NTP 179-400
NTP was a danish company specialized in broadcasting equipment. The 179-400 originally was a broadcasting limiter as well, but Mixing and Mastering Engineers like Ronald Prent started to use them as well. Bob Ludwig is using a similar NTP limiter called 179-120 since years. The special thing about the NTP compressors and Limiters are the unique VCA modules with low noise and distortion and the ZFT transformer input stages. Furthermore the 179-400 uses Lundahl output transformers. The attack time is a combination of a fixed 1ms and a simultaneous soft clipping circuit. There are two adjustable release times. When combined they result in a logarithmic release curve, which is more natural and musical than a linear one.
The 179-400 Limiter is an EURO-card module and the switches can only be adjusted with a screwdriver. So not very studio friendly at first. That’s why we wanted to rack two of the modules up and bring all the controls to the faceplate of the new housing. In order to do so we desoldered the screwdriver switches and chose Elma Typ 1 switches instead. But since the original switches were hexadecimal coded, we needed to incorporate some Arduinos as well that encode the Elma’s signals. Luckily I also found an old stereo VU meter with peak LEDs on a synthesizer flea market that has a small form factor and could be used in a 1U rack. Other than that the build was very straightforward, most of the work was to connect all the different controls to the multipin connectors of the NTPs and building a PSU.
The sound of the 179-400 can be described as transparent but not clinical. The transformers still give a little bit of sound, but the compression character is really subtle. I use the NTP always as the last device of my analog chain just to catch some peaks before AD converting. After that I still use a digital brick wall limiter to achieve the final loudness, but compressing in two different steps helps to keep the gain reduction at a more manageable level and can be more transparent. So the NTP 179-400 is a nice combination of a transparent compressing limiter that still gives a little bit of character.
Features
Lundahl output transformer
ZFT input stage
Unique NTP VCA
Elma switches
Relay bypass
