Need some troubleshooting help with balanced signal

[vwdude]

Ok so my install is in the installs section, but here's a summary:
-factory radio switched to low level out
-Phoenix gold TBAt (balanced line driver)
-Phoenix Gold ZPA0.5
--Dynaudio system 360 (3 way components)
-Phoenix Gold ZPA0.5
--Image dynamics IDQ12

So here's the thing, when I run the balanced line straight from the TBAt to the components amp it's perfect. No noise, it's actually clearer than my old McIntosh amp. I can balance left and right and it works as it should. Problem is I don't have my sub this way.

When I ran the signal from the TBAt to a ZPX2 crossover then to each amp (balanced) I noticed a buzzing in my tweeters and the balance no longer works. When at center it sounds fine but if I balance left I get no sound and balance right I get full sound out of left and right.

I tried my other ZPX2, same thing.

I tried a PLD1 with an RCA cable going to said crossovers then balanced lines to amps, same thing.

I tried running RCA to each amp, same thing.

So I figured, I must have 2 bad ZPX2 crossovers. So for a couple of weeks I ran with just the balanced line going straight from TBAt to my components amp. Perfect sound quality, just no sub.

So today I connected the balanced line out from the TBAt I to an eq232 which hyphen runs RCA out to a Phoenix gold mx2 crossover. Same issues as before...exactly. The buzzing in my tweeters and no balance left/right.

So, can I have 3 crossovers with exactly the same issue? I mean I know that my head unit, TBAt and amps work properly (at least the components amp), so the thing that causes the issue every time is the crossover.

Anyone with guidance or more troubleshooting ideas is welcome. The next experiment will be to use my balanced splitter, run straight to the components amp on one run and to the eq/crossover/sub amp on another run. I'll report back. I shouldn't need to do that though.

[vwdude]

Ok so time to muddy the waters...

I used my balanced line splitter with one line going out to the components amp and one line out to the eq, then the crossover then to the sub amp. It's works perfectly.

So question now...that doesn't seem right. Shouldn't balanced line allow a crossover to be installed?

[Weaklink]

Silly question but have you played with the ground/floating switch in the amp?

[vwdude]

I can't, it's a v2 so it's not switchable.

Not a silly question either. I have thought about that and wish I could try it as I'm not sure why they made it switchable in the first place.

[Weaklink]

I think it was because in some of the phoenix amps the chassis was common with the rca shield. Most decks do this but if grounded at both ends it can cause a ground loop instead of a emf drain shield grounded at the source.

[zeropoint0.5]

3 crossovers with exactly the same issue ?? no , probably all 3 are fine and this issue is located somewhere else.......

maybe you can solve the issue with taking the B+ for the crossover from another point of where you take it now

or take another point in the car for B- also......


about the switch that "is taken out with the V2 upgrade", i personally have them back soldered in in place of the

bridges, so i can still switch to a floating signal using the balanced signal....... so all my zpa's have or have the switch back....

it's the only thing i don't do in the V2 upgrade...........

[ttocs]

what loc are you using? Have you tried a different audio source(mp3 player and headphone-rca cable) to see if you still get noise?

[Weaklink]

Have you looked at all the balanced cables? I can't remember if the pins swap or not. One might be wrong. Check continuity to see if there is a broken wire in one. And are any of the sockets getting rusty contacts?

[Eric D]

I am pretty confident you have a ground problem. A lot of the points other members have mentioned are spot on.

First I would take all the cables and check them with a DMM to make sure the same pins match up between ends. If one of them happens to be an ethernet crossover cable, I can see this causing issues (possibly) when the two amps are connected to the same device (ZPX2). I would guess the output grounds of the ZPX2 are common, and if you had a crossover cable, you might actually be shorting one of the signals when all the equipment is connected together. The input ground and output ground of the ZPX2 may be isolated, so this might be why it works with only one amp connected, but not two.

Can you or did you try this...

Run the head unit to the TBAt, then to the ZPX2, then to the component amp and the sub amp all at the same time. Disconnect the balanced cable from the input to the sub amp and play the system. Does it sound fine? Now connect the cable back up and remove the one on the components amp. Do the subs sound fine? Now connect them both. If the noise is there, there is likely an issue with the input grounding of one of the amps.

[vwdude]

Ok thanks for the help guys.you all have valid points that seem to make sense.

I'll try some of that troubleshooting when I get time. For now it all works by using my balanced splitter, with one line going straight to the components amp and the other going to the eq then the mx2 then the sub amp.

[vwdude]

I didn't have time to troubleshoot with any of the above techniques yet, but I didn't drive a little with the latest layout that "works". Well I found out some crucial info, when I go over 15 on the head unit is where it has the issue. I wasn't going that high with the balanced line straight to the amp because no signal was lost due to splitting so it was very loud around 10 or 11. Not that I'm splitting and then running the eq and crossover it lowers the signal strength and to crank it I had to put it up to 14 or 15.

I got the pop and then the balance issue was there. So it looks like it's the head unit, for some reason it doesn't want to go over 15. I might have a lead on an inexpensive aftermarket replacement for it, so I'll give that a shot.

[ttocs]

make sure it doesn't have some kind of setting that modifies the volume/signal based on speed/noise. Some decks will get louder as you accelerate to compensate for more road noise and it could be causing some issues.

[vwdude]

I will check the settings. i wonder if it does that internally without giving the option to defeat it...

either way, i have a new head unit on its way. I might just try it out and go from there.

[ttocs]

try an mp3 player and the headphone to rca cable for an easy test.

[vwdude]

Ok I'll try that today if I have time.