OldGit Posted June 1, 2007 Share Posted June 1, 2007 (edited) My sparkling new Mark Bass LMK is causing interference on the dining room Midi Stereo unit on FM radio .. Seems strange .. It's plugged into the same power socket but a good 4 feet away from the FM wire ariel .. Does that sound normal or do I need to talk to the shop it came from. I'd rather resolve this before I gig it .. Any thoughts? OG Edited June 1, 2007 by OldGit Quote Link to comment Share on other sites More sharing options...
Sugden Posted June 1, 2007 Share Posted June 1, 2007 Cant say I'v ever exsperienced that while being at home... Not sure how common or if it should happen though. I would have thought not Quote Link to comment Share on other sites More sharing options...
Kiwi Posted June 1, 2007 Share Posted June 1, 2007 Can you describe the interference a little more? Is it hum or crackle? Quote Link to comment Share on other sites More sharing options...
OldGit Posted June 1, 2007 Author Share Posted June 1, 2007 (edited) [quote name='Crazykiwi' post='10725' date='Jun 1 2007, 07:24 PM']Can you describe the interference a little more? Is it hum or crackle?[/quote] It's radio interference - ie the station hisses when I turn the amp's power on and stops when I turn it off. I am reminded of when the air is really, really cold and the FM and telly signals weaken .. Perhaps this is one of the fabled MB LMK "Black Hole" prototypes and it's sucking all into its inner depths .... Oh sorry, They film Dr Who around here you know ..... I'll try plugging the power lead into a different spur of the house ring main. Edited June 2, 2007 by OldGit Quote Link to comment Share on other sites More sharing options...
BOD2 Posted June 1, 2007 Share Posted June 1, 2007 It's usually the other way round - you get radio stations coming through your amp ! The only thing I can think of is that the amp will be generating a reasonably strong electromagnetic field (all electrical devices to to some degree) and that this is somehow interfering with the FM aerial. I've seen problems where a freestanding power supply caused serious mains hum to be picked up by an amplifier. Moving the power supply (only a by a foot or so) or rotating the power supply would fix the problem so I figured that it's electromagnetic field was being picked up by a lead or by the amp itself. Sounds odd, but have you tried turning the amp a little, or as much as 90 degrees. The change of alignment might lessen the pickup. Quote Link to comment Share on other sites More sharing options...
DrGonzo Posted June 1, 2007 Share Posted June 1, 2007 Hmmm.... if the amp is 4ft away from the FM aerial I'd say it wouldn't be any EM interference from the amp / speaker itself. Most likely AC interference... does the radio have a CD player or some other playback device? If so, does the same thing happen, or is it only the radio? Quote Link to comment Share on other sites More sharing options...
OldGit Posted June 1, 2007 Author Share Posted June 1, 2007 Ok Tried a few things .. Same power source, moved the amp 12 feet from the radio, still some interference (its just the radio, not on CD) Different mains spur, no change Tried a portable FM radio right on top of the amp and got thw same thing. When turning the amp off I can hear the power draining out through the radio fizzzz as the lights fade away (capacitor drain I guess) So yeah EM interference is my guess too .. So part two: Working as designed or back to the shop? I guess I'd better try my wireless to see if that is affected as Iintended it to sit next to the head. Quote Link to comment Share on other sites More sharing options...
obbm Posted June 1, 2007 Share Posted June 1, 2007 Ahah found the topic. I have a similar problem with the Epi 502. It blots out my ghetto blaster in the garage. I'm sure it's from the PSU or Class D power amp. Considering that the UL502 is CE marked I would have expected it to have been properly tested. No such problems from the Ashdown ABM or the valve heads. Problem solved by running a CAT5 into the garage and installing a gash PC. Nw have acces to the music server and radio via the web. Quote Link to comment Share on other sites More sharing options...
DrGonzo Posted June 2, 2007 Share Posted June 2, 2007 Weirdness! Maybe just slap some tin foil on top of the amp? Quote Link to comment Share on other sites More sharing options...
OldGit Posted June 2, 2007 Author Share Posted June 2, 2007 [quote name='DrGonzo' post='10862' date='Jun 2 2007, 01:01 AM']Weirdness! Maybe just slap some tin foil on top of the amp?[/quote] Do I still need to do that if I'm wearing my Anti-Alien mind reading hat? Quote Link to comment Share on other sites More sharing options...
Kiwi Posted June 2, 2007 Share Posted June 2, 2007 [quote name='OldGit' post='10904' date='Jun 2 2007, 08:29 AM']Do I still need to do that if I'm wearing my Anti-Alien mind reading hat? [/quote] Blimey, if thats what he does for mind reading, I shudder at the thought of how he stops their anal probes. Quote Link to comment Share on other sites More sharing options...
