Re: Shielding, was: Constant buzzing - can it be killed!

[Matthias Grob <matilists@gmail.com>]

sorry, I did not read the whole story, so I may say something stupid, I 
just try:

- there is electrostatic and electromagnetic interference. 
If the noise is just picked up by magnetic pickups, its the magnetic noise 
and all the high frequency stuff is unlikely the problem, much rather some 
big transformer, motor or wiring loop, basically a coil. 
If a unshielded wire also picks up the noise, its electrostatic and there 
are many more options of sources.

- as long as you have suspects for any household machine, its easier to 
just disconnect that system than typing the suspect here ;-) . you can 
even try switching off whole parts of the house with the main fuses or 
connect your whole system to a different part of the house with an 
extension.

use the narrow down strategy and eliminate options systematically. 
this strategy can fail, though, if its a combination of noise sources.
so it may be interesting to put all tests on a paper and rethink them if 
nothing seems to make sense...

good luck!
Matthias

On 15 Mar 2010, at 00:10, Kris Hartung wrote:

> I'll try to do an experiment this week, Bill, and run my system with all 
>the wireless routers and sattelite TV gear off.  I was thinking something 
>similar.
> 
> Here at my house, we have a wireless router for internet, plus two relay 
>routers that expand the reach.  Then we have three separate wireless LAN 
>phones, all running on different frequencies.  Then we have a separate 
>wireless system for the TV system, which connects it to the laptop, etc.
> 
> Our house is a literal bath of wireless frequencies. I am wondering if 
>all that, with my guitar mag pickup, is part of the problem.
> 
> I'll let you know if the isolation transformer I bought solves the 
>problem.
> Kris
> 
> ----- Original Message ----- 
> 
>> I have been trouble shooting a noise problem of my own recently that  
>has finally been identified, after much consternation that I thought  I'd 
>share even though it may not be directly applicable to Krispen's  recent 
>issues. For the past several months I have had an intermittent   high 
>frequency noise issue that only manifested when I was recording  1/2 
>speed loops on the looperlative. I'd record content and get this  High 
>frequency whine, embedded in my loops that would go away when I  toggled 
>back to normal speed. My initial thought was it was the LP-1,  but like I 
>said this wasn't happening all the time and only at home,  which made 
>wonder if it was something else instead. Today after I got  home from 
>rehearsal I set my rig back up and started playing and  looping at half 
>speed and low and behold the whine was back. I first  tried turning off 
>the computer that wasn't in use thinking perhaps its  wireless might be 
>the culprit. Nope, The i realized my wife was in the  other room, nursing 
>a cold and watching TV. last October we switched  to Direct TV. I asked 
>her to turn off the TV and DTV router, and then  recorded another loop. 
>The noise did not re-appear!! Something in the  router or dish was adding 
>interference, and its at the opposite corner  of our house. I tried the 
>test twice to make sure.  This has gotten me  thinking about two things,  
>Dish TV and microwaves in general might be  causing others to have noise 
>and interference issues., and that so  much of the electric gear we use 
>requires wall wart style power  supplies which are not particularly well 
>shielded and may be potential  conduits for this type of interference. 
>I've had other interference  from time to time from neighbors with high 
>speed power tools and a  sculpture neighbor with an arc welder.  So what 
>to do?, I'm seriously  considering an isolation transformer and I'm 
>wondering if anyone might  know if bunching wall warts together might 
>perhaps increase noise issues? I've though about building a shielded box 
>to put them all in  or find some steel army surplus box to stick them in. 
> I don't know if  I'm barking up the wrong tree with that idea. I have no 
>electronics  education to speak of other than knowing not to stick a fork 
>in to a  wall socket.  I also wonder if its possible to adequately shield 
>wall  warts?  I'm also investigating which of the new crop of multiple 
>power  supplies from Voodoo labs Dunlop and T rex might be able to handle 
>the  higher voltage and milli amps of my rack gear that requires power  
>supplies. I have an older pedal power plus from Voodoo that works  great 
>with my regular pedals. I'd just as soon jettison as many wall  warts as 
>I can if possible.
>> Any suggestions would be much appreciated.
>> Bill
>