Fixing my Rode K2

[Jeff Henig]

Okay, so I've a Rode K2 condenser mic that under normal conditions has a
pretty ridiculously low self-noise level.

I lent it to a friend (oops), and when I got it back, I found a new
noisy gremlin in the works.

What I hear when I get it up and running is some sort of
static-in-motion. It's not your standard single level of hum or white
noise that I would've expected coming from, say, an electrical field or
ground loop.

It's almost like when you're tuning an A.M. radio--that whine just
before and after you lock in on the station. But it sounds more like
that whine is generating a white noise/pink noise sound via vox,
switching pitch and phase----but all underwater. So you hear the
white/pink noise but not the whine itself. And it's constantly varying
in pitch.

I googled the mic and causes of noise from a condenser mic and didn't
get much help. I found one bulletin board forum in which a K2 owner said
that he'd been ready to send his in but had been told that his mic
might've just been affected by humidity.

He was told that the easy fix was to pack the mic in a two quart-sized
ziplock baggy along with some desiccant like one would normally pack
electronics gear with and leave it alone for a while so's it could dry
out. He said it worked for him.

I'm trying it right now--just packed it this evening.

Does any of this make sense to you folks? Or am I just delaying the
inevitable: sending the mic back to Rode for repairs...

---Jeff

[Mike Clayton]

Jeff Henig wrote:
> Does any of this make sense to you folks? Or am I just delaying the
> inevitable: sending the mic back to Rode for repairs...
>
> ---Jeff

Yes it does Jeff. I have a K2 that went similarly noisy, fortunately
whilst still in its warranty period. Before I sent it back I swapped the
tube (valve in NZ, or toob in the USA), the cable and power supply with
known good ones. It came down to something in the mike body that I
didn't have the skills to locate and replace. Sent it back to Rode in
Australia and it came back fixed, and has been fine ever since.

Nice mike, I've used it on vocals and it gave me a good result on a
concert harp.

Mike

[geoff]

Presumably is a well-known and common problem - mine does the same !
Changed the valve and no fix, dessicated but no fix, but haven't got around
to delving deeper yet....

And yes, it is one of my favourite mics. Silky smooth extended treble, and
warm deep bass. The linearly variable patterns are a bonus. Often prefer to
my other similar level mics - C414(B-ULS and B-XLS), U87i, and TLM103.

If anybody actually knows what the dodgy component is, would love to
hear....

geoff

[Mxsmanic]

Jeff Henig writes:

> I lent it to a friend (oops), and when I got it back, I found a new
> noisy gremlin in the works.

Tell your "friend" to buy you a replacement for the mic that he broke.

[hank alrich]

Some conclusions aren't worth jumping to. Causality is not established
here.

--
shut up and play your guitar * http://hankalrich.com/
http://www.youtube.com/walkinaymusic
http://www.sonicbids.com/HankandShaidri

[Mxsmanic]

hank alrich writes:

> Some conclusions aren't worth jumping to. Causality is not established
> here.

True, but I learned at a very young age that if I loaned things to others,
they often came back broken. When I stopped loaning things, they stopped being
broken.

Unfortunately, most people are much more careless with equipment that they
didn't pay for and don't have to pay for than they are with equipment that
costs or cost them money. And many people also "forget" to mention the damage
that they do to equipment that they've borrowed. So a loaned piece of
equipment coming back broken could be a pure coincidence--but very often, it's
not.

I no longer loan anything to anyone unless I can afford to replace it.

[Scott Dorsey]

In article <jh726o$7pj$2...@dont-email.me>, Jeff Henig <yom...@yomama.com> wrote:
>It's almost like when you're tuning an A.M. radio--that whine just
>before and after you lock in on the station. But it sounds more like
>that whine is generating a white noise/pink noise sound via vox,
>switching pitch and phase----but all underwater. So you hear the
>white/pink noise but not the whine itself. And it's constantly varying
>in pitch.

It's breaking out into oscillation. This is most likely because of leakage
in the high-Z section of the circuit. Something needs to be cleaned, somewhere
and it could be junk in the capsule or it could be flux on the board that was
not properly removed during manufacture.

