RT8: Blown tweeter and driver

notlimah3

Tweeter is silent and the driver buzzes at low, med and high volumes. This occured after about 4 years of use and only on the speaker connected to the left side mains. I'm using a Yamaha RX-V595 (70W + 70W (8Ohms)) to run all 5 speakers. At the time there was no subwoofer in my system, although I've replaced the RT8's w/R50's and the SW202. I've already ordered replacement parts for the 1 speaker.

2 Questions
1. Should I be concerned about the fact that only the left speaker was damaged and the right seems to function perfectly?
2. Is my RX-V595 enough to run the 5 speakers and the addition of the RT8's in a different room as second mains?

HBombToo

When I rebuilt my 8T's I did all drivers and tweeters just so they would break in together. I figured if I was going to replace 1 why not do all... just my preference at the time.

HBomb

RuSsMaN

He's talking RT8, not RTA8 Henry.

HBombToo

Originally posted by RuSsMaN
He's talking RT8, not RTA8 Henry.

I know but my intent was an example of how I handled my 8T's and the purpose of my comment... nothing more nothing less.

HBomb

cfrizz

"He's talking RT8, not RTA8"


What's the difference between the 2? I have the RTA8's as well.

Also do you know how much they originally retailed for?

notlimah3

I'm new to this stuff so hope I don't step on toes here, but we're sort of off topic.

How about just 1 answer:
Does 1 speaker usually go and the other works fine, or does this indicate a possible problem with my system?

HBombToo

I would say your yammie is probably ok but at the very minimum keep an eye out for anything strange. It is very possible to just lose 1 driver.

cfrizz here is a link to the vintage RT8's but no pics are included.

http://www.polkaudio.com/home/specs.php?category=3&speaker=156&vintage=1

I have a pair of RT800i's and they sound very similar to the 8T's but the 800i has better bass for HT. For 2 channel though I prefer my 8T's at this point.

HBomb

nguyendot

I just picked up a pair of RT8's (super cheap) and they seem to have scratchy drivers at low volume. I think they're blown but they work fine at higher volumes.

Anyways, tech support tells me the drivers are not available anymore and to replace the speakers (they offered a 50% discount off msrp for some RTI A5's). I'm not in the market for 'new' speakers, i bought these as a bargain and wanted to see how they'd fare.

Any suggestions? I'm "new" to the forums, i was a member 5+ years ago and am coming back!

vbissonnette

I'm in a similar boat: I've owned and loved a pair of RT8s for many years, and one of the 6.5" drivers is blown. Polk has told me that the MW7009 drivers are not available, and suggested I buy the RTi A5s at a discounted price. This is an interesting possibility, however...

Couldn't we find some replacement drivers from a company like Parts Express that would work well in the RT8's cabinets? How would you research the technical specifications of 6.5" drivers to figure out what might be a good match for the RT8's cabinet and crossover? Can we find out the basic specs on the MW7009s and then just look for similar numbers?

Or, does changing out the drivers inevitably change the personality of the speakers, and we just have to take our chances if we change a driver? I would hate to spend $100 or more on drivers, end up hating the speakers, and then end up buying new Polks anyway. If I cannot end up with RT8s that I love, I might as well spend the money on the RTi A5s.

Thanks for your thoughts.

nguyendot

I have the specs, let me post them. Polk sent them to me, AND they're available on ebay. The ebay sellers want $49 each driver. I only spent $65 on the RT8s! Ill post them here in a second.

Title: Measured Data
Method: Fixed-Mmd (15.30 grams)
DCR mode: Measure (-0.19 ohms)
Area (Sd): 141.03 sq cm
Series resistance: 75.00 ohms
Stimulus level: 0.76 volts
0.104 RMSE-free Ohms
44.094 Fs Hz
3.311 Re Ohms[dc]
40.389 Res Ohms
6.013 Qms
0.493 Qes
0.456 Qts
0.269 L1 mH
0.426 L2 mH
1.861 R2 Ohms
0 RMSE-load Ohms
22.399 Vas(Sd) liters
16.248 Mms(Sd) grams
801.833 Cms(Sd)

nguyendot

The problem is finding a driver that isnt $100 that will handle 100+ watts rms with similar specs. That will be very difficult to find. It would probably be cheaper to go to ebay and purchase them at $49 each, which I really don't want to do. It would be cheaper to buy a set of RT7 off craigslist and gut them.

messiah

nguyendot wrote: »

The problem is finding a driver that isnt $100 that will handle 100+ watts rms with similar specs. That will be very difficult to find. It would probably be cheaper to go to ebay and purchase them at $49 each, which I really don't want to do. It would be cheaper to buy a set of RT7 off craigslist and gut them.

:eek: Gut an rt7??

