StevieD_FenderP2009 Posted December 13, 2009 Share Posted December 13, 2009 (edited) Hi there guys. I've got all my kit rackmounted which consists of: Trace Elliot GP12 Series 6 Head (mounted with a rack shelf) 2 AKG WMSPro40 Wireless Recievers Korg DTR2000 RackTuner Also, it's all plugged into a 6 way extention (with surge protection) socket thats been put onto a 1u rack piece Basically, i've got it all built in but there's this f***ing horrible buzzing noise coming from my head when it's all hooked up. I've tried all different cables etc but still the buzzing is there. and this buzz is awful, it's so loud it actually rumbles my cab the way i've got it connected is: Bass guitar 1 + 2 loaded with AKG Bugs on different frequencies -> Recievers -> inputs 1 and 2 on the back of the Korg Tuner seperately -> single output connected to the Active input on my Trace Elliot head (as both basses are active) -> output on back of head to Marshall JCM800 Cab I'll be honest when I say it's really upset me cos I am so proud of how i've worked to get all this equipment I don't know if there is an earthing problem as it started to happen when everything was fully bolted into place. Please note all the "rackears" from each component are metal so they could be interacting and causing a problem, also, the casing on the Trace head is metal and the casing on the wireless recievers is metal so could earthing/insulating be the problem? If so, how can i fix this? Everything is mounted into one of these 4u rackcases - [url="http://cgi.ebay.co.uk/ABS-4U-19-RACKMOUNT-FLIGHT-ROAD-TRANSPORT-RACK-CASE_W0QQitemZ370216164827QQcmdZViewItemQQptZUK_Musical_Instruments_Rack_Cases_MJ?hash=item56329a5ddb"]http://cgi.ebay.co.uk/ABS-4U-19-RACKMOUNT-...=item56329a5ddb[/url] That is the exact case by the way Please please help! i'm desperate, Especially as i'm meant to be playing a big make or break gig for a management company in a few weeks time Thanks so much Stevie Dewar Edited December 13, 2009 by StevieD_FenderP2009 Quote Link to comment Share on other sites More sharing options...
hubrad Posted December 13, 2009 Share Posted December 13, 2009 Hi Stevie, Disconnect everything before the amp. If the noise goes then it's not the amp (seems obvious, but basics!) Then plug in each item one at once. If one makes mad noise you have the culprit. Sooner or later you'll find the single item or combination that causes the problem. I assume you are using the proper power supplies for receivers and tuner? (Again - seems obvious but we can't see your gear at this distance!) Best of luck! [quote name='StevieD_FenderP2009' post='682763' date='Dec 13 2009, 02:49 AM']Hi there guys. I've got all my kit rackmounted which consists of: Trace Elliot GP12 Series 6 Head (mounted with a rack shelf) 2 AKG WMSPro40 Wireless Recievers Korg DTR2000 RackTuner Also, it's all plugged into a 6 way extention (with surge protection) socket thats been put onto a 1u rack piece Basically, i've got it all built in but there's this f***ing horrible buzzing noise coming from my head when it's all hooked up. I've tried all different cables etc but still the buzzing is there. and this buzz is awful, it's so loud it actually rumbles my cab the way i've got it connected is: Bass guitar 1 + 2 loaded with AKG Bugs on different frequencies -> Recievers -> inputs 1 and 2 on the back of the Korg Tuner seperately -> single output connected to the Active input on my Trace Elliot head (as both basses are active) -> output on back of head to Marshall JCM800 Cab I'll be honest when I say it's really upset me cos I am so proud of how i've worked to get all this equipment I don't know if there is an earthing problem as it started to happen when everything was fully bolted into place. Please note all the "rackears" from each component are metal so they could be interacting and causing a problem, also, the casing on the Trace head is metal and the casing on the wireless recievers is metal so could earthing/insulating be the problem? If so, how can i fix this? Everything is mounted into one of these 4u rackcases - [url="http://cgi.ebay.co.uk/ABS-4U-19-RACKMOUNT-FLIGHT-ROAD-TRANSPORT-RACK-CASE_W0QQitemZ370216164827QQcmdZViewItemQQptZUK_Musical_Instruments_Rack_Cases_MJ?hash=item56329a5ddb"]http://cgi.ebay.co.uk/ABS-4U-19-RACKMOUNT-...=item56329a5ddb[/url] That is the exact case by the way Please please help! i'm desperate, Especially as i'm meant to be playing a big make or break gig for a management company in a few weeks time Thanks so much Stevie Dewar[/quote] Quote Link to comment Share on other sites More sharing options...
