Sometimes you get visited by a very nice amp! This Peavey is a very nice amp!
On the inside of the amp two PCB's make the amp. One PCB on top is the preamp PCB that has all the circuit for the preamp and the effects. The lower PCB has the individual poweramps, the power supply and the switching boards. A big heatsink on the back takes care of the cooling.
In the 80's solid state amps were ruling. And after the release of the Roland Jazz Chorus, chorus was a known effect to be used with amps. In 1986 Peavey released the Stereo Chorus 400, a 260W (2x 130W) solid state amp with a stereo chorus effect, reverb, 2x 12" Scorpion speakers and some qualified preamps. The remote footswitch lets you choose preamps, combine preamps but also turn the effects on and off. The amp also came in a top version without the speakers. What is not to like?
The circuit
Housed in a big distinct combo amp with two Scorpion speakers the amp is pretty heavy. All knobs on the front make the amp appear a bit complicated but that easily vanishes when you plug in. The amp has two preamps that can be used together or only one preamp can be used.
The left preamp is the clean or Un-Effected preamp with controls for gain ('Pre-Gain'), saturation (an invention of Peavey that adds clipping without altering most of the sound), preamp/ master volume ('Post-Gain'), a dedicated EQ section with high, low, parametric mid control and a Presence control. The Pre control can be pulled to engage the bright function and the Precense control can be pulled to get a mid boost. You can use this preamp by plugging into Input 1 and this preamp has a green LED. The reverb also works on this preamp.
The right preamp is the Effects preamp and has similar controls and the clean preamp. This preamp though has no 'Saturation' control but has controls for the 'Chorus' and 'Vibrato' speed and depth. This preamp can be used by plugging into Input 1 in 'Combine' mode or by plugging into Input 2. This pedal has a yellow LED and the reverb also works on this preamp.
Stock, with no footswitch connected, the amp is in Combine mode. In this mode both LED's will be lit and both preamp can be used simultaneously by using Input 1. When plugging into Input 2 the Effects preamp can be used only. When you add the footswitch though you can control the preamp used. With the Stereo / Mono switch on the footswitch you can engage both preamps at the same time or choose to select which preamp you want to use. You select the preamp with the Select switch on the footswitch. The LED on the preamp will be lit to show you which preamp is used. With the Reverb footswitch the Reverb can be bypassed and with the Chorus / Vibrato switch you can turn the Chorus / Vibrato effect on and off.
This last mode is different or weird and takes some time to get to know. When engaged, both the Vibrato as the Chorus effect will be turned on simultaneously. You can control the amount of effect of both effects by their own individual 'Depth' control and you can control the rate of both effects by their individual 'Rate' control.
- The chorus effect is slow and mimics a Leslie set on a slow setting
- The Vibrato effect is fast and mimics a Leslie set on a fast setting.
Both effects feed the same chipset to add an analog chorus to the signal. The Chorus rate is done with a regular LFO as can be found in conventional chorus pedals and the Vibrato rate is doen with a specialised IC (8038) to feed a high frequency LFO to the chipset. The chorus-sound is made with a MN3007 IC combined with a MN3101 IC.
As both effects are combined very weird sounds can be achieved. At the same time, when the individual depths are regarded, also very classic sounds can be made. It takes some time to get this effect organised but the result are some interesting sounds.
I found the schematic online here (PDF)
As you can spot the amp uses two individual preamps (with some connections to each other) that feeds into two individual 130W poweramps. Both poweramps feed into their own speaker-set. In the chorus mode both poweramps can be fed with a chorus signal (Mono mode) or with speaker 1 clean and speaker 2 chorus (Combine mode). Both will add a different kind of depth to the sound and create otherworldly chorus sounds.
On the inside of the amp two PCB's make the amp. One PCB on top is the preamp PCB that has all the circuit for the preamp and the effects. The lower PCB has the individual poweramps, the power supply and the switching boards. A big heatsink on the back takes care of the cooling.
The sound
This amplifier follows the Peavey rule: if it's heavy it will sound heavy. This amp is LOUD with two individual 130W poweramps feeding the Scorpion speakers. Both preamps sound alike and can add a vintage touch of character but with the parametric mid frequency control this amp can also sound modern. Both preamps are quite clean and adding more gain by opening up the 'Pre' control will result in unpleasant and raspy overdrive sounds. The addition of the ' Saturation' control though add a nice touch of overdrive to the sound and make the amp sound good on lower volume levels. For a real OD sound though I'd recommend a good overdrive pedal.
The amp is quiet although the reverb adds some noise and some ticking to the sound. These are completely gone by turning down the reverb. In a live situation this won't be noticed but in a studio it'll be not that great. On high volumes the amount of noise if pretty low and the speakers tend to sound pretty good on this volumes.
The Chorus / Vibrato effect is where this amp shines. And although this effect is complicated by adding two effects at the same time, putting some time into the amp will make you master this effect. The Chorus / Vibrato can sound like a classic Chorus pedal, can mimic a Leslie turning but also can give you some incredible mayhem. Maybe the placement of the speakers make the true stereo sound not that noticeable but adding extra speakers increases the idea and effect of true stereo. And that, with you standing in the middle, is simply amazing!
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