Product Description
Rare Valiant Model 664 combo amp for sale.
We've sourced these for customers in the past and they make interesting recording amps. The original design isn't great but with a few modifications (details below) they are very usable and deliver plenty of crunch at low volume.
Original 8" Jensen speaker is present. See photos and report for more information on internal condition.
Report from our engineer:
Valiant model 664 combo:
Notes:
Not a great design, ignoring several best practice rules of thumb. Heaters grounded on one side, grounding done at various random points on the chassis, wrong type of speed pot with resistor making it only work over half its range, odd component values, etc etc..
Oodles of buzz and hum, this fixed by sorting out the valve heaters, rebuilding the power supply and making the grounding scheme sensible.
Trem now has better speed range and works over the whole of the pot rotation.
So, now it’s considerably more usable. What it doesn’t really do is clean, except at very low volume, but the whole point of a little amp like this is to get some crunch, I would think. It’s never going to be loud with an ECL82 as the power valve. Might make a nice harp amp, though not having one I haven’t tried this…
We've sourced these for customers in the past and they make interesting recording amps. The original design isn't great but with a few modifications (details below) they are very usable and deliver plenty of crunch at low volume.
Original 8" Jensen speaker is present. See photos and report for more information on internal condition.
Report from our engineer:
Valiant model 664 combo:
- Clean all pots, sockets and switches.
- Remove “death” capacitor
- Fit correct fuse T1A 32mm
- Redesign power supply with new bridge rectifier and smoothing capacitors
- Replace cathode capacitors x2
- Replace plate resistors x2
- New speed pot
- New sensible grounding scheme; balance valve heaters to ground
- New film capacitor
Notes:
Not a great design, ignoring several best practice rules of thumb. Heaters grounded on one side, grounding done at various random points on the chassis, wrong type of speed pot with resistor making it only work over half its range, odd component values, etc etc..
Oodles of buzz and hum, this fixed by sorting out the valve heaters, rebuilding the power supply and making the grounding scheme sensible.
Trem now has better speed range and works over the whole of the pot rotation.
So, now it’s considerably more usable. What it doesn’t really do is clean, except at very low volume, but the whole point of a little amp like this is to get some crunch, I would think. It’s never going to be loud with an ECL82 as the power valve. Might make a nice harp amp, though not having one I haven’t tried this…