amorriso

Getting crackling and popping from drivers side front speaker. Local mb mechanic recommends changing the amplifier. Looking for the amp location to confirm part number before buying the part on eBay ( local dealer says it is NLA). Any advice on where the amp is located in the car?

Floobydust

amorriso -

When you say driver's side speaker, which one are you talking about - the one on the dash, the one on the door, or the one to the left of the rear seat? On a stock '95 cabriolet, the external amplifier powers only the doors speakers. All the other speakers are driven directly from the head unit.

It has been my experience that, despite being labeled "high quality loudspeaker", the OEM Becker units are crap, resembling a high quality audio transducer in form only. Besides sounding bad when they are working, the voice coils tend to delaminate over time so they start to crack and pop.

The door speakers are particularly prone to this problem because the audio energy for the majority of music (classical music being a notable exception) is concentrated in the bass region handled by the door speakers. The external amplifiers do have an issue with the solder joints deteriorating over time that can cause the same sort of issues, but I have found that 9 times out of 10, it's the speaker that is at fault.

The amplifiers in the head units are very reliable and not likely to be an issues. However, if the cracking/popping is from the dash or rear speakers, you may have a dirty volume control optical encoder. Does the cracking/popping behavior change when you rotate the volume knob? If so, the encoder is dirty. Pulling the volume knob off and liberally spraying electrical contact cleaner through the hole (using the little red tube that comes with it) should clean that up.

If it is not the knob, the classic diagnostic technique is to swap the offending speaker left-to-right. If the problem goes with the speaker, the speaker is as fault. If it stays with the location, check the amp or the head unit.

Good luck,

- FD

amorriso

Thank you for your response. The problem is with the drivers side speaker in the dash. No change to the crackling and popping when I turn the volume control. And no change with balance and fader adjustment. However, the crackling and popping continues for a few seconds after the radio power knob is turned off. This has been an issue for over a year and it comes and goes. Some days the speakers work fine and then for weeks at a time the front right dash speaker crackles and pops like crazy. Then, mysteriously it stops for several weeks. Any other thoughts given this additional information? I will try cleaning the volume knob ( sounds easy enough ).

Floobydust

You referenced "driver's side" and then "right hand speaker" - is your cabriolet right hand drive or does the problem alternate between the left and right speaker?

I would suggest cleaning the encoder first. The basic procedure is remove knob; spray in cleaner (I have also used WD-40 for this); replace knob; rotate knob about 20-30 turns (power off); repeat these steps three or four times.

If that doesn't resolve the problem, the thing I would do next is to swap the dash speakers left-to-right. This will take about 15 minutes and requires a short Phillips screwdriver and a small straight blade screwdriver. Using the straight blade screwdriver, pry up the L shaped piece of plastic trim the goes around the edge of the speaker grill. Under this will be some Phillips screws that hold the grill on. Remove these and the grills will come off. You should then be able to remove the speakers and take them out. The speakers plug into the wiring harness with a small two prong plug on the end of a short pigtail lead. The plugs are the same on both sides, so you can just swap them left-to-right.

However, before you remove the speakers to swap them, turn the stereo on with the volume all the way down. Watch the speaker cones. Do they visibly move in or out? Do they visibly move in/out when you turn it off? If they do, that is a sign of amplifier coupling capacitor or output transistor failure in the head unit. Cracking and popping after the stereo is turned off can also be a sign of this, however, I have only seen this once on an MB head unit.

amorriso

It is the LEFT driver's side speaker ( sorry for the confusion ). I tried the WD40 and no luck. Removed the drivers side speaker grill and the speaker cones visibly move with the crackles and pops while the volume is turned down AND they continue to move when I turn off the power. Sounds like it might be the head unit.

joef

I may have one that I took out when I parted out my car. If interested, pm me

Floobydust

Most likely. As long as you have the grills off, you may want to swap the speakers left-to-right just to be sure.

Since you have a '95, you have a DIN connector head unit so it is plug and play with many later (1995 - 2002) MB head units. Or, you can go for an original such as the one joef might have.

amorriso

The plot thickens.... I replaced the amp with an amp I purchased on ebay. Crackling and popping in the drivers side dash speaker is gone. BUT.... rear speakers going in and out ( noticed this also before the amp change ). Do i need to replace the head unit or did I get a faulty amp? I'm almost ready to pull the amp and head unit and send them off to becker in NJ but was hoping to solve this without them.

Floobydust

I hate it when the plot coagulates!

Disconnect (unplug) the amplifier and run the stereo. You will have limited bass (and none from the door subs), but check to see if the speaker cones move in/out as you turn it on. If they still do, the amp has nothing to do with it. If they don't, the input coupling capacitors are bad on your "new" amp.

Hope this helps.

- FD

uvr708

So where is that ext amp located on a Cabriolet?