7b advice

xfrench

After reading around a bit, I think it'd be worth getting some advice. I have just come into possession of a pair of speakers I believe to be 7b's (ie the serial # is 7b-43xxx). They appear to have peerless tweeters judging from pictures and discussion on other posts. No holes, none of the drivers seem stuck, and they appear to work, except...
When I tested them quickly, I didn't understand about the passive woofer, but that makes sense. Anyway, when I plugged them in and ran the tuner, all of the individual drivers seemed to function, but one of the speakers, well the best way I could describe it is that that one speaker sounded as if I had switched from FM to AM (muffled, underwater-y, weird hum, although the hum seemed to be present for both speakers, the Am sound was isolated to one in particular).
I would happily put them back into the world, take them to the free shelf downstairs, but now that I have done some research, it sounds like these were/are good speakers and maybe I should try and fix them? I'm not a huge audiophile (yet) and not flush with cash, but am a bit of a diy'er and think this might be worth investigating.
Does this sound like a bad crossover? Or a bad driver? From the sound of things, I would want to replace the 6.5" driver, and that is probably a MW6500 for this unit. Is the MW6503 a suitable replacement? What's the cost involved in this sort of escapade? Should I just walk away?
Thank you for any thoughts. Customer service over at Polk isn't open so I thought I'd ask you all.

fbm211

If the drivers all function then you can recap the xovers.You will find a lot of info on this site that will help.Sonicaps are best but daytons are good too if your on a budget.Do a search on crossover mods.We need more info on your setup though.Like what componets are you running those with?

xfrench

Thanks for the suggestion. I'll go check out crossover options tomorrow when I have my wits about me...
Well, I guess what I mean by the drivers function is that none of them seem to be stuck or frozen, and when running I could feel some vibration coming from each individual one. What's more, when off, if I press gently on the larger bottom (passive?) woofers, the mid-range cones move gently in and out. Technical, I know, but that's as far as my technical knowledge goes so far. The fuses both look good (only one per cabinet) so I assume that the reason these were given to me (via the free shelf in the building) is that the PO couldn't stand the poor audio quality in the one, and probably got new speakers for Christmas.
As for components, I hooked them up to a Sony str-de515 because it's what I have set up and running at the moment. I listen to NPR on it mostly and have my Mac plugged in for when I want to run iTunes. I have a pair of Kef Coda's on that at the moment. When I get up and running, I will probably use a HK AVR35 or a Denon AVC700 for listening to music, and possibly for watching movies if I can convince my friend to give me his old projector. I also have an old pair of Advents (A3's) my buddy gave me, which are on the large size, and a pair of Boston speakers and some day I will sit down and listen to all of them and keep what works for me (and keep back ups) and get rid of anything I can't justify keeping. It just seems that the 7b's come well recommended...

george daniel

Pull the drivers (the ones in the middle) connect the speaker wires to the terminals and SLOWLY turn up the volume. You'll know if the driver is bad.But first,, do these have fuses,,id so check em,, the fuse is the tweeter protection on this model. It sounds like you either have a bad driver(s),or a crossover issue,,but test the drivers first ot rule them out. Good luck,,let us know what you find.

xfrench

The fuses (one per) look ok. Do passive drivers go bad?
Also, how can I find the ohms rating for these? (Not that it matters, but the Kef's I am using on the Sony are rated 6 ohms, but I'm not sure what Sony recommends as an Ohm rating for individual speakers... The Kef's sound fine though...)
I'll try your suggestion tomorrow when I am rested and able to concentrate
Thank you.

george daniel

xfrench wrote: »

The fuses (one per) look ok. Do passive drivers go bad?
Also, how can I find the ohms rating for these? (Not that it matters, but the Kef's I am using on the Sony are rated 6 ohms, but I'm not sure what Sony recommends as an Ohm rating for individual speakers... The Kef's sound fine though...)
I'll try your suggestion tomorrow when I am rested and able to concentrate
Thank you.

Generally speaking the passive rarely is/goes bad,, one way to tell,gently push in on the passive,and the mid-drivers should extend and then do back slowly(you are checking for air leaks)check the drivers as I mentioned abouve before you tear into the crossovers.IIRC the 7's are 8 ohm speakers. Good luck and keep us posted.

xfrench

Well, thanks for the help. I did go ahead and pull the 6" drivers out and connected them directly. They were soldered in, so I didn't completely disconnect them. Also, the passive drivers did when gently pushed, cause the 6" to go in and out smoothly, though at the exact rate as the push. Anyway, I tired the 6" with several different cd's (Coltrane, Turandot and Lo'Jo) and I'm still confused. At first, I got the same issue with the Coltrane: when I turned the balance I would get either the sound of Saxophone in my face or the sound of someone playing sax in another room. I tried switching the wires, and I still got the same issue with the speaker. I tried other music and sometimes I thought I could tell, and sometimes thought I was crazy. In the end I decided that the speaker needed fixing somehow, maybe the wire? Anyway I put them away for a couple of days, tried them out again, and now I wonder if they are fine? I definitely think that I am nuts. The only thing I can think of now is to have a friend who has built his own speakers come by and listen and tell me his opinion before I start pulling anything apart. I'm posting this update just to tank all of you for your input, and to say that no, this is not some joke/goose chase, and that if I ever get some better ears to listen I'll come back with a report.
x

rayslifecycle

Were the speakers cold when you tried them the first time - I have this problem in my office as I keep the heat off in there until I use it - when the office is sub 55 degrees - the record player plays a little slow and the SDA speakers sound a little muffled.

xfrench

Yes, the speakers were in fact cold both times I tried them and had issues. The biggest problem I had in isolating the individual drivers seems to have been not listening to them individually on Mono as opposed to Stereo. I did have my friend come by and in the end the conclusion is that both speakers work fine and sound relatively good. I'm not entirely sure what the issues were when I first listened to them, but then I don't think the amp I started with is as reliable as the subsequent one. Looks like I now have a nice new pair of speakers. All I need is a place to put them...
Thanks for all your input.

comfortablycurt

xfrench wrote: »

Yes, the speakers were in fact cold both times I tried them and had issues. The biggest problem I had in isolating the individual drivers seems to have been not listening to them individually on Mono as opposed to Stereo. I did have my friend come by and in the end the conclusion is that both speakers work fine and sound relatively good. I'm not entirely sure what the issues were when I first listened to them, but then I don't think the amp I started with is as reliable as the subsequent one. Looks like I now have a nice new pair of speakers. All I need is a place to put them...
Thanks for all your input.

You can feel free to put them in my living room if you can't find a place for em...:p

Glad to hear it worked out for ya, enjoy your 7B's.

ben62670

If you can solder do the XO's;)