The impedances on the input stage of the electronics are very, very high,
on the order of a gigohm. Consequently everything needs to be immaculately
clean or you get parasitic leakage.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Jeff Henig]

How lucky do I need to be for it to be something *I* can clean? I've never
actually opened it up. I'm not afraid to, being that if I don't, I'll have
to send it in anyway, but if it's a hard-to-get-to spot, I could just be
SOL.

--
---Jeff

[Scott Dorsey]

Jeff Henig <yom...@yomama.com> wrote:
>
>How lucky do I need to be for it to be something *I* can clean? I've never
>actually opened it up. I'm not afraid to, being that if I don't, I'll have
>to send it in anyway, but if it's a hard-to-get-to spot, I could just be
>SOL.

I don't know. josephson.com used to have directions on cleaning
center-terminated capsules somewhere on it. You could try just cleaning the
diaphragm like that.

If you disconnect the capsule and the noise goes away, the leakage is on
or inside the capsule.

[Jeff Henig]

Roger that. Thanks VERY much, Scott!

--
---Jeff

[Soundhaspriority]

"Jeff Henig" <yom...@yomama.com> wrote in message
news:jh726o$7pj$2...@dont-email.me...

> Okay, so I've a Rode K2 condenser mic that under normal conditions has a
> pretty ridiculously low self-noise level.

[snip]

>
> He was told that the easy fix was to pack the mic in a two quart-sized
> ziplock baggy along with some desiccant like one would normally pack
> electronics gear with and leave it alone for a while so's it could dry
> out. He said it worked for him.
>

One other form of desiccation is to use a desk lamp with a 100 watt light
bulb to warm it up. Production sound folks are fond of this method. At least
one manufacturer recommends it.

This worked with a noisy Studio Projects mike. I can't advise on safe
temperatures, since I simply took a gamble. An IR thermometer indicates that
the temperature with a desk lamp at 8 inches is in the range of 120F.

Never use this method on an electret mike, which yours is not.

Bob Morein
(310) 237-6511

[Frank Stearns]

"Soundhaspriority" <now...@nowhere.com> writes:

>"Jeff Henig" <yom...@yomama.com> wrote in message
>news:jh726o$7pj$2...@dont-email.me...

snip

>One other form of desiccation is to use a desk lamp with a 100 watt light
>bulb to warm it up. Production sound folks are fond of this method. At least
>one manufacturer recommends it.

>This worked with a noisy Studio Projects mike. I can't advise on safe
>temperatures, since I simply took a gamble. An IR thermometer indicates that
>the temperature with a desk lamp at 8 inches is in the range of 120F.

>Never use this method on an electret mike, which yours is not.

Interesting, Bob.

Are you saying that heat hastens the demise of the "permanent" polarization, or is
there some other problem?

Frank
Mobile Audio

--
.

[Soundhaspriority]

"Frank Stearns" <franks.pa...@pacifier.net> wrote in message
news:V6CdnS9LKOuKnKXS...@posted.palinacquisition...

Yes, exactly, particularly with AT mikes. DPA claims a much more rugged
electret.

Bob Morein
(310) 237-6511

[Ty Ford]

On Sun, 12 Feb 2012 13:54:44 -0500, Soundhaspriority wrote
(in article <GsadnTLQqvRpl6XS...@giganews.com>):

Particularly? Where's the proof on that!?!

