why sound changes with pattern switch

So my DU67 in cardioid sounds a bit harsher than figure 8 or omni .
also some audible differences front and rear in figure 8 .
Any reasons  spring to mind ?

Hi,
What capsule do you use?
For figure of 8, you may just hear the difference of phase between both lobes.
But... it could be difference between the 2 diaphragm (if this is it you can t do many things except choice the side you prefer for cardio or dump it and go for a better one), it could be some flux contamination or other usual culprit around the hi z parts ( had you gloves during built of hi z parts/switch board, capsule instalation,...). Have you cleaned everything with isopropyl alcohol during build?
If yes do you use polystirene caps? If yes maybe you killed one wiyh heat or alcool...

Thanks for the reply .
yes phase is likely with the figure 8.
cardioid is slightly suspicious though .
maybe I'll clean again  around the hi z parts tomorrow . minus polystyrene  Hopefully that helps

Don t forget to clean the switch board too. Could happen here as well.

Hmm , I have touched the capsule rim with my bare hands during installation  . could that be a issue ?
But its not like I was eating ribs while I was building  , I was trying to be quick and sanitary
I"ll check the switches as well .

I don't think that handling the capsule is the reason for a difference in sound.
If there is any pollution on the high-Z parts, you could get extra noise but not a different sound!
Of course the sound will change a bit if you switch between cardioid and figure-8 (or omni), because the signal from the rear diaphragm is added to the sound coming from the front diaphragm.
In the case of figure-8, the two capsule halves are out of phase, so this may be what you are hearing.

A good test is to set the mic in omni and place it in front of a fairly complex source (piano, acoustic guitar, or even just a mix coming from your monitors) and rotate the mic so that one diaphragm or the other diaphragm (or neither) is facing the source.

Of course, if both sides are working the same you should hear no change, or very little. If the circuitry is correct, any change you do hear is the difference between the diaphragms.

As has been previously pointed out, phase discrepancies make the same test more difficult in fig-8, but if you flip the polarity when you rotate the mic, you should still get a fairly similar response from either side.

Cardioid will always give a different response to either of the other positions, due to the deliberate phase cancellations.

gevermil said:

So my DU67 in cardioid sounds a bit harsher than figure 8 or omni .
also some audible differences front and rear in figure 8 .
Any reasons  spring to mind ?

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How are you conducting your test? The unfortunately too common test of speaking into the mic whilst listening via headphones is a gigantic mistake, because bones conduction creates phase cancellation. Since the phase response of the mic is pattern-dependant, the cancellation happens differently.

abbey road d enfer said:

How are you conducting your test? The unfortunately too common test of speaking into the mic whilst listening via headphones is a gigantic mistake, because bones conduction creates phase cancellation. Since the phase response of the mic is pattern-dependant, the cancellation happens differently.

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Gee, that's exactly how Klaus Heyne tests mics!   

AusTex64 said:

Gee, that's exactly how Klaus Heyne tests mics!   

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I've often said (and written) that KH is a good microphone historian! 

(Klaus knows to flip the polarity when he flips the mic, though - as you all know! )

Proximity effect also changes with pattern... which makes near-field sound quite different.

This is wonderfully useful.  These days I'm using figure-8 condensers on snare drums.

zebra50 said:

This is wonderfully useful.  These days I'm using figure-8 condensers on snare drums.

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Interesting! Problem is  most fig-8 mics have a form factor that's incompatible with placement on a snare. The only exceptions I know are quite expensive (Schoeps, Neumann, Josephson) and having them on loan is quite difficult.
Which are you using? How do you position them?

I'm using a Microtech Gefell UM70, either above, near the rim, but quite often further down, more to the side of the snare, to get a bit more body. Sometimes I combine that with an SM57 on top.

zebra50 said:

I'm using a Microtech Gefell UM70, either above, near the rim, but quite often further down, more to the side of the snare, to get a bit more body. Sometimes I combine that with an SM57 on top.

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Is it a native fig-8 capsule or a dual-diaphragm switchable-pattern type? If the latter, what made you choose the fig-8 setting over cardioid?

Dual diaphragm.

I picked figure 8 because I wanted to try the tonal changes from the proximity effect, which are more pronounced in figure 8.
I had used ribbons on snare too.

zebra50 said:

Dual diaphragm.

I picked figure 8 because I wanted to try the tonal changes from the proximity effect, which are more pronounced in figure 8.
I had used ribbons on snare too.

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OK. Did you manage to have better rejection of the hi-hats by orieting the null towards them?

OK. Did you manage to have better rejection of the hi-hats by orieting the null towards them?

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Hi Abbey! I tried and it was certainly part of the reason for trying the 8 in the first instance. 

As I'm sure you know, it's quite hard to find the sweet spot between good rejection and best tone. 
(I think we might have derailed this thread and gone off topic a little bit.)

zebra50 said:

I think we might have derailed this thread and gone off topic a little bit.

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Isn't it fun?  ;D

It is for me. Hope it's fun for everyone else.... :