His comment to me was that the Sennheiser were so realistic and that 40 had the freq. response of a high quality omni condensor.
They use a different approach than most condensors. They use EQ in the mic to modify the response. Not everyone likes that approach. I haven't tried'em.
This comment is pretty misleading as it does not explain things properly and invites misinterpretation.
Firstly - the Sennheiser MKH microphones are RF condensers - most other microphones are AF condensers.
Basically, AF capacitor microphones use the capsule as a capacitor to store charge. With one fixed plate and the other free to vibrate in sympathy with the sound, the capacitance varies, and the charge moves in or out of the capsule accordingly. This is measured by the head pre-amplifier and an audio signal results. All well and good, but the capsule is inherently in a high impedance circuit (over 1GigaΩ) – it has to sit there with stored charge until the diaphragm moves and any changes in the charge are perceived as audio. In a humid atmosphere the stored charge finds it easier to escape on water molecules in the air rather than through the input of the pre-amplifier, hence noisy and reduced output, and misery all round. The high biasing voltage also attracts dust particles to the diaphragm, reducing its efficiency and linearity.
The RF system (as used in Sennheiser MKH microphones) uses the capsule (a low impedance capsule) in a completely different way: as a tuning capacitor for an RF oscillator – which inherently employs it in a low impedance circuit where a high frequency signal is being passed through the capacitor all the time. Changes in capacitance (caused by sound moving the diaphragm) alter the resonant frequency of the circuit (circa 8MHz) and so its frequency becomes proportional to the audio signal. A simple RF demodulator restores the output to a conventional audio signal. More complex and sophisticated (but still very rugged), this system is highly immune to the effects of humidity and is thus the preferred design to be used out of doors (or when moving from outside to inside on a cold day!).
Secondly - most microphone manufacturers heavily damp the capsule to get a flat frequency response. This lowers the output level and putting the effort into frequency response means that, very often, the polar-pattern can get neglected.
In the MKH series, Sennheiser only lightly damp the capsule. This means that they get a smooth and rounded response and can also put more effort into the polar-pattern. In the electronics the frequency response is tailored to be the converse of the capsule response. This gives a flat response and the microphone has a higher output so you don't have to drive you mic. pre-amp. so hard. Just saying "they use EQ" is very very misleading.
This diagram shows how most manufacturers damp the capsule:-
This diagram shows how Sennheiser lightly damp and put the converse in the electronics:-
Also - The MKH 8000 series (as well as the MKH 800 and MKH 20/30/40 series) all use a symmetrical capsule design. This capsule design has an acoustically-transparent front plate identical to the back plate. This means that whatever the daphragm is doing to one plate it is doing equal and opposite to the other - ensuring the acoustic impedance of the capsule remains stable and unchanging. This vastly reduces the intermodulation distortion (double-tone distortion) of the microphone. Many normal microphones have IM-distortion figures of 2 to 3% at high frequencies. The symmetrival capsule keeps this at virtually zero and it peaks at only about 0.3% at 20kHz. This is why the comment was made that they are "so realistic" and is what I have found in my own exerience. It's like listening to a person rather than a recording of a person - a bit like looking at your garden through windows that have just been cleaned, rather than ones that were cleaned a year ago.
You may also find
THIS useful - it's an English translation of an article published in VDT magazine in Germany of an interview with the designers of the MKH 8000 microphone series. It makes fascinating reading, actually.
I hope this helps clear things up.
