Finally got the opportunity to experiment with a 314mm x196mm x 0.2mm sheet of 3M Ultraperm 80 MuMetal in my A-100 PMS12.
Having practically no formal knowledge of engineering or physics or means to measure the emissions, it came down to patching a basic sparse LPG bongo striking occasionally and CAREFULLY sliding the tank around inside the case under power listening on headphones. I took a grinding wheel and reduced the sides of a large Accutronics 17" reverb tank and hard-soldered shielded wire directly from the A-199 into the transducers in order to get it to fit. Very cramped, but will fit. Listen posterity, in my experience there is nowhere within the PMS12 to place either a 17" (type 09) or 9" (type 08) tank that will provide high quality results. It may be possible to relocate one of the power supplies. It may be possible to spend great sum of money on thicker shielding material. While the 3M mu-metal sheet does clearly reduce the inductive noise somewhat it's nowhere near what would be studio acceptable. The A-199 needs to be redesigned with a hint from Springray, external connections. When the tank is far enough away from the transformers the sound is totally beautiful. Considering building a shielded external box for tank and using XLR connection. The type 08 tank performed better than type 09 on A-199.
04.08.2015, 08:53, "
yahoo@...
[Doepfer_a100]" <
Doepfer_a100@yahoogroups.com
>:
>> at the Gräfelfing facility are there any pieces of mu-metal within easy reach to simply check if a few millimeters of
>> this substance will be sufficient to reject EM interference being emitted by run-of-the-mill 120V Doepfer power supply 2,
>> toroidal transformer, 1200mA inside a-100 pms12 It is an expensive material to purchase, if there is no hope of this
>> working would like to know in advance. Thanks!
>
> I'm sorry - we have no mu-metal here.
>
> Best wishes
> Dieter Doepfer
>
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