OldGit Posted June 2, 2007 Author Share Posted June 2, 2007 [quote name='Crazykiwi' post='10909' date='Jun 2 2007, 09:07 AM']Blimey, if thats what he does for mind reading, I shudder at the thought of how he stops their anal probes.[/quote] Why would he want to stop them? Quote Link to comment Share on other sites More sharing options...
Kiwi Posted June 2, 2007 Share Posted June 2, 2007 [quote name='OldGit' post='10917' date='Jun 2 2007, 09:19 AM']Why would he want to stop them? [/quote] LMAO why would he want to [i]encourage[/i] them?! Quote Link to comment Share on other sites More sharing options...
Dood Posted June 2, 2007 Share Posted June 2, 2007 I think they'd take one look at him, turn on all 3 heels and run away as fast as possible! Quote Link to comment Share on other sites More sharing options...
Dood Posted June 2, 2007 Share Posted June 2, 2007 Back to the point though.. Do MB heads use a switch mode powersupply? They use *in laymans terms* high frequency switching (usually 100Khz or higher I believe) could the radio be picking up this 'rf' output? Quote Link to comment Share on other sites More sharing options...
Dood Posted June 2, 2007 Share Posted June 2, 2007 I couldnt find a better way to describe it so I went on a googlehunt [url="http://en.wikipedia.org/wiki/Switched_mode_power_supply"]http://en.wikipedia.org/wiki/Switched_mode_power_supply[/url] Quote Link to comment Share on other sites More sharing options...
Gazm Posted June 2, 2007 Share Posted June 2, 2007 I'd say it was faulty. If they all do this they would have failed the EMC testing part of the CE marking. Pete. Quote Link to comment Share on other sites More sharing options...
OldGit Posted June 2, 2007 Author Share Posted June 2, 2007 [quote name='Gazm' post='10980' date='Jun 2 2007, 11:54 AM']I'd say it was faulty. If they all do this they would have failed the EMC testing part of the CE marking. Pete.[/quote] ha ha yeah well I called the shop and they guy told me it's normal for some amps to pick up strong radio tramsmissions some time "No" I said, "it's not receiving. It's [i]transmitting[/i]" at which point he got all excited and rushed round with his FM portable and found out that all the MB amps he had in the shop do it .... So I'm going to email Marco and ask him directly - hey why not. I tried the double layer of cooking foil (on the amp, not my head) and it did reduce the interference a little so I think we have identified the problem .. Thanks Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted June 2, 2007 Share Posted June 2, 2007 [quote name='OldGit' post='10987' date='Jun 2 2007, 07:11 AM']So I'm going to email Marco and ask him directly - hey why not.[/quote] It is a fault, one that wouldn't get past FCC regulations this side of the pond, I'm sure you've got a bevy of similar bureaucrats on your side who'd be similarly upset. Quote Link to comment Share on other sites More sharing options...
obbm Posted June 2, 2007 Share Posted June 2, 2007 (edited) [quote name='Bill Fitzmaurice' post='11069' date='Jun 2 2007, 03:43 PM']It is a fault, one that wouldn't get past FCC regulations this side of the pond, I'm sure you've got a bevy of similar bureaucrats on your side who'd be similarly upset.[/quote] European EMC Regulations. Like I said my Epifani UL502 does the same. Edited June 2, 2007 by obbm Quote Link to comment Share on other sites More sharing options...
ashevans09 Posted June 6, 2007 Share Posted June 6, 2007 I'll be honest when I read the title I was thinking of that "Spinal Tap" moment at the army base...I'm now slightly disappointed Yeah I'd just say try throwing some tin foil on it... Quote Link to comment Share on other sites More sharing options...
OldGit Posted June 6, 2007 Author Share Posted June 6, 2007 [quote name='ashevans09' post='13302' date='Jun 6 2007, 09:13 PM']I'll be honest when I read the title I was thinking of that "Spinal Tap" moment at the army base...I'm now slightly disappointed Yeah I'd just say try throwing some tin foil on it...[/quote] Yeah that did dull the effect a bit, as does me crouching down in front of the amp (maybe that's what the modern amps expect... ) Rotating the head on the top of the cab makes it much worse .. and No reply from Mark Bass yet ... I tred my wireless syetm and it's fine so I'm not really worrying about it. Quote Link to comment Share on other sites More sharing options...
ashevans09 Posted June 10, 2007 Share Posted June 10, 2007 Ah cool, well good luck anyways Quote Link to comment Share on other sites More sharing options...
OldGit Posted June 25, 2007 Author Share Posted June 25, 2007 [quote name='ashevans09' post='13302' date='Jun 6 2007, 09:13 PM']I'll be honest when I read the title I was thinking of that "Spinal Tap" moment at the army base...I'm now slightly disappointed Yeah I'd just say try throwing some tin foil on it...[/quote] I finally got it down to a reasonable level by repositioning the radio ariel... Thanks for everyone's help Quote Link to comment Share on other sites More sharing options...
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