Carlsboro tube reverb noise/Hiss

[Yosser]

The reverb appears to be very noisy and rather tinny sounding, is this normal? I'm wondering if it's to do with the transistors

[Jennings]

Start by checking all the resistor values and so on...they'll be carbon composite, so likely the values will have drifted high.  Test your valves too.  Replace any resistors that have drifted more than 10%.  I'd also replace all the electrolytic capacitors.  I'd probably also replace the plate resistors with metal film types.  The shielded cables to the reverb pan, and pan itself, will need to be located as far away from the mains transformer and AC wire runs as you can get them.  However there is likely more hiss/hum than in a combo as there's only so much distance to play with in a head format.  Your schematic has handy voltage indications, so you'll be able to take test voltages and compare at various points.

[Yosser]

The circuit is independent apart from it's power supply, a bit like a send and return module - if it's turned off you can't hear the hiss.
If anybody has experience of this amplifier they may be able to tell me if this noise normal?