Regards,

Ty Ford

--Audio Equipment Reviews Audio Production Services
Acting and Voiceover Demos http://www.tyford.com
Guitar player?:http://www.youtube.com/watch?v=yWaPRHMGhGA

[Soundhaspriority]

"Ty Ford" <tyre...@comcast.net> wrote in message
news:0001HW.CB5D8090...@News.Individual.NET...
[snip]

>> Yes, exactly, particularly with AT mikes. DPA claims a much more rugged
>> electret.
>>
>> Bob Morein
>> (310) 237-6511
>>
>
> Particularly? Where's the proof on that!?!
>
> Regards,
>
> Ty Ford
>
> --Audio Equipment Reviews Audio Production Services
> Acting and Voiceover Demos http://www.tyford.com
> Guitar player?:http://www.youtube.com/watch?v=yWaPRHMGhGA
>

Ty,
With apologies to those who feel a personal affinity to AT microphones,
I offer the following clarification. As far as I am aware, no company other
than DPA offers an electret technology that is durable at temperatures found
in a hot car. The A-T "do not exceed" temperature is something like 130F.
This is an abusive temperature, but one which at externally polarized
condenser mikes, and DPA mikes, are not damaged. It came to mind to use the
word "particularly" because AT use of electret technology is more prominent
than most other high-class makers -- with DPA an important exception.

Bob Morein
(310) 237-6511

[Mike Rivers]

On 2/12/2012 9:14 AM, Scott Dorsey wrote:

> josephson.com used to have directions on cleaning
> center-terminated capsules somewhere on it. You could try just cleaning the
> diaphragm like that.

I think he removed it, probably on advice of his own better
judgment. Too many people reading that stuff now who
probably shouldn't be trying it. Much as I would like to
encourage it, I hesitate to tell people that they can fix
things themselves these days. Too many who say "I know how
to sodder but I've never worked on a mixer b4."



--
"Today's production equipment is IT based and cannot be
operated without a passing knowledge of computing, although
it seems that it can be operated without a passing knowledge
of audio." - John Watkinson

http://mikeriversaudio.wordpress.com - useful and
interesting audio stuff

[Mike Rivers]

On 2/12/2012 10:13 AM, Soundhaspriority wrote:

> One other form of desiccation is to use a desk lamp with a
> 100 watt light bulb to warm it up. Production sound folks
> are fond of this method. At least one manufacturer
> recommends it.

There used to be a procedure to bake a U87 capsule in a
kitchen oven but I haven't seen it in quite some time.

I've also heard of using rice in a Zip-Lock bag as a
desiccant for mic storage.

[geoff]

Soundhaspriority wrote:
> With apologies to those who feel a personal affinity to AT
> microphones, I offer the following clarification. As far as I am
> aware, no company other than DPA offers an electret technology that
> is durable at temperatures found in a hot car. The A-T "do not
> exceed" temperature is something like 130F. This is an abusive
> temperature, but one which at externally polarized condenser mikes,

Maybe AT pick a safe ball-park figure rather than not putting out a spec for
that paramter at all ?

geoff

[Soundhaspriority]

"geoff" wrote in message
news:Gu2dnd43VeU2PqXS...@giganews.com...

I tested one AT to destruction. They do die in heat.

Bob Morein
(310) 237-6511

[Arny Krueger]

"Mxsmanic" <mxsm...@gmail.com> wrote in message
news:u85fj79dguaclnssv...@4ax.com...

Other than ribbon mics, microphones aren't supposed to be delicate little
flowers that have to be treated with white gloves.

Every once in a while we break a mic or a cable at church, and the person
using it at the time is generally full of remorse. I tell them that good
mics are supposed to be up to fair wear and tear, and if they aren't, we
just fix or replace as needed.

[Ty Ford]

On Mon, 13 Feb 2012 00:46:22 -0500, geoff wrote
(in article <Gu2dnd43VeU2PqXS...@giganews.com>):

I tend to agree with Geoff, now that he mentions this. I recall that AT is
usually very conservative with its figures.

[Ty Ford]

On Mon, 13 Feb 2012 01:11:57 -0500, Soundhaspriority wrote
(in article <x-OdnTWHPooZNKXS...@giganews.com>):

specifics?

[Soundhaspriority]

"Ty Ford" <tyre...@comcast.net> wrote in message

news:0001HW.CB5E9328...@News.Individual.NET...

>>
>> I tested one AT to destruction. They do die in heat.
>>
>> Bob Morein
>> (310) 237-6511
>>
>
> specifics?
>

AT33 mike, rear deck of Rabbit, in summertime. 6 dB down from unabused unit.

