Better Circuit for the Original Capsule from the MCA SP-1?

RuudNL said:

The test circuit is the classical Schoeps circuit.
Hfe and Vbe can be measured with most digital meters.
Noise is measured with an audio analyser and a weighting filter.

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micaddict said:

Relax, Paul. It's Sunday. 

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I have Hfe on my meter, but not Vbe.
How close do you try to match the Hfe?  Within what %?

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RuudNL said:

I have Hfe on my meter, but not Vbe.
How close do you try to match the Hfe?  Within what %?

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On most digital multimeters there is a diode test function, that shows the forward voltage.
If your meter does not have a diode test, connect the B-E junction of the transistor under test in series with a resistor of 10K.ohm to a voltage of 10 Volts or so and measure the voltage over the junction. (ca. 600-700 mV)
Keep the voltage constant and avoid temperature changes between transistors under test, since the temperature has an influence on the B-E forward voltage.

I first select transistors in groups: good, maybe usable and bad.  (Value too far off)
Then I select the ones from the group 'good' for the best match.  The closer they match, the better!

(If you want, I can send you a close matched pair of hand-selected low-noise PNP transistors, I have some selected pairs here.)

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micaddict said:

Nico Veth, the Dutch guy who made the well-known MCA SP-1 and MXL 990 mod site (site is down at the moment) uses the stock capsule, too.

Another Dutch guy, who services my vintage mics, has been doing an MCA SP-1 mod from day one. He makes a new PCB, but uses the stock the capsule.

While I'm at it, a third Dutch guy is our own Ruud. He's a rising star in mod land and, as can be seen in reply #3, he knows a thing or two.  8)
And I can tell you he's a nice guy to boot.

The fourth Dutch guy in this story would be me. And I ............ um...... love microphones.  ;D

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BTW, the SP1 is now defunct. They are shipping the new models with surface mount components, so no longer suitable for easy modding.

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