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Post by merton on Dec 26, 2006 1:05:05 GMT
there's this electrical buzzing noise coming from my amp. the noise comes from both channels but the right is quite a bit worse. what is causing this and how do i fix it? the loudness of the buzz seems to change at times. the amp is a meta 42
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Post by merton on Dec 26, 2006 1:10:25 GMT
it had been buzzing from day one... i sent it back, got it back, sent it back, got it back.. the the last time i got it back the buzzing was better than it was when i first sent it back... with these er6i's i have the buzzing is somewhat noticeable. i don't recall it being this loud with my ultrasones which were, i think, 60 or 70 ohm versus my er6i's 17 ohms.
the ety's seem harder to drive for some reason.
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rickcr42
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Post by rickcr42 on Dec 26, 2006 1:22:54 GMT
two possibles here
1-the amp is in a strong RF field and needs to be moved
2-there is a bad ground internally and if you had the amp "repaired" yet it is still there I would ask for a refund or a working amp and no less !
No way would I take delivery of an amp that buzzed like a hornets nest without expecting the amp to be 100% working as advertised.
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Post by merton on Dec 26, 2006 1:31:37 GMT
it's near my monitor, my pc, and my computer....
also, i should mention that i plugged it into a wall socket that had no other hardware plugged into it and the buzz was a little, but noticeably, louder than when i have it plugged into my surge protector that has all my pc and tv crap plugged into it.
also, that wall socket was farther from my pc than the surge protector.
is there any place to get an impedanzer for cheap? one that's also a mini to 1/4 adapter would be nice.
i've had the amp for 3 years now... i don't think i could even find the seller anymore.
i looked inside it earlier, and there was electrical tape on the bottom of the lower circuit board. ... i don't think it's even touching the case. i recall when i first got it that it did have that. i think it reduced the noise a bit.
i'm not sure what other info i have on it.
this post has been heavily modified.
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rickcr42
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Post by rickcr42 on Dec 26, 2006 1:52:12 GMT
I am going to make the assumption the amps is not only in a plastic case but has no input or output RFI filters/RFI decoupling,loop filters or a good ground scheme and that while the AC mains may not be the cleanest are likely not the problem.
An easy test here is :
Play some music through your headphone system then-
1-Grab the Ferrite clamp off your monitor cord if it has one and put it over the input cable of one channel.Does this help ? If it reduces or eliminates the problem then you fix is to get someone to add a proper RFI network to the input jacks of the amp (nternally)
2-If nothing happened try it on the output cable.If that eliminates or reduces the problem you will need either feedback loop compensation caps,some series resistance on the output or both.Really cheap to do if you can find someone to do it for you
3-listen for changes in the level or tone of the buzz as you sit there and move the amp front,back,left,right,and angled.If THIS changes the intensity or tone of the problem buzzing you neeed to used a shielded chassis to house the amp plus would not hurt to at the same time add the above filters/decoupling networks
if none of the above change the amps buzzing likely it is a design flaw or a bad assembly job where you may need to have someone make sure your grounds have a good connection or worst case re-route the grounds entirely.
A place to start anyway
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Post by merton on Dec 26, 2006 1:55:18 GMT
"17ohm impedance could have something to do with it? Or should I say the buzz will be more evident with low Z cans. Is there any buzz with high impedance 'phones MERTON?"
it was there with my grado's (32ohm)... i don't think it was there with my ultrasone(60 or so ohm)... i can't recall it being there with the ultrasone.... i'm not really sure with the ultrasone
"If you're good with a screwdriver open the amp up... take some pictures and post them here."
will do. although i can't remove the pcb from the case. the wires going to the rca's are too short for that.
"If you wave your hands across the amp does the buzzing vary in tone / magnitude?"
seems to have no effect
" Have you explained to them that you're using 17ohm 'phones? not a problem in themselves but can highlight buzz in a much more spectacular way than high impedance 'phones"
the builder was a DIYer... the amp is 3 years old. the last few time i sent it back the shipping was ridiculous in cost.
" do you have a cheater plug?" i don't know
this amp was originally designed for some grado ms2's
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Dec 26, 2006 2:07:29 GMT
well that at least is a good sign.short wires are less prone to stray RF and especially so if they are twisted pairs (hot/ground)
and folks beat me up for recommending legitimate amp manufacturers over "DIYers" that may or may not give you a usable product and if not usually you are screwed ?
Having to pay even for postage to have an amp repaired that never worked is a total rip off unless for one reason or another the problem can be shown to be user related (like screwing with the internals.dropping it hard,getting it wet,etc.).I personally would be pissed if I had an amp that NEVER worked correctly that when everything is added up ends up no bargain at all,especially when the amp never DID get fixed properly.
Buy second hand reputable products if you are on a budget or you really are rolling the dice and hoping you make your markbefore rolling craps otherwise.The odds are just not good enough for the DIYer For Profit option to be a good one unless you KNOW the track record of that person both good and bad
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rickcr42
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Post by rickcr42 on Dec 26, 2006 2:09:21 GMT
highly doubt it mike considering the topology.What a low Z combined with good efficiency WILL DO is show up existing problems but not make new ones due to the load impedance.at least that has been my experience so am open to other exanples here.
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Post by PinkFloyd on Dec 26, 2006 2:23:28 GMT
Sorry Man sorted
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rickcr42
Fully Modded
Rest in peace my good friend.
