SDA SRS problems

Commodorefirst

Well, Hello, glad to be aboard, unfortunately it is under rather bad circumstances that my first post has to be with a problem. (note I have discovered the problem but I am leaving this up for educational purposes. Further description below in another post in this thread 9-2-01)

First some history about me, Long time audiophile, currently running SDA SRS's from 1986? No replacement parts. Can't remember exactly when I bought them, to long ago, serial number 3363 if that helps anyone. I know that I could sell them now than more for what I paid for them (I guess I can't say that anymore. they are broke!)

Currently I am using two adcom amps bi amped with internal crossover: GFA 555 for the lower freg, and 545 for the upper, adcom preamp and other assorted flavors of gear from the 90's

To put it simply I screwed up. I was doing some high end audio recording in the living room (I have a Yamaha Grand Piano in the room, hence I need to record in there), forgot that I still had a microphone turned on when I started to listen to what I had just recorded (on a three head high end cassette deck - getting the picture?) and I had not switched over to tape from source on the preamp/tape deck and created a horrendous feedback loop that all recording engineers dread. The speaker playing back the feedback while the mic picks it up and amps it again and again and again. Ran for about two seconds then distorted before I could get to the preamp. Damaged the Right Channel speaker. Maybe all 8 mids, maybe 6? Maybe the crossover? Using only the upper amp the left and right speakers sound the same, with the lower amp on the right channel is very ugly sounding. The SDA effect seems gone mostly too. Much distortion on playback.

I called polk and then the repair center in CA and discussed the problem, A tech suggested pulling the drivers/mids and sending them in to them for testing? Anyway, Can I do this myself? Are the mids/drivers soldered to the wires in this model? or clipped? Any suggestions or thoughts. Is it the crossover? Both the SDA's and mains on the right channel sounds bad. Might be one or two that are good. I think the protection worked on the tweeters. They seem ok.

Any thoughts would be appreciated.

p.s. in other recording sessions you will be glad to note that contrary to the majority of other so called audiophiles in the world the SRS's can accurately reproduce the sound of a piano live. From the bedroom it is hard to tell is it live or recorded sounds coming from the living room.

Thanks for the help,

Wade aka Commodorefirst everywhere on the web, (currently crying in the suburbs of St. Louis.)

BobMcG

The three pairs of SDAs I own have the wires clipped to the drivers, not soldered. Your's will likely be the same. It will take a couple of minutes but you can test the drivers yourself. Before you remove the (bad?) mids from the right cabinet, you can first place your hand on the passive radiator and push it a few times. You'll notice the mids moving in and out opposite the action of the PR. Are there any strange scratching noises? If yes, then you certainly have some (or all) damaged drivers. If no, or not all drivers seem to make a noise, take the quiet ones out and place them in the corresponding position in the left cabinet. (As the left seems to be ok, no?) See if the problem persists. If there's no problem with the drivers while in the left side, your right crossover is suspect.

BTW: Just for the heck of it, did you swap the amps around to see if the "lower amp" works in the "upper amp" position or not and vis-versa?

BobMcG

It's nice to have another SDA fan on board. Too bad about the mishap though. Have you voted in the SDA poll over in the "Opinions Forum" yet?

The SDA-SRSs used eight MW6503 drivers. Four as stereo drivers and four as SDA drivers. Polk doesn't have any of these in stock any more? These drivers were used(/number of) in the SRS/8; SRS 1.2/4; SRS 1.2tl/4; SRS 3.1tl/4; and the SDA-2B/1. This is a lot of uses for this driver for them to be out of stock/gone. The MW-family is a fairly large one, if the '03s are gone, can Polk recommend a suitable replacement? If so, this could run from expensive to very expensive, depending on how many drivers have to be replaced/matched. (Not that it would be cheap just to replace any bad '03s with '03s.) The crossover is a BR2000-A. Are these gone too?

