capsule and grill

[Gus]

Yesterday I brought some microphones to soundguys.

Something interesting to post. I also brought some of the same microphones to ETK's. Two are fet based with matched fets same IDSS bias etc. same circuit and transformers different grills and body, same type capsules 32mm MXLs.

Both microphones sound very different. One has OK sound for a 32mm china capsule IMO.

I have exchanged the capsules between both microphones and the "sound" follows the grill.

I reason I am posting this is, two others heard the difference and like myself were suprised how different the sound was.

I read some posts here and I don't think the posters have done the tests to check if what they post is true.

The more I learn (testing and reading) about capsules/grills the more I learn not to trust what I read about them.

 

[soundguy]

I always had figured that the grill would influence the sound of a mic but I never thought in a million years it would *define* it. I nearly fell over when gus explained the only difference was the grille, sounded completely like a circuit difference to me...

Gus makes some crazy good microphones by the way.

dave

 

[CJ]

very inyeresting!
Iwonder if aging of a screen has any influence,as the wire loosens up or gets grit in between the squares.
anybody selling vintage screens on evilbay?

I wonder if the mic body has any effect?

ang Gus, how much for a mic!

:thumb:

 

[dale116dot7]

There was a paper published through the AES that did some studies on this topic - and the U67 screen design was done for this purpose. Stephen Paul also wrote about this. I also found out about this the hard way. I swapped capsules on an Apex 430 - a 'teflon' CK12. And it sounded better, but there was a spitty sound I didn't like - the same spitty sound as on the Apex, but less of it. Opening up the screen got rid of that.

I'm not sure about the aging, but I would think if the mesh gets covered in crap, it should sound a bit different. I know there are a lot of the crystal 'pill' mic cases on evilbay, the ones that look like a ribbon but aren't... I think a nice tube mic circuit and capsule could fit in there....

 

[jrmintz]

Hey Gus,

This is fascinating. Are you able to draw any conclusions or characterize the effect of different shape grills?

:thumb: :thumb: :thumb:

 

[Gus]

Seth

Very general findings.

Round grill

One layer grills (round like a u47) tends to sound more open and also seems to let a LD microphone pickup sound better at a distance.

Two or more layers(round like a u47) can sound OK or Very Good depending on the open area of the mesh. When the layers go up and /or the open area of the mesh goes down it is more a sound of like talking with your head in a 55 gallon drum but shifted in freg because of the smaller dia of the microphone

So for u47, ELA m251 etc Dia and open area are tuning, Dia more important with lower open area. Its kind of like an eq added to the microphone can be good or can be bad.

More complex shapes

Now the stuff gets harder with more complex shapes like the well designed U67 ,U87, u49 grill. They have mult layers BUT the shape helps control the res by staggering them. With this shape one can use more closed grill mesh because the refections are more staggered. I have read on the web Neumann goes after companys that use this shape with a trademark?????

The UM900 looks interesting as well as the um800? (800 kind of like the DDG I wonder who was first) I would guess the open are matters alot with the 900 shape. The few M7s, M8s and M9s I have heard I did not have enought time with.

I made a microphone with a more exteme Grill design. People seem to like it.

Again more open grill better distance sound pickup.

The next big thing is the top of the grill to the base of the capsule mount distance and shapes again more eq.

This is not new information the IRT? designed the U49 grill if what I have read is true. SPA wrote about grills in mix YEARS ago. I would guess REAL microphone designers knew about this many years ago. Dale gave a good example

You know the more I work with microphones the circuit is the easy part capsule grill is a pain.

 

[jrmintz]

Wow, this is great work Gus. Thanks for posting it. There's a lot to think about here.

:guinness: :sam: :thumb: :thumb:

 

[thenovice]

Im going to ask this because i plan to build a g7 in the near future:

In theory your saying to get a certain sound im looking for it's not necessarly the capsule but the design of the grill?
by the way it is shaped and how many layers of mesh?

but thats assuming the capsule was a standard[decent] capsule right?

because this is making me think you could have a junk capsule and get a great sound if your grill is designed right!

btw can anybody recommend a couple GOOD capsules for the g7[not super expensive though].

thank you gus,this is very intresting,it makes me look at mics in a different light.

