BRTBRT37
New member
Probably I open a can of worms: groupDIY deals with hundreds of pages about building condenser microphone (CM) copies of famous producers – especially Neumanns. There is no doubt that types such as U 87, U 67, KM 84, KM 49 and many more belong to the very best microphones available. They are robust too and have a big reputation. This is reason why so many copies – good and bad ones – of these capsules exist. Not so for ribbon microphones (RM).
What is the difference ? Every type of microphone – with one single exception – is based on a capsule structure that in short is a miniature drum. Its behavior is defined by a circular circumference, a small stretched diaphragm as coupling to the ambient sound field and an air cushion behind. Every drum - however small it is - has a resonance, based on these parameters. For most LDC microphones, this resonance is in the order of 3 …. 12 kHz. The art of microphone design consists of tuning and taming this resonance at will. The basics behind are explained in a lot of contributions of groupDIY. Eventually this gives every type its typical flavor, as it is common to keep some overshoot in the range mentioned to achieve additional brilliance.
Nevertheless the common claim of LDC brands to cover 20 Hz … 20 kHz is a lie as most measurements show a peak of 2.. 5 dB at 10 … 15 kHz and a sharp drop of – 4 … -8 dB at 20 kHz. No matter – it is the earthat decides quality. SDC types behave somewhat superior since their resonance frequency is close to 20 kHz.
There are some more problems with CM: The output of a CM capsule is not strictly linear, but rather part of a series that contains all harmonics. In common, these harmonics are very small and finally account only for a typical distortion of 1% at 115 … 130 dB SPL, before adding a pad improves distortion, but lowers S/N. Yet, even lower distortion may start to degrade quality at lower SPL.
One more problem are asymmetric FET input amplifier stages, common for impedance matching. FET have square law characteristics that add second harmonics at the conditions described above. Some people like it, but it is a step away from truth. Further problems in the CM amplifier design may not be discussed here since they are matters of incompetence. CM are widespread and can be purchased for a 2 digit to 5 digit price tag in a quality range from acceptable to excellent.
The only exception initially stated is the ribbon microphone (RM) as not belonging to the drum type. RM are accused for many drawbacks to state initially:
What is the difference ? Every type of microphone – with one single exception – is based on a capsule structure that in short is a miniature drum. Its behavior is defined by a circular circumference, a small stretched diaphragm as coupling to the ambient sound field and an air cushion behind. Every drum - however small it is - has a resonance, based on these parameters. For most LDC microphones, this resonance is in the order of 3 …. 12 kHz. The art of microphone design consists of tuning and taming this resonance at will. The basics behind are explained in a lot of contributions of groupDIY. Eventually this gives every type its typical flavor, as it is common to keep some overshoot in the range mentioned to achieve additional brilliance.
Nevertheless the common claim of LDC brands to cover 20 Hz … 20 kHz is a lie as most measurements show a peak of 2.. 5 dB at 10 … 15 kHz and a sharp drop of – 4 … -8 dB at 20 kHz. No matter – it is the earthat decides quality. SDC types behave somewhat superior since their resonance frequency is close to 20 kHz.
There are some more problems with CM: The output of a CM capsule is not strictly linear, but rather part of a series that contains all harmonics. In common, these harmonics are very small and finally account only for a typical distortion of 1% at 115 … 130 dB SPL, before adding a pad improves distortion, but lowers S/N. Yet, even lower distortion may start to degrade quality at lower SPL.
One more problem are asymmetric FET input amplifier stages, common for impedance matching. FET have square law characteristics that add second harmonics at the conditions described above. Some people like it, but it is a step away from truth. Further problems in the CM amplifier design may not be discussed here since they are matters of incompetence. CM are widespread and can be purchased for a 2 digit to 5 digit price tag in a quality range from acceptable to excellent.
The only exception initially stated is the ribbon microphone (RM) as not belonging to the drum type. RM are accused for many drawbacks to state initially:
- Vulnerability to any kind of air movement such as wind or blowing against.
- Most RM are not usable for handheld and close singing.
- Low output and problems of hum and noise.
- Directivity intrinsically figure 8 which is not always easy to handle. However figure 8 vertical is not true at high frequencies.
- Restricted high frequency response.
- Need for a properly designed transformer.
- No high frequency resonance that has to be tamed.
- Much lower diaphragm mass and therefore better transient response.
- Frequency range may be extended at least equal to CM.
- No intrinsic high level distortion - no need for -10 dB / -20 dB pads.
- Symmetrical signal generation.
- Absence of high frequency resonance makes RM much more equalizer friendly.
- With exception to the first 2 points stated, all other may be overcome by proper design, which unfortunately is not often found.
