FAQ

• What is the maximum SPL of a dynamic microphone?

  It is a common saying that dynamic microphones just have no maximum SPL.
  This saying is not technically exactly correct but for every day use use of dynamic microphones you will not find gain limitations. At SPL levels above 160 dB some mechanical problems might occur (for example the voice coil might crash onto the magnet) but these SPL levels are very hard to find in real world.
  Here at Sennheiser we use dynamic microphones for distortion measurements on loudspeakers at very high sound pressure levels. At Sennheiser we have measured the SPL and THD inside a large 2" driver/horn combination with a MD 421. The max SPL this combination was able to produce was 150 dB and the THD level recorded by a MD 421 was below 1% (produced by the driver not by the mic)
  So as a conclusion we can state the MD 421 has no maximum SPL limitations for practical use. However if using dynamic microphones at high SPL levels a user should be aware that the very high voltage (up to several volts) delivered by the microphone might cause problems when connected to mic preamps.

  
  
  
• What are the primary differences between the different HD 25 models?

  Currently Sennheiser offers three (3) models in the HD 25 line
  
  • HD 25 LIGHT

  - The HD 25 LIGHT is the essential sound of a HD 25 with a simplified headband.

  - Impedance = 60 Ohms

  - Frequency response = 30-16,000 Hz
  
  • HD 25

  - The HD 25 is our legendary HD 25 headphone with splayed headband and straight cable.

  - Impedance = 70 Ohms

  - Frequency response = 16-22,000 Hz
  
  • HD 25 PLUS

  - The HD 25 PLUS is our legendary HD 25 headphone with coiled cable, an additional straight cable, a second set of ear cushions and a protective pouch

  - Impedance = 70 Ohms

  - Frequency response = 16-22,000 Hz
  
  These models offer the same sound signature as the legendary HD 25 and sound signature of the headphones is the same across the three models.

  
  
  
• Are the ear pads of the HD 25 real leather or leatherette?
  The ear pads of the HD 25 are made of a synthetic leatherette.