I picked up a pair of ACI G3 three way floorstanders and have been searching for information on the factory crossover. Anyone have anything to share?
They appear to be in mint condition and have been in storage for many years but I sensed an “edginess” and harshness in the upper registers, so I disassembled the Vifa metal dome tweeters, carefully removed the dents in the domes and cleaned out the ferrofluid which had turned to a paste. Presently running gently without fluid. Sounds a little less harsh.
The crossovers are well glued into the cabinets and I would like to hear from anyone who may have upgraded them. There are a few electrolytic caps but can’t read the values in situ.
Cheers
Peter
They appear to be in mint condition and have been in storage for many years but I sensed an “edginess” and harshness in the upper registers, so I disassembled the Vifa metal dome tweeters, carefully removed the dents in the domes and cleaned out the ferrofluid which had turned to a paste. Presently running gently without fluid. Sounds a little less harsh.
The crossovers are well glued into the cabinets and I would like to hear from anyone who may have upgraded them. There are a few electrolytic caps but can’t read the values in situ.
Cheers
Peter
Old speakers always full of problems. Check for rubbing voicecoils on the basses by pressing them in. Rotating 90 degrees can help.
Poor connections are the worst thing usually. Those old spring clips on the back are rubbish. Best replaced with banana plugs hard soldered to fresh speaker cable. Crimped speaker connections benefit from redoing to fresh metal again.
It's a fun old speaker by the looks of it. Roy Allison style low woofer to avoid floor bounce. He wrote papers about this preferred arrangement.
I don't know what you are going to do about the crossover. You'll need to unattach it for any work or analysis.
W.Marshall Leach, Georgia Tech's finest son was good at this sort of thing. I think he even used your tweeter here! A Zobel network on the bass, just because he was good at that sort of thing.
Poor connections are the worst thing usually. Those old spring clips on the back are rubbish. Best replaced with banana plugs hard soldered to fresh speaker cable. Crimped speaker connections benefit from redoing to fresh metal again.
It's a fun old speaker by the looks of it. Roy Allison style low woofer to avoid floor bounce. He wrote papers about this preferred arrangement.
I don't know what you are going to do about the crossover. You'll need to unattach it for any work or analysis.
W.Marshall Leach, Georgia Tech's finest son was good at this sort of thing. I think he even used your tweeter here! A Zobel network on the bass, just because he was good at that sort of thing.
Attachments
Nice work. I can't believe how much PE charge for ferrofluid, but when you need it, you need it badly... 
I usually fit a 7.5R plus 0.68uF zobel to metal tweeters. It's a good theory because that supersonic resonance causes problems according to one of our brightest designers:
Sonics by Joachim Gerhard cabinets and kits.
That thread is good reading. Be good.
I usually fit a 7.5R plus 0.68uF zobel to metal tweeters. It's a good theory because that supersonic resonance causes problems according to one of our brightest designers:
Sonics by Joachim Gerhard cabinets and kits.
That thread is good reading. Be good.
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