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Klaus Heyne's Mic Lab / Re: Silica Bags As Desiccants: Do they work?
« Last post by klaus on April 23, 2018, 03:33:58 pm »
The opening sentence in my reply suggests that a dehumidifying cabinet or room for microphones is overkill. We have enough data from more than 50 years of condenser mic use all over the world to confirm this.

As a matter of fact, the original AKG C12 was specified to be impervious to even high levels of humidity, as its primary market initially was South America.
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Klaus Heyne's Mic Lab / Re: Silica Bags As Desiccants: Do they work?
« Last post by DarinK on April 23, 2018, 03:03:19 pm »
My question is, if desiccant packs are useful for mic storage, why not instead use a dehumidifying cabinet for storage? And if such a cabinet were to be used, for what humidity range should it be set?
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Klaus Heyne's Mic Lab / Re: Silica Bags As Desiccants: Do they work?
« Last post by klaus on April 23, 2018, 02:45:17 pm »
Darin,
All high-end studio condenser mics are resistant to moisture back-down in high humidity environments, as long as the capsule surfaces are clean.

A contaminated capsule in high humidity behaves differently: when the the level of contaminants (often specks of dust or a film of dried saliva) is dense enough it will form a conductive path between diaphragms and backplate, as soon as enough moisture is present.

The conductive path between the two capacitor plates discharges the plates, and the mic becomes noisy.
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Klaus Heyne's Mic Lab / Re: Silica Bags As Desiccants: Do they work?
« Last post by DarinK on April 23, 2018, 01:33:16 pm »
What is the best humidity range for microphones?

There are de-humidifying cabinets, made for camera equipment and selling for a couple hundred dollars, that could be used for microphone storage. I don't live in a humid enough area to ever really need something like that, but they could probably come in handy in studios in humid environments, like in Florida or Southeast Asia.
With an air-tight dehumidified cabinet, you wouldn't need to bother with plastic bags and desiccants every time you used a mic. For those with very expensive microphone collections (not me, sadly), a couple/few hundred dollars for such a cabinet may not seem that big of an expense.
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Klaus Heyne's Mic Lab / How to (Re-)Mount Badges on Microphone Bodies
« Last post by klaus on April 21, 2018, 10:47:22 pm »
Comes a time when a badge fell off the precious U47, or was never there on the used KM84 you bought. You may have bought an overpriced badge on eBay and now want to be absolutely sure to not waste the effort and expense.
Years of trials and mess-ups have taught me how to (re-)mount badges on Neumann, Telefunken and other mics, and I herewith share my tips.

1. Initial Check
Check the radius of the badge against that of the body tube. For a flush fit, both must be the same. If necessary, you can bend and flatten or arch the badge a tiny bit, but do not try to fit a badge made for a different body radius: the body holes may not line up. KM8x badges will not fit U87 housing tubes and vice versa. M49 badges need to be re-bent to fit a U47 housing tube, and vice versa. Once the same radius of badge and housing tube has been confirmed, hold the badge over the correct position and check that the holes for inserting the rivets will line up.

2. Test-Fit
Insert rivets into badge - thumb pressure only - no tools
With rivets in badge, insert all the way into the housing tube, to check correct rivet length: if rivets stick out on the inside, they are too long and need to be shortened until flush with the inside surface of housing tube: On some Neumann mics there is zero clearance between frame and housing tube during insertion.

To shorten rivets that are too long: insert into badge (best for holding rivet in place) and carefully grind down length with a Dremel diamond wheel or other tool.
If rivet shafts are too thick to go into holes without extreme pressure: use diamond wheel to slender the shafts until only light pressure is necessary to seat them

3. Final Installation
Insert rivets through badge, apply a small dab of Eclectic E6000 styrene glue* to center of badge’s back, and guide badge into correct position by lining up rivet shafts with body holes. Press badge firmly into position, making sure that all edges are flush with body. Thumb pressure is optimal. Finally, use your wooden dowel and gently press the rivets until heads are flush with badge. DO NOT HAMMER.
Do not trust the rivets to hold in the badge. They are primarily for looks. To avoid rivets from falling off: place a drop of Crazy Glue to each of the rivet holes from inside the housing tube.

* Eclectic E6000 is great: firm hold, yet easily removed without residue if necessary. 
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Klaus Heyne's Mic Lab / Re: Silica Bags As Desiccants: Do they work?
« Last post by Noah Scot Snyder on April 21, 2018, 12:22:42 pm »
I use the metal cased rechargeable desiccants with success. The style I use starts orange and turns clear as it absorbs water. Once it is clear you toss it in a 300 degree oven for 3 hours and it dries out ready to be used again. One lives in each of my well sealed mic cases (the style often used for camera equipment). 
7
Glad it went so well, and glad to hear you're working on the historical end of the convention -- you have to know where you've been before you can figure out where you're going!!

Let's talk closer to October... I have no idea what my travel schedule will be [I go Oktoberfest in München every year] until later in the summer.

Peace
8
Hi Fletcher,

Thank you for the well-wishes and help last October, sorry for the delay in replying. It did go well, there was an attentive audience for the big talk and several had been there and shared their memories.

