POLK SR124 failing!!! 3 times in as many months :S

[Sutho_]

Just wanting people thought/opinions on an on going incident I have been going through ever since buying my SR124 subwoofers.

I have 2 Polk audio SR124, SVC 12" subwoofers, each powered off their own Polk audio C300.2 Feeding them is currently an Alpine CDA-9887, prior to this was an Eclipse CD8455.

While driving I noticed that the bass was very weak, which is odd for me as my setup is purely an SQ tune. So after getting to my destination I open up the boot to find that one sub isn't working... next step is turn it all off and evaluate the damage at home. At the time my HU (CD8455) was at ~60 out of 80.

After various voltage and continuity checks, I place the DMM on the subwoofers terminals to get a reading of 0ohms. With the terminals still wired to the DMM I press the cone lightly to see if the Voice coil has let go, to my surprise it is free flowing (normal) and the Ohm meter starts reading! however returns to 0ohms, when the sub is at rest.

After sending the subwoofer away for repairs, it is found the the lead between the terminal and voice coil had snapped/de-soldered for what ever reason. repaired under warrenty :) smile back on the face and all is fantastic!

A few weeks later... same thing again! This time with the other sub! send it away and reported back to be the same problem! However this time they replace the subwoofer. yet again big smiles on my face, as I really do love the sound from these speakers!

I put it down to been a bad batch/run or they were finished on a Friday afternoon... these things happen, the serial numbers were one digit off each other.

So all is fine and I'm driving along when I hear that oh to common sound of unbalanced sub-bass... sure enough... the original repaired subwoofer has come to the same position. reading 0ohms... move the cone and you get a reading, but returns to 0 when at rest....

In all honesty I am at a loss as to what is happening, I have been through many woofers in my life and have never had one fail, let alone 3 in as many months!

All of the gains are set using a DMM and CRO and after the first incident they were turned down further from fear of another dead subwoofer. Those that have been in my car have commented on the superb sound but have also asked why they cant hear much bass, again showing that I don't try to over drive my speakers. They are in their own sealed enclosure (~1cf after displacement) and crossed over 80hz@24db or 63hz@24db depending on the tune.

I did read a while back about someone having the lead in question snap in half. Has anyone had any other issues with their SR12's? or does anyone have any thoughts regarding the issues? I am in Australia so calling Polk direct is something will be my last resort, The importer into Australia is currently away for our holiday period, so cannot be contacted and i'd like to get a feel for possible case before i get the "gain isn't a volume control" lecture, you cooked it buy a replacement.

Any help would really be appreciated!

Current setup is:
Alpine CDA-9887
Polk Audio SR6500
Polk Audio SR124 times 2
Polk Audio C400.4
Polk Audio C300.2 times 2

with the C400.4 biamp'ing the SR6500's.

[GLN305]

Sounds like you either received a bad batch of subs or possibly B-stock or refurb subs. I can't see gain settings being the problem with the lead wires, normally killing the VC by heat is a gain setting issue. The only other thing I can come up with is overexcursion, which I don't think is possible with the small wattage in a sealed box unless you play in the 20Hz region often. Are you positive that the dealer you bought the subs from is authorized? Post their information here and I'll call Polk and ask them for you if you would like.

[Jstas]

What kind of box are they mounted in?

A box that is too large or ported will not necessarily offer the proper dampening effects and the sub is moving beyond the designed physical range. That would definitely fatigue and snap voice coil and tinsel leads.

[ben62670]

What kind of box are they mounted in?

A box that is too large or ported will not necessarily offer the proper dampening effects and the sub is moving beyond the designed physical range. That would definitely fatigue and snap voice coil and tinsel leads.

I can attest to this. I broke the cone loose from a speaker rated at 800watts. If the cab is too big, and it is overdriven it will break something. If your sub is in a trunk you might not hear it bottoming out. What are your box/port dimensions?

[greg2350]

Sutho I had the same problem with my sr124 I repaired it 3 times wire kept breaking not the solder.
http://www.polkaudio.com/forums/showthread.php?t=60607

[GLN305]

He said above that they are in 1 cubic foot each after sub displacement. That's no where near big enough to cause any problems.

[Sutho_]

Tanks for the quick replies! The Dealer is 100% authorized and it came straight from the importer (Directed). So I Cannot see how/why it would be B-stock/refurb, But there is always the possibility?

The subs are mounted in their own airtight SEALED 1cf (after driver displacement) enclosure, so nothing relating to port tuning. The boxes are in the boot (trunk) of my car, however all settings where checked with the boot open to make sure there was no distortion.

greg2350: Thats interesting, I notice your cover is snapped off (out of frustration?) do you see anyway that cover can be removed with out damaging it? It looks like there maybe some mounting screws at the bottom? You said you just ordered a replacement one.. Id love that to happen in my case, except the SR124 retails over here for $999.00 AUD ($873.901 USD)...

[greg2350]

Sutho I wasnt trying to break the cover I was trying to pull it back to get to the wire and it snapped. I didnt see a way to get the cover off. I ended up giving the sub to russman if the new one breaks or my other one I would have to say there is a problem with these subs.

[black magic]

sorry to hear about that, might be a bad batch. I have both of mine in 1 cu ft (net) enclosures for each sub and they've been playing without any problems for 6 months.

[1996blackmax]

That's not a cool thing to be going through....

