Silent Screamer Posted July 20, 2021 Posted July 20, 2021 I sold some Sonus Fabrer Cremona mains I bought about 20 years ago to my brother in law about 10 years ago. He barely ever uses them. About a year ago one of the mid drivers just up and died. So I bought a couple of replacements from Speakerbits and changed them both.  Problem is I have now found several more dead drivers in both of the speakers. In total there are 3 x mid woofers, 1 x mid, and possibly 1 x tweeter gone. I suspect that for some reason the crossovers are the source of the issue. I'm not that electrical savvy that I want to risk thousands of dollars worth of replacement drivers to my limited crossover knowledge.  I do have a Lutron LCR-9183 meter which I could check some components over, but before we start buying replacement drivers, I want to find out if there is anyone in the Ipswich / Brisbane area that can help diagnose the problem.  The reason why I sold these speakers to him in the first place was I wanted to upgrade from the ScanSpeak Revelator series drivers to the ScanSpeak Illuminator series drivers. Now there are so many dead drivers in the boxes we are playing with the idea of upgrading the drivers to the Illuminator series, but this would probably require reworking the crossover.  Thoughts, ideas, suggestions???
rockeater Posted July 20, 2021 Posted July 20, 2021 When you say dead drivers, do you mean open voice coils? They normally go only if you drive speakers too hard with underpowered amp which goes into distortion. Or, there is to much moisture in the air and they corrode, but this would perhaps only happen if you live right on the beach. Â Open them up, get the crossovers out and check the components one by one. Unsoldering them, testing, and then putting them right back to where they were. Take plenty of pictures, so that you do not put them wrong way round. Short circuit capacitor in series with tweeter or a mid-range would put high power of lower frequencies through them and fry them but that is not the case with woofers which are designed to take big watts.
Silent Screamer Posted July 20, 2021 Author Posted July 20, 2021 (edited) 17 minutes ago, rockeater said: When you say dead drivers, do you mean open voice coils? They normally go only if you drive speakers too hard with underpowered amp which goes into distortion. Or, there is to much moisture in the air and they corrode, but this would perhaps only happen if you live right on the beach. Â Open them up, get the crossovers out and check the components one by one. Unsoldering them, testing, and then putting them right back to where they were. Take plenty of pictures, so that you do not put them wrong way round. Short circuit capacitor in series with tweeter or a mid-range would put high power of lower frequencies through them and fry them but that is not the case with woofers which are designed to take big watts. Â Not passing the 1.5v battery test. Some did, some did nothing. Last time I tested them I used the meter and it was a dead short in the driver. Â I did some quick and dirty measurements in place, just testing between the two crossovers. The cap on the lower left is showing a considerable difference between them. Some of the cheap green caps I think are dead. Â They own a property on the Sunshine Coast right on a canal. The amp powering them is a hybrid valve / SS and should be more than enough to drive them (provided it is ok). Edited July 20, 2021 by Silent Screamer
Gryffles Posted July 20, 2021 Posted July 20, 2021 (edited) @Silent Screamer are you sure those green caps aren't resistors?  Talk to Nigel at Speaker Bug if you need some help. He's not that far from you Edited July 20, 2021 by Gryffles
Silent Screamer Posted July 20, 2021 Author Posted July 20, 2021 4 minutes ago, Gryffles said: @Silent Screamer are you sure those green caps aren't resistors?  Talk to Nigel at Speaker Bug if you need some help. He's not that far from you  Got out the magnifying glass, you are correct they are resistors. The meter is auto LCR which I probably read wrong, but they should be showing some other than OL. Do you have contact details for Nigel?
Silent Screamer Posted July 20, 2021 Author Posted July 20, 2021 My bad it was showing OL because it was on Cap instead of Resistance.
