First experience with an AKG D25 microphone

Just preliminary test:


Hard to believe.


What a sound.


Possibly the first cardiod mic that has a proximity bass effect which sounds nice. The bass is deep but not offending.


So far it was only tested with the 12dB minus at 50Hz filter on. Is it an inductor in series with a resistor filter, Pleiades (R,L) filter?


The signal path used is as follows:


male singing voice at 3-20 in - AKG D25 with its deeper low cut on - Western Electric 1:2, (1H:4H) transformer - Sony TC-D5 Pro - Sennheiser HD580


What is also striking about this mic is the sound that makes you fall in love with it. Lack of coloration. Smooth frequency response. As if there are no abrupt microvariations. High frequency detail. No s problem. No s problem at all.


And the fact that it can be used more than a foot away in unfavorable acoustics and still get a world class sound quality.


Out of curiosity the Beyer M61 which was lying around in its box was tried. It is a mic that has a lot of proximity effect, a Pleiades (R,L) filter was connected. The sound is big but there are peaks in frequency response and coloration, hardness is apparent.


The AKG D25 sounds smooth as silk.


How is this done? Is it the impedance matching of the acoustic wave at the back creating an infinite tranmission line and no reflections or reasonant frequency spots of the membrane? See previous posts on the relevant AKG patent.


The sound also reminded the Beyer M88 example on YouTube:
https://m.youtube.com/watch?v=ar_YpOI9abU
Apparently D88 uses a similar acoustic impedance matching mechanism with its long tube at the back, see previous posts. An M88 has not been tried yet.



Also the very very much cheaper Beyer M55 omni was tried. It sounds very respectable. And also the Philips N8 207/10. The latter sounded bigger than M55 less clear but with a nice sense of harmonic distortion and a less somewhat plastic feel. Is it because it has an aluminum membrane?


But back to AKG D25. What a deep sound without offense. A ribbon mic kind of sound delivery at a larger distance. Singing at the back of it created an attenuated but still smooth sound. So nice detail.


Big output mic with its rocking balls.