 

[Marik]

The best grill is no grill.
Unfortunately this is impossible. Manufacturers ought to make those layers as a protection and for rigidity and to deal with warranty as little as it is possible. They never know what kind of jerks will be using mics, spitting into them and using as high hats.
BBC training manual has some information on processes inside the grill. It is mostly reflections and standing waives. Stephen Paul in his article gives nice graphs of how grill affects U47 response.
Amount of open area, size, and shape is the key and need a lot of experiments. As a rutine, working on modding Chinese mics, I always leave only outer, thicker mesh, removing a couple inside layers.
I agree with Gus--the grill is pain in the neck. Its seeming simplicity is very deceptive.
Ha-ha! We are talking about condensers. Ribbon mic grills are hundred times more complicated. It took me over a year of thinking and experimenting, making more less acoustically transparent grill, and I am still not even close.


[quote author="CJ"]

I wonder if the mic body has any effect?

[/quote]

Of course!!! It sets polar response in vertical plane, and gives nasty reflections. Even capsule mount does. That's why Gefell makes conus-like capsule mounts and goes for those elaborate mic shapes:

 

[Guest]

[quote author="Marik"]The best grill is no grill.
Unfortunately this is impossible. Manufacturers ought to make those layers as a protection and for rigidity and to deal with warranty as little as it is possible. They never know what kind of jerks will be using mics, spitting into them and using as high hats.
BBC training manual has some information on processes inside the grill. It is mostly reflections and standing waives. Stephen Paul in his article gives nice graphs of how grill affects U47 response.
Amount of open area, size, and shape is the key and need a lot of experiments. As a rutine, working on modding Chinese mics, I always leave only outer, thicker mesh, removing a couple inside layers.
I agree with Gus--the grill is pain in the neck. Its seeming simplicity is very deceptive.
Ha-ha! We are talking about condensers. Ribbon mic grills are hundred times more complicated. It took me over a year of thinking and experimenting, making more less acoustically transparent grill, and I am still not even close.


[quote author="CJ"]

I wonder if the mic body has any effect?

[/quote]

Of course!!! It sets polar response in vertical plane, and gives nasty reflections. Even capsule mount does. That's why Gefell makes conus-like capsule mounts and goes for those elaborate mic shapes:

[/quote]

except, that they can no longer make the claim they have the only 48v phantom supplied tube mic, as audio technica has one out now as well...although MG might have been the first....

i wonder if an akg414 would be worse at this due to it's shape ?

 

[Gus]

The grill is not going to make a bad capsule good.

It is just part of the mess that definds the sound of a microphone. IMO you still need a good capsule.

Very good capsules cost good money.

I am picky with capsules. If I am building a non test microphone > $125.00 USA for a transformer and > $500.00 for a capsule are not a big deal because I am building something to hopefully compete with the BEST.

If you want to use the cheaper china 32mm the 6 micron ones seem to be better than the 3 micron ones get the stock ones

34mm 797 or superlux 34mm seem to be the better china stuff. I bought a beringer B2 pro just for the capsule and mount and 6, 1 gig resistors.

Soundguy heard two microphone built in a MXLv67 body with the stock 32mm capsules one tube one solid state he made a statement something like he did not think the little different between the circuits was worth the money for the tube circuit. I guess what I am saying is the 32mms can be limiting.

I have not tried a plastic CK12 but they might sound good. New plastic ck12s are hard to get in the USA I have not been able to purchase any yet.

 

[soundguy]

[quote author="Gus"]
Soundguy heard two microphone built in a MXLv67 body with the stock 32mm capsules one tube one solid state he made a statement something like he did not think the little different between the circuits was worth the money for the tube circuit. I guess what I am saying is the 32mms can be limiting.
[/quote]

both mics gus made there sounded very good. the tube mic sounded like a tube mic but the fet mic did not sound 100 times easier to make, it sounded just as good, just slightly different, didnt have the open bigness to it. For what my time is worth, that difference is not at all worth the pain and drama of building a high voltage power supply, machining the body to get a good multipin connector in there, etc.

One of the big lessons I learned from gus the other day was that for my taste, in my world, if I am going to go through the trouble of building a tube mic, Im going to build it with the absolute best capsule and transformer I can find just to simply justify the extra steps in construction. At least when its done, it can be truly truly awesome if youve done your homework.

dave

 

[Guest]

Very interesting stuff Gus... I actually just bought a new plastic CK12 capsule. It came up on ebay and I snatched it up. I am planning on putting a tube circuit with it, probably G7 unless anyone has had experience with this capsule and would suggest something else. I am thinking a round single layer grill, U47 style.

Thanks for sharing your thoughts Gus... I need to reread the Stephen Paul article...

 

[Gus]

EF86 tube based microphone do seem to sound nice.