Help! Did I blow my Sr-6500's or maybe the crossovers?!

[monologuist]

sorry if you have already read this on my other thread....I'm panicking a bit at the moment!

crap...something just went awry with my system. I was listening to Kraftwerk (their most recent release), a record with a ton of sub-bass and highs but not too much in the mids, trying to break in the SR-6500's. I had my Alpine PDX-4.100 (channels 1 and 2) set at about 2 o'clock gain( I think that is 0.5v?) and my Pioneer p6900ub head unit with all settings flat and volume at 45-50 out of 62. There seemed to be no obvious clipping even with the midbass drivers working hard to pump out the electronic kick drums (it almost sounded like I had a sub!).

THen all of a sudden there was a very loud POP....and a pretty loud buzzing noise ensued. I turned everything off for a couple hours, and started the system again at low volume. The buzzing sound commenced as soon as the head unit powered on and only went away after turning it off. I tried turning the volume up slowly to see if the speakers were blown....but there seemed to be pretty much a full range signal coming through both tweeters and drivers...except the buzzing was actually as loud or louder, so I could not turn the volume up too high before the buzzing was unbearable. Then the popping sound hit again, so I quickly turned the head unit off again.

What the hell is going on?! I will begin troubleshooting tomorrow, but if this scenario sounds familiar to anyone, please fill me in! If I had blown a fuse either in my power chain or on the Alpine amp, there wouldn't have been any signal at all right? And if I had blown a tweeter or driver, there would be either no sound or very distorted sound right? So I'm thinking it might be either somethin to do with the head unit or the SR-6500 crossovers.

I rad that the crossovers' tweeter protection circuit causes a popping sound when it kicks in....is it a very loud one? Also, after it pops off, how long does it take for the tweeter to run normally? I hadn't read anything about buzzing though, relating to the protection circuit.

Can anyone shed some light on this before I go ripping my car apart for the umpteenth time searching for the problem?

[exalted512]

The crossovers have a fuse looking thing in them for the tweeters. I would try replacing that with your standard fuse and turn the radio on very low. If it fixes the problem, get replacements for the tweeter protection thing from polk or ask them where you can get new ones.
-Cody

[MacLeod]

My first guess would be that a speaker lead is touching another lead or maybe grounding out to some metal in the door panel (or wherever youve mounted them). Playing the loud bass got the cone a rockin' and may have caused this.

All you have to do to test this is to pull the speakers out of the doors to see if they still buzz.

[monologuist]

ok...after troubleshooting for a couple hours, this is what I can surmise:
1. The 6500's seem to be fine. I switched them to the rear channels of the head unit and there is no problem. Rear speakers seem to be fine as well when hooked up to the rear channels
2. I've got a 4 channel RCA running from head unit to amp, and it seems that when I've got the FRONT channels of the head unit hooked up, the other 2 RCA tips seem to be ungrounded or something: when I touch them or touch them against another RCA tip, there is loud static buzzing, like it's ungrounded or a ground loop or something....also, when there are RCA tips plugged into the front channel outputs of the head unit, the bass frequencies sound intermittent; if you put pressure on the RCA tips on the outputs or pull them slightly out, the bass comes back, but the slightest touch and the bass is gone. It may even be that one or both channels keep going in and out of phase when distrubed. Weird. BTW, this is the Pioneer DEH-P6900ub...I had heard of some Pioneer receivers having issues with noise onset that required grounding the RCA cables somehow to fix...the P880prs I think sometimes has this problem. Maybe this is similar?
3. I guess there could be something wrong with the RCA cables themselves, but I'm doubting that, as each of the 4 RCA channel tips incur the same problem when plugged into the front channel outputs of the head unit; what are the chances that all 4 channels of the cable are somehow malfunctioning?

Can anyone think of any other steps to troubleshoot? If not, I am going to assume its the front channels of the head unit that are defective, and I will have to try to return the unit to Sounddomain.com. Luckily they are authorized dealers...has been over 30 days, but maybe they will give me a break. I'm actually kind of secretly hoping this is it, b/c I was starting to hate on the receiver anyway! I was regretting that it didn't have more processing features, crossover flexibility, time alignment, etc! Also, I was beginning to wonder if the head unit was the weak link in the audio chain I've got running...as I mentioned the SR-6500 tweeters were sounding a bit painful, and I don't think it was just their levels. Might have just been the inherent sound of the Pioneer...sort of bright, almost metallic sounding, in an artificial way (this is with no eq or processing).

Either that or it's the sound of the PDX-4.100....

[MacLeod]

It could be a problem with the head unit but first I would run down to RadioShack and buy a set of $10 RCA's and hook them up to the head unit and then run them to your amps (dont run them under panels and such, just hanging loosely). If you still have the same problem then the RCA's are not the problem.

I doubt its the amp cause you said it only screws up when you use the front outputs of the head unit. Everything works fine if you use the rear channels, right?

[monologuist]

It could be a problem with the head unit but first I would run down to RadioShack and buy a set of $10 RCA's and hook them up to the head unit and then run them to your amps (dont run them under panels and such, just hanging loosely). If you still have the same problem then the RCA's are not the problem.

I doubt its the amp cause you said it only screws up when you use the front outputs of the head unit. Everything works fine if you use the rear channels, right?

ok...it is definitely not the RCA's..I checked 3 different sets of RCA's and the screwed up output is the same on all. So the head unit it is, and back it goes. Now I have to find a new head unit!