nice one mate. I have a brand new 2200 that is getting zero input on channel 1 with clip light permanently on, makes you wonder if channel 1 comes prone to issues out of the factory. I think I'll suffer a warranty claim on mine given I only took it out of the box this morning.
@@cambridgemart2075 This preamp is a four stage per channel. The tube is the second stage and is used in cathode follower configuration. Plate voltage comes from the +48V phantom power line, also the grid via a resistive divider (+24V grid bias) and the two filaments are connected in series in order to need 12,6V. That voltage comes from the +15V line through a 39Ω resistor needed for the necessary voltage drop. A design issue at this preamp is that the labeled "OUTPUT LEVEL" led series actually does not monitor the output level but the output of the first stage only! This makes confusion and somebody by looking these leds can believe that has enough output power while this is not true. That was my case. I had only 25mV output measured with external instrument while leds indicated that was full power (8.7V). The issue was a blown filament at the one half of the triode. Tube replaced and preamp is now back to life again. The filament was blown after 7 years of usage for about 2 to 4 hours per day.
nice one mate. I have a brand new 2200 that is getting zero input on channel 1 with clip light permanently on, makes you wonder if channel 1 comes prone to issues out of the factory. I think I'll suffer a warranty claim on mine given I only took it out of the box this morning.
🤦🏽♂️🤦🏽♂️🤦🏽♂️🤦🏽♂️🤦🏽♂️Thats crazy! i May steer clear. i was trying to give them another shot. But the reputation is still being proven.
The tube in that is just for show it's not doing anything, maybe the led behind it is a giveaway
Given that there's no filament or HV windings on the transformer, I would tend to agree!
@@cambridgemart2075 This preamp is a four stage per channel. The tube is the second stage and is used in cathode follower configuration. Plate voltage comes from the +48V phantom power line, also the grid via a resistive divider (+24V grid bias) and the two filaments are connected in series in order to need 12,6V. That voltage comes from the +15V line through a 39Ω resistor needed for the necessary voltage drop.
A design issue at this preamp is that the labeled "OUTPUT LEVEL" led series actually does not monitor the output level but the output of the first stage only! This makes confusion and somebody by looking these leds can believe that has enough output power while this is not true.
That was my case. I had only 25mV output measured with external instrument while leds indicated that was full power (8.7V). The issue was a blown filament at the one half of the triode. Tube replaced and preamp is now back to life again. The filament was blown after 7 years of usage for about 2 to 4 hours per day.