Since there seems to be some resistance to the fact that electrets have
varying degrees of stability, here's a link, which while not necessarily
indicative of DPA's proprietary technology, to which I am not privy, it
gives an idea of the issues:

http://cap.ee.ic.ac.uk/~pdm97/powermems/2008/pdfs/501-504%20Mescheder,%20U.pdf

But the most common form of electret is not the above; it is a thin sheet of
a teflon-type plastic, which has a surface charge. Stability is a relative
thing. The decay rate is a function of two things:

1. Relaxation of the polar molecules, which manifests as dissipation of the
surface charge.
2. Electromigration of surface contaminants. Any other polar molecules that
may be around, as aerosols, nearby surface contaminants, etc, are attracted
by the constant electric field, and will move considerable distances,
aligning to cancel the surface charge. Cancellation is possible because,
unlike a true electret, there is no source of replenishment.
Electromigration increases with humidity.

Failure does not occur all at once. An electret mike gradually loses output,
which may or may not be noticeable for many years. The charge on a PTFE
electret does not disappear for hundreds of years. But as mike users, we are
interested in how strong it is, because s/n is proportional to the strength.

When you spend $3K for a DPA mike, you get their electret, of which they are
very proud. Based upon available technology, it's probably an inorganic,
charged by ion implantation, resulting in a much stronger field. Since the
field is created by ions, not polar molecules, relaxation does not occur in
the same way as a PTFE electret. The ions must migrate through structural
defects in the base substance, which could take millenia. Electromigration
is still possible, but the mikes are worth servicing.

Bob Morein
(310) 237-6511

[Ty Ford]

On Mon, 13 Feb 2012 10:52:13 -0500, Soundhaspriority wrote
(in article <rPidnRU14uYwrKTS...@giganews.com>):

> AT33

Can't find it with Googel. How much is it? I do recall a Countryman EMW
failing on me in the infield of the Orioles Stadium on a VERY VERY hot
afternoon. I swapped it out for another EMW and kept going.

The thermostat across the field said something like 120F, as I recall.
Probably not that hot, but the makeup gal said I was purple, a good sign that
heat stroke was not far off.

The EMW returned to normal operation after it cooled off.

Regards,

Ty Ford

[Soundhaspriority]

"Ty Ford" <tyre...@comcast.net> wrote in message

news:0001HW.CB5EF507...@News.Individual.NET...

> On Mon, 13 Feb 2012 10:52:13 -0500, Soundhaspriority wrote
> (in article <rPidnRU14uYwrKTS...@giganews.com>):
>
>> AT33
>
> Can't find it with Googel. How much is it?

http://www.audio-technica.com/cms/wired_mics/59839e17c695dade/index.html

Bob Morein
(310) 237-6511

[Ty Ford]

On Mon, 13 Feb 2012 20:43:23 -0500, Soundhaspriority wrote
(in article <jMCdnXlwpcWmIaTS...@giganews.com>):

Oh, ATM33. Discontinued and not in the same league as their studio stuff.

[Soundhaspriority]

Ty,
The A-T do-not-exceed temperature for electrets is 110 Fahrenheit. For
reference, see

http://www.audio-technica.com/cms/resource_library/literature/216a4dc2c3d3e9d6/atm710_ss_e.pdf
http://www.audio-technica.com/cms/resource_library/literature/bdcb8131ab1a8b43/at2035_ss_e.pdf

So it's not surprising that the rear deck of a Rabbit in summertime would
kill one.

But they make plenty of fine true-condenser types, which is what I assume
you mean with your preference for "studio stuff." I have a AE5400 true
condenser, I like it a lot.

A DPA mike is specified for use up to 158F. See
http://www.dpamicrophones.com/en/products.aspx?c=Item&category=188&item=24010#specifications
The capsules are tested at 200C = 392F, see
http://www.dpamicrophones.com/en/mic-university/technology-guide/microphone%20stability.aspx

But, of course, DPA mikes are much more expensive than AT. Don't have any,
wish I did.

Bob Morein
(310) 237-6511