Effect of SDC body slots

[callgrlmusic]

does anyone have any good information about how body slots in SDCs affect performance? i read somewhere online about “opening up” the grille slots on SDC bodies doing something for the high end, but i have yet to build a test rig for these. i’m trying to find out if anyone has tried blocking them/different variations of the below/etc?

related question: why is there so much variation in this part of the design between manufacturers? has anyone here done a deep dive?

 

[pasarski]

They are essential in forming the polar pattern. Lots of information here if you search SDC vent/vents/venting etc. For a deep dive this is also gold for anything microphone related, including venting (EDIT: not true. The kind of venting that op is interested is not discussed in the paper) https://www.google.com/url?sa=t&sou...QQFnoECBIQAQ&usg=AOvVaw3ZO0fEsIX9q6-VZIQl8MkO

 

[callgrlmusic]

They are essential in forming the polar pattern. Lots of information here if you search SDC vent/vents/venting etc. For a deep dive this is also gold for anything microphone related, including venting. https://www.google.com/url?sa=t&sou...QQFnoECBIQAQ&usg=AOvVaw3ZO0fEsIX9q6-VZIQl8MkO

thank you! i wasn’t searching the right terms so nothing popped up for me initially. i’ll take a look at this and check back.

 

[kingkorg]

Changing the slots changes the sound in many ways, and not for the better necessarily. They have to be carefully engineered as they are the part of the equation. Just opening up for the sake of doing so doesn't make a mic sound better.

On the image you posted the body with larger holes doesn't improve things with that particular capsule because it relies on it's own slots. If the capsule is well engineered, it doesn't need any additional slots, and adding them like in the image is either detrimental, or doesn'tdo anything.

Some capsules, like kk105/104 (kms105/104) are engineered to "not care" what's behind them.

Conclusion is that it depends, and it's best to buy a reputable mic from a reputable source. The mod you ask about comes from dark ages of microphone modifications where different mic "gurus" performed mods like this without having any idea about what they were doing. And as a rule, whatever they did improved the sound and justified their guru title, and the price of specific mod.

Altering back vents could in theory change (not necessarily improve) high end, but that is by altering polar pattern. Which is the wrong way to do it, as it obviously - changes the pattern. No one can tell you what you will end up with.

 

[ricardo]

Some capsules, like kk105/104 (kms105/104) are engineered to "not care" what's behind them.

This isn't quite the case. The housing & slots have 'as much' effect as the capsule itself.

The Calrec cardioid capsule was much simpler than the AKG SDCs cos Clem Beaumont, my mike mentor, realised he could use the housing/slots (with far easier tolerances) to do much of what AKG did in the capsule. Bernhard Weingartner, a personal friend of Clem who designed many of the old AKG capsules including the CK12, was very impressed. But even the 'simple' Calrec capsule was a precision item as there was important stuff that the housing couldn't do.

The slots affect HF and pattern. Don't forget the cavity behind the capsule, it's shape, volume, bla bla too. Some of this stuff is non-intuitive.

Butchering the slots on a well designed mike will certainly change the sound. But as kingkorg says, usually not for the better.

BTW, the B&K Handbook says nothing about cardioid capsules or their venting ... which was the OP's interest.

 

[kingkorg]

This isn't quite the case. The housing & slots have 'as much' effect as the capsule itself.

We agree on most of the stuff as usual. In this particular case i think we might stumbled upon a confusion.

I was talking particularly about kk104 and kk105, the capsules found in Neumann KMS 104 and 105 HANDHELD STAGE mics.

They are different than say kk84, among other things, that the rear of the capsule is sealed, and the slots on the sides are the main part of the delay network, like the only vents the rear of the diaphragm "sees". KK105 doesn't have the second metal plate with the 8 holes, it's just a piece of metal with a "built in" spacer. The slots themselves are the missing 8 holes of the second backplate on kk84.

So the capsule is blint to what's behind it. It has insanely good rear rejection. It's kinda ingenious, newer design. Take a look at the images.

 

[pasarski]

BTW, the B&K Handbook says nothing about cardioid capsules or their venting ... which was the OP's interest.

Oops, true dat. Only pressure equalisation venting is discussed. Must have been thinking of some other paper.