The talk went so well that it gave me some credibility with the powers-that-be and this year I'll be in charge of the Historical Track (track = sequence of talks/papers on a given overall subject; there are many tracks).

The Convention is October 17-20 in New York City at the Javits; if anyone has an historical subject which they are knowledgeable about and want to share and can get themselves to NYC at that time, please PM me and I'll tell you how to get into my Track.

It could be a panel discussion, a solo or duo presentation, or something different. It should involve history of that audio subject.

Thanks again for having me at your place in October; it was a fun time. I'll be doing another version of my presentation, both expanded and contracted, at the Convention and Tom Fine will be in my track with his History of Commercial Stereophony series.

If you wanted to, I'd be happy to come to Suffern again so that people who are not going to the Convention could still get together. That Sunday afternoon is a very fond memory.

PS It took me quite a while to process all that happened at the Convention and my talks, and I honestly avoided the subject altogether for many months which is why it's taken so long to post a followup.
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Klaus Heyne's Mic Lab / Re: Capsule Diaphragms: Nickel vs. Gold
« Last post by Marik on April 16, 2018, 08:15:07 pm »
Using as low tension as possible is a quote from Schoeps's chief engineer Mr. Wutke with whoom I had close contact. I even tested a prototype mic for them at that time. Schoeps is located in my hometown.

Kai,

As always, the evil is in details. In order to compensate for high frequency loss (as a result of diaphragm' lower tension) Schoeps uses resonator system, which is just another way of implementation...


Specially on fig. of eight mic's the low frequency response is of major concern, as the pressure gradient (the pressure difference between front and backside of the capsule / diaphrag) gets lower with frequency.
The stiffer the diaphrag the less it will follow the air movement.
Most REAL (single diaphragm, not double-cardiod) fig. of eight condensors roll off below 200Hz or even higher because of this.

The single diaphragm fig8 condenser is very specialized capsule and there were only a few more or less successful models on the market. Of course, I was talking about cardioid capsules.

In general, to make a fig8 single diaphragm we need a mass controlled system, so the diaphragm is tuned to a very low frequency. In this case the sensitivity will drop with rate of 6dB per octave going up. At the same time the pressure gradient forces on the diaphragm will increase twice per each octave. That's how we get a linear frequency response. That's why ribbon microphones naturally have a linear response up to the point of cancellation where the front to back distance is equal to the frequency of wave length and pressure gradient is 360 degree out of phase.

Condenser single diaphragm works as mass controlled only above the frequency of tuning resonance. Below it is a stiffness controlled system. In order to make a flat response we need to introduce acoustical resistance. The lower the tuning resonance, the less acoustical resistance we need, the more output such capsule will have for a given linearity. But of course, as you rightly mentioned, here we are faced with diaphragm stability problems, which is the main limiting factor.

Quote
You are right with cardiods, they present a complex system using a combination of even more then the mentioned accoustic effects, needing to be properly tuned to each other.
Still, low tension is desirable here if you need to cover the full range.
Klaus prefers the lower tensioned specimen of the Neumann capsules e.g., for their fuller bodied sound.

This low tension close to the possible is one of the main reasons for cardiod capsule failure, there is no big margin like with higher tensioned omnis.

As I mentioned before, the diaphragm tensioning depends on the desired voicing and very much depends on entire system it is part of. In general, all the capsules are tuned differently. For example K47 is considerably low, K67 quite a bit higher. On the other hand, CK12 way higher than either. The reason being the first two are aperiodic designs and introduce quite high acoustical resistance and damping to the diaphragm, while the CK12 is a multi-chambered and rather resonant system.

Best, M
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Klaus Heyne's Mic Lab / Re: Capsule Diaphragms: Nickel vs. Gold
« Last post by Kai on April 16, 2018, 05:24:54 pm »
But with lower tension then you are losing top end response.
In fact you linearize the bass.
Using as low tension as possible is a quote from Schoeps's chief engineer Mr. Wutke with whoom I had close contact. I even tested a prototype mic for them at that time. Schoeps is located in my hometown.

Specially on fig. of eight mic's the low frequency response is of major concern, as the pressure gradient (the pressure difference between front and backside of the capsule / diaphrag) gets lower with frequency.
The stiffer the diaphrag the less it will follow the air movement.
Most REAL (single diaphragm, not double-cardiod) fig. of eight condensors roll off below 200Hz or even higher because of this.

Schoeps CCM8 reaches 50Hz with a soft rolloff to only -6dB (often compensated by the proximity effect when used as spot mic). There is no problem in the high range with this mic, it's ruler flat up to 15kHz and sounds very nice and rounded.
The mic uses mylar sputtered with gold, but in former times Schoeps built mic's with pure nickel diaphragms with comparable accoustic properties.

You are right with cardiods, they present a complex system using a combination of even more then the mentioned accoustic effects, needing to be properly tuned to each other.
Still, low tension is desirable here if you need to cover the full range.
Klaus prefers the lower tensioned specimen of the Neumann capsules e.g., for their fuller bodied sound.

This low tension close to the possible is one of the main reasons for cardiod capsule failure, there is no big margin like with higher tensioned omnis.
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