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 / de-esser & equaliser in a 1U package. Designed originally as a voice processor for radio work, it fits neatly into the channel strip genre
I couldn’t resist the urge to tinker with the 400 and the revamped unit now 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 four model 400 channel strips in stock and will modify them as required
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 dives deep into Dynamite territory with huge, pumping 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
