RT800 high's are nonexistent

mar504

I want to preface this by saying I've never owned a high quality sound system, I've been trying to read up on similar issues, but there are probably obvious things I haven't tried yet. The best speakers I've owned are M-Audio AV40's which I like, but I found some good deals so I'm hoping I can move up to the next level.

I received a pair of RT800 floorstanding speakers from a friend of mine for free, he mentioned they never sounded right since he got them used from another guy (hence the free part), mentioned the mids and highs were not there but he didn't have a high powered amp. I hooked them up and home and I see what he means, sounds like they are underwater, both sound identical. I took the covers off and everything looks great visually.

I noticed there are 4 binding posts on each speaker, 2 for lows and 2 for highs. I used speaker wire as a jumper for the highs/lows. I had original used some really thin speaker wire and thought that might be the problem, so I tried some better 12 gauge wire and no difference. I hooked up just the highs to my receiver to see if the tweeters were putting out any sound, and it does, but it's pretty quiet and the sound is not "clear".

I also purchased a pair of OWM3 speakers I want to use as rears a few weeks ago, they sounded great when the guy tested them for me, but they sound scratchy and just bad when I use them.

With my limited knowledge is seems like the problem may be my receiver. I'm using an old Sherwood RD-7106, I believe its seen quite a bit of use as I got it from a business, but I know they weren't blasting it. Could this be my problem? Is there any way I can test this short of buying a new receiver? Or could my problem be elsewhere?

I'm not looking for super loud, I just want a system that will give me decent quality sound on a limited budget. Please share your wisdom on what I should test to isolate the issue.

pitdogg2

Look at the cross over for any discoloration or better yet show the XO on here for us to look at. If you could find another receiver that would also be helpful for you.

rpf65

Sounds like you have more than one problem.

I would start by disconnecting everything, and start with one of the OWM 3. Hook that speaker up to one speaker outputs, and slowly raise the volume, until you can hear it. It doesn't have to be loud, kind of like office back ground music volume. I would stop at about 1/8 or so of volume range.

If that first speaker works, leave the volume alone, un-plug your AVR, connect the speaker to the next output, and it should be approximately the same volume. Repeat with each channel. This will tell you if you have a problem with your AVR. If all channels work, pick one and check the other OWM 3. Then connect ne of the 800's up, and make sure all speaker connections, including jumpers are tight, and no stray strands of wire are touching anything.

If you have determined that the output channels of your AVR are all good, and you still only have the lower freq sounds on the 800's, then it's time to look at cross-overs.

mar504

So I checked all the speakers. I'm still figure out how to use this AVR, but both the OWM3's sounded good on the the front channels. There was no sound when they were on the back channels and the AVR is on the stereo mode (assuming this is normal?), when I put it on the circle setting I got sound, but the main vocals quiet (maybe normal?). Both front channels were pretty close on both speakers. Then I tried the 800's and I got the same result, no high end on both speakers.

I'm trying to figure out how to get into the cabinet, took the front cover off but I don't see any more screws for an access panel. Also, the back of the tweeter magnet looked slightly off color, the kind you see when exposing metal to a lot of heat (purplish). Don't know if that's normal.
Pictures posted here: http://imgur.com/a/2ch0y

I'll get back to trying to figure out a way into this safe, let me know if you have other ideas on things I should check for if the cross-overs look ok.

mar504

ok, I added some more pictures to the album of what I assume is the cross-over is mounted to the back of the binding posts. No burn marks or discoloration or anything. I just pulled the speakers out and it doesn't look like there is anything else in there other than some white foam material.

treitz3

Can you post a picture of the front of the tweeter(s)? BTW, you access the speaker by removing the bigger drivers. Oh, my manners. Welcome to the forum.

Tom

treitz3

Also, do you happen to have a multimeter? (A digital or analog one will work)

Tom

mar504

Thanks treitz3! A picture of the front has been added to the album.

And it's funny you mention the multimeter, I decided to take all the speakers out of their holes and test the ohm's.
Tweeter: 5.5
2nd speaker down: 2.1
3rd speaker down: 2.1

Shouldn't these be 8????

treitz3

It doesn't "look" like the tweeters have been melted or over driven but that doesn't mean that this isn't the case. I'm not sure of the individual impedance of each driver, been a long time since I had these speakers. Your pair looks to be pristine. Go ahead and connect all of the drivers back up on each speaker and ohm each speaker out using the jumper between the lower and upper binding posts. Let us know how they measure please.

Tom

mar504

So I tested some different combinations...
Top red to bottom red: infinite
Top black to bottom black: infinite
Top black to top red: infinite
bottom black to bottom red: 4.2

treitz3

Looks like you have an open in the tweeter/mid network. It is definitely the speakers. Is this the case with both of them? [Top black to top red]

Tom

mar504

Sorry for the delay, had to grab a bite to eat.

I just tested the other speaker, it's exactly the same as the first one.

treitz3

No problem. If all of the drivers were hooked up when measuring, then the issue has been isolated to the mid/tweeter network. I would advise calling Polk (don't email, call) tomorrow and inquire about your next step for repair. Mention that you are a Club Polk forum member for a discount and please do follow up with the progress.

Tom

mar504

Thanks for all the help Tom! I'll call tomorrow and see what they say.