EBS_freak Posted December 13, 2009 Share Posted December 13, 2009 Check your common ground, make sure you are running off one power supply, try and isolate each unit from toucing each other, use humfrees and pray to the Gods. Quote Link to comment Share on other sites More sharing options...
2x18 Posted December 13, 2009 Share Posted December 13, 2009 Take your 6 way extension out of the rack and keep it away from the amp and recievers! Its probably the adaptor transformers that are too close to your other gear. Will. Quote Link to comment Share on other sites More sharing options...
Musky Posted December 13, 2009 Share Posted December 13, 2009 +1 for everything that's been said here. Especially the humfrees since the problem seems to have started when it was bolted together. Quote Link to comment Share on other sites More sharing options...
StevieD_FenderP2009 Posted December 13, 2009 Author Share Posted December 13, 2009 (edited) Hi again guys I have moved the power supply out of the casing but the noise still occurs. i'm using the power transformers that came with the wireless kits, tuner and head as well. Also, i know it's not the head because when using the head as a stand alone, it doesn't make the noise Basically, unhooked everything and pieced it together bit by bit and the buzzing doesnt occur until i put all the things back in the rack. As said, i re-connected everything then started to put everything back into the rack and it seems to be when everything is back in there, almost like when all the components are touching that it makes the noise so is there any way to sort that at all? By the way, just to clairfy, all my cables are custom made noiseless cables in the rack. I have also tried out standard cables but the noise is still there Cheers guys Edited December 13, 2009 by StevieD_FenderP2009 Quote Link to comment Share on other sites More sharing options...
BigRedX Posted December 13, 2009 Share Posted December 13, 2009 Sounds like an earth loop problem. The way you appear to have everything wired up I would suspect the tuner to be at the centre of the problem. I would suspect either the tuner to amp connection or the fact you are using both inputs to the tuner. Put everything back in the rack but don't connect any cables (mains or signal). Connect your amp to the speaker(s) and the bass directly to the amp. That should be fine. If it isn't try removing the 6 way extension. If everything is fine, keep adding things in the order of this list and stop and report back when the hum reappears. 1. Plug in and switch on the tuner, but don't connect any signal leads to it. 2. Connect the bass to the tuner and the tuner to the amp. Try this with both inputs that you are going to use 3. Power up just one of the wireless receivers. 4. Connect this to the tuner. Also try it with the bass connected directly to the other input. 5. Power up the other wireless receiver. 6. Connect this up to the tuner. Because of how tightly everything is fitted into the rack (you'd be using a 6U case for all of this ideally) Humfree's probably won't work as the actually metal chassis of the individual units will be touching. You'll need to make up some ground-lift cables to put in the appropriate places which you'll have found by going through the sequence above. Details of how to do this can be found [url="http://www.epanorama.net/documents/groundloop/groundlift.html"]here[/url] Quote Link to comment Share on other sites More sharing options...
StevieD_FenderP2009 Posted December 13, 2009 Author Share Posted December 13, 2009 It does seem to be when ive connected everything to the tuner. later on, i shall try attaching the wirelesses into a splitter later on and then putting the splitter into a single input. I really hope this works... Also, thanks to BigRedX for the link, i shall try and work out how to do that. haha. So yeah, would it help if i connected a wire from the from rack piece to the rear one? Thanks so much Quote Link to comment Share on other sites More sharing options...
BigRedX Posted December 13, 2009 Share Posted December 13, 2009 So you don't get any hum with just one of the wireless receivers connected? Only when you connect the second one as well? If using the splitter instead of multiple inputs on the tuner doesn't work, you might also want to look at getting a single regulated power adaptor for both receivers. Actually since it appears you don't need both wireless units connected at the same time an A/B switch the connect the two to a single input on the tuner should be a better option. Quote Link to comment Share on other sites More sharing options...
