Valley International 400 Channel Strip, Mic Pre, EQ & Compressor, Modified & Recapped, #2

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:

• 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

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 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.

In use the 400 sounds clean & clear with plenty of gain – too much for line level signals. If you want to use the mic input for line-level signals, and have the benefit of the EQ, I suggest using an inline 20 dB pad. The additional back-panel line level input is post-eq.

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

Condition
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 on the BN1studio website