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Re: noisy 8020 mics

Subject: Re: noisy 8020 mics
From: "bruce seifried" spookyaura
Date: Fri Sep 23, 2011 3:30 pm ((PDT))
Oh, man. I know this issue well. Unfortunately.

Rather than trust my sometimes quirky memory, I will copy/paste part
of one of my emails to my dealer:

*********

"Here's a recap of my MKH8020/8040 adventure:

=95 Original order was for one pair each of MKH8020 stereo set, and
MKH8040 stereo set. Order date 5/8/08.

=95 One of the 8020 omnis went bad on my first remote job. Intermittent =

full output noise spikes ruined recording.
This pair was replaced by Sennheiser on approximately 7/1/08.

=95 New pair of 8020's both went bad before my first job with them. Both =

initially had low-level crackly noise problems. One of them
subsequently improved, but both were returned to Sennheiser for a
refund.

=95 The 8040 pair were initially fine, and worked in my studio. They
were set up here prior to a remote job in October, and one developed
the same low-level crackles that the second 8020 pair had. This noise
took about a minute to get going before manifesting itself, and was
then continuous. These were returned to Sennheiser for a refund.

I returned the 8020/8040 pairs for a refund reluctantly, since I did
very much like their sound, especially the 8020s, but I no longer
trust that these microphones are reliable enough for me to use in a
professional situation.

As a circuit designer myself, I will hazard a guess as to what might
be the cause of these problems.

If it were not for the intermittent full-level noise problem with the
first 8020 pair, I would guess that there was some form of
contamination to the high impedance section of the pc boards happening
during manufacture, perhaps due to incomplete removal of flux during
soldering. Another possibility is a bad batch of FETs or transistors
sneaking into production. Less likely but still possible would be bad
capacitors. Obviously, I did not open these to determine for certain
what the problem(s) was/were.

However, I did notice that the small circular pc board located between
the two halves of the microphones was not firmly attached in place,
and was not always accurately centered. In fact, in one of the mics as
initially received it was so far out of alignment that there were
positions of rotation of the XLR assembly where the pin was barely, if
at all, making contact with the circular pc board trace. This might be
a design decision that should be rethought, at least to improve on the
dimensional tolerances  involved."

*********

My dealer, Steve Remote at Aura Sonic, was a complete saint during
this nightmare, and managed to get Sennheiser to completely refund the
cost of these microphones. I have refrained from going public about
all this, since I had not seen any other mention anywhere of anyone
else having these sorts of problems, and I was beginning to doubt my
own sanity. I tried these mics with different mic cables, two
different Sound Devices 702 recorders, the KORG DSD recorder, and the
outcome was always the same. Sennheiser denied that anyone else was
having these problems. Apparently, I'm not insane, as is now apparent.
Yay!

I feel your pain!


bruce seifried
eclair engineering


On Sep 22, 2011, at 4:21 AM, vickipowys wrote:

> All,
>
> Does anyone else have problems with periodic loud fizzing noise from
> Sennheiser 8020 mics?
>
> Sennheiser replaced one set of mics ('faulty capsule' they said) but
> the noise persists in the replacement mics despite me checking
> absolutely everything by way of leads and phantom power voltage and
> connectors etc. etc.
>
> Help please!
>
> Vicki Powys
> Australia
>
>










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