Tengu Posted December 13, 2009 Share Posted December 13, 2009 I presume that the reason you have two wireless receivers is because you switch instruments during a gig. How about changing the frequency of the transmitters so that they are both the same and only use one receiver? As long as you ensure that you mute the transmitter that you are not using you would have no interference. Quote Link to comment Share on other sites More sharing options...
StevieD_FenderP2009 Posted December 13, 2009 Author Share Posted December 13, 2009 [quote name='Tengu' post='683264' date='Dec 13 2009, 07:22 PM']I presume that the reason you have two wireless receivers is because you switch instruments during a gig. How about changing the frequency of the transmitters so that they are both the same and only use one receiver? As long as you ensure that you mute the transmitter that you are not using you would have no interference.[/quote] Hi there dude Yeah i do change basses during the gig for different tunings but unfortunately i can't adjust the frequencies as theyre both fixed single frequency bugs and recievers. i'm going to try a few different things out with the setup tonight and post the results. If the noise is still there then i will go beserk haha Quote Link to comment Share on other sites More sharing options...
Mog Posted December 13, 2009 Share Posted December 13, 2009 is there a tuner out on the T.E? you could try taking it out of the signal path?Does the input led's indicate clipping/overloading when you get the noise? also are both recievers sending signals to the head at the same time? Quote Link to comment Share on other sites More sharing options...
StevieD_FenderP2009 Posted December 13, 2009 Author Share Posted December 13, 2009 [quote name='Mog' post='683430' date='Dec 13 2009, 09:34 PM']is there a tuner out on the T.E? you could try taking it out of the signal path?Does the input led's indicate clipping/overloading when you get the noise? also are both recievers sending signals to the head at the same time?[/quote] Hi there With regards to the input, it comes up flashing that there is an input signal even with no bass plugged in and the signal is pretty high. and regards to the reciever connections to the tuner, on the front of the tuner there is a button to select input 1 or 2 and when either one is selected, it deactivates un-used input until it is selected. There is an effects out from the front of the TE head but the reason i havent used it is because i dont want more wires running from the front of my head. Everything seems to work perfectly and the signal is crystal clear all apart from this buzzing noise I'm just about to try the splitter into the single input so i'll let you all know Quote Link to comment Share on other sites More sharing options...
StevieD_FenderP2009 Posted December 13, 2009 Author Share Posted December 13, 2009 Splitter hasnt worked... Quote Link to comment Share on other sites More sharing options...
StevieD_FenderP2009 Posted December 14, 2009 Author Share Posted December 14, 2009 (edited) right guys, just connected one wireless reciever straight to the TE head (still all rackmounted) without the tuner in the circuit and the noise is still there. then tried just my bass into the head and no noise, so i've determined it's not the head that has a problem. I think it's a grounding problem with the wireless kits but im most probably wrong so please tell me if you know EDIT!: Plugged bass directly into both input channels on back of tuner then ran a cable from the output on the back of the tuner to the TE head and there's no buzzing, just the pure signal. Definately the wireless kits causing this noise now. Any advise? please? Also, when i had everything connected but no bolts holding the wireless kit in place, there was no buzz, then i put 2 bolts in on the left hand size and still no buzz, then as i was putting the 2nd one in on the right hand side, the buzzing started... what the hell is wrong with my equipment! also it's worth noting that all the time i didnt have any bolts in, the wireless's were pushed in as far as they could and the ears were touching the case... so it's just when the bolts are in and screwed in as tight as possible Edited December 14, 2009 by StevieD_FenderP2009 Quote Link to comment Share on other sites More sharing options...
