Ultra Pimped Alice - my take on a classic DIY design

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bxershrts said:
Ah....one last thing -

I will implement a pin socket for the HFEQ capacitor on the pcb until I find one that suits ---using the suggested 8n2 ,3n9 or 2n2 - what capacitor location on the pcb do I socket..?

Thanks for you help,

Hudson

It will be C17.

Regards!

 
Hello again ;-) I have assembled the circuit and am ready to calibrate. What is the correct method to calibrate and voltage levels to shoot for?

Thanks
 
bxershrts said:
Hello again ;-) I have assembled the circuit and am ready to calibrate. What is the correct method to calibrate and voltage levels to shoot for?

Thanks

Hi!

Voltage reading at SRC_T pad should be 1/4 voltage reading at VCC pad.

This allows to maximize headroom for your mic.

There are other forms of calibration, but they require different equipment.

Regards!

 
Thanks for all your shared input.

I have assembled the mic , calibrated it easily - voltages are all in the correct range , the mic is clear crisp and detailed yet there is one problem .

The mic dies with plosives or in close proximity.

At VCC_T voltage drops a whole volt from 11.62 down to 10.34.

At SRC_T Voltage goes up from 2.89 to 5.02 vdc.

Bad Jfet?

Thanks!!
 
bxershrts said:
Thanks for all your shared input.

I have assembled the mic , calibrated it easily - voltages are all in the correct range , the mic is clear crisp and detailed yet there is one problem .

The mic dies with plosives or in close proximity.

At VCC_T voltage drops a whole volt from 11.62 down to 10.34.

At SRC_T Voltage goes up from 2.89 to 5.02 vdc.

Bad Jfet?

Thanks!!

It may be a capsule problem. :(  Could you try with a different capsule?

This kind of problem most of the time is due to diaphragm collapsing.

Another thing you could do is replace 9.1V Zener to a lower value (8V?), so polarization voltage is reduced.

Regards!

 
Hello again Homero :)

Always appreciate your help and advice.

Yeah...I have tried 3 different capsules and they all do the same thing.

I will try a different zener - good idea!

The polarization voltage sits at about 52.7v and doesnt move when the mic goes dead...perhaps this is too high voltage for all my capsules?
 
bxershrts said:
Hello again Homero :)

Always appreciate your help and advice.

Yeah...I have tried 3 different capsules and they all do the same thing.

I will try a different zener - good idea!

The polarization voltage sits at about 52.7v and doesnt move when the mic goes dead...perhaps this is too high voltage for all my capsules?

It's a little bit strange, since 52.7V is not to high polarization voltage.
What kind of capsule do you have?
I have used 60V on some cheap LDCs from EBay and AliExpress, and they work fine.
Are you using the mic in a high humidity environment?
 

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