Easy Runnin

What about putting your meter directly on the disconnected tweeter? What do you get there?

mar504

Was getting 5.5 directly on the tweeter, I've got the results from all the speakers a couple posts up. Are these results normal?

I guess I don't understand this well enough... if I have an open how am I getting sound when I put speaker wire on the top two binding posts? If the circuit is open shouldn't it be completely silent?

mar504

So the word from Polk is it looks like a crossover issue. He had me connect my AVR directly to the tweeters to see if there was a difference, it was MUCH louder and more clear. I'm waiting for a response on how I should proceed with the crossover, is it worth trying to troubleshoot it and replace some caps? Or do I need to look at a complete replacement? Are crossovers built specifically for certain speakers or are they all more or less compatible with each other? (sorry for the stupid questions, like I said, this is a new game to me)

rooftop59

Get in touch with VR3. He is the man when it comes to modding crossovers, lots of satisfied customers on this forum. They will sound BETTER than new when he gets through with them.

As for your specific questions, crossovers are specific to the speakers, but you can get the values of each cap, resistor, etc. and replace them using parts from partsexpress.com or many other sites. If you have a soldering iron and basic skills I think it is something you could tackle yourself if you have time and willingness.

treitz3

Just for your knowledge, if the tweeter ohms out at 5.5 [good] but the network shows infinity [or an open], then the issue lies within the crossover network [or crossover]. Sorry, I should have been a little more clear. VR3 is a well known crossover specialist, charges really good rates, has a plethora of positive referrals/feedback, performs top notch work and I can recommend him for a crossover repair/upgrade with no reservations. In fact, he's working on a speaker upgrade for me as we speak. BTW, that speaker provided me with a lot of good sound for years. It is of my opinion that it is worth getting repaired. If you don't want to do this, I may be interested in purchasing the speakers from you. Yes, I enjoyed them that much.

Tom

mar504

Thanks guys! I'll contact VR3 and see what needs to be done. I'm comfortable with a soldering iron, so I may just hire him to let me know what components I need to order and where they go.

rooftop59

He does sell diy kits as well, so that's another option. Good luck and let us know how it turns out!

mar504

Couple quick updates...

So I sent VR3 a message to see what he thinks, I'm comfortable using my iron and am happy to pay for advice on what caps I need to replace and with what.

I spoke with Polk and they have some crossovers for the RT800's in stock, probably run me about $100 shipped for a pair.

And now for an interesting piece... I took the crossovers out and removed the plastic piece that holds the binding posts on. The black cap in the picture below is CLEARLY bulging out, same with the other speaker. Can I just replace this cap or is this just a good time to rebuild the whole thing (maybe it's not the only thing that's bad)? Or should I go with the stock crossover from Polk? What would you guys do?

Here is the cap: http://imgur.com/Q6hDo1Y
Here is the RT800 schematic: http://www.polkaudio.com/forums/attachment.php?attachmentid=18740&d=1155782632

mar504

Ok! I've got my caps in and took the old ones off referencing this thread: http://www.polkaudio.com/forums/showthread.php?124943-Can-we-improve-or-modify-the-RT800

Does polarity matter for these caps and how they go on the board? There is a red and black wire on the larger 8.2 cap and the smaller 2.2 has 2 black wires.
http://imgur.com/OCL112W

If so, which way do they go?

treitz3

Your photo site states that it is above capacity, so we can not view any image. Yes, polarity definitely does matter.

Tom

mar504

Sorry, try this one: http://s196260749.onlinehome.us/photo%20(3).jpg
The two new caps on the left, the larger one will go into the C4 position and smaller one will go into C1

Tronman

mar504 wrote: »

Ok! I've got my caps in and took the old ones off referencing this thread: http://www.polkaudio.com/forums/showthread.php?124943-Can-we-improve-or-modify-the-RT800

Does polarity matter for these caps and how they go on the board? There is a red and black wire on the larger 8.2 cap and the smaller 2.2 has 2 black wires.
http://imgur.com/OCL112W

If so, which way do they go?

If those are clarity caps ( metalized polypropylene film capacitors) http://www.partsconnexion.com/capacitor_film_clarity_tc.html Metalized polypropylene are a bipolar capacitor so they can go in either way. To be safe the red lead is the (+) Positive side and (-) Black is negative

The 8uf capacitor that was bulging is definitely bad and looking at the schematic below it is right in series with the signal path, so your tweeter can be good but with the bad capacitor it is only passing a little bit of signal that is why it sounds really low and crappy but works when you hook it directly to the receiver.

FYI If you look at the schematic for your tweeter there is the 8uf capacitor is series, you will be unable to read continuity (DC) through a capacitor since it basically like the picture looks. There is a gap in the wire so DC will be unable to pass showing an open. Which is how a multi-meter measures the resistance.

Well you are definitely on the right track, well more like you ALL OVER IT :-) - just finish putting your caps in and you will be up and running.

Hope this helps you a little bit. Good luck

Tronman

One last thing try measuring the resistance once you have the new cap in the tweeter circuit you should see the resistance value changing as the capacitor charges up then flip the leads opposite of what you just did and you should see the numbers go the other way. Let me know if this is true if you get a chance.

kennyj

I see this forum is old but was wondering if I could ask some questions. I have the same speakers (RT-800) having the same issues. I’m trying to find some one to walk me through building mine better then stock . How do I find VR3 ? Lol

F1nut

VR3 has closed down.