2 points:

A: If you do get the RT7's, listen to them first. They may surprise you.
B: You can't gut them to fix the RT8. RT7 = 7.5" woofer, RT8 = 6.5" woofer.

nguyendot

My apologies, I meant RT5 (since the RT8 is just the floor standing version of it, right?)

dorokusai

nguyendot wrote: »

The problem is finding a driver that isnt $100 that will handle 100+ watts rms with similar specs. That will be very difficult to find. It would probably be cheaper to go to ebay and purchase them at $49 each, which I really don't want to do. It would be cheaper to buy a set of RT7 off craigslist and gut them.

I'd gut an RT loudspeaker in a heartbeat.

nguyendot

Why?

dorokusai

You're looking for a part right?....for a particular Polk loudspeaker? or am I missing something? That RT lineup isn't rare but it is rare for parts from Polk.....find a host.

nguyendot

I thought you had something against them

I'm trying to find a host. Dad has a pair of RT20p lol... But I'm sure he'll miss the 6.5" driver if I took one. The MW7009 seems to be hard to find. Someone on the forum has them for sale but has not responded to PM's...

vbissonnette

Thanks for posting the specs on the MW7009! Quick question:

What is the nominal impedance for the MW7009? 4 or 8 ohms?

Thank you.

nguyendot

8 ohms.

I contacted Polk Engineering and they told me to send my drivers in and they'll take a look. If they can fix them, cool. If not, i'm out a pair of drivers. I suppose it's worth the risk. Gonna go to fedex tonight.

messiah

dorokusai wrote: »

I'd gut an RT loudspeaker in a heartbeat.

That's only because you're a ruthless cold-hearted speaker killer:p

I understand that it makes sense to look for another pair of similar speakers and cannibalize when you can no longer get OEM, but my point was why kill an RT7 to revive an RT8? Not that it's possible (except maybe for the tweeter, not sure), but uh...was I saying something.....nevermind lol.

vbissonnette

When I removed the WM7009 from the RT8 that buzzes on low frequencies, I made an interesting discovery. There is a hard yellow cover over the magnet area under the main cone of the speaker. When I touch the underside of the cone, this hard cover pulls away from the magnet area -- obviously the glue holding it has failed.

The cone and the rubber support around it look to be in good condition. So, I'm going to reglue the loose cover over the magnet area, reinstall this driver, and crank up some bass to see if that was the problem. If not, then I'll go back to shopping for replacement drivers or new speakers.

nguyendot

Emailed Kim from Polk Engineering today, and my MW7009's are on the way back to me, repaired. I can't wait to enjoy my RT8's again. Just more proof that Polk has great Customer Service.

Thanks!

messiah

Great news! Keep us posted.

nguyendot

Came home yesterday and a huge box was on my porch from Polk.

Got both my original drivers back, triple wrapped in foam sheets + bubble wrap! Took 5 minutes each to unwrap! Anyways, Kim from Polk Customer Service/Engineering had them repaired for me, the technician even branded his name on my drivers! I'll post pictures up here later tonight (I have to work 1-10....and it's holiday!).

Reinstalled them and the RT8's have come back to life! I finally have a full Polk set after only having a PSW150, CS250-S and RT/FX for over 10 years now!

What's next? ---whatever's on craigslist!

nguyendot

Pictures!


Boxed drivers - the box was VERY large for a pair of 6.5" drivers.


Sliced open - lots of packing peanuts and the drivers are wrapped in this:


LOTS of bubble wrap. Took 5 minutes to unwrap each one because there was so much tape. Great attention to detail on making sure the drivers were not damaged.


Drivers after I removed all bubble wrap and tape. They taped some bubble wrap directly to the back of the magnet. No wonder the bubble wrap wasn't moving!


Each driver tagged by the engineer to repaired it. Look at that mfg date! 1997...


One driver installed, one to go....

All I can say...they sound sweet.

AudioGenics

polk customer service is the best....

nguyendot

Breaking them in for a few days.... They're sounding warmer and warmer as the music plays. I left them on for three hours today while i was out running errands.

Can't wait for them to break in completely.

Windsor351

What did you to do get Polk CSRs to repair them? I've had a couple problems with speakers over the years and they've always been very good to me. The mid in one of my RT-20P towers is scratching at low volumes and low to mid frequencies. Did you just call in and explain what was happening and they told you to send them in?

nguyendot

I emailed CS, then asked a bunch of questions that only the engineers could ask. They forward it to an engineer and then the engineer responds. I asked the engineer directly.

I asked them what the tech specs of the MW7009 driver was so I could get a similar replacement.

My dad had the same problem with his RT20P - it uses the same MW7009 driver as my RT8s that i had repaired

Windsor351

Just out of curiosity, what kind of questions did you ask? Was it regardhing how the speaker was designed and built and what kind of specs it was built to match? I love my Polks and I've converted numerous people to fans because of my stereo! I hate to have a driver go out on me again. My last one that failed was a tweeter that let loose a poof of steam...

nguyendot

I asked for the driver specifications of the Mw7009 driver.