Quick, ready to pull the trigger.

Nightfall

http://www.ebay.com/itm/POLK-AUDIO-MONITOR-5-SW-80-PASSIVE-RADIATOR-/310703274192?pt=US_Speaker_Parts_Components&hash=item48575bb8d0

Do all Monitor 5's have the same PR? Not counting JR's, but all regular Monitor 5's. I believe I have 5A's as they are Peerless and am ready to buy the linked PR, just want to make sure I have the correct one.

Mystery

I don't see any spec mentioning the PR.
However, all following versions of 5 below have 6502 mid driver as per schematics so PR may be the same.
Monitor 5B
Monitor 5B
Monitor 5jr
Monitor 5jr+

westmassguy

Mystery wrote: »

I don't see any spec mentioning the PR.
However, all following versions of 5 below have 6502 mid driver as per schematics so PR may be the same.
Monitor 5B
Monitor 5B
Monitor 5jr
Monitor 5jr+

I owned an early pair of 5As with SL1000 tweeters, and MW6500 woofers. The crossover was unlike any listed in the schematics section. It had an 8" PR with a front mounted fiber gasket. Since all later models used the 4 ohm MW6502 drivers, I would guess the 8" PRs were tuned differently than the original 5s

westmassguy

Nightfall wrote: »

http://www.ebay.com/itm/POLK-AUDIO-MONITOR-5-SW-80-PASSIVE-RADIATOR-/310703274192?pt=US_Speaker_Parts_Components&hash=item48575bb8d0

Do all Monitor 5's have the same PR? Not counting JR's, but all regular Monitor 5's. I believe I have 5A's as they are Peerless and am ready to buy the linked PR, just want to make sure I have the correct one.

That appears to be the later version, which may be weighted differently than your Peerless 5As

cnh

My 5A Peerless also have the MW6500s in them. Not sure about differences in the 8" Passive driver, but all full sized 5s did have an 8" that, at least, looked similar from the front?

cnh

westmassguy

cnh wrote: »

My 5A Peerless also have the MW6500s in them. Not sure about differences in the 8" Passive driver, but all full sized 5s did have an 8" that, at least, looked similar from the front?

cnh

The PRs are tuned to the size of the enclosure, and the T/S Parameters of the driver. The 8 ohm 6500's T/S parameters are vastly different than the 4 ohm 6502s. The older 8" PRs had a front mounted fiber gasket, just like the drivers from that era. Later drivers and PRs had no front gasket. It would not surprise me if the early PRs were weighted differently than the newer PRs for the 5Bs

Nightfall

Well it's too late, I ordered it last night. If my scale goes high enough I will compare weight. Might as well pull the one I have and see. Yes, MW's are 6500.

westmassguy

Nightfall wrote: »

Well it's too late, I ordered it last night. If my scale goes high enough I will compare weight. Might as well pull the one I have and see. Yes, MW's are 6500.

That might not work. The older PRs were made by a different company. The baskets themselves may be different weight, in addition to the ballast Polk added.

Nightfall

The one I have now weighs 318.3 grams. Want to weigh one of your 5B PR's?

Now that I pull it out and look at the back, it looks the same as the one I bought? I guess I'll find out Friday or Saturday.

westmassguy

Any writing on it?

Nightfall

Only what appears to be somebodies initials. No dates or model numbers.

Nightfall

I see a single difference between the two. The ripped up one I have now has 8 notches cut out of the front rim where screws would go even though only 4 screws hold it in. The one I'm buying only has 4 notches. They both have what looks to be the same foam as a seal between the cabinet. They both have the same size "puck" in the middle of the PR, I suppose that doesn't automatically mean they are the same weight though.

westmassguy

Nightfall wrote: »

I see a single difference between the two. The ripped up one I have now has 8 notches cut out of the front rim where screws would go even though only 4 screws hold it in. The one I'm buying only has 4 notches. They both have what looks to be the same foam as a seal between the cabinet. They both have the same size "puck" in the middle of the PR, I suppose that doesn't automatically mean they are the same weight though.

The puck is part of the ballast. I've also seen hot glue added to the back of the Styrofoam, probably to fine tune the weight.

Nightfall

These appear to be made from a cardboard type material where the PR's on my RTA12s are made from styrofoam.

westmassguy

Sometimes we'll never know what secret sauce the used back then to tune them

Nightfall

Something else I have noticed is that whenever I see a picture of the inside of some modded speakers around here they aren't packed full of this white foam material that mine are.

westmassguy

Nightfall wrote: »

Something else I have noticed is that whenever I see a picture of the inside of some modded speakers around here they aren't packed full of this white foam material that mine are.

