[sdiy] shielding question

[Wooster Audio]

For mumetal, somebody recommended this place to me

http://www.lessemf.com/mag-shld.html

Not cheap, but they have a pretty good PDF that explains how to install it

Nathan

On 6/29/2010 4:26 PM, Harry Bissell wrote:
> I'd say that a bent piece of Mumetal is still better than a sheet
> of steel, even a really thick sheet of steel. I still try and get a complete
> wrap to create a flux path.
>
> The Matrix 1000 is awful. Most small transformers run at high flux to start with,
> even worse if its overloaded.  A saturated core does not contain ~any~ flux...
>
> H^) harry
>
>
>
> ----- Original Message -----
> From: Andre Majorel<aym-htnys at teaser.fr>
> To: synth-diy at dropmix.xs4all.nl
> Sent: Tue, 29 Jun 2010 04:21:13 -0400 (EDT)
> Subject: Re: [sdiy] shielding question
>
> On 2010-06-28 13:30 -0400, Harry Bissell wrote:
>
>    
>> Try Mumetal shielding. Best is to make a complete turn around
>> the power transformer, if possible. DON'T get it too close or it
>> will get VERY hot (if there is a lot of flux leakage)
>>
>> Its possible that a flat sheet on top of the offensive unit
>> might be effective, but you really want a complete path for the
>> flux to run around in.
>>
>> you might try to shield the receiving coils (inside the reverb)
>> as well.
>>
>> DON'T get too close to any magnetic pickup.
>>      
> The Matrix-1000 has been out of the rack recently. I've discovered
> how much 50 Hz hum it can induce into a jazz bass pick-up. At 15 cm,
> it's about as loud as your playing. You need to move back about 1 m
> before it fades into the background. And this is with the lid on !
> (1 mm steel.)
>
> It's an unusual design, a laminated core shaped like a rectangular
> doughnut with one winding on each long side. Perhaps those leak
> more.
>
> 			    _____________
> 			   |             |
> 			   |   _______   |
> 			 __|__|__   __|__|__
> 			|        | |        |
> 			|        | |        |
> 			|        | |        |
> 			|        | |        |
> 			|________| |________|
> 			   |  |_______|  |
> 			   |             |
> 			   |_____________|
>
>    
>> Ask me about the time I made a mu-metal shield for an ARP Avitar
>> hex pickup (to stop the 60Hz um). Describing WHY that was a
>> really really BAD idea is left to the reader...   :^)
>>      
> It got hot and burned your fingers ? ;-)
>
>    
>> http://www.goldmine-elec-products.com/prodinfo.asp?number=G16600A
>>      
> Is ultraperm like mu-metal, in that it must not be bent ?
>
>