mostly from westmassguy. If you are planning on rebuilding the crossovers, you might consider upgrading both tweeters to the RDO-198's vs the RDO-194's. I think the only change to use the RDO-198's is a different capacitor value on the crossovers (TL upgrade), but are a physical drop in replacement and according to most people here sound a little better than the RDO-194.

The wiring schematics have disappeared for the moment, so double check on the changes to the crossover if you go with the RDO-198.