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Post by rickcr42 on Dec 26, 2006 2:29:09 GMT
you are a better man than me mike considering the time zone differences (just a tad before 9:30 PM here) because my ass is whipped after a very long though festive day so the rickmonster bids all a g'night.tomorrow is another day so better a refreshed know nothing than a half buzzed tired old man posting nonsense
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Post by merton on Dec 26, 2006 2:30:24 GMT
oh... and i recall him not finding any problem with buzzing. he had some hd 600's though... so that could be why.
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Post by PinkFloyd on Dec 26, 2006 2:41:30 GMT
simple question Rick,,,,75ohmh would stop the buzzing? If so job done? or not so.......in fact 75ohm may cover over the real problem.
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Dec 26, 2006 2:55:15 GMT
I'm thinking cover the problem much like using an amp that is noisy with efficient speakers with low efficiency speakers does and why you can get two entirely different opinions on the same amp even though both are correct in the system context.
You are not getting rid of the noise just lowering the levels which may or may not be good enough in this case though for me personally not a "fix" but a bandaid
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Post by merton on Dec 27, 2006 6:01:29 GMT
so... what should i do?
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rickcr42
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Post by rickcr42 on Dec 27, 2006 6:21:58 GMT
did you try all the above recommended steps ?
Almost impossible to track down noise or hum online unless you isolate the reason so you need to nail down if it is an internal problem (likely if it has always buzzed) or caused by the surrounding environment.
Internal will likely be a real bitch to fix without pictures and your willingness to grab a soldering iron to make any needed corrections.
External can be easier to deal with if it means just adding RF clamps to the interconnects or headphone wire depending on entry point of the RFI/EMI and that more of a process of elimination than anything else though even here it would be far better to get to the internals and add proper compensation internally.
BTW-does it buzz with both battery operation AND AC line powering ?
all about the process of elimination
**
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Post by merton on Dec 27, 2006 7:33:14 GMT
it's wall wart powered only.
i don't know what a ferrite clamp is... what is it?
nothing i seem to do changes the buzz. sometimes it quietens a little... but that may just be my ears settling around my ety's...
i'll post pics when i use up this roll of film.
are there any particular shots you want?
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Dec 27, 2006 15:47:45 GMT
can you get someone to whip you up a properly terminated (correct plug) battery pack ? Would really go a long way if the power supply could be eliminated right away as the cause. those big BLOBS on your computer AC cables are ferrite clamps.They prevent RFI from going into a piece of equipment by filtering anything above a certain frequency but they only work if they are on the cable RIGHT AT the input connection.any gaps and you defeat the purpose. If you have any old computer power cords laying around not being used remove them and add them to your amp,if not Radio shack carries them (a bit expensive is my opinion but convenient) and maybe Circuit City,Home Depot.Etc. they look like this (but can be any color from white to grey to red to blue...) : cheap Mouser mail order www.mouser.com/catalog/627/1836.pdfRadio Shack "walk in and buy" instant gratification www.radioshack.com/product/index.jsp?productId=2103222&cp=&origkw=ferrite&kw=ferrite&parentPage=searchIf your amp uses RCA jack inputs you need two if the problem is the input cables,a singl one if coming into th feedback loop from the headphone cable so you would open one,try it on the output FIRST then if that does not work open the other package and put them over the input cables. Again they only work if snugged right up close to the jack end of the cables closeup shot of the board from the top with the cover removed,closeup shot of the power supply entry and audio entry,close up of the output connections and finally a pic of the wall wart so we can see what type it is
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Post by PinkFloyd on Dec 27, 2006 15:58:47 GMT
Take a piece of aluminium foil and wrap it around the amp ....and bake in a moderate oven until tender ;D
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Dec 27, 2006 16:14:10 GMT
"Is it done yet ! I'm getting friggin' hungry over here !"
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Post by merton on Dec 28, 2006 7:27:49 GMT
the buzzing increases a good bit when i connect the amp to the line out of my pc. i'm using a cheap straightwire rca to mini cable.
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Dec 28, 2006 17:09:39 GMT
do you nhave access to an equalizer ? if yes put it between your source and the amp then just for thre hell of it slide the top band control (usually 10KHz) to full cut.If that solves the problem you need to have someone get inside the amp and add in input RFI filter (caps across the input jacks ). If not your amp may have a wonky ground structure and may need a ground breaker at the input.Try the cheap Rat Shack ones for a test then if it fixes the problem throw the amp in the trash or sell it because the fix,real audio quality transformers,will cost more than the amp is worth. we really could use some pics to "see" if there is an obvious screwup in either the design or construction of the amp that can be easily/cheaply fixed
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Post by merton on Dec 31, 2006 3:49:28 GMT
i'll have pics up tommorow...
it's supposed to "thack" when turned on and "thoomp" when turned off .... right?
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rickcr42
Fully Modded
Rest in peace my good friend.
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Post by rickcr42 on Dec 31, 2006 4:47:25 GMT
nope
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Post by merton on Dec 31, 2006 5:16:51 GMT
oh.... how bad is that it does that? is the amp safe to use?
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lini
Been here a while!
Groanings from Han(g)over
Posts: 191
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Post by lini on Dec 31, 2006 12:56:34 GMT
Merton: Is there anything in your system that's connected to an antenna wall-socket - e.g. a tv card in your pc? If so, plug out the antenna cable and give it a check: If the buzzing is significantly reduced, then you usually just need an antenna ground breaker/hum filter (e.g. Xantech 634-00; ~ US$ 10).
Greetings from Munich!
Manfred / lini
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