BigRedX Posted December 14, 2009 Share Posted December 14, 2009 As pretty much everyone who's posted here has suggested you've got an earth loop problem and now you've tracked down which piece of equipment is causing it - the wireless receivers. What is happening is that there are two discrete earth paths between the wireless receiver and the rest of the equipment in the rack, one via the signal cable and the second via the equipment casing. You need to remove one of these paths. You have two courses of action now. 1. You can try using some [url="http://www.thomann.de/gb/adam_hall_humfrees_5635.htm"]Humfrees[/url] to fit the wireless receivers into the rack. I would also fit a sheet of insulating material between the receivers and whatever equipment is above or below them in the rack to make absolutely sure that there is no way that the there is any electrical connection between the receivers casing and rack mounts and anything else in the rack. 2. You can make up 2 earth lift cables to connect your two wireless receivers to the tuner. You'll need one for each receiver. This is a normal unbalanced signal cable except that the earth (screen) cable is either completely disconnected or connected via a 10nF capacitor. The completely disconnected one is the easiest to make since you simply trim back the screen and don't solder it to the plug. make sure that the is no chance of the screen touching the earth of the jack plug by wrapping it in insulation tape. The capacitor version is better since it maintains the continuity of the screen and therefore reduces the chance or RF interference, but obviously you need to fit a capacitor into the jack plug. Mark up the cable as ground lift so you don't accidently use it for something else (it won't work) and connect it with the lifted jack plug going into the receiver (this gives the best screen continuity). Hope one of these solutions will sort out your problem. Quote Link to comment Share on other sites More sharing options...
StevieD_FenderP2009 Posted December 14, 2009 Author Share Posted December 14, 2009 Hey cheers BigRedX I think i'm going to have to go for the Humfree's as i got slightly confused when reading about the earth lift cables (i'm a bit stupid haha) So yeah, i'll order some and see what happens with it all This is really wierd though. today i turned it all on and had it re-built EXACTLY how i had it before and all bolted in as tightly as possible and guess what... NO BUZZING?!!?!?!! Really wierd man. I'm scared the problem will come back and it might even come back during a gig which wont be good so i'm going to take every precaution necessary Cheers Quote Link to comment Share on other sites More sharing options...
BigRedX Posted December 15, 2009 Share Posted December 15, 2009 If you're going to go the Humfree route, I suggest that you get them for every piece of equipment in the rack, not just the receivers. Incidentally, how are the receivers rack mounted? I had a look on the AKG web site and they appear to be 1/2 rack units. Do they have a special AKG rack mounting kit or have you fitted them to a generic 1U rack shelf? I also noticed that the amp isn't a dedicated rack mount model, but something you've modified to make fit. Has this been done professionally? What order do you have the equipment mounted from top to bottom in the rack? It might be worth posting some good, clear (in focus) photos of the front and back of the rack with everything in place and cabled up, it might shed some light on the problem. Quote Link to comment Share on other sites More sharing options...
StevieD_FenderP2009 Posted December 15, 2009 Author Share Posted December 15, 2009 Hi mate I'll add some photo's for you later on When the buzzing first started, i had the tuner at the top (1u), recievers underneath that (1u) and the Trace head at the bottom (2u) Now i've got it with the Trace at the top, recievers in the middle and tuner at the bottom so the light from it beems down onto my cab and lights up the Marshall logo (tarty aint it haha) With regards to the Reciever rack mounts, they are half units but AKG do a kit called the RMU40 which has 2 small attachments pieces to connect the 2 recievers to each other and then 2 rack ears to put either side of the kit. Also, if you want to use just one reciever, it has a half unit rack ear to take up the empty gap. here's a link to the mounting instructions for you to take a look at: [url="http://www.akg.com/mediendatenbank2/psfile/datei/15/rmu40pro4469973552698.pdf"]AKG RMU40 Mounting Instructions[/url] I'm popping down to my dads a bit later so i'll get the pictures for you when i go down there. As you said, i'll get humfrees for each piece of equipment. Oh, just noticed your question about the head. and no, it's not the rack specific version but with a 2u rack tray bolted to the top of the chassis it fits in to a rack (i was advised to do this by a fellow basschatter). It's just plainly bolted on to the chassis by the 4 bolts that had it screwed into the wooden casing it came in. There is also a small washer inbetween the tray and the rack chassis. This was all done by my dads mate who has the tools for doing stuff like that. it's fit so securely to the tray it has no hope of coming out of it Cheers dude! Quote Link to comment Share on other sites More sharing options...
Mog Posted December 15, 2009 Share Posted December 15, 2009 Hey steve,sorry for not getting back sooner,had bloody exams today.Seems like BigRedX is on the ball.If its not a grounding issue im stumped. Good luck with it lad, hope it works out for Quote Link to comment Share on other sites More sharing options...
