Where does the wiper of the 56 Ohm hum balance potentiometer go to? In your picture, there are two red resistors that go from pin 2 and pin 4 to the ends of a 56 Ohm hum balance potentiometer. The picture you attached of your amplifier parts, is not the same as the schematic you attached. Thank you very much for your guidance in advance.Īctual Unit Photo underneath 300B tube socketġ. I attached actual unit photo as well as schematics.

I have two multimeters with aligator clips on each end of probes so will measure both voltage and current simultaneously without moving probes to be extra safe. I got fixed bias 300B SE tube amp that does not have testing point so need to open the bottom plate to measure the plate voltage and plate current.ġ) To measure the plate voltage, do I connect MultiMeter one probe to Pin 1 (Filament/Cathode) and the other probe to Pin 2 (Plate/Anode)?Ģ) I am not 100% sure where to put probes to measure the plate current.

I had a couple of tube amplifiers before but it had testing point on top plate so not needed to open the bottom plate. A master Tone switch allows you to select between Normal and Intense, which removes lower-mid frequencies, resulting in added grit and attack.First of all, I am a newbie on tube gear but understand that it is dangerous poke anything inside high voltage device like tube amplifier so I will take extra caution when I measure the voltage. It features a Drive Tone selection knob with four tone selections for sculpting the drive. The Drive section of the GAV19T is a Boost or Overdrive circuit that works only on the power section to achieve distortion, rather than adding preamp gain. It is controlled via Bass and Treble knobs, and is designed to function as a treble boost that can be used to add sustain and presence.

The Tone section of the amp features a Baxendall-style EQ which uses an ECC803 along with an ECC83 preamp tube to preserve the natural tone of the amp. This allows the tube to run hotter or colder, resulting in changes to the amp's responsiveness, sustain and frequency response. It has an adjustable bias control that affects only the preamp section. The GAV19T 19-Watt Guitar Amplifier Head from Chandler Limited features a hand-wired, all-tube, cathode-biased/Class-A design that is capable of 19 watts of output.

Adjustable bias guitar amp heads