Monitor 10 pasive radiator

tin_can

Hi!
I found a pair of Monitor 10's for sale but they will need the passive radiators. Does anyone know if they're interchangeable between the different versions of Monitor 10's or would they have to be from the same version?

Gardenstater

Most likely interchangeable and their design would most likely be a function of cabinet volume, which didn't change ever with the Monitor 10's or any other Polk speaker afaik. I'm pretty darn sure, anyone please correct me if I'm wrong. When you get the speakers home you will be able to pull the damaged PR's and look for any identifying #'s to make sure you match them up properly.

I don't know if the PR's from any other models were interchangeable with the M10 PR's, like if you could get one from a M7 and it might be OK?

pitdogg2

It's likely that any driver changes could impact the passive. Take for instance the SRS SDA2 1st model used all mw6509 2nd model used mw6510 and mw6511 they had same cabinet volume yet 2 different passives. Ebay has had many 10" passive radiators over the years. Get the number and set up a watch to notify you.

Gardenstater

It appears you may be correct (no surprise there). There's lots for sale on eBay and it looks like up to '89 or so they used the SW100 and '90 and later used the SW105, which seems to have a disc on the back of the basket? I learned something here.

PS: Oops I see a couple SW103 as well, 1993,1994 appears to have some sort of disc on the basket as well.

pitdogg2

M10 used mw6500,mw6501 and mw6503 so each should have a different model passive.

Nightfall

Gardenstater wrote: »

I learned something here.

Ivan's not as dumb as you think I am.

Gardenstater

Well I did think there was a chance that they were designed to match the MW engineering parameters but I was not sure on that, as far as whether they did that with the monitor line. I did know that they had different PRs in the same SDA speaker, from reading the manual. I also learned that there were PRs that have some sort of disc adhered to them, perhaps to control the resonant frequency similar to Dynamat.

PS: I do not think anyone here is dumb

pitdogg2

The disc or bolt are weights to match the woofer parameters. Just like ports are longer or shorter. You know in the grand scheme of things all passives will work whether or not you hear a difference is hard to tell. My SDA1 Signatures came with the first foam front passive. They had bubbled terribly. I found a newer SDA1a passive(hard plastic front) and used it, personally I thought I got better bass from the change. Weight difference between the two I have no idea. IIRC I went from SW120 to SW121

tin_can

That's very informative! Thank you all!

So it should be fine as long as the PR model number matches, regardless of year of manufacture? This can be challenging in some cases as the only identification on some of those is just some hand written, difficult to decipher scribbling. Of course making sure the correct drivers are in the enclosure? Which, after seeing all those parts for sale, may not be taken for granted as I'm sure there are a lot of these speakers with replaced parts floating around and I doubt everyone made sure to use the correct ones. Other than the collective knowledge here, is there some kind of a guide to all this? From what I see there are four versions of Monitor 10's with different combinations of parts but at least the cabinets seem to be almost the same? I think I've been bitten by the vintage audio bug as right now I'm also researching Monitor 7 and it seems monitor 5's are well liked, as well. Although there are a lot of great modern speakers out there, for some strange reason I feel a need to have at least a pair of good, vintage ones and it seems like I'll need to uncover information I never thought I'd need.

Gardenstater

I think I'd use those eBay pictures as a guide because often they were clearly marked with model # and date of mfg. by Polk. There are also usually dates of mfg on the MW's as well as the crossover. So assuming no previous tampering you should be able to correlate your mfg date with the correct PR model # and I'm sure there are plenty of original owners or 2nd owners of Monitor 10's here that can verify that they have a certain PR model # with a certain MW model #.

The Monitor 7 is generally preferred over the M10 due to the imaging issues of using 2 MW's with the same frequency ranges, side by side. There is also an issue called lobing that effects the soundstage. These issues were not present in the Monitor 11 due to the more complicated crossover design, and in the RTA12 as well.

tin_can

Excellent! Thank you for sharing that! So is there any reason one would prefer the M10 over M7? Aside from looking cool?

mhardy6647

tin_can wrote: »

Excellent! Thank you for sharing that! So is there any reason one would prefer the M10 over M7? Aside from looking cool?

It is a bit more sensitive and, at least on paper, goes a little deeper. Max SPL is a little higher, too.

All in all, though, I've always -- and still -- prefer the tonal balance of the 7.
It is possible that, even after 42 years, I am just rationalizing -- because in 1978 it was all I could do to afford a demo pair of 7As The 10s were outta reach.

At this late date, and with a pair of the original morph of the Monitor Series Model 10 here as well as the 7As -- I don't think so.

Here're the specs for the original versions of the 7 and 10. I really do need to re-scan this brochure (or even just find the original scans and upload them!).


polk_brochure_back_pg by Mark Hardy, on Flickr

Gardenstater

The brochure I got when I bought my 7B says freq response 33 Hz - 20,500 Hz +/- 2dB, so it is kind of weird the way what they reported varied throughout the production variants.

tin_can

Cool! Thanks! Looks like the M7 is good down to 40 Hz; that's plenty. Might have to re-calibrate my original search criteria! LOL! But damn! What have you done to me? Now I'm looking at a nice pair of Monitor 11T's. That escalated quickly! How would M11T compare to M7 and M10? As an aside, especially for the dual woofer ones: do they have to be played loud to be enjoyed?