StevieD_FenderP2009 Posted December 15, 2009 Author Share Posted December 15, 2009 (edited) [quote name='Mog' post='685493' date='Dec 15 2009, 06:03 PM']Hey steve,sorry for not getting back sooner,had bloody exams today.Seems like BigRedX is on the ball.If its not a grounding issue im stumped. Good luck with it lad, hope it works out for[/quote] Hey there mog, no worries man, cheers anyways and hope the exams went well dude. But as i promised earlier, here are the pictures of the inside of the back of my rack and the front Please remember the yellow cable from the output on the tuner is the yellow cable running into the input on he head Front view Back view also, the buzzings back again ARGH! Edited December 15, 2009 by StevieD_FenderP2009 Quote Link to comment Share on other sites More sharing options...
BigRedX Posted December 15, 2009 Share Posted December 15, 2009 I'll wait for the photos, but from what you've said you will probably need more than just Humfrees to sort out your problems for good. Thanks also for the link to the AKG mounting kit. I'm assuming you're using the two side by side method? I also have a sneaking suspicion that the culprit is actually the amp. I'm guessing that normally this would have been in a wooden 'sleeve' (I seem to remember a thread about this some time ago) and therefore there wouldn't have been any reason for other bits of equipment in the signal chain to be touching the metal of the front or back panels. Now that you've made a rack mounting for it the whole casing has become connected to earth, and because in some configurations of your set up it was touching the casings of the other equipment you are getting earth loop hum. Well-designed audio equipment isolates the signal earth from the mains earth at signal level voltages so that you don't get earth loops, but if there is a mains fault the earth will still work and blow the fuse. I would suggest that you get your amp conversion looked at by someone with good audio equipment electrical knowledge to make sure that it's still safe. The Humfrees will isolate each piece of equipment from the rack itself. but they can't do anything about the top of one piece of equipment touching the bottom of another, which is what is causing the problem, so you may have to look at adding some insulating material between each layer in the rack so that none of the metal parts of one piece of equipment are touching another. Also while the current arrangement of gear in the rack may look good, it is always best practice to fit the heaviest piece (usually the amp) in the bottom of the rack to lower the centre of gravity and also so you aren't relying on the rack ears and the mounting frame of the rack to take the whole weight of the equipment. You might not be getting any hum and buzz at the moment from the current arrangement, because it just so happens that the casing earths of the the two culprits aren't touching, but load the case in an out of a few gigs/rehearsals and everything might settle and bring back the problems. Quote Link to comment Share on other sites More sharing options...
BigRedX Posted December 15, 2009 Share Posted December 15, 2009 Also having seen the photos I'd start right away by getting all your power cables as far away from your signal cables as possible. Looking at the rack from the back, it seems that most of your audio connections are being made on the right hand side of the rack, so run all your power cables on the left and keep them there. Don't mix them up with the audio it's not good. Get some cable ties and self-adhesive cable clamps and keep everything neat and separate. Then work through the advice in my previous post. Quote Link to comment Share on other sites More sharing options...
StevieD_FenderP2009 Posted December 15, 2009 Author Share Posted December 15, 2009 Ok dude, cheers for the advise. I'll have a go at that tomorrow when i get in then go through the other steps you posted on there cheers Quote Link to comment Share on other sites More sharing options...
StevieD_FenderP2009 Posted December 21, 2009 Author Share Posted December 21, 2009 Close to throwing it all out the window now Took it all apart again today as it was still humming then re-wired it Put it so that i had both wirelesses running into a dual to single splitter which was run into the input on my head with the "effects out" output being run to the input on the tuner and guess what BUZZZZZZZZZZZZZZZZZZZZZ so i threw a bit of a strop, turned it off, put it in my cupboard and locked it away. didnt want to even look at it as it's annoyed me that much (sounds like a kid has pissed me off haha) I think i might have to take it into my local music shop and have them look at it for me. See what they say about it all £600's worth of equipment and i can't even use it properly... ~ARGH~ Quote Link to comment Share on other sites More sharing options...
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