I have a pair of Infinity IRS Sigma speakers which I bought new about 15 years ago. The sound started deteriorating over the last few years and the degradation was most noticeable at the upper end. Based on a bit of research I concluded that the diaphragms of the EMIM & EMIT tweeters might be damaged but having opened the worst sounding one up I can exclude this possibility. This leads me to conclude that the problem might lie in the crossovers possibly in the form of blown capacitors.
I first attempted to gain entry to the speaker cabinets via the woofer but the speaker remained firmly attached despite removal of the screws leading me to conclude that it must be bonded in place. I have now gained access via the speaker base which affords me good access to the woofer circuit but the midrange/tweeter and midbass boards are visible but pretty hard to get at.
I would appreciate any thoughts and suggestions as to where I should go from here both as regards gaining better access to the circuit boards and what I should try in terms of fault finding. At this point I am absolutely certain that the tweeters are performing badly (they sound very fuzzy) and am reasonably certain that the diaphragms are good. If it might be of assistance in diagnosing the fault I suspect that the problems might have been caused by the way my wife used to switch off the Krell 250m monoblocks used to drive the speakers at the wall socket. The process always resulted in a “whoomph” sound which could not have been good for the speakers.
I am desperate to get my old sound back and would appreciate any input.
I first attempted to gain entry to the speaker cabinets via the woofer but the speaker remained firmly attached despite removal of the screws leading me to conclude that it must be bonded in place. I have now gained access via the speaker base which affords me good access to the woofer circuit but the midrange/tweeter and midbass boards are visible but pretty hard to get at.
I would appreciate any thoughts and suggestions as to where I should go from here both as regards gaining better access to the circuit boards and what I should try in terms of fault finding. At this point I am absolutely certain that the tweeters are performing badly (they sound very fuzzy) and am reasonably certain that the diaphragms are good. If it might be of assistance in diagnosing the fault I suspect that the problems might have been caused by the way my wife used to switch off the Krell 250m monoblocks used to drive the speakers at the wall socket. The process always resulted in a “whoomph” sound which could not have been good for the speakers.
I am desperate to get my old sound back and would appreciate any input.
Sorry to hear about your Sigma issues.
Some useful info on them can be found here:
Infinity Reference Standard Serie
There is a link near the bottom to the Sigma Technical Manual, besides containing schematics it also has an exploded view for the Sigmas.
Some useful info on them can be found here:
Infinity Reference Standard Serie
There is a link near the bottom to the Sigma Technical Manual, besides containing schematics it also has an exploded view for the Sigmas.
Thanks for the help and suggestion. At this stage I am really trying to find the answer to essentially 2 questions:
1) How do I get access to the cross over circuits. As I said the woofer seems to be bonded in place but I am sure others have encountered this problem and found a solution.
2) Does anybody have a ideas as to what the problem might be and where I should start looking for faults. As far as I can see all the components seem to be good order with no outward signs of damage but I have no idea whether a damaged capacitor would show visible signs like for eg a burnt resistor.
Regards
Dale
1) How do I get access to the cross over circuits. As I said the woofer seems to be bonded in place but I am sure others have encountered this problem and found a solution.
2) Does anybody have a ideas as to what the problem might be and where I should start looking for faults. As far as I can see all the components seem to be good order with no outward signs of damage but I have no idea whether a damaged capacitor would show visible signs like for eg a burnt resistor.
Regards
Dale
Dale,
maybe you can take pictures of it all and then we'll see.
Have you got means to measure impedance ? This would
tell you a lot about the condition of your tweeters.
Regarding bonded woofers, "use the force Luke", but very
gently 😉, and possibly from the inside.
maybe you can take pictures of it all and then we'll see.
Have you got means to measure impedance ? This would
tell you a lot about the condition of your tweeters.
Regarding bonded woofers, "use the force Luke", but very
gently 😉, and possibly from the inside.
In the old times speakers manufacturers used an auto sealant adhesive elastomer that would dry with time, à la Dynaco. (1)
Opening up a Dynaco A25 - AudioKarma.org Home Audio Stereo Discussion Forums
Opening up a Dynaco A25 - AudioKarma.org Home Audio Stereo Discussion Forums
Never came across an Infinity bass driver glued into an enclosure myself, and I have taken apart at least 6 different pairs. They can be stuck in there fairly good though, as the gasket on them often sticks really well to the enclosure as well as the driver. The trick is to carefully pry them out, without damaging the surrounding enclosure. Make sure to protect any surface you are prying against, and try using a softer automotive type pry tool made of polypropylene or nylon.
If you look at that exploded diagram, it indicates the mid bass and tweeter crossover boards behind the mid bass driver, you might want to try removing that to get access to the boards.
That whole crossover system is quite different that past Infinitys, multiple crossover boards spread out through the enclosure and connected to an input board.
Damage to the crossover components may not be obvious by just looking at them, and looking at the schematics doesn't reveal any obvious weak points to me, they should be fairly tough.
I would think that without protection, the drivers themselves would be a weak link.
I think Lojzek is right on the mark, verify that the affected drivers are good before going crazy and tearing everything apart.
If you look at that exploded diagram, it indicates the mid bass and tweeter crossover boards behind the mid bass driver, you might want to try removing that to get access to the boards.
That whole crossover system is quite different that past Infinitys, multiple crossover boards spread out through the enclosure and connected to an input board.
Damage to the crossover components may not be obvious by just looking at them, and looking at the schematics doesn't reveal any obvious weak points to me, they should be fairly tough.
I would think that without protection, the drivers themselves would be a weak link.
I think Lojzek is right on the mark, verify that the affected drivers are good before going crazy and tearing everything apart.
I would say so. (Aren't those Infinity EMIT tweeters a special weak link?)
http://www.diyaudio.com/forums/planars-exotics/230346-rplacement-repair-infinity-emit-tweeters.html
That's what I was thinking, the Neo's were poorly plated and once exposed will corrode. An up close and personal inspection is required.
Based on all the input received I think it is best to start with the tweeters. I have opened an EMIT and found fluffy material between the magnets and diaphragm which I take to be corrosion as suggested by Greebster. I therefore propose strip and clean the 4 EMITS and 2 EMIMS. This will entail making jigs to manage the disassembly process and buying a heavier duty soldering iron capable of soldering the thick wiring so it will take a few days to get to the job.
Based on the amount of oxidised material in the tweeter disassembled I think that it quite likely that have found the cause of my problems. I will report back on the outcome shortly but in the meantime thanks for the helpful suggestions.
Based on the amount of oxidised material in the tweeter disassembled I think that it quite likely that have found the cause of my problems. I will report back on the outcome shortly but in the meantime thanks for the helpful suggestions.
Checked mine and didn't notice any fluffy material on the drivers, but did notice this on my midrange units. There is no corrosion yet, but the plating is flaking off of the magnet strips, one more so than the other. Having that plating flapping / vibrating will degrade the drivers output.
Post some pics if you get a chance.
Post some pics if you get a chance.
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