Yes, mine has 470 ohms. I have read somewhere that the older model had 100R=
. Think I need sit back and process all the info, and find a way to do this=
effectively. Thanks again!
Best
-Anders
--- In "Mike Rooke" <> wrote:
>
> Not sure this is correct, 470 ohms sounds like your measuring the wrong p=
ads?
>
> The EM172-Z1 capsules I hacked at back in 2009 had 100R on the source to =
ground so unless Primo have changed the design or perhaps your using differ=
ent capsules?
>
> 3 2
> 1
>
> 1=3DGND, 3=3DSource between 3&1 is 100 ohms on the EM172-Z1 part, if your=
capsules
> are different ignore my message entirely.
>
> Using a fluke meter I measured 3-1 and sorted according to close results =
per capsules.
> Then placed the (bare) capsule in a calibrator and with spring loaded gol=
d contact pins
> measured the sensitivity via 3V and 2.7K RL as per the datasheet at the t=
ime.
>
> That only gets you so far. Matching for frequency response is a pretty fu=
tile exercise if your time constrained plus theres not much that can be don=
e to alter the response and sensitivity *at the same time* so I matched for=
sensitivity only.
>
> Think about it, match sensitivity, then match response from a pool of 10 =
capsules? good luck with that one - I had hundreds at my disposal and didn'=
t go for frequency response matching until the final mic assembly. Which is=
another issue entirely.
>
> Let me know if I can be of further help.
>
> BR
> Mike.
>
> --- In Peter Shute <pshute@> wrote:
> >
> > Mike did say to check them with a calibrator once you'd pre sorted them=
by resistance.
> >
> > Peter Shute
> >
> > Sent from my iPad
> >
> > On 06/04/2013, at 8:54 PM, "Raimund" <raimundspecht@<raimundspec=
ht@>> wrote:
> >
> >
> >
> > > Thanks for excellent input everyone!
> > > I think I will go for the multimeter-solution.
> > > I am currently on the EM172=C2=B4s and getting the 470 ohm across the=
pad 1 and 3, with a variance of 2-3 (469-472)
> > > So am I right that the capsules should be within 0.1 of eachother (f.=
ex 470.1 and 470.2)? If so, I need a better multimeter.
> > > Secondly, if this is right, am I right to assume one would be lucky t=
o get a matched pair out of a batch of ten capsules?
> > > Sorry for my lack of insight BTW, I=C2=B4m working on it:-)
> >
> > Hi Anders,
> >
> > I think that John Hartog's approach is the way to go.
> >
> > I'm afraid that measuring the tiny differences of the 470 ohm source re=
sistor does not help here at all. I'm pretty sure the 1% tolerance of the r=
esistor has nothing to do with the actual sensitivity differences of the ca=
psules.
> >
> > What instead matters are the specific tolerances of the internal FET tr=
ansistor (its gain), the electret foil and perhaps a few geometric toleranc=
es within the capsule. These much more relevant tolerances however cannot b=
e measured by a simple multimeter.
> >
> > Regards,
> > Raimund
> >
>
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