Commodorefirst

Thanks for the input Bob. The tech thought that the old srs might be soldered. Hence my heistation to swap out unless this would be the simplest way. I appreciate the tip with the passive radiator. I will pull out a driver this weekend and let you all know what is up (soldered vs clip).

Hope I don't have to go one a scavenger hunt to track down drivers or crossovers. I have almost bought several other SDAs on ebay and elsewhere
Would hate to just to buy them to scavenge parts.

Wade

Commodorefirst

Well BobMcg,

If you are ever in St. Louis I owe you a beer, glass of wine, 18yr old scotch, soda, or whatever your favorite beverage is.

I tried the passive radiator test, hmmm, everything worked as it was supposed to do, hmmm, pulled a driver and it is clipped, good to know for future reference. But something was nagging in the back of my mind. I did a cursory check of the amps, and after all the left channel was working sweet, but I remember you asking did you check out your amps. I initially said yes, but it was just cursory. Tried the right speaker with the bridging wires with the 545. Sounded Fine!! Tried it with the 555...yuck! Brought up a second set of speakers from downstairs and tried it right channel 545 sounded great, tried it with the 555 no sound at all! Bingo. Now have a known problem with the amp. Very unusual with adcoms to have one channel out and not trip the breakers inside the unit,

First order of business is to take the Adcom in for repair, then throw her back in to the system and check once again for problems, but with just the 545 running the right channel everything sounded fine. No distortion, nothing.

So everyone, please remember to always check the obvious things. I have been a hi fi enthusiast for years. I have probably set up nearly 30 high end systems during the last 20 or so years, done several HT systems also, and usually if there is a problem it is with something obvious. Of course I just assumed I had torn up my SDA's. That is why the word assume starts with the first three letters it does. I was one of those since I didn't check things starting from the power cord into my system. :mad: Check everything before you start replacing. Learn from me. I would have been sick to find out it was the amps after all of the switching out of drivers etc.

Thanks for the help BobMcg

Wade (happier in St. Louis unless we are discussing baseball)

p.s. at least I am now registered with a new forum!

jcaut

Man! I was feeling for you on that one! Glad to hear that you found the problem. I don't own any SDA's, but it's not because I wouldn't like to. I can imagine your disgust at the thought of messing them up like that (without even taking into account the money involved in the repair).

I've been reading this forum for a while now, and the regulars on here, like Bob, are great about helping out. I appreciate them, as I'm sure you do.

My former boss just about broke me of using the word "assume". He'd always say "Spell that for me

---

that's far enough."

BobMcG

Wade,

It's not good to hear you have an amp problem but at least you have the problem located. And I'm a bit relieved to hear the problem isn't with the speakers. (If parts are getting scarce.)

I'm glad I could be of some help in the trouble shooting.

Commodorefirst

Mondavi 97 white/pink zinfandel with your name on it here in town Bob.

thanks, Wade

George Grand

Totally flabbergasted to see you are part of the "wine & cheese" crowd Bob. Live and learn.

George Grand (of the Jersey Grand's)

BobMcG

Wade,

Sounds good to me. Now, getting to St. Louis.... that, I'll have to work on!

G.,

Make it wine & cheese for me!
Actually, during the ten years my wife and I were together, we'd plan some of our vacations around trips to wine country in the Finger Lakes region of our native New York. There are plenty of wineries and all have tastings. Not to mention, wine country is beautiful! We'd make the trip back home with around a dozen cases of wines and champanges both mixed and whole. There would hardly be room for us and luggage! We even belonged to a wine club for a few years that shipped us wines.
Wine is still my favorite way to enjoy an occasional drink and is always in my fridge, along with a selection of different cheeses. (Sorry, the crackers are usually the fat-free kind. Cheese & f-f crackers? Go figure.)

George Grand

I like the taste of the stuff, but it gives me a sour/rotten stomach for days afterwards, so I shy away from it. Cheese helps to promote kidney stones, which can be a real picnic if you've ever squirted a couple of those out. Man, getting older is just SO messed up.

George Grand (of the Jersey Grand's)