Gardenstater

That speaker was not very highly reviewed I'm afraid. I haven't had ears on them: https://www.stereophile.com/floorloudspeakers/polk_rta_11t_loudspeaker/index.html

mhardy6647

tin_can wrote: »

...As an aside, especially for the dual woofer ones: do they have to be played loud to be enjoyed?

No, not at all.

tin_can

mhardy6647 wrote: »

No, not at all.

Thanks!

tin_can

Gardenstater wrote: »

That speaker was not very highly reviewed I'm afraid. I haven't had ears on them: https://www.stereophile.com/floorloudspeakers/polk_rta_11t_loudspeaker/index.html

Thanks for the heads up! I totally would've bought them for $100!

tin_can

Gardenstater wrote: »

The brochure I got when I bought my 7B says freq response 33 Hz - 20,500 Hz +/- 2dB, so it is kind of weird the way what they reported varied throughout the production variants.

Thanks for the specs! Looks like the M5 ain't too shabby, either! Maybe good for a smaller room? Probably too big for a desktop, though.

mhardy6647

The Monitor 5 was also a dandy little loudspeaker -- at least the original morph with the Peerless silk dome tweeter.

F1nut

tin_can wrote: »

Cool! Thanks! Looks like the M7 is good down to 40 Hz; that's plenty. Might have to re-calibrate my original search criteria! LOL! But damn! What have you done to me? Now I'm looking at a nice pair of Monitor 11T's. That escalated quickly! How would M11T compare to M7 and M10? As an aside, especially for the dual woofer ones: do they have to be played loud to be enjoyed?

Not the Monitor 11T, the Monitor 11 also known as the Model 11. It looks a bit like the Monitor 10, but it's a floor model. A rare bird, good luck finding a pair.

These...

tin_can

mhardy6647 wrote: »

The Monitor 5 was also a dandy little loudspeaker -- at least the original morph with the Peerless silk dome tweeter.

Pardon my ignorance, but what's a "morph" in this context?

tin_can

F1nut wrote: »

tin_can wrote: »

Cool! Thanks! Looks like the M7 is good down to 40 Hz; that's plenty. Might have to re-calibrate my original search criteria! LOL! But damn! What have you done to me? Now I'm looking at a nice pair of Monitor 11T's. That escalated quickly! How would M11T compare to M7 and M10? As an aside, especially for the dual woofer ones: do they have to be played loud to be enjoyed?

Not the Monitor 11T, the Monitor 11 also known as the Model 11. It looks a bit like the Monitor 10, but it's a floor model. A rare bird, good luck finding a pair.

These...

Semantics...such a fickle ****. One letter, one letter! And it means something totally different. So that is the "11" that Gardenstater meant... they're a beaut! Thanks for pointing that out. In my ignorance I assumed M11T would be to M11 what M10A or M10B is to M10 without looking into it first.

mhardy6647

In biology, one may have different morphs of the same species. For example, hawks of a given species on the east coast and west coast may look very different, but be genetically almost (!) indistinguishable. Sometimes even within the same region, one may see variations within a species (e.g., "grey" squirrels which are black -- the black coat color gene is dominant, so the black squirrels can be locally very common).

Especially in the early years, Polk's loudspeakers might exhibit subtle, sometimes even perplexing variation in configuration that doesn't necessarily line up with prevaling wisdom about various recognized "versions" of the model(s) in question.

I like to call those morphs.

You might find a original Monitor Series Model 10 with 1 fuse, or two fuses -- maybe even no fuse (?!???). The back panel (crossover cup) configurations may differ. The "Polk Audio" badges may differ. The original Monitor Series Model 7 had an 8" passive radiator; later models had a 10" PR. My Monitor Series Model 7A have two fuses (but many "Monitor 7As" have only one). The original Model 10 had an uncoated paper PR. Stuff like that.

tin_can

Thank you for the detailed explanation! So they're ...evolving?

xschop

Polk models are indeed chimeras. Made in a lab and dropped on the masses.

mhardy6647

tin_can wrote: »

Thank you for the detailed explanation! So they're ...evolving?

Well, not so much that as... shall we say... the 1970s version (ahem, morph) of Polk Audio [edit] probably wasn't ISO 900x-compliant. Like many smaller/older companies, they... did what they did. One might even imagine that, for example*, business was really good one day, and they were crankin' out Monitor 10s...and ran out of binding posts. Some poor schmuck might have been dispatched to run down to Radio Shack and buy a bunch.

That sort of thing.



____________
* I am making this up -- but in the less standardized days of the mid 20th Century, changes could be made on the fly. That's why so many brochures and what not would have disclaimers like "specifications subject to change without notice".