I'm trying to determine whats wrong.
I got an old pair of Jamo 707 for free, but they were ripe with issues. 130€ later, most of them are gone and they play nice, however they're a bit unbalanced, especially in the bass region.
I did some testing with oscillator and took them apart, and considering that @40Hz, midrangers are giving substantial output, and that the speakers don't put out the same amount of power even when I swapped the drivers, that crossovers have gone bad.
All four woofers have been refoamed and the tweeters rewound. I'm suspecting (due to the damage done to the speakers - one cone ripped apart, all foams destroyed, tweeters blown) that somewhere among the line, crossovers went bad and caused the tweeters and one bass to overload and do the damage it did.
Previous owner was someone who had no clue how speakers are handled, and they're at least 25years old.
To the crossovers:
Caps don't seem damaged, but one resistor (plastic case) on one speaker is cracked. Do I need to replace the coils, or is it enough that I replace the capacitors and resistors?
I got an old pair of Jamo 707 for free, but they were ripe with issues. 130€ later, most of them are gone and they play nice, however they're a bit unbalanced, especially in the bass region.
I did some testing with oscillator and took them apart, and considering that @40Hz, midrangers are giving substantial output, and that the speakers don't put out the same amount of power even when I swapped the drivers, that crossovers have gone bad.
All four woofers have been refoamed and the tweeters rewound. I'm suspecting (due to the damage done to the speakers - one cone ripped apart, all foams destroyed, tweeters blown) that somewhere among the line, crossovers went bad and caused the tweeters and one bass to overload and do the damage it did.
Previous owner was someone who had no clue how speakers are handled, and they're at least 25years old.
To the crossovers:
Caps don't seem damaged, but one resistor (plastic case) on one speaker is cracked. Do I need to replace the coils, or is it enough that I replace the capacitors and resistors?
Just to get you started... and you'll hopefully receive far more knowledgeale answers on your speakers than I can give...
1/ I'd be surprised if any coil were bad. Electrically they would have to suffer extreme abuse to the point of passing enough current to heat/melt the winding insulation. Very unlikely. If any coil has an iron or ferrite core, then if that is cracked there could be issues.
2/ If this split resistor measures OK value wise then it probably is OK. Are you sure its a resistor and not a cap ?
3/ Room placement can show up amazing differences in response. Always prove by physically swapping left and right boxes over.
(If you post pictures of the crossover then others might gain more insight into what could be wrong)
1/ I'd be surprised if any coil were bad. Electrically they would have to suffer extreme abuse to the point of passing enough current to heat/melt the winding insulation. Very unlikely. If any coil has an iron or ferrite core, then if that is cracked there could be issues.
2/ If this split resistor measures OK value wise then it probably is OK. Are you sure its a resistor and not a cap ?
3/ Room placement can show up amazing differences in response. Always prove by physically swapping left and right boxes over.
(If you post pictures of the crossover then others might gain more insight into what could be wrong)
Hi, I just re-tested the speakers with different stereo 1/8" to 2x RCA cable and the response is pretty even.
I can't bloody believe it, I automatically assumed something is wrong with the speakers and somewhere on the top of my head I had thought that I was always using a different 1/8" to RCA cable, but seems it was always the same cable.
I can't believe I'm so stupid.
I'm actually an audio engineer so I tested these in my fairly treated studio.
What I did figure it, since the refoam, the distance between the drivers is a bit too narrow and the foam surround hit against each other, so I might as well fix it while I'm at it.
edit: Ha, i did test them with more cables, even more stupid, the foam insulation on the top part of the cab was dampening the driver. my god
I can't bloody believe it, I automatically assumed something is wrong with the speakers and somewhere on the top of my head I had thought that I was always using a different 1/8" to RCA cable, but seems it was always the same cable.
I can't believe I'm so stupid.
I'm actually an audio engineer so I tested these in my fairly treated studio.
What I did figure it, since the refoam, the distance between the drivers is a bit too narrow and the foam surround hit against each other, so I might as well fix it while I'm at it.
edit: Ha, i did test them with more cables, even more stupid, the foam insulation on the top part of the cab was dampening the driver. my god
Last edited:
- Status
- Not open for further replies.