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#1
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Mackie HR824 Woofer Problem
My HR824's have worked well for about 4 years. Recently, both speakers
have had the woofer cut out entirely. I found that cranking the volume for a moment or two seemed to "unstick" the woofer and get it going again. (As the volume is cranked, the woofer emits bursts of sound, as if struggling to come on, hence my description of "unsticking.") Anyway, I was able to get a spare woofer off ebay for $30, so I replaced the woofer that had the problem more frequently. As soon as I put the new woofer in, it started "sticking" but a shot of high volume got it going right away. ( Because the problem is so intermittent (and the speakers are out of warranty) I haven't brought them to my local Mackie repair joint. But that might be the next step, unless anyone has some insight into the problem? It seems the woofer may not even be the root of the problem. Incidentally, I noticed some differences between the old woofer and the replacement. I'll probably check with Mackie, but here are the details in case anyone knows about this. Old woofer marked: 490-001-00 2 04 ‡ 811 New woofer marked: 490-001-00 04 ‡ 703 Which suggests the "new" woofer may in fact be older, due to the lower part numbers? Also, the "old" woofer had an additional magnet (doughnut-shaped) epoxied to the back of the speaker. The "new" woofer lacks this magnet. There's a definite difference to the sound; the bass is not as strong on the "new" speaker. (By changing the bass response setting on the back, I was able to get the bass closer to the other speaker.) Perhaps Mackie's parts department will be willing to sell the magnet--but of course they're not open at the moment. Does anyone know the details on the speaker differences? Was the additional magnet a "retrofit" or something like that? -- Jedd Haas - Artist http://www.gallerytungsten.com http://www.epsno.com |
#2
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Jedd Haas wrote:
My HR824's have worked well for about 4 years. Recently, both speakers have had the woofer cut out entirely. I found that cranking the volume for a moment or two seemed to "unstick" the woofer and get it going again. (As the volume is cranked, the woofer emits bursts of sound, as if struggling to come on, hence my description of "unsticking.") When this happens, does disconnecting the woofer from the amp fix the problem? If so, it's the amp throwing out major DC offset. If not, the woofer cone is mechanically sticking. Anyway, I was able to get a spare woofer off ebay for $30, so I replaced the woofer that had the problem more frequently. As soon as I put the new woofer in, it started "sticking" but a shot of high volume got it going right away. ( This sounds to me like a DC offset problem. Try running it on the bench with the woofer removed, make it stick, then disconnect it from the amp and see if you don't have an amp problem. On the other hand, you might also have got a bad driver off Ebay. It would not be the first time someone sold pulls from bad equipment on Ebay. Perhaps Mackie's parts department will be willing to sell the magnet--but of course they're not open at the moment. Does anyone know the details on the speaker differences? Was the additional magnet a "retrofit" or something like that? It may well have been a factory change to reduce magnetic leakage or something like that. But I bet a nickel the problem is the amp. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#4
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#5
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Jedd Haas wrote:
In article , (Scott Dorsey) wrote: Jedd Haas wrote: My HR824's have worked well for about 4 years. Recently, both speakers have had the woofer cut out entirely. I found that cranking the volume for a moment or two seemed to "unstick" the woofer and get it going again. (As the volume is cranked, the woofer emits bursts of sound, as if struggling to come on, hence my description of "unsticking.") When this happens, does disconnecting the woofer from the amp fix the problem? If so, it's the amp throwing out major DC offset. If not, the woofer cone is mechanically sticking. I'm not following you here; if I disconnect the woofer, how will I know if the problem is fixed? Are you suggesting putting in another woofer? If not, won't it be bad for amp to run it with no speaker? Or do you mean to disconnect the woofer, then reconnect it to see if it works again immediately? Okay, I am assuming that the woofer is stuck at one end of travel, right? If you unplug it, does it return to the zero point or does it stay stuck? OR it it acting like a bad connection to the voice coil, where tapping on the cone with your fingers and wiggling the tinsel wires temporily fixes the problem? --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#6
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#7
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#8
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Jedd Haas wrote: My HR824's have worked well for about 4 years. Recently, both speakers have had the woofer cut out entirely. I found that cranking the volume for a moment or two seemed to "unstick" the woofer and get it going again. (As the volume is cranked, the woofer emits bursts of sound, as if struggling to come on, hence my description of "unsticking.") Check the bass rolloff switches in back. They can get intermittant and "microphonic" in a raggedy sort of way. Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
#9
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In article ,
Bob Cain wrote: Jedd Haas wrote: My HR824's have worked well for about 4 years. Recently, both speakers have had the woofer cut out entirely. I found that cranking the volume for a moment or two seemed to "unstick" the woofer and get it going again. (As the volume is cranked, the woofer emits bursts of sound, as if struggling to come on, hence my description of "unsticking.") Check the bass rolloff switches in back. They can get intermittant and "microphonic" in a raggedy sort of way. Bob To the OP: While you're playing with switches, try reseating any connectors/switch and switch back any switches/hit any buttons and bring them back to the position they were in. I'm with the camp that its something in the amp. Usually speakers either work or don't work. -- Cyrus *coughcasaucedoprodigynetcough* |
#11
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#12
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In article znr1102875235k@trad, wrote:
