Polk speaker problem

Wildman262

Hi, I need some help. I have a pair of Real Array Series RTA 8TL 900 7911 speakers. Both speakers sound as if they are in a mono mode. It almost sounds like they are in "AM" mode versus a rich stereo FM sound. This happened to both speakers at the same time.

I know it is something with the speakers, because I checked the wiring and it was connected correctly, and I also connected my stereo to another set of polk speakers and the stereo works fine.

I've taken the cover off and examined the speakers, and there are no visible problems. (ie. tears) Can someone tell me what is going on.

They were working fine one day, and suddenly they went into this "mono" mode.
Are the speakers "blown"? I've heard of blown speakers, but I don't know what it really means or what the symptoms are.

F1nut

I think what you're trying to say is that they have lost their full, rich sound. Is that correct? If so, I suspect you either cooked the tweeters and/or cooked the polyswitches. Take out the tweeters, connect them (one at a time) directly to your power source at a very LOW volume. If they play, then you probably have bad polyswitches. If they don't play, you probably have bad tweeters. How loud were you playing it the last time?

Wildman262

F1nut, Thanks for the reply. Yes, they have lost their full rich sound. What do you mean when you say take out the tweeters and connect them to the power source? Connect them directly to the tuner? The speakers have been played loud. What is a polyswitch and are they easily replaced?

BrentMcGhee

Well for your first question Yes, you got it right. Disconnct the tweeters from the rest of the speaker and wire them directly to your receiver. (MAKE SURE you have the receiver turned off when hooking up the tweeter, then turn it on with the VOLUME ALL THE WAY DOWN and gradually increase the volume until you either hear sound from the tweeter or find out that nothing comes out of the tweeter at all meaning it is blown.)

As for the second question, i have not the slightest clue what a polyswitch is either

Wildman262

BrentMcGhee wrote:

Well for your first question Yes, you got it right. Disconnct the tweeters from the rest of the speaker and wire them directly to your receiver. (MAKE SURE you have the receiver turned off when hooking up the tweeter, then turn it on with the VOLUME ALL THE WAY DOWN and gradually increase the volume until you either hear sound from the tweeter or find out that nothing comes out of the tweeter at all meaning it is blown.)

As for the second question, i have not the slightest clue what a polyswitch is either

Thanks, I will give that a try. Thanks for the help.

Eric W

BrentMcGhee wrote:

As for the second question, i have not the slightest clue what a polyswitch is either

Great advice from all for checking each component. The polyswitch is used for the high frequency driver protection, it will add resistance after a predetermined threshold in order to divert power away from the tweeter.

Over time, the polyswitch may become "tired" and may start engaging at lower thresholds then appropriate. It is on the crossover board, looks like a round disc that is vertical with two leads. It is typically the size of a pea, and is either blue or a brownish yellow.

F1nut

Yep, good answers everyone. I'll add one more thing, if you're turning the volume up close to or past halfway, you are causing the receiver to clip, which in turn causes distortion at the speakers, which in turn will damage both receiver and speakers. Turn it down or get a better power source.

Wildman262

Eric Wong wrote:

Great advice from all for checking each component. The polyswitch is used for the high frequency driver protection, it will add resistance after a predetermined threshold in order to divert power away from the tweeter.

Over time, the polyswitch may become "tired" and may start engaging at lower thresholds then appropriate. It is on the crossover board, looks like a round disc that is vertical with two leads. It is typically the size of a pea, and is either blue or a brownish yellow.

Eric, the loss in quality of sound from my Polk speakers was sudden. I have the Real Array Series RTA 8TL9007911. Where is the polyswitch located? I don't know what a crossover board is. I haven't been able to test the tweeters. I hope to get to it tomorrow.

Could you guys tell me what it means when you say I may have caused the receiver to clip? Yes, I know I've turned it up past 1/2 way. At the time I bought the speakers (along with a Denon tuner) I was told the speakers could handle. It seems odd that I have to be so cautious with the volume knob that can blow the tweeters.

F1nut

Let's get on the same page. Your speakers are RTA 8TL, the RTA stands for Real Time Array, 8 is the design number and TL stands for tri-laminated. The other numbers you posted must be the serial numbers.

Here's a break down of the components per cabinet:
Tweeter: SL2500
Mid-drivers: 2x MW6516
Crossover: BE0800-B

The polyswitch is located on the crossover board, which is mounted inside the cabinet of each speaker.

Clipping is a term to discribe what happens when you overdrive the power supply into distortion, a BAD thing. Your power supply is the amp section inside your Denon receiver, not a tuner. In your case, the tuner is the AM/FM section of your Denon receiver. Almost every power supply has it's limits (point of clipping) and generally this is about halfway on the volume control. However, you can reach clipping much early than that depending on other factors, which I won't go into at this time.

Think of it like this. If you push the gas pedal in your car to the floor all the time, bad things will happen. The same applies to your receiver and it seems that from turning up the volume too far, too many times it's caused damage to your speakers.

Edit: for spelling.......hehe

george daniel

Damn, F-1 you have the best of everything, my car has a gas pedal,how did you get a "petal",is it an aftermarket item? See what being AMPLESS will do for you! BTW thanks for the list of x-over components, ordering this am,you too Wm2 Oh well, back to spell checking other posts..

Wildman262

F1nut wrote:

Let's get on the same page. Your speakers are RTA 8TL, the RTA stands for Real Time Array, 8 is the design number and TL stands for tri-laminated. The other numbers you posted must be the serial numbers.

Here's a break down of the components per cabinet:
Tweeter: SL2500
Mid-drivers: 2x MW6516
Crossover: BE0800-B

The polyswitch is located on the crossover board, which is mounted inside the cabinet of each speaker.

Clipping is a term to discribe what happens when you overdrive the power supply into distortion, a BAD thing. Your power supply is the amp section inside your Denon receiver, not a tuner. In your case, the tuner is the AM/FM section of your Denon receiver. Almost every power supply has it's limits (point of clipping) and generally this is about halfway on the volume control. However, you can reach clipping much early than that depending on other factors, which I won't go into at this time.

Think of it like this. If you push the gas pedal in your car to the floor all the time, bad things will happen. The same applies to your receiver and it seems that from turning up the volume too far, too many times it's caused damage to your speakers.

Edit: for spelling.......hehe

F1- thanks for your patient explanation. I love music and am a musician, but as you could tell from my posts, I am not a techie. Thanks for your clear explanation and example. I'm sure I've clipped my reciever many times.

Now I just have to check the tuners. If I didn't have to be a contortionist, I'd have had it done by know. But, all the cords and compononts are set up on a shelf in relatively tight quarters, which means unconnecting everything to get at it. I will let you all know how it goes. I am appreciative of the help and explanations.. Thanks so much.