SDA CRS continuity issue (crackling drop outs)

tat

The SDA CRS have begun acting up with what sounds like a continuity issue: a "staticy" cutting in and out of the stereo driver of the left channel. It took weeks before I 1st heard the issue and though it seems to be getting worse it is still unpredictable and unreproducible. It seems to kick back into normal function right on stronger signal peaks, but is more related to the initiation of a signal than its actual volume relative to the passage. It will go an hour or so working normally tempting me to think my past attempts of switching pre-amp input/output, interconnect connection, or internal connection checks, have solved the issue. But then it returns, ranging from completely losing the left channel signal to crackling partial response.

I was hoping it would be a cold solder joint in 1 of the crossovers (hence easy fix). But I wonder what the likelihood this type of intermittent continuity break could originate in a failing component like a cap? Does anyone have any opinions on what this issue is likely in an old original 1984 SDA CRS model? Any recommendations on troubleshooting tests? The Xovers are pretty tightly wired in there so they are tough to get at for a novice like me. But Id love to dive into them if I haf a clue of what to look for. I'm dying to get these things working properly as I love the tone and cant afford to replace them right now. I cannot enjoy them as much when I am preoccupied by monitoring for the dropouts lol. I wanted to upgrade the Xover components but without knowing it will solve this issue I hesitate to invest the time and money. I imagine it would almost have to, they are that complicated after all. Recommendations? Should

txcoastal1

Not the best one to speak up right of the bat,

Hey guys is he having issues with the poly switches????

pitdogg2

No not on stereo driver. I'd check for voice coil rub. Maybe magnet slipped some.

F1nut

You have a poor connection somewhere and the only way to find it is to get inside. The first place to check is the connections on the driver itself as they could be oxidized. Bottom line, there is no simple answer trying to chase intermittent issues.

tonyb

Yep, getting inside to see what you can see is going to need to be done. First though, make sure the outside is up to snuff. What I mean by that is....if your using bare wire speaker cable connections, make sure none of the strands of copper is touching another post, on both ends of the cable. Make sure the connections on the back of the speakers are not oxidized, have crud on them.

Make sure all your cables are not old/oxidized/damaged. Use decent cables and interconnects, not that red and white crap that came with a dvd player. If all that is up to snuff, then you need to get inside.

befuddle

My apologies if the obviousness seems condescending,but have you tried with another set of spks in a attempt to eliminate the possibility of the issue being equipment related? As it could be a amp,balance pot or funky interconnect intermittent connection problem

tonyb

Good point ^^^^ Volume pots can easily mimic the same sound description. I would try the easier more obvious things first. Sorting out intermittent problems is always a pain in the rear end.

tat

I don't think it is a failing manual connection (but I am not above overlooking obvious things when they are numerous), I poked around inside/out pretty good. This is why I suspect a cold solder joint or failing component. I have fixed multiple cold solder issues on guitar equiptment with similar symptoms, but I could narrow down the joints to hit there, where here I may need to hit every one..in both speakers even bc of SDA! I'm not a total noob when it comes to hardware, it is the engineering side of things that I am quite dense about.

I appreciate the help. I do need to try the speakers with other equipment as I originally was hoping it was the preamp. I think I noticed a change in DCR of 6" driver when the signal cut out. Pinpointing this stuff in person is tough enough, I was hoping this might be a common failing in the line (cold solders common in Polks?). I tried monitoring the DCR of 6" while running (varies from 7-11ohms) to see if there was big change when signal cut-out, but it stopped cutting out. Not sure that would work anyway unless it was that particular driver that was problematic.

Its so annoying having them begin to work fine again, re-assemble/set-up, and then the issue comes right back the next day lol. Ill substitute sources, then hit all the joints this week (and recheck connects), then report back as to what/whether it was successful...

ptrooper

Will be interesting to hear what the problem was?