Valley International 400 Channel Strip, Mic Pre, EQ & Compressor

Description

Channel strip / preamp from Valley International, one of the later incarnations of Allison Research / Valley People. The model 400 channel strip has a mic pre, compressor / gate & equaliser in a 1U package. Designed originally as a voice processor for radio work, it fits neatly into the modern channel strip genre

I couldn’t resist the urge to tinker with the 400 and the revamped unit has:

  • Mic / Line switch
  • Altered EQ points
  • Low frequency turnover point is now lower ~ 60 Hz
  • Mid centre frequency is lower ~ 700 Hz
  • Hi frequency turnover still ~ 5 kHz
  • Revamped power supply
  • 220 Volt power for UK / EU
  • Recapped throughout
  • Larger value bipolar caps in the audio path

I have five model 400 channel strips in stock and will modify them as required. Phantom power is an option that can be added

The 400 combines a very clean mic preamp with a simple three-band EQ with fixed frequencies and compressor / de-esser / expander / gate. The expander & gate are not as simple as they seem – there’s a description in the owners manual (see the Links tab) but the simple explanation is that the expander / de-esser & compressor work together when switched to Comp and the gate works alone when switched to Gate

The preamp and eq feed the back-panel insert send and a parallel preamp output. The insert return then feeds the compressor VCA and output stage. The new line input uses the existing mic XLR input

In use the 400 sounds clean & clear with plenty of gain – too much for line level signals. To compensate for this I’ve included a line-level switch which reduces gain to around 10 dB. The gain structure of the 400 is a little complex: at unity gain the compressor is triggering on peaks. Increasing the compressor gain – to get more compression – raises the overall level, requiring the output gain to be lowered to maintain unity gain

When pushed the compressor does deep into Dynamite territory with huge, compression & explosive release available on higher settings. The compressor has Heavy, Normal and De-ess settings and a fixed ratio of 20:1. Release time is program-dependent

I have one Model 400 ready now and more to follow. Photos show the first completed unit – the others look similar

Tested & working 100%. Manual available here

Owners Manual

https://medias.audiofanzine.com/files/vp400-479828.pdf