As I've mentioned here several times I worked at CBC for many years and we had an RF problem with many cables. One of the maintenance gurus had decided that mike cables should not have the shield connected to pin 1 on both ends. I asked them to make me cables which were connected at both ends and the RF problem dissappeared. They were so adamant that this was wrong that they put warning signs on these cables that I was the only one who was allowed to use them. Even commercially made cables that were wired properly had to go to maintenance to have the shield disconnected from pin 1 before we could use them.
On Sunday, June 22, 2014 8:32:10 AM, Louis Hone <[log in to unmask]> wrote:
>When I started to work in the music studio of the National Film Board of
>Canada in 1979, we had a mic cupboard full of good stuff. There were a
>number of brand new AKG-414s. But I was told that I couldn't use them
>because of RF problems, and the NFB was actually considering selling the
>mics since they were unusable. I got our maintenance department to make a
>"special" cable that tied pin 1 to the shell of the connector. Bingo, the
>mics were clean of RF and I scored big points with my new boss. In the 20
>years I was there, I never found the RF source even though the studio was
>surrounded with chicken wire supposedly well grounded.
>2014-06-21 16:00 GMT-04:00 Richard L. Hess <[log in to unmask]>:
>> On 2014-06-21 3:54 PM, Paul Stamler wrote:
>>> Remarkably, I heard similar stories from the engineers at the Ravinia
>>> Festival about Neumann mics. They also went to C451s and some Shure
>>> SM81s, and the problem was solved. The SM81s and C451s had far fewer
>>> problems with humidity than the KM 84s.
>> That is interesting as Neumann has published on the subject and also
>> developed their double wound (in opposing directions) spiral-shielded mic
>> cable (called double Reussen shielding, I believe). Here, the cable is
>> called "Gotham" cable after Gotham Audio, for a long time the sole importer
>> of Neumann mics into the USA. I had thought it was Neumann cable, but
>> perhaps it was Gotham. It is still available. I still have a pair of 50'
>> and some 10' cables that I bought in the 1970s and they are still
>> performing well (though I don't use them that often).
>> Although this was not the article I recall, it seems interesting and talks
>> about Pin 1 and Pin 0 (the shell) and I do recall some of that discussion
>> from the earlier paper.
>> Part of what they published (IIRC) was relating to the shield ground and
>> pin one. I do not recall exactly what they recommended, but I do think that
>> it was an early indicator of a pin one problem.
>> I have yet to have an RF problem with my KMS-105 or TLM-103, but neither
>> of those were hung in the church, used on the floor.
>> In fact, the only mics that ever gave me a problem here in Aurora were the
>> ATM10a's, which, also, coincidentally were the least expensive condenser
>> mics I ever bought.
>> To fill out the list, although none hung in the church, all were used
>> there without any RFI issues: Rode NT5, Rode S1, Sennheiser MKH416T with
>> homemade P48-T12 adapters, and dynamic Shure PG58, SM58, and EV ND767.
>> Richard L. Hess email: [log in to unmask]
>> Aurora, Ontario, Canada 647 479 2800
>> Quality tape transfers -- even from hard-to-play tapes.