Best stereo upgrade options

[MisterB]

I've put many hours into trying to install the Polk MM6501s. I finally got something that I was really happy with, until i did a test run of the speakers. They sound like they are farting instead of solid bass. they aren't bottoming out, I tried sealing the enclosure and held them as tighly against the frame with no improvement. I'm not sure if I have defective speakers or what to do. After putting all this time into it and finding the fit to be insane, I'm deflated. I'm not sure what to do next.

-R

Did you stuff the cabinets with polyfill or other cabinet dampening material? It's the white fluffy stuff you see in speakers. You can get something similar at walmart in the arts and crafts dept.
I notice some notes resonate horribly with the stock speakers.
If you've ever been in a big building and a truck drives by you might hear standing waves, that's when certain frequencies reinforce themselves as they bounce around inside an area.
Then there's resonant frequency. If the plastic enclosure is not rigid enough it will vibrate at frequencies that match its resonant frequency or frequencies.
I plan to stuff mine like crazy to see if it smooths out the response. Every bass note of "Papa was a Rolling Stone" plays at a different volume!
I'm no expert, you can probably find more info here.

If it's not the above issues; the farting noise could be over-extension of the speaker cone, the cone could have a wire too close to it that it's bouncing off when driven, it may be defective and the "spider"(the surround that is underneath and surrounds the voice coil) could have come loose. Maybe you'll hear from another Polk user who went through this. I'm still on the fence as I don't expect much from such small enclosures. May just try better tweeter and stuffed cabs before committing to new speakers.

[CoCoKola]

this is either defective speakers, or these require a sealed box. I'm going to call polk tomorrow for advice. I don't think the hacking did any damage, despite my lack of experience fabricating, I'm highly technical but with electronics and computers.

in any case, stay tuned. I did use rubber seals on both sides,I tried sealing the two holes behind Wenger you mount the speakers. (I suspect they are not sealed, but.. ) this is not a power amp problem, the problem starts at 5 on the volume and just gets worse with more power. the coil is not fried as it is very sensitive even at lower power. it Just sounds like crap. I'll keep diving in and let you know.

[CoCoKola]

mrB

thanx for the reply. I know exactly what you are describing. this isn't a standing wave which is typically when you have two sound sources and you have cancellation or frequencies that re enforce.. nor a resonating frequencies like you described.

I use a sweeping sine wave generator to test for this. check your play store or Apple store for a sweeping sine wave generator. try 700hz to 40hz and listen for volume of the tone getting louder or softer. it should generally get quieter but gently.

I.May try stuffing it once I get this farting noise fixed. if it was over extension, which is exactly what it sounds like, I should be able to turn down the volume and it go away. not so much.

thanx everyone!

[Jimmytee]

The enclosures are not sealed. Mine sound awesome, no polyfill. The poly fill mainly aids in enhancing bass by tricking the sound wave into acting like their in a larger enclosure than they are, plus some dampening it might add. The sound you describe , seems more like a problem than a characteristic of how these speakers should sound. Are you sure you didn't trim too close to the speaker surround and possibly have an unsecured speaker surround? That would cause the sound you are talking about.

[MisterB]

I use a sweeping sine wave generator to test for this. check your play store or Apple store for a sweeping sine wave generator. try 700hz to 40hz and listen for volume of the tone getting louder or softer. it should generally get quieter but gently.

Ha! I wondered if such an app existed buy never got around to checking, thanks for the tip.
I'm fixing to do an omnibus farkle job on the F6B to get it all done in one fell swoop. (dream on!) Heated grips, 12v and USB here and there, maybe some lighting, and speaker upgrade if I can settle on one. I really don't need more power as I don't listen very loud, but would prefer more accurate reproduction if possible.
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[CoCoKola]

Jimmy.. totally agree about cut too close causing the sound, but I inspected both speakers closely and can't find a problem. normally you can hold the speaker in different places to settle down the area that causes the problem if there is a rip or cut, but no dice. the only way to make it better is to hold the entire speaker inward a ways.. like maybe the atmosphere of Jupiter it might work..lol

never ran into this one..

thanks again for all the 💡 s. keep them coming!

[Jimmytee]

Jimmy.. totally agree about cut too close causing the sound, but I inspected both speakers closely and can't find a problem. normally you can hold the speaker in different places to settle down the area that causes the problem if there is a rip or cut, but no dice. the only way to make it better is to hold the entire speaker inward a ways.. like maybe the atmosphere of Jupiter it might work..lol

never ran into this one..

thanks again for all the  s. keep them coming!

Well, could be something wrong with the voice coil. Usually what I'm talking about happens when the speaker has over heated from being over driven. However I imagine there could be a defect. I wouldn't expect a defect to be in both of the speakers though. Have you tried both drivers?

[Jimmytee]

Ha! I wondered if such an app existed buy never got around to checking, thanks for the tip.
I'm fixing to do an omnibus farkle job on the F6B to get it all done in one fell swoop. (dream on!) Heated grips, 12v and USB here and there, maybe some lighting, and speaker upgrade if I can settle on one. I really don't need more power as I don't listen very loud, but would prefer more accurate reproduction if possible.
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More power isn't always just about volume. In fact, "accurate reproduction", can rely on proper power. The Polk ,MM series anyways, need more power than what the stock OEM amplifier is capable of in order operate correctly. IMHO,I wouldn't pick the MM series unless you were adding an amplifier. I think there might be some who have installed these without adding an amp, and they might have found it to be ok.

[Dirtstiff's F6B]

Rob,
Something I was thinking about while playing with my MM 651 Polks. The MM are a 2 ohm rated speaker, the OEM are 3.7 ohm, I believe. Don't know for sure, but my guess the oem amp is rated for 4 ohm speakers and the MM operate at a lower resistance level, whereby they reguire more power with less resistance, hence the burp sound you seem to be getting.
I'm not sure the net effect on the oem amp either. I never thought about it because I installed a 2 channel, 2 ohm amp that will handle 4 ohm loads, but I specifically matched it to the 2 ohm MM 651.
Anyway, I'd suggest perhaps it's a resistance issue( too much resistance-too ltitle power). I've heard no others trying MM Polks with an OEM amp.
Good luck

Jim

[Dirtstiff's F6B]

According to Polk, all are Marine rated. The UM are made specifically for boats and wet enviornments. They have the grill and basket as one piece.
I'm replacing my DXI 651 Polks with a pair of MM 651, today.

I have a Polk PA D2000.2 amp. It's certified at 100 watts per channel RMS and 200 bridged. Very good amp.
The MM 651 also are rated for 100 watts per channel. RMS. They are a perfectly matched combo. The amp still has power for additional speakers or a sub woofer.

The MM 6501 which I don't have, are component speakers and have appx 50 watt higher RMS and Peak power rating along with adjustable crossovers.
I didn't want to find places to mount the tweeter, therefore I chose the MM 651.

Good luck in your choice.
Back to my project or as the wife says, obsession....
J

Attachment 17270
Polk MM 651 work in progress trimming to fit. They kick serious but even un mounted.
I wouldn't however, reccomend them to anyone without an aftermarket amp and the patience of a snail. They are a butch to make fit. Go with DXI or DB Polk 6.5 speakers.
Do not use these MM with OEM amp. The speakers are 2 ohm and OEM system is likely not compatable.
I'm out
Jim