Remplacement (because product stoped) for Polkaudio MM651 MM

[Music]

Hi every body,
I have to change one of ma speakers polkaudio mm651 MM (Black). Is every body can tell me by what sort or new reference I can replace it? I have allready 6 same speakers...
Thank's a lot for your answer!
Claude

[TXtiki hut]

subcribing to see if anyone has any suggestions. one of my polk tower speakers stopped working.

[j.mo]

Darn. I just threw away 10 of these things that were basically brand new.
I still have a 2 left If anyone needs them. Pay the shipping I'll send em out


Sent from my iPhone using Tapatalk

[TechBeer]

I just replaced 2 of the 6 Polk speakers with Kicker 45KM645. The original Polk speakers in my boat had a silver grill but the Kickers come with both black and white grills. Since my gel coat interior is white I went with the white grills. Looks great. The Kickers fit fine into the original cutouts, but....I did have to drill 4 new holes in the gel coat since the Kicker grills are slightly larger than the old Polks and holes are further apart. They suggest a 7/64" pilot hole but in gel coat I found this to be too small. I ended up with a 9/64" pilot hole and VERY carefully threaded the OLD screws back in. I didn't have my tap set with me, but that might have been a better option. If you try and thread the screw into a hole that is too small the gel coat will start to flake/crack (a really bad thing). I will replace the other 4 Polks at some point with the same Kickers. They sound great. There are more expensive options with LEDs, etc. but for my 2006 vintage I went without the LEDs.

I also replaced the original Clarion APX480M (which had gone bad) with a Kicker 48KMA360.4. I actually wanted the more powerful KMA600.4 but it seems to be out of stock everywhere. The 360 is plenty of power for me though and it sounds great. Installation is pretty straightforward although you do have to drill 4 new holes since this amp is physically smaller than the Clarion. But this gives much better access to the adjustment dials/switches, which you will need. The other "catch" is that the original +12V and GND wiring uses "ring" type connectors vs. "fork" type connectors. The ring type connector implies that you would remove the screw from the amp and insert the connector. Unfortunately the screws did not want to come out of the amp. So.....I improvised and cut an opening in the ring, essentially creating a "fork" connector for both the +12V and GND connections. All the other connectors are "fork" type which work fine.

Finally....the default settings for the gain is really low. So, when I first powered up the amp the front 2 speakers, driven by the head unit, played fine. But the rear 4 speakers, driven by the outboard amp, were VERY faint. I had to crank up the gain on the amp quite a bit to get the front and back balanced. Works great now....

[MLA]

With the correct size pilot hole, you should use the new self-taping screws that are supplied with the KM654 speakers. No thread tap needed.

Amps do not come with default settings or in any way pre-set. They need to be tuned to your specific application. There are specific steps to setting the gain and other settings in order to get optimal performance and to prevent damage to the equipment.

[TechBeer]

MLA Well noted. I was a bit concerned with the Kicker screws since they are philips head vs. hex head. But to be honest I didn't try them since I think the hex head look better. And really hard to strip out.

On the gain settings, totally. I just wanted to pass on the knowledge that if you don't hear anything don't panic...

[TechBeer]

OK, on second thought I would not recommend the Kicker 48KMA360.4. On a recent guys weekend we cranked up the stereo to ear splitting levels. Somewhere during AC/DC "For Those About to Rock" the amp shut down. I made the mistake of putting my hand on the amp and it was HOOOOTTTT!! The good news is that once it cooled off it ran fine. Granted under normal use it's probably OK, but every now and then you want to really crank it up.

For you techies, this amp is a Class AB which is not as efficient as a Class D and will generate more heat. Does anyone have experience with the 48KMA600.4 which is Class D?? This is the one I really wanted but was out of stock everywhere.

[MLA]

So, when I first powered up the amp the front 2 speakers, driven by the head unit, played fine. But the rear 4 speakers, driven by the outboard amp, were VERY faint. I had to crank up the gain on the amp quite a bit to get the front and back balanced

For you techies, this amp is a Class AB which is not as efficient as a Class D and will generate more heat.

While it is true that a class-A/B does generate more heat for the same wattage produced v's a class-D, I feel you have a turning or voltage problem, not an amp problem. You are running 4 speakers. Thats a single 4 ohm load p/chnl. That amp should be running very comfortable. Ive got this amp out in the wild running bridged 8" speakers, with no heat issues. A bridged speaker puts a lower 2 ohm load p/chnl. So thats essentially 2X the load you have on your amp.

Remember what I said about amp settings are not pre-set or default? The gain dial(s) is not the only setting that needs to be set according to YOUR application. Where they are set out of box, is just where they were left after testing.

[TechBeer]

MLA , Actually the way this is set up is the way the original Clarion was set up. The head unit drives the front 2 speakers directly. 2 of the Kicker channels drive the left and right rear speakers in stereo mode. So a single channel drives 2 speakers in parallel since there are a total of 4 speakers in the back. In think the Polks are 4 ohms nominally so we are talking 2 ohms per channel. The other 2 channels of the amp drive a mono sub-woofer in bridged mode, the original Polk unit. No tower speakers. I'm pretty sure it's all hooked up correctly but I could certainly double check.

Again, it plays fine at nominal volumes and does recover when it shuts down. I did not do a rigorous calibrating exercise with the adjustments. Since I'm tweaking from the storage area I simply had a buddy listen to the front and rear to set the gain on the rears. I have the rear speaker crossover set to full range just because it sounded better. The sub crossover is set to LP but I forget the exact crossover frequency. I could certainly look at all these setting again and do some tweaks.

You bring up a good point about the voltage. I would guess if the input supply voltage was low it might work harder and overheat. I'm guessing it would shut down at something below 12V. BTW when it shuts down the engine was running which is normally ~+14V or so.

Open to additional thoughts.

[MLA]

I have the rear speaker crossover set to full range just because it sounded better

This tells me the system is not tuned correctly.

Running the speakers on FR makes the amp and speakers work harder, leading to additional heat generation.

[TechBeer]

I agree. What I probably need to do is set AMP2 (which is driving the coaxial speakers) to HP and set the crossover to ~200Hz. Not sure the frequency response of the factory sub but obviously I want some overlap at the bottom. It's probably currently at 50Hz so only getting the very bottom. I'll make some tweaks. I might even get the Kicker app so I'm not completely tuning by ear.

I did run it over the weekend and at normal to loud volumes it sounds great. Only in "ear splitting mode" did the amp get really hot.