It's still not clear if the woofer is actually physically stuck - like when it moves from its centered position, it stays put after the signal and power is removed (that's bad) or if it moves off center when power is applied and goes back to center when power is removed (that's an amplifier problem). Or even if "stuck" means that it simply stops working and we have no information at all about the actual motion of the cone. It doesn't appear to be stuck at either end of the normal movement. As I noted in the original post, I used the term "stuck" (actually, I referred to "unsticking" it) in reference to the woofer behaviour when overcoming the problem (cutting out entirely). By giving it a shot of high-volume signal after it cuts out, it will typically work in a series of short bursts, as if "unsticking" itself, then start working normally. Based on the responses so far, I am leaning towards something in the amp, perhaps something as simple as the bass response switches. So far, it hasn't cut out since my first post, so I'll try the switches if (when) it does it again. -- Jedd Haas - Artist http://www.gallerytungsten.com http://www.epsno.com |
#13
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In article ,
Hannibul Artese wrote: In article , (Scott Dorsey) wrote: Okay, I am assuming that the woofer is stuck at one end of travel, right? If you unplug it, does it return to the zero point or does it stay stuck? OR it it acting like a bad connection to the voice coil, where tapping on the cone with your fingers and wiggling the tinsel wires temporily fixes the problem? Why not just measure the DC component, once the woofer is stuck? Just because that seems like more work than disconnecting the plug on the back. But yes, that would tell you what is going on just as well. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#14
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From: (Jedd Haas) It doesn't appear to be stuck at either end of the normal movement. As I noted in the original post, I used the term "stuck" (actually, I referred to "unsticking" it) in reference to the woofer behaviour when overcoming the problem (cutting out entirely). By giving it a shot of high-volume signal after it cuts out, it will typically work in a series of short bursts, as if "unsticking" itself, then start working normally. This is pretty clearly an amplifier problem. There may be an op amp that's (literally) locking up in the full-voltage state. This can be a fault of the IC, but also could be a problem with a capacitor surrounding it, or a preceeding IC. I wouldn't expect it to be a switch. I think this is a real electronic troubleshooting problem, and the fact that it's intermittent makes it all the harder to diagnose. Sorry, but it's going to be a bugger. -- I'm really Mike Rivers ) However, until the spam goes away or Hell freezes over, lots of IP addresses are blocked from this system. If you e-mail me and it bounces, use your secret decoder ring and reach me he double-m-eleven-double-zero at yahoo |
#15
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It may be the "Auto Power" circuit is cutting out? Try turning that off
if it is on. (while fiddling with the switches) Roger Foote |
#16
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Sounds like an oxidized connection someplace in athe amp or in the
speaker. Mark |
#17
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"Jedd Haas" wrote in message ... My HR824's have worked well for about 4 years. Recently, both speakers have had the woofer cut out entirely. I found that cranking the volume for a moment or two seemed to "unstick" the woofer and get it going again. (As the volume is cranked, the woofer emits bursts of sound, as if struggling to come on, hence my description of "unsticking.") Anyway, I was able to get a spare woofer off ebay for $30, so I replaced the woofer that had the problem more frequently. As soon as I put the new woofer in, it started "sticking" but a shot of high volume got it going right away. ( Because the problem is so intermittent (and the speakers are out of warranty) I haven't brought them to my local Mackie repair joint. But that might be the next step, unless anyone has some insight into the problem? It seems the woofer may not even be the root of the problem. Incidentally, I noticed some differences between the old woofer and the replacement. I'll probably check with Mackie, but here are the details in case anyone knows about this. Old woofer marked: 490-001-00 2 04 ‡ 811 New woofer marked: 490-001-00 04 ‡ 703 Which suggests the "new" woofer may in fact be older, due to the lower part numbers? Also, the "old" woofer had an additional magnet (doughnut-shaped) epoxied to the back of the speaker. The "new" woofer lacks this magnet. There's a definite difference to the sound; the bass is not as strong on the "new" speaker. (By changing the bass response setting on the back, I was able to get the bass closer to the other speaker.) Perhaps Mackie's parts department will be willing to sell the magnet--but of course they're not open at the moment. Does anyone know the details on the speaker differences? Was the additional magnet a "retrofit" or something like that? -- Jedd Haas - Artist http://www.gallerytungsten.com http://www.epsno.com Sounds like there is some cold solder joint on the PCB in the amp have a look for something heavy in there that has come loose do the pencil probe to see if wiggling components makes anything happen. Doug |
#18
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"Jedd Haas" wrote in message
Also, the "old" woofer had an additional magnet (doughnut-shaped) epoxied to the back of the speaker. The "new" woofer lacks this magnet. Was the additional magnet a "retrofit" or something like that? The external magnet is there to reduce the speakers external magnetic field. It makes the speakers more friendly for CRT monitors. |
#19
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Thanks for all your replies. I'm leaning toward the flaky connection
theory. (I had a similar problem about six months back that was solved by switching from the XLR inputs to the TRS inputs.) So far it hasn't cut out again, so perhaps it was the bass switch or the wires connecting to the speaker lugs. -- Jedd Haas - Artist http://www.gallerytungsten.com http://www.epsno.com |
#20
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Jedd Haas wrote: Thanks for all your replies. I'm leaning toward the flaky connection theory. (I had a similar problem about six months back that was solved by switching from the XLR inputs to the TRS inputs.) So far it hasn't cut out again, so perhaps it was the bass switch or the wires connecting to the speaker lugs. -- Jedd Haas - Artist http://www.gallerytungsten.com http://www.epsno.com This exact thing happened to me yesterday.The problem was a dirty switch on the back. Scott Alger |
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