POLK AUDIO - RT55 - Speaker XO Schematic

Polksaladanni

Can't find it. Found RT800. It's not the same...

Help

ben62670

What kinda problems are you having?

Polksaladanni

Lower woofer output on one of the speakers=dying electrolytic cap.

One of the large value caps went bad on 1 speaker. Decided too replace all 4 while I'm at it. I can read the 3 out of 4 values. 16.5,9,3uf the "orange drop" looking, epoxy, trim cap "looks" like it's .47uf but I'm old and blind now and the print isn't so good anyways on that one. Would love to replace the trim w/ a FFoil cap, the rest will be Metallized Polys.

I'd like to see the value of the coils also. Which are on the pdf's that darkekinght posted for other models.

Paul

Polksaladanni

Anyone?

ben62670

Looking at the specs it appears that both woofers run the same frequency range. I am pretty sure that they are two 4 ohm speakers wired in series to get 8 ohms. Did you test the drivers with an ohm meter yet?
Ben

Polksaladanni

Doh! No I did not. I can't imagine a woofer going bad though. My M4's from 1991 are still working fine...
Well. the drivers were the EC's were replaced 2 years ago. They were a little dull.

I already order the 2 large value caps from MadSound. PE has the FF trims and the 3.0 in the Dayton/Sounder/Bennic line.

Hell! somebody with good eves pull 4 screws out on the back and look.

I am a big fan of spending the extra 6 bucks each for MP's, they are self-healing and never go bad. So, if I decide to keep these I or give them to some deserving sole they are good for the long run.

What specs? On the Polk site? You're right about the XO it is non-cascading.

Paul

Polksaladanni

Not the drivers. Dying capacitor.

Kex

Polksaladanni wrote: »

... Hell! somebody with good eves pull 4 screws out on the back and look. ...

I'll take a look at my RT55 if you tell me what to look for and what you need to know. The whole thread is like chinese to me!

Polksaladanni

Thank You My Man!

The crossover is mounted on the back of the speaker terminal cup.

Remove the 4 phillips screws, tap on the terminal or pop off with a thin blade.

Looking at the cup as you would from the back of you speaker, it is the one in the bottom RH corner.

Printed on it. It's the small thin rectangled one. Looks orange in color.

I need the value. Printed on it. I think I am reading .47 on mine. It has TI printed above.

Mine are double printed, so it really hard to read even with my solder buddy. (magnifying glass with arms)

I saw a post of someone wanting to see a recap of an XO.

I suck at posting pictures and typing but I will show the RT55 and RTi6's I'm doing also.

Paul

ben62670

Could you take a reading on the woofer for giggles? It may save you some time;)

Kex

Polksaladanni wrote: »

Thank You My Man! ...

No problem at all. I'll let you know if I think I don't know what I'm doing!

Polksaladanni

Sure,

I believe it was 4.1-4.2 Znom. But that was at halftime..

Gimme 10 minutes to replace the battery.

God I suck at typing!

Paul

Polksaladanni

Sorry for the delay, I type SLOWWWWW.

Znom is about 4.7 (it floats between 4.6&4.8ohms) Yes, the speakers are tied in tadem (+-+-) So, you are right nominal Z is around 8ohms.

Which tells me without seeing a diagram it's probably a parallel XO with a high pass trim cap. I'm horrible at parlaying curcuit boards to paper now. I quit being a EE 20 years ago, got into industrial sales.

I measured 4.2znom on the RTi6 6.5" bookshelf BTW. Which is the same Z as my 91 Monitor4's which uses a simple yet, genius serial XO.

Here's an interesting read about the differences. http://sound.westhost.com/parallel-series.htm

Running high wattage through mini 50v Ecaps that are rated so close to the wattage limits, is going to to make them die over time. It's unavoidable. Most people don't notice the degradation, because the process is so slow and you live with your speakers daily... Commercial builders use them because of the cost factor of large value caps.(low pass section) It's not a sin it's good business sense on their part.

I'm not trying to be a brainiac, it's just college knowledge. Hell, when I went to school AC curcuitry was the main study of electronics along with many math courses.

Paul

ben62670

Well that is kinda weird. If the speakers are in series you should get the same output from both drivers. Just to get this straight one of the two woofers is putting out less than the other in the same cab?

Kex

Polksaladanni wrote: »

... it is the one in the bottom RH corner. ... the small thin rectangled one. Looks orange in color.

... I think I am reading .47 on mine.

...

Paul,

It was exactly as you described. Silver "printed" on a brick orange color: quite hard to read, actually IMO! You are right: ".47J 100"

... I suck at posting pictures and typing ...

I can't judge your pictures, but there's nothing wrong with your typing, although I'm guessing that if your eyesight is bad, it takes more effort than for some of us internet freaks.

