Why you should never use multi pattern mics

[abbey road d enfer]

Du.uuh! First hit is an evil Harman page pretending to be AKG
AKG 75th Anniversary Retrospective: C Series Microphones – The Evolution of a Studio Icon –

Interestingly, the first picture shows a young Bernhardt W. busying himself with an extended mini capsule.

 

[kingkorg]

Coming very late to this discussion, I noticed a few posts, particularly the OP mentioning "phasing issues".
Phase is an old endemic scapegoat, often used by barely qualified people to support their criticism of a particular equipment.
I'm not saying it's the case for kingkorg or Recording Engineer.
If there was no phase, there would simply be no cardioid mics.
Single diaphragm cardioids are cardioid because of an acoustic phase device, when dual-diaphragm rely on simple spacing, but in the end it's the same principle that is at work. Of course they have a different response but they both have "phase issues".

Just to be clear about "phasing issues" I mentioned in the op. I am talking about introducing signal coming from rear diaphragm which is separated by the thickness of the backplate from the front one. So there is slight delay, although small it falls in the audible range.

 

[abbey road d enfer]

Just to be clear about "phasing issues" I mentioned in the op. I am talking about introducing signal coming from rear diaphragm which is separated by the thickness of the backplate from the front one. So there is slight delay, although small it falls in the audible range.

For sure, but if it wasn't there, there would be no directivity. Actually, there would be no signal either.
It's because the rear pressure is phase-shifted compared to the front pressure that the diaphragm moves.

 

[soliloqueen]

ears have all sorts of phase and resonance issues too. the brain just corrects for them. stand in the bathroom with the fan on and cover your ears fully for about 15 seconds, then slowly tilt your hands away (listening to the pitch of the noise go up as the resonance changes). there will be a point at which you can still hear the pitch, but your hands are fully off your ears. congratulations, you can now (temporarily) hear the acoustic system of your ear.

 

[abbey road d enfer]

ears have all sorts of phase and resonance issues too.

Resonance, yes, but phase???
The very notion of phase implies there is a reference; what would be this reference?

 

[soliloqueen]

Resonance, yes, but phase???
The very notion of phase implies there is a reference; what would be this reference?

i was actually agreeing with you and disagreeing with kingkorg a bit here. it's just a bit of a joke. the reference would be a signal coming from a pressure transducer in the same location with none of the the acoustic system around it, which would be completely inapplicable to the material reality of the ear and how it works. that was my point

 

[kingkorg]

@soliloqueen @abbey road d enfer ,

I am not even sure if i agree or disagree on this, or if we are even talking about the same thing.

Here's an example of a typical k67 behaviour. This is the response of cardioid vs omni. Both are campensated so that cardioid seems flat, just for the effect to be more obvious. Both sides are just summed together at same level. Green is cardioid, blue is omni. More than 5db notch at 5k is created as a result of just summing them in a traditional way. Very uneven response above 2k.


This is the same exact situation, but both diaphragms are "virtually" alligned by adjusting the time delay between the two. The omni response is much smoother. It sounds much better, and off axis sound is way more even regardless of angle of incidence.

 

[soliloqueen]

@soliloqueen @abbey road d enfer ,

I am not even sure if i agree or disagree on this, or if we are even talking about the same thing.

Here's an example of a typical k67 behaviour. This is the response of cardioid vs omni. Both are campensated so that cardioid seems flat, just for the effect to be more obvious. Both sides are just summed together at same level. Green is cardioid, blue is omni. More than 5db notch at 5k is created as a result of just summing them in a traditional way. Very uneven response above 2k.
View attachment 106490

This is the same exact situation, but both diaphragms are "virtually" alligned by adjusting the time delay between the two. The omni response is much smoother. It sounds much better, and off axis sound is way more even regardless of angle of incidence.
View attachment 106491

makes me want to design a capsule that has intakes for the rear at almost the same place as the front diaphragm, routes it around the back and then back to the front. i wonder what would happen.

 

[Gus]

Have you looked at a C700?

 

[abbey road d enfer]

Here's an example of a typical k67 behaviour. This is the response of cardioid vs omni. Both are campensated so that cardioid seems flat, just for the effect to be more obvious. Both sides are just summed together at same level. Green is cardioid, blue is omni. More than 5db notch at 5k is created as a result of just summing them in a traditional way. Very uneven response above 2k.

OK, I didn't read properly your post. I thought you were questioning the use of applying back pressure to the rear of the diaphragm. Chalk iot up to language barrier and not enough sleep.

 

[soliloqueen]

Have you looked at a C700?

Yes, I've always been fascinated by multi-pattern mics that use omni and bidirectional base patterns instead of dual cardioid!

 

[ricardo]

This is the same exact situation, but both diaphragms are "virtually" alligned by adjusting the time delay between the two. The omni response is much smoother. It sounds much better, and off axis sound is way more even regardless of angle of incidence.

kingkorg, which K67 capsule is this?

Can you explain a bit more about your "adjusting the time delay"?
If this is an "on-axis" response and the delay is adjusted for this, surely the "back" response will now have the delay 2x the original.
So the "back" response, and other directions, will be even worse.

 

[kingkorg]

kingkorg, which K67 capsule is this?

Can you explain a bit more about your "adjusting the time delay"?
If this is an "on-axis" response and the delay is adjusted for this, surely the "back" response will now have the delay 2x the original.
So the "back" response, and other directions, will be even worse.

No, the sound from all directions is more coherent. The back response is not adjusted, it won't have the 2x of the original. I basically delay the front diaphragm in time so it gets virtually alligned with the rear one. The goal is to make one virtual diaphragm out of the two physically separated. Like when you have two mics on a guitar cabinet, but one is say 1cm further. You delay the one closer to the speaker in order to allign it with the other one.

 

[abbey road d enfer]

No, the sound from all directions is more coherent. The back response is not adjusted, it won't have the 2x of the original. I basically delay the front diaphragm in time so it gets virtually alligned with the rear one. The goal is to make one virtual diaphragm out of the two physically separated. Like when you have two mics on a guitar cabinet, but one is say 1cm further. You delay the one closer to the speaker in order to allign it with the other one.

Then, as ricardo mentioned, the rear pick-up is altered.