You sound like you know what you are doing, so this may have already been looked at.....have you made sure that the enclosures are airtight? Even a very small leak can lead to problems with sealed enclosures. I blew two subs this way back in the 90's. Luckily I dealt with Crutchfield (very good online store), and they ended up sending me all new gear (3 subs, and 2 boxes when it was all done). This time though I made sure I sealed the box up. This setup ended up lasting me for several years.

Good luck...

[MacLeod]

Id contact Polk and let them know. Sounds like there may be a defect somewhere in production.

[Sutho_]

1996blackmax: 100% airtight, MDF glued/screwed together and then fiberglassed the inside to be sure.

MacLeod: Thats the next stage, just wanted to see if i've overlooked something first :(

[1996blackmax]

Seems as if all your bases are covered pertaining to any installation problems. Looks like you just got some bad drivers.

[BradimusMaximus]

My second SR124 is arriving tomorrow in San Diego. They replaced my first woofer after it experienced identical symptoms. I was using a 1.2 sealed box made from the websites sub box plans. At around $36 each time I ship it I'm not to happy about it. Polk gave no explanation of why it failed the first time. The second time I found the pieces of wire insulation in the bottom of the enclosure. The wires were cracking apart exactly where they meet up with the cone. I'm definitely going to investigate any possible leaks in my enclosure.

I have my woofer facing forward in my 2001 Buick Regal and have sealed it from the trunk using dynamat and latex expanding foam. The enclosure front panel spans the 36 inches from wheel well to wheel well directly behind the back seats. Because it is facing forward I do run it in reverse phase but this couldn't be causing this could it?

[Sutho_]

Not a pleasant experience in the slightest. I can't see how the phase could cause the issue. Out of interest do you still have the Serial Number of that sub? I wouldn't mind seeing how close it is to my first pair (Pm it to me if you like).

What amp are you using to power yours?

[BradimusMaximus]

AA122400418 is the serial number for the original sub. I really don't think phase should have anything to do with it either, but I was just throwing it out there for speculations sake.

[BradimusMaximus]

I just got an email from Polk customer service that says the .88 enclosure volumed listed in the manual is an error and that the woofers recommended enclosure volume is 1.2 cubes.

[Kinetic]

I just got an email from Polk customer service that says the .88 enclosure volumed listed in the manual is an error and that the woofers recommended enclosure volume is 1.2 cubes.

i knew it, thats a big big mistake, the white paper says a different size of enclosure.

[Sutho_]

My box was ~1cf when i had them mounted "normally", when inverting them, that would make the box ~1.14cf (before factoring in the area of the cone concave) and failed both times (when I got my subs back, I inverted them). Thats very close to the new 1.2cf that's been suggested.

Why would this issue be happening in a box that is too small? If Polk know about the incorrect size guide in the manual, why wouldn't they change it?

[exalted512]

Maybe its just me, but I would like to think that Polk would make a sub where the tinsel leads will meet or exceed the mechanical excursion of the driver...
-Cody

[Sutho_]

Maybe its just me, but I would like to think that Polk would make a sub where the tinsel leads will meet or exceed the mechanical excursion of the driver...
-Cody

I totally agree, when showing a friend the damaged sub-woofer, the reply was "that lead just isn't long enough...why is it hard? wouldn't a softer wire work the same and have a higher tolerance?"

Time will tell on what happens. I have spoken to local speaker repairers and they suggested that this lead is a common fault in speakers. As manufactures use cheap wire to save on costs (I guess $2 worth of cable per speaker starts to add up..). The repair/upgrade of these leads is ~$99 per speaker. So this might be the next option, depending on the outcome of this latest incident.

[BradimusMaximus]

I really wish they would have use a woven tinsel lead design. I'm sure it costs more and maybe it isn't conducive to sound quality - I don't know about that one - but reliability would be greatly improved. I don't want a new 350 dollar paper weight every month.

[greg2350]

My new sub is holding up so far I had the same thought the wire seems to be cheasy. I gave the broken one to russman dont if he was able to repair it.

[BradimusMaximus]

I just got my 3rd SR tonight. I'm crossing my fingers. The leed wires seem slightly softer than my last sub.

[greg2350]

WOW 3rd 1 starting to see a pattern here.

[BradimusMaximus]

Not a pattern I'm fond of. My first subs that have every failed in my possession of course are worth 350 dollars a piece and 36 dollars each time I ship it back. I think both the original and the first replacement failed where the leads meet the cone. I'm only sure of this on the second woofer however.

Crossing my fingers

[black magic]

Goodluck to you guys. I have yet to run into any problems with my SR subs. They sound amazing and play loud when Told to. Even though I rarely turn it up that loud, I've never had any problems at all.

[Sutho_]

I just got my 3rd SR tonight. I'm crossing my fingers. The leed wires seem slightly softer than my last sub.

3rd? as in you now have 3 or as in ou have had one replaced twice an your up to your 3rd now?


update on mine... still waiting to even be told what is wrong (although it's pretty obvious what the issue is)

[BradimusMaximus]

3rd? as in you now have 3 or as in ou have had one replaced twice an your up to your 3rd now?


update on mine... still waiting to even be told what is wrong (although it's pretty obvious what the issue is)

As in my second replacement woofer is in my car and breaking in slowly but surely now. So it is the 3rd woofer I have had in my possession. On both occasions I sent in a woofer I requested to have explained what the problem was but to no avail. I can tell its failure of the leads but they haven't said its from my doing or theirs.

[Sutho_]

Well it's good that it's not just me having the issue (in a way),
But sucks that it's happening at all!

I am still one sub down :( waiting waiting waiting