I was disappointed by the strong A199 hum noise in my brand new Doepfer
A100 suitcase.


Perhaps I didn't care enough about Doepfer's home page warning :

"The spring reverb system is connected to the A-199 module via 2 cables
with RCA phono connectors. As the reverb system is very sensitive to
magnetic fields it has to be placed in a big distance from the
transformer of the A-100 power supply - privileged in the left upper
corner of the A-100 frame. The reverb system is mounted with screws and
nuts or double-faced self-adhesive tape. There has to be sufficient
space for the reverb system (about 20 x 7 x 5 cm).

For frames that include the A-199 we recommend the usage of the new
power supply PSU2. PSU2 has much less magnetic radiation (because of the
ring core transformer) that may cause hum noise in the A-199."


Nevertheless, I began to find another position for the A199 reverb
spring.

Now it is mounted inside the suitcase, on the top/handle side of the
suitcase, open side of the spring reverb unit upwards, with double-faced
adhesive tape.


Hum noise used to appear with a mix at 8 (9 o clock : almost dry
effect), now I can work easily with a mix at 5:5 (12 o clock).


Someday I'll try to build a full shield around the spring unit, but I'm
already completely satisfied of my brand new A100 suitcase.


Cheers,

Pierre


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