Dave The Rave Posted June 13, 2004 Share Posted June 13, 2004 I'm at my wit's end One of my Mackie HR824 speakers seems to be much more sensitive to RF than the other one. Wierd. When I key up one of my transmitters (ham stuff), one of the speakers turns itself ON and belts out all kinds of spikey sounding noise. The other one is completely silent. If I unplug the audio feed cable to it, it doesn't do it, so the RF is getting in there. However, the cables and the cable routing are identical for both speakers - I even tried swapping the cables - no difference, the problem stays with the speaker. Putting an RF choke toroid on the audio cable makes no difference. All the tests I have done point to an internal problem in the Mackie speaker. Anyone ever heard of a problem like this? I guess I should contact Mackie support and ask them about it too. The only cure I have right now is to completely unplug the power cord to the offending speaker if I want to go on the air (which sucks as a solution....). Any ideas/insight? Cheers, :DTR Cambrian Guitars Link to comment Share on other sites More sharing options...
Dave Horne Posted June 13, 2004 Share Posted June 13, 2004 Have you tried physically repositioning the speaker? Instead of patch cords can you use shielded mic cable as an input to speaker ... would that be effective in reducing the RF? The easiest solution might just be a power strip with an on/off switch that you can easily press with your foot or your hand. Sorry not to be of more help - you know more about this stuff than I. No guitarists were harmed during the making of this message. In general, harmonic complexity is inversely proportional to the ratio between chording and non-chording instruments. Link to comment Share on other sites More sharing options...
synthetic Posted June 13, 2004 Share Posted June 13, 2004 Try switching to balanced cables if you can, but this may not work. I had this problems with some JBL speakers in my old studio and could never track it down. Link to comment Share on other sites More sharing options...
Markyboard Posted June 13, 2004 Share Posted June 13, 2004 Before calling Mackie, I would anticipate all questions. Beside swapping cables (good start)I would also swap monitors. I would want to know if the AC outlet where the problem speaker is plugged in has something to do with it and/or whether speaker placement changes things. If your problem stays with the original problem speaker then I would think there's something different in the power filtering going on. Of course this could all be retribution for when my brother would operate his ham while I was trying to watch Gilligan's Island. CQ...CQ Link to comment Share on other sites More sharing options...
NoLights Posted June 13, 2004 Share Posted June 13, 2004 Try different lengths of cable - the one you're using may actually be resonant at some harmonic frequency of the RF source. Another quick fix might be to use ferrite beads (no, not ferret beads, that's something very different). These are little clamp-shaped devices made of metal (tho maybe covered in a plastic skin) you can clamp over a wire, and it can drain away currents that are running along the outer skin of the cable. In extreme cases, you can cut the cable, and insert a small disc capacitor in the (I think) ground wire. If you get to that point, let me know - I've got the diagram in a book somewhere. And yes, I'm a ham op (K1ZQC), and was an engineer for a 50,000 watt FM station - so I've had to fix a lot of RF interference. A LOT of RF interference. At one of the venues I play at, an upscale bar at the top of Portland, Maine's tallest building (12 stories), I often get sudden bursts of shortwave radio. Generally in the middle of a quiet ballad, you'll hear "this is the BBC World Service." It can be a mood killer. _______________________________________________ Kurzweil PC4; Yamaha P515; EV ZXA1s Link to comment Share on other sites More sharing options...
Steve LeBlanc Posted June 13, 2004 Share Posted June 13, 2004 without knowing more...my guess would be it's a problem with how the speaker is getting AC Make sure both speakers are receiving power from the same source (same powerstrip, outlet) and that they are both grounded (or ground-lifted)...also make sure your computer/monitor/audiocard/etc. are on a different power strip...try lifting the ground on both the speakers while keeping the rest of the system grounded...or vice-versa hope that helps...good luck http://www.youtube.com/notesleb Link to comment Share on other sites More sharing options...
Dave The Rave Posted June 14, 2004 Author Share Posted June 14, 2004 Thanks for all the suggestions folks. I tried swapping the speakers over, swapping the ac cables over, more RF toroids (clamp-on ferrites) moving them around etc. all to no avail. It's the speaker itself that has the problem - my bet is that there's a dry solder joint or poor mechanical connection in the chassis ground somewhere. The cables I have are balanced (XLR's into the monitors) but they are not shielded at all - I will buy some shielded cable and make a set of cables with it to see if that helps (it should, since the problem goes away if the audio input cable is unplugged from the monitor). For now, I'm going with the separate power outlet strip that I can turn off when I want to transmit. Maybe it's a hint that I should be spending less (wasted) time on the air and more time making music?! Cheers for now, :DTR Cambrian Guitars Link to comment Share on other sites More sharing options...
boxerpaws Posted August 11, 2004 Share Posted August 11, 2004 Hey Dave, what's your call? "boxerpaws" aka N3XFQ..almost had my general class license. 73's. http://img.villagephotos.com/p/2003-9/409907/CatholicPill_30223.gif http://p075.ezboard.com/fcatholicpillarandfoundationfrm24 Link to comment Share on other sites More sharing options...
Dave The Rave Posted August 11, 2004 Author Share Posted August 11, 2004 Hi there Boxerpaws "old man", nice to make your acquaintance! My callsign is AD6A ( www.ad6a.com ). I'm one of them there "real" extras (you know, 20 wpm Morse code days). Look for my callsign in the 10GHz and Up Cumulative Contest again this year - that's what I spend my ham-time doing mostly. You'd be surprised to find out how many hams own Hammond organs and play keyboards...I don't get the connection myself, but it's there. Cheers for now es best 73, :DTR Cambrian Guitars Link to comment Share on other sites More sharing options...
Slowly Posted August 11, 2004 Share Posted August 11, 2004 Do these speakers automatically turn themselves on when you start playing? Kcbass "Let It Be!" Link to comment Share on other sites More sharing options...
Dave The Rave Posted August 12, 2004 Author Share Posted August 12, 2004 Nope, they don't Kcbass. You have to turn them on or off manually. They have a small power switch on the front that always seems to be live (driven by a standby low-power supply I think). I think the small front panel switches drive a more powerful semiconductor switch (or relay?) that applies power to the amps. The RF interference is affecting the on/off switch circuitry, turning the speaker ON and giving humungously loud blasts of noise! What's very telling is that one of the speakers does it and t'other doesn't. If I swap the speakers over, the problem goes with the speaker! Seems like a problem just with that particular speaker to me. I have been simply turning off the power altogether when I'm not using my studio setup, like Dave H. suggested earlier in this thread. It's a bit of a pain, but it works. I will take the matter up with Mackie sometime.... Maybe it's time for some Adam's? Cheers, :DTR Cambrian Guitars Link to comment Share on other sites More sharing options...
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