DEH-P860MP Headunit, Alpine spx-177R components (front), Alpine spx-17mb midbass woofers (rear), Alpine Type R 10" sub, Alpine MRV-F545 amp (125x2 + 500x1, Front/sub), Alpine 3552 (85 x 2) (rear)
This setup has worked relatively flawless for the past year. The other day while driving I noticed an unbalanced sound. After some playing around, I found that the front left channel had no mid/lows, and the highs were scratchy.
After some head scratching, I did some diagnostic work. If i swap the rca's around at the amp and turn off all other channels, the scratchy sound moves to the right side. The left side plays fine then. This eliminates the amp and speakers.
What leaves at fault is possibly the HU or the rca's. The rca cables are high quality 4channel (4 rca's, 1 cable) knukoncepts premium cable. If the rca was shorting out, I could see not getting any sound at all, but not a lack of certain frequencies, and passing of others.
Later today I will try swapping the rca's at the HU and see if this behavior follows.
I'm leaning more so that something is fried in the HU.
Anyone experience this with this HU, or has other ideas?
It may be you HU settings (probably in the crossover department).
It may be your passive crosover at your components.
It may be your RCA cables.
It sounds as if it is a crossover related issue. For some reason your mid-bass is getting deleted. This may be caused by the mid-bass circuit gtting shorted with the tweeter circuit, or the coil on the mid-bass circuit is not working properly, and therefeore the only thing left is the cap, which may cross at a much higher frequency now.
Personally I have always been leary about HU crossovers. When I build crossovers, they are pretty decent size. For a good crossover, the size of the coil and/or cap is pretty big. So whatever methods of crossover they use in the HU is probably a crappy design and/or quality.
A lot of people love Pioneer for their crossover features and high pre-out voltage, but there are a lot of drawbacks as well.
Even if they are well designed, there will always be a few that will not come out right. Sorry to tell you this, but it sounds as if you may need to take the HU in for repair if the RCA cable and/or component crossovers arent the problem
I pulled the HU this morning, turned it on, and listed to all the channels separately (FL, FR, RL, RR, etc..)
Nothing, no loss of bass, no loss of midbass, no scratchy highs. Only thing left to scratch is my head.
I wonder if one of the rca's was making a partial contact where the rca patch cable meets the HU dongle. For good measure, I pulled and reseated all the rca's (hate pulling the hu out). Had some errands to do, and so far so good.
It can't be the HU cross over settings because they apply to the front channels as a pair, not individually. Also, that would not explain the scratchy highs.
Can't be the component cross overs because when I swapped rca's at the amp (FL became FR, and FR became FL), the behavior shifted to the front right. That rules out the speakers and crossovers.
It may be a good idea to ebay this thing while it still works The HU uses DSP for filtering purposes, so who knows.
We'll see if it returns.
I looked at the new 980BT, and while the display is really nice, the single rotatary commander design stinks. Also, you can't see which functions you get by rotating left/right like you can on the 860/960 (shows 6 or 7 tab functions at the top).
The BT would be nice especially since I have a BT enabled cell phone and drive a stick.
I'm guessing by pulling the HU, something shifted in a cable (either the rca's or the dongle), and now its making full contact - for how long? we'll see..
Guy at the store seems to think its possible there's a bad solder connection either in the unit or the rca's, which changes the characteristics of the signal and acts like a HP filter. This too makes little sense since coils act as LP filters when in series, not HP...
The HU uses DSP for filtering purposes, so who knows.