Upgrading M40 series II Crossovers...?

I honestly don’t think it’s worth the effort with those speakers. The mdf is thin, and the woofers and tweeter are super cheap. You might slightly improve the sound quality with better crossover parts, but I doubt the difference will be pronounced given the overall quality of the speakers.

Based on when reviews started I would guess 2005. The caps should still be "ok". There could be a little improvement with some better caps, although many people still run some the better polk speakers from the 2000's with the original caps. Different caps would not add any value. If you go for it, I would stick to parts express and the like. Some Dayton or Solen metallized polypropylene fast caps would be about as much as I would spend. Others may have some different budget recommendations.

I use mine in my bedroom HT, work well in smaller room with sub. They do tend to open up as you increase the power.

I wasn't aware these had bi-wire capability. If I recall if you bi-wire them without the jumpers you are bypassing the crossovers and using the AVR for the crossover. I would have to see the wiring to be sure. I know some speakers did this, but others still went through the crossover so people would not run full range to the tweeters and then wonder why they blew

Just an FYI. Bi-amping with an AVR does not accomplish much if anything power wise or sonically since everything is powered from one power transformer. Search for bi-amping on here and you will see a number of more detailed posts.

No need to completely rebuild the crossovers if they have inductors (wound wire parts). Those are not affected by age. You might also want to replace any cast resistors with something like mills, vishay-mills, or mundorf.

you're not bypassing the crossover that I'm aware of, although there is little advantage to what you're doing.

My comments above were based on what Monitor 40’s and alternatives cost in U.S. (and that you indicated you were looking for smaller bookshelves.) Sounds like Polks are much more costly in Canada. For example, a pair of Monitor 40’s appear to be available for $99 USD on Polk’s Ebay store. I had a pair of the Euro version of the Monitor 60’s a long time ago and I recall I was impressed with them, but they now reside with my cousin. Regardless, if it were me, I would not rebuild the crossovers on Monitor 40’s, for the reasons the other guys mentioned above.

As mentioned that schematic shows Bi-Wiring is going through each crossover and not bypassing it.

The easy way to think of bi-amping / bi-wiring, especially with an AVR, is connect a fire hose to your average outdoor house spigot. The fire hose has very little resistance. You can only get up to a certain flow out of the nozzle at the end. Now split the flow from the spigot into another fire hose with the same nozzle. You will not get any more flow. Similarly, do the same with a small water pump that has just enough to barely pressurize one hose at max flow rate. Again, when you split it, there will be little to no gain. True bi-amping involves 2 power supplies and amps, i.e. two pumps drawing from two suction hoses in a very large pond. Now you have twice the amount of water. Another way to think of true bi-amping is to have a speaker and powered sub woofer setup. One amp / power supply is powering the high end, and one amp / power supply is powering the low end. The crossover is happening before the amps (in many cases), and the crossover is adjustable. Bi-amping only really becomes an advantage when you want to tailor the crossover setting and the type of amp used for the high and low ends.

I would keep an eye out in the used market for some polks. Some deals even in CA do show up. The peerless tweeters are ideal in either the M4 or M5's. The M5's of that era can have cracking on the PR surrounds or the rubber gets stiff and will crack.

The M4's with the "triforce" tweeters are also nice, or M5JR's. Of the smaller speakers the M5jr+ with the 6.5" PR is a sweet spot. When bargan shopping though, sometimes you can find some M5's or even large M7's for the price of the 5jr+.

The 5Jr's have the least expensive crossover to upgrade as well.

I noticed a pair of what appear to be Peerless Monitor 4 on the Toronto Craigslist although they say they are Monitor 3. Lol.

Canadianguy55 wrote: »

When i looked inside, everything is so well put together and in it's place. I doubt I'm going to do a thing to them, I 'll keep them the way they are!



Greg

dromunds wrote: »

I noticed a pair of what appear to be Peerless Monitor 4 on the Toronto Craigslist although they say they are Monitor 3. Lol.

Are they for a 100 dollars, they have 6.50" woofers? What's the difference? I'm new to the Polk products.

Yes they are.
https://toronto.craigslist.org/tor/ele/d/scarborough-polk-audio-vintage/6807077135.html

Considering its $100CAD, that is a really good price. The peerless is a preferred tweeter. It is very smooth sounding, and blends very well with the midrange driver. The imaging is great as well. The crossovers on these will likely need to be rebuilt, but they should still sound pretty good. The 6.5"MW has the signature polk midrange sound that reproduces vocals, strings, guitar, well pretty much everything with great detail and clarity. These will also have more bass that what you currently have. Some here may cringe at tone control, but I had a nice ~ 50Hz tone control on a pre-amp that picked up as these rolled off. At low to moderate volumes they sounded like a much bigger speaker.

The resale value on these is much higher. These are sought after. I wish I had a pair my self. I have the later version that does not have the peerless tweeter.