AL-III Upgrades

[Hans5849 0]

Hello,

 

My dad has a pair of AL-III's that don't work. I'm in the process of troubleshooting them, he says the ribbons are bad but I'm going to investigate the system before saying the ribbons are toast. I have the service manual, but is there anything you all would suggest looking at? I don't have an O-Scope available to really get into the system, only a multimeter

 

Are there any upgrades that would be prudent to complete on these speakers? So far I've seen getting a 12-14 gauge wire connected to the speakers and putting a 10" car stereo sub in.

[cuda 526]

The ribbons have daughter boards at the bottom and can either get loose or wear through the trace, use a multimeter to check.

[UncleMeat 1,173]

The circuit boards are at both the top and bottom of the ribbon. The lower board sends the signal from the amp; the upper board completes the circuit. Try torquing the three screws that clamp the boards to the ribbon both top and bottom. Be careful not to get the screwdriver too close to the ribbon openings; the magnets are very strong and can pull the screwdriver (or driver tip) into the ribbon and damage or destroy it. If you are using a screwdriver with a bit tip, tape the tip to the screwdriver so it cannot be pulled out by the magnets.

[RodH 4,866]

McMaster-Carr # 54035A83: Titanium nonmagnetic #2 Philips screwdriver.

[kve777 6,888]

You should be able to track down an open in the circuit for the ribbons with just the meter.

Pull out the crossover and check for continuity across the entire circuit with the ohm meter. I would measure the ribbon circuit, first, yes. Good place to start. Should read under 10 ohms. If open or more than 10, your problem is somewhere in the ribbon, bad solder joints in the boards at top and bottom are highly suspect, yes. One trick, hook up a known good conventional speaker driver, like a car speaker you might have, to the crossover instead of the ribbon. If it plays, the crossover is not the problem. You can do the same test for the woofer, too, if one is not working.

 

I have a pair of AL-III crossovers if you find a problem and need parts from them...PM me.

 

Note: Not just any 10" car sub will be satisfactory.  High efficiency(about 94dB@ 2.83V/1M) and high Qts(over .40) are key.  The Infinity Kappa Perfect 10.1, 4 ohm, single VC has been determined to be the best, but are now hard to find.

[UncleMeat 1,173]

I just want to add a note; the AL ribbons are tricky to test. If you put an ohm meter on them they might read fine, but under AC power load they might still have open circuit problems if the PCB's are loose or not making good contact. My 60" ribbons tested fine with a meter but did not sound right until I re-torqued (lightly) the clamp screws. The right ribbon was buzzing and weak; once it was fixed the left ribbon was weak sounding, and I thought that one was correct previously. With both ribbons re-torqued they sound balanced with much more clarity and image.

 

IIRC the OE woofer has 85 dB efficiency, I'm not sure if that' with or without the rubber strips that were added to the VC dust covers. However, the AL-III's are missing the low end of the ALS series so higher efficiency woofers should help that.