xeawr

Schoeps circuit de-emphasis - a new approach
« on: April 22, 2020, 10:22:37 AM »
maybe this is a better way to implement a de-emphasis for cheap generic K67-type capsules. What do you think?

(see resistor values in red)



Together with the 22n caps that makes a -3dB point of about 15kHz (going from memory here). At 20kHz this would be about 4-5dB of attenuation (again going from memory), sounds about right for a cheap K67 capsule.

This is not my "discovery" or idea, I saw this first in a video on youtube where a guy reverse engineered the FAME CM2 microphone. Have a look at the output resistors: there are two 470 ohm.



What do you guys think?


EmRR

Re: Schoeps circuit de-emphasis - a new approach
« Reply #1 on: April 22, 2020, 10:28:12 AM »
Without looking more closely I’ll speculate the effect will vary wildly with the type of preamp load, since it’s not isolated from it. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

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analogguru

Re: Schoeps circuit de-emphasis - a new approach
« Reply #2 on: April 22, 2020, 10:45:41 AM »
Unfortunately this guy got it wrong.  The Fame CM2 is built with SMD-components and the part in doubt is a resistor which is marked with "470" wich means a 4 a 7 and zero 0, which is a 47 Ohm resistor and NOT a 470 Ohm resistor.  Even then the circuit is wrong because during cloning the clone of a  clone of a schoeps-circuit, someone got it wrong and confused a resistor with a coil which is originally there instead of the two resistors.  You shouldn't watch so much videos of unskilled people - it will save you a lot of time.

RuudNL

Re: Schoeps circuit de-emphasis - a new approach
« Reply #3 on: April 22, 2020, 12:10:57 PM »
Yes, as EmRR already said, the increased output impedance of the circuit is a bad idea and makes the result unpredictable.
Besides that, -3 dB @ 15 KHz may not be enough in some cases.  5 to 6 dB @ 15 KHz seems more realistic.
(The U67 for example uses -7 dB @ 16 KHz.)
There is a solution for every problem!

http://www.vansteenisaudio.nl

xeawr

Re: Schoeps circuit de-emphasis - a new approach
« Reply #4 on: April 24, 2020, 09:55:00 AM »
alriiiiight, thanks for taking away another spark of hope...  :'(


 :D on a more serious note I really appreciate your input!!!


 

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