Foam or Dacron Batting? The batting should be in the upper portion of the cabinet, above the PR opening

cnh

Nightfall wrote: »

Something else I have noticed is that whenever I see a picture of the inside of some modded speakers around here they aren't packed full of this white foam material that mine are.

I remember someone on this site asking me to check this material when I was replacing an inappropriate driver in one of my 5As (6502) with the correct 6500. He had a set of 5Bs and asked me if my padding ran the entire distance down to the PR. His did NOT have padding behind the passive, evidently, and mine did. It sounds like yours does too. So what does that DO to the "fine" tuning of a PR, I wonder?

cnh

Nightfall

Dacron Batting. The cabinet is full of it. There is a rolled up section of it on the bottom of the cabinet and another unrolled section of it taking up space in the top. The only place in the cabinet that doesn't have it is in front of the crossover between it and the PR.

westmassguy

Nightfall wrote: »

Dacron Batting. The cabinet is full of it. There is a rolled up section of it on the bottom of the cabinet and another unrolled section of it taking up space in the top. The only place in the cabinet that doesn't have it is in front of the crossover between it and the PR.

All of it should be tacked above the PR opening. The bottom section where the PR is should be free of batting.

cnh

I do believe there may be some variation on how the batting fits in different model 5s? But I would wait on the old timers to confirm this. Mine do not show any difference between the two; the batting is fairly evenly distributed behind the PR. And it does not seem like it fell or to be the result of a mistake.

But who knows! We all know various Polk runs were not ALWAYS uniform. And that there is a lot of variation and some unexpected surprises.

cnh

Nightfall

cnh

That looks pretty much like my 5As do in there. So you have to wonder if that's not the standard for those? It also seems unlikely that the batting fell from anywhere above.

cnh

westmassguy

The current thinking for all the vintage Monitors and SDAs, is the batting should only be in the upper portion, behind the woofers and tweeters. The lower section, which includes the PR should be free of any batting. This allows the PR to operate freely. I've done all my Polks this way.

Nightfall

Another quick question. Is there anything I can apply to all the rubber surrounds to keep them healthy and "hydrated" so they don't end up like the PR I am replacing? I have 11 other MW's and PR's that I'd rather not replace for this same reason in my setup.

westmassguy

Nightfall wrote: »

Another quick question. Is there anything I can apply to all the rubber surrounds to keep them healthy and "hydrated" so they don't end up like the PR I am replacing? I have 11 other MW's and PR's that I'd rather not replace for this same reason in my setup.

There is no dressing or coating that you can put on them without risking destroying them. Most rubber dressings have some form of silicone in them which will eventually ruin them. It's best to keep them clean with pure Windex and a Micro-Fiber cloth. Get the dirt and brown oxidation off them. The surrounds are rubber, and will eventually deteriorate no matter what you do.

Nightfall

So it is likely that one day I will be running the Chinese made replacements? Bummer. Polk doesn't make PR replacements though, so what will happen with that?

westmassguy

Nightfall wrote: »

So it is likely that one day I will be running the Chinese made replacements? Bummer. Polk doesn't make PR replacements though, so what will happen with that?

Do what I did for my 2As, buy a spare set, as perfect as possible, and keep them in a cool dry place. Maybe one of those vacuum sealed storage bags would work.

Nightfall

Well, they're a little different. The material the cone part is made of on the replacement is smoother compared to the old one which has a very bumpy texture to it. Weight is a little different too.

Old - 318 grams
Replacement - 303 grams

Not sure if 15 grams is enough to actually hear a difference or not, that is not much weight. At least the cabinet is sealed now, though. Dates are different too. I forget the actual date, but the MW6500's I think were 1983 so I assume the PR is the same year. The replacement is dated 1989.

Maybe I will just try and find another 1989 Monitor 5 PR so that even if it does change the bass a bit, they will both be the same.

Nightfall

Something else I thought of is there is no way I can tell if the weight lost is from the cone and puck or if it's from the basket as I'm weighing the entire PR. If it's lost in the basket then I'd guess they both sound the same?

westmassguy

Nightfall wrote: »

Something else I thought of is there is no way I can tell if the weight lost is from the cone and puck or if it's from the basket as I'm weighing the entire PR. If it's lost in the basket then I'd guess they both sound the same?

The baskets could have been made with a lighter gauge steel, or simply production variances. They could have been sourced from different vendors. There's quite a few years difference in the production dates.