Gryffles Posted July 20, 2021 Posted July 20, 2021 3 minutes ago, Silent Screamer said: Â Got out the magnifying glass, you are correct they are resistors. The meter is auto LCR which I probably read wrong, but they should be showing some other than OL. Do you have contact details for Nigel? Mate just google him. Easy peasy
Silent Screamer Posted July 20, 2021 Author Posted July 20, 2021 12 minutes ago, Gryffles said: Mate just google him. Easy peasy  Found him and he is fairly local.
rockeater Posted July 20, 2021 Posted July 20, 2021 15 minutes ago, Silent Screamer said: My bad it was showing OL because it was on Cap instead of Resistance. Your meter will not work well with components in circuit. You need to remove them or at least lift one leg of each one before testing. There is nothing cheap on that board and certainly there are no greencaps there. Before you measure any capacitors, short them out with some wire to discharge them. Failure to do so means risking blowing up your LCR meter. Â
Silent Screamer Posted July 20, 2021 Author Posted July 20, 2021 (edited) 7 minutes ago, rockeater said: Your meter will not work well with components in circuit. You need to remove them or at least lift one leg of each one before testing. There is nothing cheap on that board and certainly there are no greencaps there. Before you measure any capacitors, short them out with some wire to discharge them. Failure to do so means risking blowing up your LCR meter. Â I wasn't expecting accurate measurements I was just doing a like for like caparison. For example on one crossover the 4.7uF is measuring something like 4.68uF and on the other is it measuring 71uF. The speakers have been off for a few days, so hopefully not holding any charge. The resistors are showing less than stamped values but that is to be expected in a circuit. Â Thankfully the 72uF caps are both showing 66.7uF so they don't look damaged those suckers would be several hundred dollars each to replace. Edited July 20, 2021 by Silent Screamer
Silent Screamer Posted July 20, 2021 Author Posted July 20, 2021 (edited) Just tried measuring the resistance at the speaker wires one tweeter is 9.6 ohm and the other is .33 ohm. All four of the mid woofers are around 1.3 ohms. Definately something not right there. 11.6 and 14.0 ohms for the mids. No wonder several of the drivers called it a day. Edited July 20, 2021 by Silent Screamer
rockeater Posted July 20, 2021 Posted July 20, 2021 10 minutes ago, Silent Screamer said: The speakers have been off for a few days, so hopefully not holding any charge Do not hope  Short them out with wire. I blew one of my LCR testers out of laziness.  11 minutes ago, Silent Screamer said: those suckers would be several hundred dollars each to replace. I was not aware that there are capacitors used in audio that cost that much. At least not from trade suppliers.
Silent Screamer Posted July 20, 2021 Author Posted July 20, 2021 3 minutes ago, rockeater said: Do not hope  Short them out with wire. I blew one of my LCR testers out of laziness.  I was not aware that there are capacitors used in audio that cost that much. At least not from trade suppliers. Caps can get crazy real quick... https://speakerbug.com.au/index.php?route=product/category&path=25_31 $156 and that is only 22uF
Silent Screamer Posted July 20, 2021 Author Posted July 20, 2021 Although in the picture they are only 5% caps so they are much cheaper... https://speakerbug.com.au/index.php?route=product/category&path=25_30
rockeater Posted July 20, 2021 Posted July 20, 2021 4 minutes ago, Silent Screamer said: https://speakerbug.com.au/index.php?route=product/category&path=25_30 This is all retail. :-)
Silent Screamer Posted July 20, 2021 Author Posted July 20, 2021 20 minutes ago, rockeater said: This is all retail. Yeah but unfortunately that is the price I pay, so there is no getting around that. Â With a bit of luck I have talked my brother in law out of repairing these speakers for the time being. He is using the system for predominately TV, Netflix, movies on the NAS, so I am trying to steer him in the direction of buying some home theatre speakers for that room, and we can do these up at a later date for music.
Silent Screamer Posted October 18, 2021 Author Posted October 18, 2021 Quick update. BIL took the speakers to a guy up the coast to repair the drivers. Apparently the lead wires delaminated over time. The glue dried out and they stopped making contact. The guy scraped out the old glue and replaced the lead wires. Took a couple of albums before they sounded right but they eventually come good. 3
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