What's up with the sound of that mic?

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GBall
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What's up with the sound of that mic?

Post by GBall » Thu Sep 05, 2019 12:59 pm

Just for a fun discussion, and maybe some insight? Or if someone wants to correct this:

I'm condensing (bad pun) an article I read on the history of mics made in China. The story goes: In the early 1950's a German company shared the K67 Mic Capsule that is used in the Neuman U87 and U67 microphones with a Chinese company. The result were NOT cheap knock-offs - but more or less licensed and approved by the original manufacturer. They are good capsules (or can be) that are close if not identical to the ones still used today in the U87. But...

The K67 capsule has a feature that goes back to the early days when AM radio effectively only had 24db of gain above the noise floor (Yah, you read that right, 24db) They came up with a trick of boosting certain higher frequencies quite a lot before transmission. They called this "pre-emphasis". Once received, your better radios would "de-emphasize" those same frequencies back down to something approaching normal, and it was a way to get more signal with less noise. Pre-emphasis/De-emphasis is one of the tricks still used by noise reduction systems like Dolby.

Neuman built the same trick into the U87 microphone. The K67 capsule was intentionally designed so that it has a sharp 8db pre-emphasis peak around 7-8 kHz which was then followed by some pretty expensive and cool de-emphasis circuitry in the rest of the mic. That combination gives you a very quiet mic with a hot signal and a slightly warm presence bump.

But there are other kinds of circuitry out there (Shoeps) that happen to be a LOT cheaper. You could even argue Shoeps is a better circuit design because it is so flat and transparent. --IF -- that is, you pair it with a capsule that is itself also very flat. What would happen if you built a mic that paired the boosted K67 Capsule with this much cheaper but flat circuitry? eh... I'm guessing you know and have heard it.

The story is that certain well known American retailers wanted "a U87 clone at very cheap price point" and so possibly against the better judgment of the Chinese Mic makers, we got what we got. As I understand it, both parts of the mic are probably reasonably good quality - they just don't belong together.

Wouldn't something like that show up in those frequency graphs on the box and manufactures web site? Heh. Mic manufacturers are allowed to use "smoothing" in the graphs they display. I wish I knew a better way to insert images here and I'd show you the raw graph I have of my badly behaving room, and then another of how great the exact same room looks with smoothing applied to the graph. Smoothing is supposed to represent "what humans can really distinguish" but I think sometimes that's called denial. :) Or - maybe with narrow peaks our inability to distinguish it is partially true. We hear a problem but its hard to distinguish what the problem actually is.


Anyway, thought it might help to know (and verify) if what you're hearing with certain mics is that pretty narrow 8db boost that's been added by the mic capsule around 7k. You've heard all this before? Heard a different story? Have a better answer? Anyone here into mic mods? I should probably be writing more music instead....

Greg

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Re: What's up with the sound of that mic?

Post by andygabrys » Thu Sep 05, 2019 4:06 pm

What I have read confirms what you wrote.

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