As for pictures, I should be posting them too, but we moved recently and I have no clue where to find our digital camera or the USB cable to hook it up!

These are a very solid speaker IMO, in more ways than one. I have four of them matched up with a CS400 and really like them, at least for the time being. I would suggest they are probably at the top end of what most here would consider entry level speakers, for want of a better term, and are probably at the limit of what most decent receivers are capable of driving. After that, you have to spend a lot more to get to the next level. I am sure I will want to upgrade within the next year, but that will have to wait until we are settled in and I figure out the decor and placement issues a bit more.

Good luck, Kex!

Polksaladanni

Ben.

No, one of the speakers is a few db's quieter. Don't go there on the amps. Last Saturday, I auditioned 4 separate pairs of speakers with the same familiar material. The RT55's audibly had a small level difference. Switched em from L to R channels also. That tells me either the choke is off or most likely the cheap 50v electrolytics are leaking. It happens. I am going to measure the chokes once the caps and resistors are off the board. But they almost never die.

On the measurements. The XO and hook up wires were out of the box so, I measured each driver seperately. The tweeter read 7.1ohm I believe. Each woofer read 4.6ohm. If I tied them together it might read 7,8,9 or 10 ohm for all I know. All I have is a DVOM, no speaker measuring equipment.

Bottom line is, I always put metalized poly caps (250v/400w) in my speakers anyway. It's a inexspensive upgrade, makes them bullet proof to clean high wattage and in the case of the RT55 and RTi6 you can refine them more. They both have trim caps that can be replaced with F&Foils for 80 cents more. Ordered all the caps for both today.

Kex,

You rule! for pulling your terminal cup and XO for a complete stranger. You got one hella system running all 55's and a CS400. You must have a giant media room or you don't go as loud as these things can go. I bought more for 2ch music and am more impessed with the RTi6 for that purpose. The things are more directional than I thought. I had to set them at abot 12 feet apart in my room for good sound.Which is excellent! for HT. Hell, it says that in Polks discription...

"The RTibookshelf models are intensely musical, presenting a large soundstage without sacrificing pinpoint localization, and are so transparent that they allow you to focus on the entertainment values of the performance without thinking about the speakers from which the performance is emanating. RTiBookshelf Speakers are superb music listening speakers. At the same time, they possess the wide dynamic range necessary to make them great choices for home theater systems, particularly when teamed with a powered subwoofer."

Paul

Kex

Polksaladanni wrote: »

... You got one hella system running all 55's and a CS400. You must have a giant media room or you don't go as loud as these things can go. ...

Not such a big room (we live in SoCal, where space costs a lot of money). I find they are a lot more convincing for home theater than for pure music listening, but that might be the subwoofer's fault. I use a modest harman/kardon AVR147 for the moment, which I have compared very favorably to a much more expensive Denon AVR (that is still in my garage until I decide what to do with it).

For home theater, I really could ask for nothing more in all honesty. For more "precise" music listening, I probably need something extra, unless I am just dreaming. The sub may also be at fault (it is excellent for movies, perhaps not so much for music).

I want to try some SACD and DVD audio next, but have not set things up as yet. I did try an Emotiva seperates system about a year ago or so and was very disappointed to discover it did not add anything extra when compared to the h/k 147 (other than price, obviously), so I got rid of it while I could still get most of my money back.

It sounds as though you really know what you are doing though!

Polksaladanni

Well, pretty soon it seems the feds are most likely are gonna be the country's largest real estate owner. Maybe you can get some sq footage on the cheap!

Don't waste your time on SACD if you have a large collection of CD's already.
I'll get flame but, I love the sound of any Sony cd or now, dvd players. And I have had plenty of equipment down the stereo road.

Get Vinyl. A real full sinewave of music. No sampling.

Your wrong on these speakers. They are by no means an entry level speaker, the cabs are built like a brick shithouse, they can fill a room with sound and can be upgraded for less than 25 bucks each. I love the ARC/PPORT noise cancelling tech on the bass. They sound great about 1 foot off the wall. I was just suprised a little by the directionality. Both of my my monitor series (entry level) and the RTi6 have flush-mount speakers which, to me, makes more sense for a more "spacious" sound. The bessel on the 55 looks like the speakers are kinda semi-horn loaded from it. Theydo have a LARGE soundstage though.

All of them are nice. I am just trying to find my "last" set of speakers at the moment. i thought about The RTi8's and RTiA5's just because they would look fabulous in our living room in cherry. But my better half might not think so. Hmmm.

I bought the 55 and rti6 in bookshelf so I can put them away when I am not listening to music only. I decided (along with the wife) in-walls will suffice just fine for HT and that way we can remote stow the equipment and leave only a subwoofer in the living room. I'm putting all the equipment in a closet.

Paul